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2021-06-29Merge branch 'akpm' (patches from Andrew)Linus Torvalds
Merge misc updates from Andrew Morton: "191 patches. Subsystems affected by this patch series: kthread, ia64, scripts, ntfs, squashfs, ocfs2, kernel/watchdog, and mm (gup, pagealloc, slab, slub, kmemleak, dax, debug, pagecache, gup, swap, memcg, pagemap, mprotect, bootmem, dma, tracing, vmalloc, kasan, initialization, pagealloc, and memory-failure)" * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (191 commits) mm,hwpoison: make get_hwpoison_page() call get_any_page() mm,hwpoison: send SIGBUS with error virutal address mm/page_alloc: split pcp->high across all online CPUs for cpuless nodes mm/page_alloc: allow high-order pages to be stored on the per-cpu lists mm: replace CONFIG_FLAT_NODE_MEM_MAP with CONFIG_FLATMEM mm: replace CONFIG_NEED_MULTIPLE_NODES with CONFIG_NUMA docs: remove description of DISCONTIGMEM arch, mm: remove stale mentions of DISCONIGMEM mm: remove CONFIG_DISCONTIGMEM m68k: remove support for DISCONTIGMEM arc: remove support for DISCONTIGMEM arc: update comment about HIGHMEM implementation alpha: remove DISCONTIGMEM and NUMA mm/page_alloc: move free_the_page mm/page_alloc: fix counting of managed_pages mm/page_alloc: improve memmap_pages dbg msg mm: drop SECTION_SHIFT in code comments mm/page_alloc: introduce vm.percpu_pagelist_high_fraction mm/page_alloc: limit the number of pages on PCP lists when reclaim is active mm/page_alloc: scale the number of pages that are batch freed ...
2021-06-29virt/kvm: use vma_lookup() instead of find_vma_intersection()Liam Howlett
vma_lookup() finds the vma of a specific address with a cleaner interface and is more readable. Link: https://lkml.kernel.org/r/20210521174745.2219620-11-Liam.Howlett@Oracle.com Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com> Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com> Acked-by: David Hildenbrand <david@redhat.com> Acked-by: Davidlohr Bueso <dbueso@suse.de> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-28Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds
Pull kvm updates from Paolo Bonzini: "This covers all architectures (except MIPS) so I don't expect any other feature pull requests this merge window. ARM: - Add MTE support in guests, complete with tag save/restore interface - Reduce the impact of CMOs by moving them in the page-table code - Allow device block mappings at stage-2 - Reduce the footprint of the vmemmap in protected mode - Support the vGIC on dumb systems such as the Apple M1 - Add selftest infrastructure to support multiple configuration and apply that to PMU/non-PMU setups - Add selftests for the debug architecture - The usual crop of PMU fixes PPC: - Support for the H_RPT_INVALIDATE hypercall - Conversion of Book3S entry/exit to C - Bug fixes S390: - new HW facilities for guests - make inline assembly more robust with KASAN and co x86: - Allow userspace to handle emulation errors (unknown instructions) - Lazy allocation of the rmap (host physical -> guest physical address) - Support for virtualizing TSC scaling on VMX machines - Optimizations to avoid shattering huge pages at the beginning of live migration - Support for initializing the PDPTRs without loading them from memory - Many TLB flushing cleanups - Refuse to load if two-stage paging is available but NX is not (this has been a requirement in practice for over a year) - A large series that separates the MMU mode (WP/SMAP/SMEP etc.) from CR0/CR4/EFER, using the MMU mode everywhere once it is computed from the CPU registers - Use PM notifier to notify the guest about host suspend or hibernate - Support for passing arguments to Hyper-V hypercalls using XMM registers - Support for Hyper-V TLB flush hypercalls and enlightened MSR bitmap on AMD processors - Hide Hyper-V hypercalls that are not included in the guest CPUID - Fixes for live migration of virtual machines that use the Hyper-V "enlightened VMCS" optimization of nested virtualization - Bugfixes (not many) Generic: - Support for retrieving statistics without debugfs - Cleanups for the KVM selftests API" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (314 commits) KVM: x86: rename apic_access_page_done to apic_access_memslot_enabled kvm: x86: disable the narrow guest module parameter on unload selftests: kvm: Allows userspace to handle emulation errors. kvm: x86: Allow userspace to handle emulation errors KVM: x86/mmu: Let guest use GBPAGES if supported in hardware and TDP is on KVM: x86/mmu: Get CR4.SMEP from MMU, not vCPU, in shadow page fault KVM: x86/mmu: Get CR0.WP from MMU, not vCPU, in shadow page fault KVM: x86/mmu: Drop redundant rsvd bits reset for nested NPT KVM: x86/mmu: Optimize and clean up so called "last nonleaf level" logic KVM: x86: Enhance comments for MMU roles and nested transition trickiness KVM: x86/mmu: WARN on any reserved SPTE value when making a valid SPTE KVM: x86/mmu: Add helpers to do full reserved SPTE checks w/ generic MMU KVM: x86/mmu: Use MMU's role to determine PTTYPE KVM: x86/mmu: Collapse 32-bit PAE and 64-bit statements for helpers KVM: x86/mmu: Add a helper to calculate root from role_regs KVM: x86/mmu: Add helper to update paging metadata KVM: x86/mmu: Don't update nested guest's paging bitmasks if CR0.PG=0 KVM: x86/mmu: Consolidate reset_rsvds_bits_mask() calls KVM: x86/mmu: Use MMU role_regs to get LA57, and drop vCPU LA57 helper KVM: x86/mmu: Get nested MMU's root level from the MMU's role ...
