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2022-12-29KVM: x86: Serialize vendor module initialization (hardware setup)Sean Christopherson
Acquire a new mutex, vendor_module_lock, in kvm_x86_vendor_init() while doing hardware setup to ensure that concurrent calls are fully serialized. KVM rejects attempts to load vendor modules if a different module has already been loaded, but doesn't handle the case where multiple vendor modules are loaded at the same time, and module_init() doesn't run under the global module_mutex. Note, in practice, this is likely a benign bug as no platform exists that supports both SVM and VMX, i.e. barring a weird VM setup, one of the vendor modules is guaranteed to fail a support check before modifying common KVM state. Alternatively, KVM could perform an atomic CMPXCHG on .hardware_enable, but that comes with its own ugliness as it would require setting .hardware_enable before success is guaranteed, e.g. attempting to load the "wrong" could result in spurious failure to load the "right" module. Introduce a new mutex as using kvm_lock is extremely deadlock prone due to kvm_lock being taken under cpus_write_lock(), and in the future, under under cpus_read_lock(). Any operation that takes cpus_read_lock() while holding kvm_lock would potentially deadlock, e.g. kvm_timer_init() takes cpus_read_lock() to register a callback. In theory, KVM could avoid such problematic paths, i.e. do less setup under kvm_lock, but avoiding all calls to cpus_read_lock() is subtly difficult and thus fragile. E.g. updating static calls also acquires cpus_read_lock(). Inverting the lock ordering, i.e. always taking kvm_lock outside cpus_read_lock(), is not a viable option as kvm_lock is taken in various callbacks that may be invoked under cpus_read_lock(), e.g. x86's kvmclock_cpufreq_notifier(). The lockdep splat below is dependent on future patches to take cpus_read_lock() in hardware_enable_all(), but as above, deadlock is already is already possible. ====================================================== WARNING: possible circular locking dependency detected 6.0.0-smp--7ec93244f194-init2 #27 Tainted: G O ------------------------------------------------------ stable/251833 is trying to acquire lock: ffffffffc097ea28 (kvm_lock){+.+.}-{3:3}, at: hardware_enable_all+0x1f/0xc0 [kvm] but task is already holding lock: ffffffffa2456828 (cpu_hotplug_lock){++++}-{0:0}, at: hardware_enable_all+0xf/0xc0 [kvm] which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (cpu_hotplug_lock){++++}-{0:0}: cpus_read_lock+0x2a/0xa0 __cpuhp_setup_state+0x2b/0x60 __kvm_x86_vendor_init+0x16a/0x1870 [kvm] kvm_x86_vendor_init+0x23/0x40 [kvm] 0xffffffffc0a4d02b do_one_initcall+0x110/0x200 do_init_module+0x4f/0x250 load_module+0x1730/0x18f0 __se_sys_finit_module+0xca/0x100 __x64_sys_finit_module+0x1d/0x20 do_syscall_64+0x3d/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #0 (kvm_lock){+.+.}-{3:3}: __lock_acquire+0x16f4/0x30d0 lock_acquire+0xb2/0x190 __mutex_lock+0x98/0x6f0 mutex_lock_nested+0x1b/0x20 hardware_enable_all+0x1f/0xc0 [kvm] kvm_dev_ioctl+0x45e/0x930 [kvm] __se_sys_ioctl+0x77/0xc0 __x64_sys_ioctl+0x1d/0x20 do_syscall_64+0x3d/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(cpu_hotplug_lock); lock(kvm_lock); lock(cpu_hotplug_lock); lock(kvm_lock); *** DEADLOCK *** 1 lock held by stable/251833: #0: ffffffffa2456828 (cpu_hotplug_lock){++++}-{0:0}, at: hardware_enable_all+0xf/0xc0 [kvm] Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221130230934.1014142-16-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: VMX: Do _all_ initialization before exposing /dev/kvm to userspaceSean Christopherson
Call kvm_init() only after _all_ setup is complete, as kvm_init() exposes /dev/kvm to userspace and thus allows userspace to create VMs (and call other ioctls). E.g. KVM will encounter a NULL pointer when attempting to add a vCPU to the per-CPU loaded_vmcss_on_cpu list if userspace is able to create a VM before vmx_init() configures said list. BUG: kernel NULL pointer dereference, address: 0000000000000008 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] SMP CPU: 6 PID: 1143 Comm: stable Not tainted 6.0.0-rc7+ #988 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:vmx_vcpu_load_vmcs+0x68/0x230 [kvm_intel] <TASK> vmx_vcpu_load+0x16/0x60 [kvm_intel] kvm_arch_vcpu_load+0x32/0x1f0 [kvm] vcpu_load+0x2f/0x40 [kvm] kvm_arch_vcpu_create+0x231/0x310 [kvm] kvm_vm_ioctl+0x79f/0xe10 [kvm] ? handle_mm_fault+0xb1/0x220 __x64_sys_ioctl+0x80/0xb0 do_syscall_64+0x2b/0x50 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7f5a6b05743b </TASK> Modules linked in: vhost_net vhost vhost_iotlb tap kvm_intel(+) kvm irqbypass Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221130230934.1014142-15-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: x86: Move guts of kvm_arch_init() to standalone helperSean Christopherson