2021-06-28Merge tag 'sched-core-2021-06-28' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler udpates from Ingo Molnar: - Changes to core scheduling facilities: - Add "Core Scheduling" via CONFIG_SCHED_CORE=y, which enables coordinated scheduling across SMT siblings. This is a much requested feature for cloud computing platforms, to allow the flexible utilization of SMT siblings, without exposing untrusted domains to information leaks & side channels, plus to ensure more deterministic computing performance on SMT systems used by heterogenous workloads. There are new prctls to set core scheduling groups, which allows more flexible management of workloads that can share siblings. - Fix task->state access anti-patterns that may result in missed wakeups and rename it to ->__state in the process to catch new abuses. - Load-balancing changes: - Tweak newidle_balance for fair-sched, to improve 'memcache'-like workloads. - "Age" (decay) average idle time, to better track & improve workloads such as 'tbench'. - Fix & improve energy-aware (EAS) balancing logic & metrics. - Fix & improve the uclamp metrics. - Fix task migration (taskset) corner case on !CONFIG_CPUSET. - Fix RT and deadline utilization tracking across policy changes - Introduce a "burstable" CFS controller via cgroups, which allows bursty CPU-bound workloads to borrow a bit against their future quota to improve overall latencies & batching. Can be tweaked via /sys/fs/cgroup/cpu/<X>/cpu.cfs_burst_us. - Rework assymetric topology/capacity detection & handling. - Scheduler statistics & tooling: - Disable delayacct by default, but add a sysctl to enable it at runtime if tooling needs it. Use static keys and other optimizations to make it more palatable. - Use sched_clock() in delayacct, instead of ktime_get_ns(). - Misc cleanups and fixes. * tag 'sched-core-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (72 commits) sched/doc: Update the CPU capacity asymmetry bits sched/topology: Rework CPU capacity asymmetry detection sched/core: Introduce SD_ASYM_CPUCAPACITY_FULL sched_domain flag psi: Fix race between psi_trigger_create/destroy sched/fair: Introduce the burstable CFS controller sched/uclamp: Fix uclamp_tg_restrict() sched/rt: Fix Deadline utilization tracking during policy change sched/rt: Fix RT utilization tracking during policy change sched: Change task_struct::state sched,arch: Remove unused TASK_STATE offsets sched,timer: Use __set_current_state() sched: Add get_current_state() sched,perf,kvm: Fix preemption condition sched: Introduce task_is_running() sched: Unbreak wakeups sched/fair: Age the average idle time sched/cpufreq: Consider reduced CPU capacity in energy calculation sched/fair: Take thermal pressure into account while estimating energy thermal/cpufreq_cooling: Update offline CPUs per-cpu thermal_pressure sched/fair: Return early from update_tg_cfs_load() if delta == 0 ...
2021-06-24KVM: debugfs: Reuse binary stats descriptorsJing Zhang
To remove code duplication, use the binary stats descriptors in the implementation of the debugfs interface for statistics. This unifies the definition of statistics for the binary and debugfs interfaces. Signed-off-by: Jing Zhang <jingzhangos@google.com> Message-Id: <20210618222709.1858088-8-jingzhangos@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-24KVM: stats: Support binary stats retrieval for a VCPUJing Zhang
Add a VCPU ioctl to get a statistics file descriptor by which a read functionality is provided for userspace to read out VCPU stats header, descriptors and data. Define VCPU statistics descriptors and header for all architectures. Reviewed-by: David Matlack <dmatlack@google.com> Reviewed-by: Ricardo Koller <ricarkol@google.com> Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com> Reviewed-by: Fuad Tabba <tabba@google.com> Tested-by: Fuad Tabba <tabba@google.com> #arm64 Signed-off-by: Jing Zhang <jingzhangos@google.com> Message-Id: <20210618222709.1858088-5-jingzhangos@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-24KVM: stats: Support binary stats retrieval for a VMJing Zhang
Add a VM ioctl to get a statistics file descriptor by which a read functionality is provided for userspace to read out VM stats header, descriptors and data. Define VM statistics descriptors and header for all architectures. Reviewed-by: David Matlack <dmatlack@google.com> Reviewed-by: Ricardo Koller <ricarkol@google.com> Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com> Reviewed-by: Fuad Tabba <tabba@google.com> Tested-by: Fuad Tabba <tabba@google.com> #arm64 Signed-off-by: Jing Zhang <jingzhangos@google.com> Message-Id: <20210618222709.1858088-4-jingzhangos@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-24KVM: do not allow mapping valid but non-reference-counted pagesNicholas Piggin
It's possible to create a region which maps valid but non-refcounted pages (e.g., tail pages of non-compound higher order allocations). These host pages can then be returned by gfn_to_page, gfn_to_pfn, etc., family of APIs, which take a reference to the page, which takes it from 0 to 1. When the reference is dropped, this will free the page incorrectly. Fix this by only taking a reference on valid pages if it was non-zero, which indicates it is participating in normal refcounting (and can be released with put_page). This addresses CVE-2021-22543. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Tested-by: Paolo Bonzini <pbonzini@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-24KVM: stats: Add fd-based API to read binary stats dataJing Zhang
This commit defines the API for userspace and prepare the common functionalities to support per VM/VCPU binary stats data readings. The KVM stats now is only accessible by debugfs, which has some shortcomings this change series are supposed to fix: 1. The current debugfs stats solution in KVM could be disabled when kernel Lockdown mode is enabled, which is a potential rick for production. 2. The current debugfs stats solution in KVM is organized as "one stats per file", it is good for debugging, but not efficient for production. 3. The stats read/clear in current debugfs solution in KVM are protected by the global kvm_lock. Besides that, there are some other benefits with this change: 1. All KVM VM/VCPU stats can be read out in a bulk by one copy to userspace. 2. A schema is used to describe KVM statistics. From userspace's perspective, the KVM statistics are self-describing. 3. With the fd-based solution, a separate telemetry would be able to read KVM stats in a less privileged environment. 4. After the initial setup by reading in stats descriptors, a telemetry only needs to read the stats data itself, no more parsing or setup is needed. Reviewed-by: David Matlack <dmatlack@google.com> Reviewed-by: Ricardo Koller <ricarkol@google.com> Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com> Reviewed-by: Fuad Tabba <tabba@google.com> Tested-by: Fuad Tabba <tabba@google.com> #arm64 Signed-off-by: Jing Zhang <jingzhangos@google.com> Message-Id: <20210618222709.1858088-3-jingzhangos@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-24KVM: stats: Separate generic stats from architecture specific onesJing Zhang
Generic KVM stats are those collected in architecture independent code or those supported by all architectures; put all generic statistics in a separate structure. This ensures that they are defined the same way in the statistics API which is being added, removing duplication among different architectures in the declaration of the descriptors. No functional change intended. Reviewed-by: David Matlack <dmatlack@google.com> Reviewed-by: Ricardo Koller <ricarkol@google.com> Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com> Signed-off-by: Jing Zhang <jingzhangos@google.com> Message-Id: <20210618222709.1858088-2-jingzhangos@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-18sched,perf,kvm: Fix preemption conditionPeter Zijlstra
When ran from the sched-out path (preempt_notifier or perf_event), p->state is irrelevant to determine preemption. You can get preempted with !task_is_running() just fine. The right indicator for preemption is if the task is still on the runqueue in the sched-out path. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Link: https://lore.kernel.org/r/20210611082838.285099381@infradead.org
2021-06-17KVM: switch per-VM stats to u64Paolo Bonzini
Make them the same type as vCPU stats. There is no reason to limit the counters to unsigned long. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-17kvm: add PM-notifierSergey Senozhatsky
Add KVM PM-notifier so that architectures can have arch-specific VM suspend/resume routines. Such architectures need to select CONFIG_HAVE_KVM_PM_NOTIFIER and implement kvm_arch_pm_notifier(). Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org> Acked-by: Marc Zyngier <maz@kernel.org> Message-Id: <20210606021045.14159-1-senozhatsky@chromium.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-17KVM: mmu: Add slots_arch_lock for memslot arch fieldsBen Gardon
Add a new lock to protect the arch-specific fields of memslots if they need to be modified in a kvm->srcu read critical section. A future commit will use this lock to lazily allocate memslot rmaps for x86. Signed-off-by: Ben Gardon <bgardon@google.com> Message-Id: <20210518173414.450044-5-bgardon@google.com> [Add Documentation/ hunk. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-06-17KVM: mmu: Refactor memslot copyBen Gardon
Factor out copying kvm_memslots from allocating the memory for new ones in preparation for adding a new lock to protect the arch-specific fields of the memslots. No functional change intended. Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Ben Gardon <bgardon@google.com> Message-Id: <20210518173414.450044-4-bgardon@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-05-27KVM: VMX: update vcpu posted-interrupt descriptor when assigning deviceMarcelo Tosatti
For VMX, when a vcpu enters HLT emulation, pi_post_block will: 1) Add vcpu to per-cpu list of blocked vcpus. 2) Program the posted-interrupt descriptor "notification vector" to POSTED_INTR_WAKEUP_VECTOR With interrupt remapping, an interrupt will set the PIR bit for the vector programmed for the device on the CPU, test-and-set the ON bit on the posted interrupt descriptor, and if the ON bit is clear generate an interrupt for the notification vector. This way, the target CPU wakes upon a device interrupt and wakes up the target vcpu. Problem is that pi_post_block only programs the notification vector if kvm_arch_has_assigned_device() is true. Its possible for the following to happen: 1) vcpu V HLTs on pcpu P, kvm_arch_has_assigned_device is false, notification vector is not programmed 2) device is assigned to VM 3) device interrupts vcpu V, sets ON bit (notification vector not programmed, so pcpu P remains in idle) 4) vcpu 0 IPIs vcpu V (in guest), but since pi descriptor ON bit is set, kvm_vcpu_kick is skipped 5) vcpu 0 busy spins on vcpu V's response for several seconds, until RCU watchdog NMIs all vCPUs. To fix this, use the start_assignment kvm_x86_ops callback to kick vcpus out of the halt loop, so the notification vector is properly reprogrammed to the wakeup vector. Reported-by: Pei Zhang <pezhang@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Message-Id: <20210526172014.GA29007@fuller.cnet> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-05-27KVM: rename KVM_REQ_PENDING_TIMER to KVM_REQ_UNBLOCKMarcelo Tosatti
KVM_REQ_UNBLOCK will be used to exit a vcpu from its inner vcpu halt emulation loop. Rename KVM_REQ_PENDING_TIMER to KVM_REQ_UNBLOCK, switch PowerPC to arch specific request bit. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Message-Id: <20210525134321.303768132@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-05-27KVM: PPC: exit halt polling on need_resched()Wanpeng Li