Move the guts of kvm_arch_init() to a new helper, kvm_x86_vendor_init(), so that VMX can do _all_ arch and vendor initialization before calling kvm_init(). Calling kvm_init() must be the _very_ last step during init, as kvm_init() exposes /dev/kvm to userspace, i.e. allows creating VMs. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221130230934.1014142-14-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: VMX: Move Hyper-V eVMCS initialization to helperSean Christopherson
Move Hyper-V's eVMCS initialization to a dedicated helper to clean up vmx_init(), and add a comment to call out that the Hyper-V init code doesn't need to be unwound if vmx_init() ultimately fails. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20221130230934.1014142-13-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: VMX: Don't bother disabling eVMCS static key on module exitSean Christopherson
Don't disable the eVMCS static key on module exit, kvm_intel.ko owns the key so there can't possibly be users after the kvm_intel.ko is unloaded, at least not without much bigger issues. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221130230934.1014142-12-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: VMX: Reset eVMCS controls in VP assist page during hardware disablingSean Christopherson
Reset the eVMCS controls in the per-CPU VP assist page during hardware disabling instead of waiting until kvm-intel's module exit. The controls are activated if and only if KVM creates a VM, i.e. don't need to be reset if hardware is never enabled. Doing the reset during hardware disabling will naturally fix a potential NULL pointer deref bug once KVM disables CPU hotplug while enabling and disabling hardware (which is necessary to fix a variety of bugs). If the kernel is running as the root partition, the VP assist page is unmapped during CPU hot unplug, and so KVM's clearing of the eVMCS controls needs to occur with CPU hot(un)plug disabled, otherwise KVM could attempt to write to a CPU's VP assist page after it's unmapped. Reported-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20221130230934.1014142-11-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: Drop arch hardware (un)setup hooksSean Christopherson
Drop kvm_arch_hardware_setup() and kvm_arch_hardware_unsetup() now that all implementations are nops. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Eric Farman <farman@linux.ibm.com> # s390 Acked-by: Anup Patel <anup@brainfault.org> Message-Id: <20221130230934.1014142-10-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: x86: Move hardware setup/unsetup to init/exitSean Christopherson
Now that kvm_arch_hardware_setup() is called immediately after kvm_arch_init(), fold the guts of kvm_arch_hardware_(un)setup() into kvm_arch_{init,exit}() as a step towards dropping one of the hooks. To avoid having to unwind various setup, e.g registration of several notifiers, slot in the vendor hardware setup before the registration of said notifiers and callbacks. Introducing a functional change while moving code is less than ideal, but the alternative is adding a pile of unwinding code, which is much more error prone, e.g. several attempts to move the setup code verbatim all introduced bugs. Add a comment to document that kvm_ops_update() is effectively the point of no return, e.g. it sets the kvm_x86_ops.hardware_enable canary and so needs to be unwound. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221130230934.1014142-9-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: x86: Do timer initialization after XCR0 configurationSean Christopherson
Move kvm_arch_init()'s call to kvm_timer_init() down a few lines below the XCR0 configuration code. A future patch will move hardware setup into kvm_arch_init() and slot in vendor hardware setup before the call to kvm_timer_init() so that timer initialization (among other stuff) doesn't need to be unwound if vendor setup fails. XCR0 setup on the other hand needs to happen before vendor hardware setup. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221130230934.1014142-8-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29Merge branch 'kvm-late-6.1' into HEADPaolo Bonzini
x86: * Change tdp_mmu to a read-only parameter * Separate TDP and shadow MMU page fault paths * Enable Hyper-V invariant TSC control selftests: * Use TAP interface for kvm_binary_stats_test and tsc_msrs_test Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: x86: Hyper-V invariant TSC controlVitaly Kuznetsov
Normally, genuine Hyper-V doesn't expose architectural invariant TSC (CPUID.80000007H:EDX[8]) to its guests by default. A special PV MSR (HV_X64_MSR_TSC_INVARIANT_CONTROL, 0x40000118) and corresponding CPUID feature bit (CPUID.0x40000003.EAX[15]) were introduced. When bit 0 of the PV MSR is set, invariant TSC bit starts to show up in CPUID. When the feature is exposed to Hyper-V guests, reenlightenment becomes unneeded. Add the feature to KVM. Keep CPUID output intact when the feature wasn't exposed to L1 and implement the required logic for hiding invariant TSC when the feature was exposed and invariant TSC control MSR wasn't written to. Copy genuine Hyper-V behavior and forbid to disable the feature once it was enabled. For the reference, for linux guests, support for the feature was added in commit dce7cd62754b ("x86/hyperv: Allow guests to enable InvariantTSC"). Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221013095849.705943-4-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: x86: Add a KVM-only leaf for CPUID_8000_0007_EDXVitaly Kuznetsov
CPUID_8000_0007_EDX may come handy when X86_FEATURE_CONSTANT_TSC needs to be checked. No functional change intended. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221013095849.705943-3-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29x86/hyperv: Add HV_EXPOSE_INVARIANT_TSC defineVitaly Kuznetsov
Avoid open coding BIT(0) of HV_X64_MSR_TSC_INVARIANT_CONTROL by adding a dedicated define. While there's only one user at this moment, the upcoming KVM implementation of Hyper-V Invariant TSC feature will need to use it as well. Reviewed-by: Michael Kelley <mikelley@microsoft.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221013095849.705943-2-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: x86/mmu: Pivot on "TDP MMU enabled" when handling direct page faultsSean Christopherson
When handling direct page faults, pivot on the TDP MMU being globally enabled instead of checking if the target MMU is a TDP MMU. Now that the TDP MMU is all-or-nothing, if the TDP MMU is enabled, KVM will reach direct_page_fault() if and only if the MMU is a TDP MMU. When TDP is enabled (obviously required for the TDP MMU), only non-nested TDP page faults reach direct_page_fault(), i.e. nonpaging MMUs are impossible, as NPT requires paging to be enabled and EPT faults use ept_page_fault(). Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221012181702.3663607-8-seanjc@google.com> [Use tdp_mmu_enabled variable. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: x86/mmu: Pivot on "TDP MMU enabled" to check if active MMU is TDP MMUSean Christopherson
Simplify and optimize the logic for detecting if the current/active MMU is a TDP MMU. If the TDP MMU is globally enabled, then the active MMU is a TDP MMU if it is direct. When TDP is enabled, so called nonpaging MMUs are never used as the only form of shadow paging KVM uses is for nested TDP, and the active MMU can't be direct in that case. Rename the helper and take the vCPU instead of an arbitrary MMU, as nonpaging MMUs can show up in the walk_mmu if L1 is using nested TDP and L2 has paging disabled. Taking the vCPU has the added bonus of cleaning up the callers, all of which check the current MMU but wrap code that consumes the vCPU. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221012181702.3663607-9-seanjc@google.com> [Use tdp_mmu_enabled variable. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: x86/mmu: Replace open coded usage of tdp_mmu_page with is_tdp_mmu_page()Sean Christopherson
Use is_tdp_mmu_page() instead of querying sp->tdp_mmu_page directly so that all users benefit if KVM ever finds a way to optimize the logic. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221012181702.3663607-10-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: x86/mmu: Rename __direct_map() to direct_map()David Matlack