This is inspired by commit 262de4102c7bb8 (kvm: exit halt polling on need_resched() as well). Due to PPC implements an arch specific halt polling logic, we have to the need_resched() check there as well. This patch adds a helper function that can be shared between book3s and generic halt-polling loops. Reviewed-by: David Matlack <dmatlack@google.com> Reviewed-by: Venkatesh Srinivas <venkateshs@chromium.org> Cc: Ben Segall <bsegall@google.com> Cc: Venkatesh Srinivas <venkateshs@chromium.org> Cc: Jim Mattson <jmattson@google.com> Cc: David Matlack <dmatlack@google.com> Cc: Paul Mackerras <paulus@ozlabs.org> Cc: Suraj Jitindar Singh <sjitindarsingh@gmail.com> Signed-off-by: Wanpeng Li <wanpengli@tencent.com> Message-Id: <1621339235-11131-1-git-send-email-wanpengli@tencent.com> [Make the function inline. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-05-17Merge tag 'kvmarm-fixes-5.13-1' of ↵Paolo Bonzini
git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD KVM/arm64 fixes for 5.13, take #1 - Fix regression with irqbypass not restarting the guest on failed connect - Fix regression with debug register decoding resulting in overlapping access - Commit exception state on exit to usrspace - Fix the MMU notifier return values - Add missing 'static' qualifiers in the new host stage-2 code
2021-05-15Revert "irqbypass: do not start cons/prod when failed connect"Zhu Lingshan
This reverts commit a979a6aa009f3c99689432e0cdb5402a4463fb88. The reverted commit may cause VM freeze on arm64 with GICv4, where stopping a consumer is implemented by suspending the VM. Should the connect fail, the VM will not be resumed, which is a bit of a problem. It also erroneously calls the producer destructor unconditionally, which is unexpected. Reported-by: Shaokun Zhang <zhangshaokun@hisilicon.com> Suggested-by: Marc Zyngier <maz@kernel.org> Acked-by: Jason Wang <jasowang@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Tested-by: Shaokun Zhang <zhangshaokun@hisilicon.com> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com> [maz: tags and cc-stable, commit message update] Signed-off-by: Marc Zyngier <maz@kernel.org> Fixes: a979a6aa009f ("irqbypass: do not start cons/prod when failed connect") Link: https://lore.kernel.org/r/3a2c66d6-6ca0-8478-d24b-61e8e3241b20@hisilicon.com Link: https://lore.kernel.org/r/20210508071152.722425-1-lingshan.zhu@intel.com Cc: stable@vger.kernel.org
2021-05-07kvm: Cap halt polling at kvm->max_halt_poll_nsDavid Matlack
When growing halt-polling, there is no check that the poll time exceeds the per-VM limit. It's possible for vcpu->halt_poll_ns to grow past kvm->max_halt_poll_ns and stay there until a halt which takes longer than kvm->halt_poll_ns. Signed-off-by: David Matlack <dmatlack@google.com> Signed-off-by: Venkatesh Srinivas <venkateshs@chromium.org> Message-Id: <20210506152442.4010298-1-venkateshs@chromium.org> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-05-03kvm: exit halt polling on need_resched() as wellBenjamin Segall
single_task_running() is usually more general than need_resched() but CFS_BANDWIDTH throttling will use resched_task() when there is just one task to get the task to block. This was causing long-need_resched warnings and was likely allowing VMs to overrun their quota when halt polling. Signed-off-by: Ben Segall <bsegall@google.com> Signed-off-by: Venkatesh Srinivas <venkateshs@chromium.org> Message-Id: <20210429162233.116849-1-venkateshs@chromium.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Cc: stable@vger.kernel.org Reviewed-by: Jim Mattson <jmattson@google.com>
2021-04-21KVM: Boost vCPU candidate in user mode which is delivering interruptWanpeng Li
Both lock holder vCPU and IPI receiver that has halted are condidate for boost. However, the PLE handler was originally designed to deal with the lock holder preemption problem. The Intel PLE occurs when the spinlock waiter is in kernel mode. This assumption doesn't hold for IPI receiver, they can be in either kernel or user mode. the vCPU candidate in user mode will not be boosted even if they should respond to IPIs. Some benchmarks like pbzip2, swaptions etc do the TLB shootdown in kernel mode and most of the time they are running in user mode. It can lead to a large number of continuous PLE events because the IPI sender causes PLE events repeatedly until the receiver is scheduled while the receiver is not candidate for a boost. This patch boosts the vCPU candidiate in user mode which is delivery interrupt. We can observe the speed of pbzip2 improves 10% in 96 vCPUs VM in over-subscribe scenario (The host machine is 2 socket, 48 cores, 96 HTs Intel CLX box). There is no performance regression for other benchmarks like Unixbench spawn (most of the time contend read/write lock in kernel mode), ebizzy (most of the time contend read/write sem and TLB shoodtdown in kernel mode). Signed-off-by: Wanpeng Li <wanpengli@tencent.com> Message-Id: <1618542490-14756-1-git-send-email-wanpengli@tencent.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-21KVM: x86: Support KVM VMs sharing SEV contextNathan Tempelman
Add a capability for userspace to mirror SEV encryption context from one vm to another. On our side, this is intended to support a Migration Helper vCPU, but it can also be used generically to support other in-guest workloads scheduled by the host. The intention is for the primary guest and the mirror to have nearly identical memslots. The primary benefits of this are that: 1) The VMs do not share KVM contexts (think APIC/MSRs/etc), so they can't accidentally clobber each other. 2) The VMs can have different memory-views, which is necessary for post-copy migration (the migration vCPUs on the target need to read and write to pages, when the primary guest would VMEXIT). This does not change the threat model for AMD SEV. Any memory involved is still owned by the primary guest and its initial state is still attested to through the normal SEV_LAUNCH_* flows. If userspace wanted to circumvent SEV, they could achieve the same effect by simply attaching a vCPU to the primary VM. This patch deliberately leaves userspace in charge of the memslots for the mirror, as it already has the power to mess with them in the primary guest. This patch does not support SEV-ES (much less SNP), as it does not handle handing off attested VMSAs to the mirror. For additional context, we need a Migration Helper because SEV PSP migration is far too slow for our live migration on its own. Using an in-guest migrator lets us speed this up significantly. Signed-off-by: Nathan Tempelman <natet@google.com> Message-Id: <20210408223214.2582277-1-natet@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-20KVM: Add proper lockdep assertion in I/O bus unregisterSean Christopherson