Rename __direct_map() to direct_map() since the leading underscores are unnecessary. This also makes the page fault handler names more consistent: kvm_tdp_mmu_page_fault() calls kvm_tdp_mmu_map() and direct_page_fault() calls direct_map(). Opportunistically make some trivial cleanups to comments that had to be modified anyway since they mentioned __direct_map(). Specifically, use "()" when referring to functions, and include kvm_tdp_mmu_map() among the various callers of disallowed_hugepage_adjust(). No functional change intended. Signed-off-by: David Matlack <dmatlack@google.com> Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20220921173546.2674386-11-dmatlack@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: x86/mmu: Stop needlessly making MMU pages available for TDP MMU faultsDavid Matlack
Stop calling make_mmu_pages_available() when handling TDP MMU faults. The TDP MMU does not participate in the "available MMU pages" tracking and limiting so calling this function is unnecessary work when handling TDP MMU faults. Signed-off-by: David Matlack <dmatlack@google.com> Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20220921173546.2674386-10-dmatlack@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: x86/mmu: Split out TDP MMU page fault handlingDavid Matlack
Split out the page fault handling for the TDP MMU to a separate function. This creates some duplicate code, but makes the TDP MMU fault handler simpler to read by eliminating branches and will enable future cleanups by allowing the TDP MMU and non-TDP MMU fault paths to diverge. Only compile in the TDP MMU fault handler for 64-bit builds since kvm_tdp_mmu_map() does not exist in 32-bit builds. No functional change intended. Signed-off-by: David Matlack <dmatlack@google.com> Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20220921173546.2674386-9-dmatlack@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: x86/mmu: Initialize fault.{gfn,slot} earlier for direct MMUsDavid Matlack
Move the initialization of fault.{gfn,slot} earlier in the page fault handling code for fully direct MMUs. This will enable a future commit to split out TDP MMU page fault handling without needing to duplicate the initialization of these 2 fields. Opportunistically take advantage of the fact that fault.gfn is initialized in kvm_tdp_page_fault() rather than recomputing it from fault->addr. No functional change intended. Signed-off-by: David Matlack <dmatlack@google.com> Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20220921173546.2674386-8-dmatlack@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: x86/mmu: Handle no-slot faults in kvm_faultin_pfn()David Matlack
Handle faults on GFNs that do not have a backing memslot in kvm_faultin_pfn() and drop handle_abnormal_pfn(). This eliminates duplicate code in the various page fault handlers. Opportunistically tweak the comment about handling gfn > host.MAXPHYADDR to reflect that the effect of returning RET_PF_EMULATE at that point is to avoid creating an MMIO SPTE for such GFNs. No functional change intended. Signed-off-by: David Matlack <dmatlack@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20220921173546.2674386-7-dmatlack@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: x86/mmu: Avoid memslot lookup during KVM_PFN_ERR_HWPOISON handlingDavid Matlack
Pass the kvm_page_fault struct down to kvm_handle_error_pfn() to avoid a memslot lookup when handling KVM_PFN_ERR_HWPOISON. Opportunistically move the gfn_to_hva_memslot() call and @current down into kvm_send_hwpoison_signal() to cut down on line lengths. No functional change intended. Signed-off-by: David Matlack <dmatlack@google.com> Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20220921173546.2674386-6-dmatlack@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: x86/mmu: Handle error PFNs in kvm_faultin_pfn()David Matlack
Handle error PFNs in kvm_faultin_pfn() rather than relying on the caller to invoke handle_abnormal_pfn() after kvm_faultin_pfn(). Opportunistically rename kvm_handle_bad_page() to kvm_handle_error_pfn() to make it more consistent with is_error_pfn(). This commit moves KVM closer to being able to drop handle_abnormal_pfn(), which will reduce the amount of duplicate code in the various page fault handlers. No functional change intended. Signed-off-by: David Matlack <dmatlack@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20220921173546.2674386-5-dmatlack@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: x86/mmu: Grab mmu_invalidate_seq in kvm_faultin_pfn()David Matlack