Convert a comment above kvm_io_bus_unregister_dev() into an actual lockdep assertion, and opportunistically add curly braces to a multi-line for-loop. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210412222050.876100-4-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-20KVM: Stop looking for coalesced MMIO zones if the bus is destroyedSean Christopherson
Abort the walk of coalesced MMIO zones if kvm_io_bus_unregister_dev() fails to allocate memory for the new instance of the bus. If it can't instantiate a new bus, unregister_dev() destroys all devices _except_ the target device. But, it doesn't tell the caller that it obliterated the bus and invoked the destructor for all devices that were on the bus. In the coalesced MMIO case, this can result in a deleted list entry dereference due to attempting to continue iterating on coalesced_zones after future entries (in the walk) have been deleted. Opportunistically add curly braces to the for-loop, which encompasses many lines but sneaks by without braces due to the guts being a single if statement. Fixes: f65886606c2d ("KVM: fix memory leak in kvm_io_bus_unregister_dev()") Cc: stable@vger.kernel.org Reported-by: Hao Sun <sunhao.th@gmail.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210412222050.876100-3-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-20KVM: Destroy I/O bus devices on unregister failure _after_ sync'ing SRCUSean Christopherson
If allocating a new instance of an I/O bus fails when unregistering a device, wait to destroy the device until after all readers are guaranteed to see the new null bus. Destroying devices before the bus is nullified could lead to use-after-free since readers expect the devices on their reference of the bus to remain valid. Fixes: f65886606c2d ("KVM: fix memory leak in kvm_io_bus_unregister_dev()") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210412222050.876100-2-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-17KVM: Take mmu_lock when handling MMU notifier iff the hva hits a memslotSean Christopherson
Defer acquiring mmu_lock in the MMU notifier paths until a "hit" has been detected in the memslots, i.e. don't take the lock for notifications that don't affect the guest. For small VMs, spurious locking is a minor annoyance. And for "volatile" setups where the majority of notifications _are_ relevant, this barely qualifies as an optimization. But, for large VMs (hundreds of threads) with static setups, e.g. no page migration, no swapping, etc..., the vast majority of MMU notifier callbacks will be unrelated to the guest, e.g. will often be in response to the userspace VMM adjusting its own virtual address space. In such large VMs, acquiring mmu_lock can be painful as it blocks vCPUs from handling page faults. In some scenarios it can even be "fatal" in the sense that it causes unacceptable brownouts, e.g. when rebuilding huge pages after live migration, a significant percentage of vCPUs will be attempting to handle page faults. x86's TDP MMU implementation is especially susceptible to spurious locking due it taking mmu_lock for read when handling page faults. Because rwlock is fair, a single writer will stall future readers, while the writer is itself stalled waiting for in-progress readers to complete. This is exacerbated by the MMU notifiers often firing multiple times in quick succession, e.g. moving a page will (always?) invoke three separate notifiers: .invalidate_range_start(), invalidate_range_end(), and .change_pte(). Unnecessarily taking mmu_lock each time means even a single spurious sequence can be problematic. Note, this optimizes only the unpaired callbacks. Optimizing the .invalidate_range_{start,end}() pairs is more complex and will be done in a future patch. Suggested-by: Ben Gardon <bgardon@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210402005658.3024832-9-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-17KVM: Move MMU notifier's mmu_lock acquisition into common helperSean Christopherson
Acquire and release mmu_lock in the __kvm_handle_hva_range() helper instead of requiring the caller to do the same. This paves the way for future patches to take mmu_lock if and only if an overlapping memslot is found, without also having to introduce the on_lock() shenanigans used to manipulate the notifier count and sequence. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210402005658.3024832-8-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-17KVM: Kill off the old hva-based MMU notifier callbacksSean Christopherson
Yank out the hva-based MMU notifier APIs now that all architectures that use the notifiers have moved to the gfn-based APIs. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210402005658.3024832-7-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-17KVM: Move x86's MMU notifier memslot walkers to generic codeSean Christopherson