Grab mmu_invalidate_seq in kvm_faultin_pfn() and stash it in struct kvm_page_fault. The eliminates duplicate code and reduces the amount of parameters needed for is_page_fault_stale(). Preemptively split out __kvm_faultin_pfn() to a separate function for use in subsequent commits. No functional change intended. Signed-off-by: David Matlack <dmatlack@google.com> Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20220921173546.2674386-4-dmatlack@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: x86/mmu: Move TDP MMU VM init/uninit behind tdp_mmu_enabledDavid Matlack
Move kvm_mmu_{init,uninit}_tdp_mmu() behind tdp_mmu_enabled. This makes these functions consistent with the rest of the calls into the TDP MMU from mmu.c, and which is now possible since tdp_mmu_enabled is only modified when the x86 vendor module is loaded. i.e. It will never change during the lifetime of a VM. This change also enabled removing the stub definitions for 32-bit KVM, as the compiler will just optimize the calls out like it does for all the other TDP MMU functions. No functional change intended. Signed-off-by: David Matlack <dmatlack@google.com> Reviewed-by: Isaku Yamahata <isaku.yamahata@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20220921173546.2674386-3-dmatlack@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: x86/mmu: Change tdp_mmu to a read-only parameterDavid Matlack
Change tdp_mmu to a read-only parameter and drop the per-vm tdp_mmu_enabled. For 32-bit KVM, make tdp_mmu_enabled a macro that is always false so that the compiler can continue omitting cals to the TDP MMU. The TDP MMU was introduced in 5.10 and has been enabled by default since 5.15. At this point there are no known functionality gaps between the TDP MMU and the shadow MMU, and the TDP MMU uses less memory and scales better with the number of vCPUs. In other words, there is no good reason to disable the TDP MMU on a live system. Purposely do not drop tdp_mmu=N support (i.e. do not force 64-bit KVM to always use the TDP MMU) since tdp_mmu=N is still used to get test coverage of KVM's shadow MMU TDP support, which is used in 32-bit KVM. Signed-off-by: David Matlack <dmatlack@google.com> Reviewed-by: Kai Huang <kai.huang@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20220921173546.2674386-2-dmatlack@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29kvm: x86/mmu: Warn on linking when sp->unsync_childrenLai Jiangshan
Since the commit 65855ed8b034 ("KVM: X86: Synchronize the shadow pagetable before link it"), no sp would be linked with sp->unsync_children = 1. So make it WARN if it is the case. Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com> Message-Id: <20221212090106.378206-1-jiangshanlai@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: VMX: Resurrect vmcs_conf sanitization for KVM-on-Hyper-VVitaly Kuznetsov
Commit 9bcb90650e31 ("KVM: VMX: Get rid of eVMCS specific VMX controls sanitization") dropped 'vmcs_conf' sanitization for KVM-on-Hyper-V because there's no known Hyper-V version which would expose a feature unsupported in eVMCS in VMX feature MSRs. This works well for all currently existing Hyper-V version, however, future Hyper-V versions may add features which are supported by KVM and are currently missing in eVMCSv1 definition (e.g. APIC virtualization, PML,...). When this happens, existing KVMs will get broken. With the inverted 'unsupported by eVMCSv1' checks, we can resurrect vmcs_conf sanitization and make KVM future proof. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20221104144708.435865-5-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: nVMX: Prepare to sanitize tertiary execution controls with eVMCSVitaly Kuznetsov
In preparation to restoring vmcs_conf sanitization for KVM-on-Hyper-V, (and for completeness) add tertiary VM-execution controls to 'evmcs_supported_ctrls'. No functional change intended as KVM doesn't yet expose MSR_IA32_VMX_PROCBASED_CTLS3 to its guests. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20221104144708.435865-4-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: nVMX: Invert 'unsupported by eVMCSv1' checkVitaly Kuznetsov
When a new feature gets implemented in KVM, EVMCS1_UNSUPPORTED_* defines need to be adjusted to avoid the situation when the feature is exposed to the guest but there's no corresponding eVMCS field[s] for it. This is not obvious and fragile. Invert 'unsupported by eVMCSv1' check and make it 'supported by eVMCSv1' instead, this way it's much harder to make a mistake. New features will get added to EVMCS1_SUPPORTED_* defines when the corresponding fields are added to eVMCS definition. No functional change intended. EVMCS1_SUPPORTED_* defines are composed by taking KVM_{REQUIRED,OPTIONAL}_VMX_ defines and filtering out what was previously known as EVMCS1_UNSUPPORTED_*. From all the controls, SECONDARY_EXEC_TSC_SCALING requires special handling as it's actually present in eVMCSv1 definition but is not currently supported for Hyper-V-on-KVM, just for KVM-on-Hyper-V. As evmcs_supported_ctrls will be used for both scenarios, just add it there instead of EVMCS1_SUPPORTED_2NDEXEC. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20221104144708.435865-3-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29KVM: nVMX: Sanitize primary processor-based VM-execution controls with eVMCS tooVitaly Kuznetsov
The only unsupported primary processor-based VM-execution control at the moment is CPU_BASED_ACTIVATE_TERTIARY_CONTROLS and KVM doesn't expose it in nested VMX feature MSRs anyway (see nested_vmx_setup_ctls_msrs()) but in preparation to inverting "unsupported with eVMCS" checks (and for completeness) it's better to sanitize MSR_IA32_VMX_PROCBASED_CTLS/ MSR_IA32_VMX_TRUE_PROCBASED_CTLS too. No functional change intended. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20221104144708.435865-2-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-28KVM: x86: fix deadlock for KVM_XEN_EVTCHN_RESETPaolo Bonzini
While KVM_XEN_EVTCHN_RESET is usually called with no vCPUs running, if that happened it could cause a deadlock. This is due to kvm_xen_eventfd_reset() doing a synchronize_srcu() inside a kvm->lock critical section. To avoid this, first collect all the evtchnfd objects in an array and free all of them once the kvm->lock critical section is over and th SRCU grace period has expired. Reported-by: Michal Luczaj <mhal@rbox.co> Cc: David Woodhouse <dwmw@amazon.co.uk> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-27KVM: x86/xen: Add KVM_XEN_INVALID_GPA and KVM_XEN_INVALID_GFN to uapiDavid Woodhouse
These are (uint64_t)-1 magic values are a userspace ABI, allowing the shared info pages and other enlightenments to be disabled. This isn't a Xen ABI because Xen doesn't let the guest turn these off except with the full SHUTDOWN_soft_reset mechanism. Under KVM, the userspace VMM is expected to handle soft reset, and tear down the kernel parts of the enlightenments accordingly. Suggested-by: Sean Christopherson <seanjc@google.com> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Message-Id: <20221226120320.1125390-5-dwmw2@infradead.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-27KVM: x86/xen: Simplify eventfd IOCTLsMichal Luczaj
Port number is validated in kvm_xen_setattr_evtchn(). Remove superfluous checks in kvm_xen_eventfd_assign() and kvm_xen_eventfd_update(). Signed-off-by: Michal Luczaj <mhal@rbox.co> Message-Id: <20221222203021.1944101-3-mhal@rbox.co> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Message-Id: <20221226120320.1125390-4-dwmw2@infradead.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-27KVM: x86/xen: Fix SRCU/RCU usage in readers of evtchn_portsPaolo Bonzini
The evtchnfd structure itself must be protected by either kvm->lock or SRCU. Use the former in kvm_xen_eventfd_update(), since the lock is being taken anyway; kvm_xen_hcall_evtchn_send() instead is a reader and does not need kvm->lock, and is called in SRCU critical section from the kvm_x86_handle_exit function. It is also important to use rcu_read_{lock,unlock}() in kvm_xen_hcall_evtchn_send(), because idr_remove() will *not* use synchronize_srcu() to wait for readers to complete. Remove a superfluous if (kvm) check before calling synchronize_srcu() in kvm_xen_eventfd_deassign() where kvm has been dereferenced already. Co-developed-by: Michal Luczaj <mhal@rbox.co> Signed-off-by: Michal Luczaj <mhal@rbox.co> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Message-Id: <20221226120320.1125390-3-dwmw2@infradead.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-27KVM: x86/xen: Use kvm_read_guest_virt() instead of open-coding it badlyDavid Woodhouse