Move the hva->gfn lookup for MMU notifiers into common code. Every arch does a similar lookup, and some arch code is all but identical across multiple architectures. In addition to consolidating code, this will allow introducing optimizations that will benefit all architectures without incurring multiple walks of the memslots, e.g. by taking mmu_lock if and only if a relevant range exists in the memslots. The use of __always_inline to avoid indirect call retpolines, as done by x86, may also benefit other architectures. Consolidating the lookups also fixes a wart in x86, where the legacy MMU and TDP MMU each do their own memslot walks. Lastly, future enhancements to the memslot implementation, e.g. to add an interval tree to track host address, will need to touch far less arch specific code. MIPS, PPC, and arm64 will be converted one at a time in future patches. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210402005658.3024832-3-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-17KVM: Assert that notifier count is elevated in .change_pte()Sean Christopherson
In KVM's .change_pte() notification callback, replace the notifier sequence bump with a WARN_ON assertion that the notifier count is elevated. An elevated count provides stricter protections than bumping the sequence, and the sequence is guarnateed to be bumped before the count hits zero. When .change_pte() was added by commit 828502d30073 ("ksm: add mmu_notifier set_pte_at_notify()"), bumping the sequence was necessary as .change_pte() would be invoked without any surrounding notifications. However, since commit 6bdb913f0a70 ("mm: wrap calls to set_pte_at_notify with invalidate_range_start and invalidate_range_end"), all calls to .change_pte() are guaranteed to be surrounded by start() and end(), and so are guaranteed to run with an elevated notifier count. Note, wrapping .change_pte() with .invalidate_range_{start,end}() is a bug of sorts, as invalidating the secondary MMU's (KVM's) PTE defeats the purpose of .change_pte(). Every arch's kvm_set_spte_hva() assumes .change_pte() is called when the relevant SPTE is present in KVM's MMU, as the original goal was to accelerate Kernel Samepage Merging (KSM) by updating KVM's SPTEs without requiring a VM-Exit (due to invalidating the SPTE). I.e. it means that .change_pte() is effectively dead code on _all_ architectures. x86 and MIPS are clearcut nops if the old SPTE is not-present, and that is guaranteed due to the prior invalidation. PPC simply unmaps the SPTE, which again should be a nop due to the invalidation. arm64 is a bit murky, but it's also likely a nop because kvm_pgtable_stage2_map() is called without a cache pointer, which means it will map an entry if and only if an existing PTE was found. For now, take advantage of the bug to simplify future consolidation of KVMs's MMU notifier code. Doing so will not greatly complicate fixing .change_pte(), assuming it's even worth fixing. .change_pte() has been broken for 8+ years and no one has complained. Even if there are KSM+KVM users that care deeply about its performance, the benefits of avoiding VM-Exits via .change_pte() need to be reevaluated to justify the added complexity and testing burden. Ripping out .change_pte() entirely would be a lot easier. Signed-off-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-17KVM: Explicitly use GFP_KERNEL_ACCOUNT for 'struct kvm_vcpu' allocationsSean Christopherson
Use GFP_KERNEL_ACCOUNT when allocating vCPUs to make it more obvious that that the allocations are accounted, to make it easier to audit KVM's allocations in the future, and to be consistent with other cache usage in KVM. When using SLAB/SLUB, this is a nop as the cache itself is created with SLAB_ACCOUNT. When using SLOB, there are caveats within caveats. SLOB doesn't honor SLAB_ACCOUNT, so passing GFP_KERNEL_ACCOUNT will result in vCPU allocations now being accounted. But, even that depends on internal SLOB details as SLOB will only go to the page allocator when its cache is depleted. That just happens to be extremely likely for vCPUs because the size of kvm_vcpu is larger than the a page for almost all combinations of architecture and page size. Whether or not the SLOB behavior is by design is unknown; it's just as likely that no SLOB users care about accounding and so no one has bothered to implemented support in SLOB. Regardless, accounting vCPU allocations will not break SLOB+KVM+cgroup users, if any exist. Reviewed-by: Wanpeng Li <kernellwp@gmail.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210406190740.4055679-1-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-04-17KVM: Move arm64's MMU notifier trace events to generic codeSean Christopherson
Move arm64's MMU notifier trace events into common code in preparation for doing the hva->gfn lookup in common code. The alternative would be to trace the gfn instead of hva, but that's not obviously better and could also be done in common code. Tracing the notifiers is also quite handy for debug regardless of architecture. Remove a completely redundant tracepoint from PPC e500. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210326021957.1424875-10-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-02-22KVM: x86/mmu: Consider the hva in mmu_notifier retryDavid Stevens
Track the range being invalidated by mmu_notifier and skip page fault retries if the fault address is not affected by the in-progress invalidation. Handle concurrent invalidations by finding the minimal range which includes all ranges being invalidated. Although the combined range may include unrelated addresses and cannot be shrunk as individual invalidation operations complete, it is unlikely the marginal gains of proper range tracking are worth the additional complexity. The primary benefit of this change is the reduction in the likelihood of extreme latency when handing a page fault due to another thread having been preempted while modifying host virtual addresses. Signed-off-by: David Stevens <stevensd@chromium.org> Message-Id: <20210222024522.1751719-3-stevensd@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-02-09KVM: Use kvm_pfn_t for local PFN variable in hva_to_pfn_remapped()Sean Christopherson
Use kvm_pfn_t, a.k.a. u64, for the local 'pfn' variable when retrieving a so called "remapped" hva/pfn pair. In theory, the hva could resolve to a pfn in high memory on a 32-bit kernel. This bug was inadvertantly exposed by commit bd2fae8da794 ("KVM: do not assume PTE is writable after follow_pfn"), which added an error PFN value to the mix, causing gcc to comlain about overflowing the unsigned long. arch/x86/kvm/../../../virt/kvm/kvm_main.c: In function ‘hva_to_pfn_remapped’: include/linux/kvm_host.h:89:30: error: conversion from ‘long long unsigned int’ to ‘long unsigned int’ changes value from ‘9218868437227405314’ to ‘2’ [-Werror=overflow] 89 | #define KVM_PFN_ERR_RO_FAULT (KVM_PFN_ERR_MASK + 2) | ^ virt/kvm/kvm_main.c:1935:9: note: in expansion of macro ‘KVM_PFN_ERR_RO_FAULT’ Cc: stable@vger.kernel.org Fixes: add6a0cd1c5b ("KVM: MMU: try to fix up page faults before giving up") Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210208201940.1258328-1-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-02-09mm: provide a saner PTE walking API for modulesPaolo Bonzini
Currently, the follow_pfn function is exported for modules but follow_pte is not. However, follow_pfn is very easy to misuse, because it does not provide protections (so most of its callers assume the page is writable!) and because it returns after having already unlocked the page table lock. Provide instead a simplified version of follow_pte that does not have the pmdpp and range arguments. The older version survives as follow_invalidate_pte() for use by fs/dax.c. Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-02-04KVM: x86/mmu: Use an rwlock for the x86 MMUBen Gardon
Add a read / write lock to be used in place of the MMU spinlock on x86. The rwlock will enable the TDP MMU to handle page faults, and other operations in parallel in future commits. Reviewed-by: Peter Feiner <pfeiner@google.com> Signed-off-by: Ben Gardon <bgardon@google.com> Message-Id: <20210202185734.1680553-19-bgardon@google.com> [Introduce virt/kvm/mmu_lock.h - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-02-04KVM: X86: use vzalloc() instead of vmalloc/memsetTian Tao
fixed the following warning: /virt/kvm/dirty_ring.c:70:20-27: WARNING: vzalloc should be used for ring -> dirty_gfns, instead of vmalloc/memset. Signed-off-by: Tian Tao <tiantao6@hisilicon.com> Message-Id: <1611547045-13669-1-git-send-email-tiantao6@hisilicon.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-02-04KVM: do not assume PTE is writable after follow_pfnPaolo Bonzini
In order to convert an HVA to a PFN, KVM usually tries to use the get_user_pages family of functinso. This however is not possible for VM_IO vmas; in that case, KVM instead uses follow_pfn. In doing this however KVM loses the information on whether the PFN is writable. That is usually not a problem because the main use of VM_IO vmas with KVM is for BARs in PCI device assignment, however it is a bug. To fix it, use follow_pte and check pte_write while under the protection of the PTE lock. The information can be used to fail hva_to_pfn_remapped or passed back to the caller via *writable. Usage of follow_pfn was introduced in commit add6a0cd1c5b ("KVM: MMU: try to fix up page faults before giving up", 2016-07-05); however, even older version have the same issue, all the way back to commit 2e2e3738af33 ("KVM: Handle vma regions with no backing page", 2008-07-20), as they also did not check whether the PFN was writable. Fixes: 2e2e3738af33 ("KVM: Handle vma regions with no backing page") Reported-by: David Stevens <stevensd@google.com> Cc: 3pvd@google.com Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-01-25Merge tag 'kvmarm-fixes-5.11-2' of ↵Paolo Bonzini
git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD KVM/arm64 fixes for 5.11, take #2 - Don't allow tagged pointers to point to memslots - Filter out ARMv8.1+ PMU events on v8.0 hardware - Hide PMU registers from userspace when no PMU is configured - More PMU cleanups - Don't try to handle broken PSCI firmware - More sys_reg() to reg_to_encoding() conversions
2021-01-21KVM: Forbid the use of tagged userspace addresses for memslotsMarc Zyngier
The use of a tagged address could be pretty confusing for the whole memslot infrastructure as well as the MMU notifiers. Forbid it altogether, as it never quite worked the first place. Cc: stable@vger.kernel.org Reported-by: Rick Edgecombe <rick.p.edgecombe@intel.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Marc Zyngier <maz@kernel.org>
2021-01-08Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds
Pull kvm fixes from Paolo Bonzini: "x86: - Fixes for the new scalable MMU - Fixes for migration of nested hypervisors on AMD - Fix for clang integrated assembler - Fix for left shift by 64 (UBSAN) - Small cleanups - Straggler SEV-ES patch ARM: - VM init cleanups - PSCI relay cleanups - Kill CONFIG_KVM_ARM_PMU - Fixup __init annotations - Fixup reg_to_encoding() - Fix spurious PMCR_EL0 access Misc: - selftests cleanups" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (38 commits) KVM: x86: __kvm_vcpu_halt can be static KVM: SVM: Add support for booting APs in an SEV-ES guest KVM: nSVM: cancel KVM_REQ_GET_NESTED_STATE_PAGES on nested vmexit KVM: nSVM: mark vmcb as dirty when forcingly leaving the guest mode KVM: nSVM: correctly restore nested_run_pending on migration KVM: x86/mmu: Clarify TDP MMU page list invariants KVM: x86/mmu: Ensure TDP MMU roots are freed after yield kvm: check tlbs_dirty directly KVM: x86: change in pv_eoi_get_pending() to make code more readable MAINTAINERS: Really update email address for Sean Christopherson KVM: x86: fix shift out of bounds reported by UBSAN KVM: selftests: Implement perf_test_util more conventionally KVM: selftests: Use vm_create_with_vcpus in create_vm KVM: selftests: Factor out guest mode code KVM/SVM: Remove leftover __svm_vcpu_run prototype from svm.c KVM: SVM: Add register operand to vmsave call in sev_es_vcpu_load KVM: x86/mmu: Optimize not-present/MMIO SPTE check in get_mmio_spte() KVM: x86/mmu: Use raw level to index into MMIO walks' sptes array KVM: x86/mmu: Get root level from walkers when retrieving MMIO SPTE KVM: x86/mmu: Use -1 to flag an undefined spte in get_mmio_spte() ...
2021-01-07kvm: check tlbs_dirty directlyLai Jiangshan
In kvm_mmu_notifier_invalidate_range_start(), tlbs_dirty is used as: need_tlb_flush |= kvm->tlbs_dirty; with need_tlb_flush's type being int and tlbs_dirty's type being long. It means that tlbs_dirty is always used as int and the higher 32 bits is useless. We need to check tlbs_dirty in a correct way and this change checks it directly without propagating it to need_tlb_flush. Note: it's _extremely_ unlikely this neglecting of higher 32 bits can cause problems in practice. It would require encountering tlbs_dirty on a 4 billion count boundary, and KVM would need to be using shadow paging or be running a nested guest. Cc: stable@vger.kernel.org Fixes: a4ee1ca4a36e ("KVM: MMU: delay flush all tlbs on sync_page path") Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com> Message-Id: <20201217154118.16497-1-jiangshanlai@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-12-20Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds
Pull KVM updates from Paolo Bonzini: "Much x86 work was pushed out to 5.12, but ARM more than made up for it. ARM: - PSCI relay at EL2 when "protected KVM" is enabled - New exception injection code - Simplification of AArch32 system register handling - Fix PMU accesses when no PMU is enabled - Expose CSV3 on non-Meltdown hosts - Cache hierarchy discovery fixes - PV steal-time cleanups - Allow function pointers at EL2 - Various host EL2 entry cleanups - Simplification of the EL2 vector allocation s390: - memcg accouting for s390 specific parts of kvm and gmap - selftest for diag318 - new kvm_stat for when async_pf falls back to sync x86: - Tracepoints for the new pagetable code from 5.10 - Catch VFIO and KVM irqfd events before userspace - Reporting dirty pages to userspace with a ring buffer - SEV-ES host support - Nested VMX support for wait-for-SIPI activity state - New feature flag (AVX512 FP16) - New system ioctl to report Hyper-V-compatible paravirtualization features Generic: - Selftest improvements" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (171 commits) KVM: SVM: fix 32-bit compilation KVM: SVM: Add AP_JUMP_TABLE support in prep for AP booting KVM: SVM: Provide support to launch and run an SEV-ES guest KVM: SVM: Provide an updated VMRUN invocation for SEV-ES guests KVM: SVM: Provide support for SEV-ES vCPU loading KVM: SVM: Provide support for SEV-ES vCPU creation/loading KVM: SVM: Update ASID allocation to support SEV-ES guests KVM: SVM: Set the encryption mask for the SVM host save area KVM: SVM: Add NMI support for an SEV-ES guest KVM: SVM: Guest FPU state save/restore not needed for SEV-ES guest KVM: SVM: Do not report support for SMM for an SEV-ES guest KVM: x86: Update __get_sregs() / __set_sregs() to support SEV-ES KVM: SVM: Add support for CR8 write traps for an SEV-ES guest KVM: SVM: Add support for CR4 write traps for an SEV-ES guest KVM: SVM: Add support for CR0 write traps for an SEV-ES guest KVM: SVM: Add support for EFER write traps for an SEV-ES guest KVM: SVM: Support string IO operations for an SEV-ES guest KVM: SVM: Support MMIO for an SEV-ES guest KVM: SVM: Create trace events for VMGEXIT MSR protocol processing KVM: SVM: Create trace events for VMGEXIT processing ...
2020-12-19mm, kvm: account kvm_vcpu_mmap to kmemcgShakeel Butt
A VCPU of a VM can allocate couple of pages which can be mmap'ed by the user space application. At the moment this memory is not charged to the memcg of the VMM. On a large machine running large number of VMs or small number of VMs having large number of VCPUs, this unaccounted memory can be very significant. So, charge this memory to the memcg of the VMM. Please note that lifetime of these allocations corresponds to the lifetime of the VMM. Link: https://lkml.kernel.org/r/20201106202923.2087414-1-shakeelb@google.com Signed-off-by: Shakeel Butt <shakeelb@google.com> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-11-15KVM: Don't allocate dirty bitmap if dirty ring is enabledPeter Xu
Because kvm dirty rings and kvm dirty log is used in an exclusive way, Let's avoid creating the dirty_bitmap when kvm dirty ring is enabled. At the meantime, since the dirty_bitmap will be conditionally created now, we can't use it as a sign of "whether this memory slot enabled dirty tracking". Change users like that to check against the kvm memory slot flags. Note that there still can be chances where the kvm memory slot got its dirty_bitmap allocated, _if_ the memory slots are created before enabling of the dirty rings and at the same time with the dirty tracking capability enabled, they'll still with the dirty_bitmap. However it should not hurt much (e.g., the bitmaps will always be freed if they are there), and the real users normally won't trigger this because dirty bit tracking flag should in most cases only be applied to kvm slots only before migration starts, that should be far latter than kvm initializes (VM starts). Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20201001012226.5868-1-peterx@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-11-15KVM: Make dirty ring exclusive to dirty bitmap logPeter Xu
There's no good reason to use both the dirty bitmap logging and the new dirty ring buffer to track dirty bits. We should be able to even support both of them at the same time, but it could complicate things which could actually help little. Let's simply make it the rule before we enable dirty ring on any arch, that we don't allow these two interfaces to be used together. The big world switch would be KVM_CAP_DIRTY_LOG_RING capability enablement. That's where we'll switch from the default dirty logging way to the dirty ring way. As long as kvm->dirty_ring_size is setup correctly, we'll once and for all switch to the dirty ring buffer mode for the current virtual machine. Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20201001012224.5818-1-peterx@redhat.com> [Change errno from EINVAL to ENXIO. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-11-15KVM: X86: Implement ring-based dirty memory trackingPeter Xu
This patch is heavily based on previous work from Lei Cao <lei.cao@stratus.com> and Paolo Bonzini <pbonzini@redhat.com>. [1] KVM currently uses large bitmaps to track dirty memory. These bitmaps are copied to userspace when userspace queries KVM for its dirty page information. The use of bitmaps is mostly sufficient for live migration, as large parts of memory are be dirtied from one log-dirty pass to another. However, in a checkpointing system, the number of dirty pages is small and in fact it is often bounded---the VM is paused when it has dirtied a pre-defined number of pages. Traversing a large, sparsely populated bitmap to find set bits is time-consuming, as is copying the bitmap to user-space. A similar issue will be there for live migration when the guest memory is huge while the page dirty procedure is trivial. In that case for each dirty sync we need to pull the whole dirty bitmap to userspace and analyse every bit even if it's mostly zeros. The preferred data structure for above scenarios is a dense list of guest frame numbers (GFN). This patch series stores the dirty list in kernel memory that can be memory mapped into userspace to allow speedy harvesting. This patch enables dirty ring for X86 only. However it should be easily extended to other archs as well. [1] https://patchwork.kernel.org/patch/10471409/ Signed-off-by: Lei Cao <lei.cao@stratus.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20201001012222.5767-1-peterx@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-11-15KVM: Pass in kvm pointer into mark_page_dirty_in_slot()Peter Xu
The context will be needed to implement the kvm dirty ring. Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20201001012044.5151-5-peterx@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>