In particular, we shouldn't assume that being contiguous in guest virtual address space means being contiguous in guest *physical* address space. In dropping the manual calls to kvm_mmu_gva_to_gpa_system(), also drop the srcu_read_lock() that was around them. All call sites are reached from kvm_xen_hypercall() which is called from the handle_exit function with the read lock already held. 536395260 ("KVM: x86/xen: handle PV timers oneshot mode") 1a65105a5 ("KVM: x86/xen: handle PV spinlocks slowpath") Fixes: 2fd6df2f2 ("KVM: x86/xen: intercept EVTCHNOP_send from guests") Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Message-Id: <20221226120320.1125390-2-dwmw2@infradead.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-27KVM: x86/xen: Fix memory leak in kvm_xen_write_hypercall_page()Michal Luczaj
Release page irrespectively of kvm_vcpu_write_guest() return value. Suggested-by: Paul Durrant <paul@xen.org> Fixes: 23200b7a30de ("KVM: x86/xen: intercept xen hypercalls if enabled") Signed-off-by: Michal Luczaj <mhal@rbox.co> Message-Id: <20221220151454.712165-1-mhal@rbox.co> Reviewed-by: Paul Durrant <paul@xen.org> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Message-Id: <20221226120320.1125390-1-dwmw2@infradead.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-27kvm: x86/mmu: Remove duplicated "be split" in spte.hLai Jiangshan
"be split be split" -> "be split" Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com> Message-Id: <20221207120505.9175-1-jiangshanlai@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-23KVM: x86/mmu: Don't install TDP MMU SPTE if SP has unexpected levelSean Christopherson
Don't install a leaf TDP MMU SPTE if the parent page's level doesn't match the target level of the fault, and instead have the vCPU retry the faulting instruction after warning. Continuing on is completely unnecessary as the absolute worst case scenario of retrying is DoSing the vCPU, whereas continuing on all but guarantees bigger explosions, e.g. ------------[ cut here ]------------ kernel BUG at arch/x86/kvm/mmu/tdp_mmu.c:559! invalid opcode: 0000 [#1] SMP CPU: 1 PID: 1025 Comm: nx_huge_pages_t Tainted: G W 6.1.0-rc4+ #64 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:__handle_changed_spte.cold+0x95/0x9c RSP: 0018:ffffc9000072faf8 EFLAGS: 00010246 RAX: 00000000000000c1 RBX: ffffc90000731000 RCX: 0000000000000027 RDX: 0000000000000000 RSI: 00000000ffffdfff RDI: ffff888277c5b4c8 RBP: 0600000112400bf3 R08: ffff888277c5b4c0 R09: ffffc9000072f9a0 R10: 0000000000000001 R11: 0000000000000001 R12: 06000001126009f3 R13: 0000000000000002 R14: 0000000012600901 R15: 0000000012400b01 FS: 00007fba9f853740(0000) GS:ffff888277c40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000010aa7a003 CR4: 0000000000172ea0 Call Trace: <TASK> kvm_tdp_mmu_map+0x3b0/0x510 kvm_tdp_page_fault+0x10c/0x130 kvm_mmu_page_fault+0x103/0x680 vmx_handle_exit+0x132/0x5a0 [kvm_intel] vcpu_enter_guest+0x60c/0x16f0 kvm_arch_vcpu_ioctl_run+0x1e2/0x9d0 kvm_vcpu_ioctl+0x271/0x660 __x64_sys_ioctl+0x80/0xb0 do_syscall_64+0x2b/0x50 entry_SYSCALL_64_after_hwframe+0x46/0xb0 </TASK> Modules linked in: kvm_intel ---[ end trace 0000000000000000 ]--- Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221213033030.83345-5-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-23KVM: x86/mmu: Re-check under lock that TDP MMU SP hugepage is disallowedSean Christopherson
Re-check sp->nx_huge_page_disallowed under the tdp_mmu_pages_lock spinlock when adding a new shadow page in the TDP MMU. To ensure the NX reclaim kthread can't see a not-yet-linked shadow page, the page fault path links the new page table prior to adding the page to possible_nx_huge_pages. If the page is zapped by different task, e.g. because dirty logging is disabled, between linking the page and adding it to the list, KVM can end up triggering use-after-free by adding the zapped SP to the aforementioned list, as the zapped SP's memory is scheduled for removal via RCU callback. The bug is detected by the sanity checks guarded by CONFIG_DEBUG_LIST=y, i.e. the below splat is just one possible signature. ------------[ cut here ]------------ list_add corruption. prev->next should be next (ffffc9000071fa70), but was ffff88811125ee38. (prev=ffff88811125ee38). WARNING: CPU: 1 PID: 953 at lib/list_debug.c:30 __list_add_valid+0x79/0xa0 Modules linked in: kvm_intel CPU: 1 PID: 953 Comm: nx_huge_pages_t Tainted: G W 6.1.0-rc4+ #71 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:__list_add_valid+0x79/0xa0 RSP: 0018:ffffc900006efb68 EFLAGS: 00010286 RAX: 0000000000000000 RBX: ffff888116cae8a0 RCX: 0000000000000027 RDX: 0000000000000027 RSI: 0000000100001872 RDI: ffff888277c5b4c8 RBP: ffffc90000717000 R08: ffff888277c5b4c0 R09: ffffc900006efa08 R10: 0000000000199998 R11: 0000000000199a20 R12: ffff888116cae930 R13: ffff88811125ee38 R14: ffffc9000071fa70 R15: ffff88810b794f90 FS: 00007fc0415d2740(0000) GS:ffff888277c40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000115201006 CR4: 0000000000172ea0 Call Trace: <TASK> track_possible_nx_huge_page+0x53/0x80 kvm_tdp_mmu_map+0x242/0x2c0 kvm_tdp_page_fault+0x10c/0x130 kvm_mmu_page_fault+0x103/0x680 vmx_handle_exit+0x132/0x5a0 [kvm_intel] vcpu_enter_guest+0x60c/0x16f0 kvm_arch_vcpu_ioctl_run+0x1e2/0x9d0 kvm_vcpu_ioctl+0x271/0x660 __x64_sys_ioctl+0x80/0xb0 do_syscall_64+0x2b/0x50 entry_SYSCALL_64_after_hwframe+0x46/0xb0 </TASK> ---[ end trace 0000000000000000 ]--- Fixes: 61f94478547b ("KVM: x86/mmu: Set disallowed_nx_huge_page in TDP MMU before setting SPTE") Reported-by: Greg Thelen <gthelen@google.com> Analyzed-by: David Matlack <dmatlack@google.com> Cc: David Matlack <dmatlack@google.com> Cc: Ben Gardon <bgardon@google.com> Cc: Mingwei Zhang <mizhang@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221213033030.83345-4-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-23KVM: x86/mmu: Map TDP MMU leaf SPTE iff target level is reachedSean Christopherson
Map the leaf SPTE when handling a TDP MMU page fault if and only if the target level is reached. A recent commit reworked the retry logic and incorrectly assumed that walking SPTEs would never "fail", as the loop either bails (retries) or installs parent SPs. However, the iterator itself will bail early if it detects a frozen (REMOVED) SPTE when stepping down. The TDP iterator also rereads the current SPTE before stepping down specifically to avoid walking into a part of the tree that is being removed, which means it's possible to terminate the loop without the guts of the loop observing the frozen SPTE, e.g. if a different task zaps a parent SPTE between the initial read and try_step_down()'s refresh. Mapping a leaf SPTE at the wrong level results in all kinds of badness as page table walkers interpret the SPTE as a page table, not a leaf, and walk into the weeds. ------------[ cut here ]------------ WARNING: CPU: 1 PID: 1025 at arch/x86/kvm/mmu/tdp_mmu.c:1070 kvm_tdp_mmu_map+0x481/0x510 Modules linked in: kvm_intel CPU: 1 PID: 1025 Comm: nx_huge_pages_t Tainted: G W 6.1.0-rc4+ #64 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:kvm_tdp_mmu_map+0x481/0x510 RSP: 0018:ffffc9000072fba8 EFLAGS: 00010286 RAX: 0000000000000000 RBX: ffffc9000072fcc0 RCX: 0000000000000027 RDX: 0000000000000027 RSI: 00000000ffffdfff RDI: ffff888277c5b4c8 RBP: ffff888107d45a10 R08: ffff888277c5b4c0 R09: ffffc9000072fa48 R10: 0000000000000001 R11: 0000000000000001 R12: ffffc9000073a0e0 R13: ffff88810fc54800 R14: ffff888107d1ae60 R15: ffff88810fc54f90 FS: 00007fba9f853740(0000) GS:ffff888277c40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000010aa7a003 CR4: 0000000000172ea0 Call Trace: <TASK> kvm_tdp_page_fault+0x10c/0x130 kvm_mmu_page_fault+0x103/0x680 vmx_handle_exit+0x132/0x5a0 [kvm_intel] vcpu_enter_guest+0x60c/0x16f0 kvm_arch_vcpu_ioctl_run+0x1e2/0x9d0 kvm_vcpu_ioctl+0x271/0x660 __x64_sys_ioctl+0x80/0xb0 do_syscall_64+0x2b/0x50 entry_SYSCALL_64_after_hwframe+0x46/0xb0 </TASK> ---[ end trace 0000000000000000 ]--- Invalid SPTE change: cannot replace a present leaf SPTE with another present leaf SPTE mapping a different PFN! as_id: 0 gfn: 100200 old_spte: 600000112400bf3 new_spte: 6000001126009f3 level: 2 ------------[ cut here ]------------ kernel BUG at arch/x86/kvm/mmu/tdp_mmu.c:559! invalid opcode: 0000 [#1] SMP CPU: 1 PID: 1025 Comm: nx_huge_pages_t Tainted: G W 6.1.0-rc4+ #64 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:__handle_changed_spte.cold+0x95/0x9c RSP: 0018:ffffc9000072faf8 EFLAGS: 00010246 RAX: 00000000000000c1 RBX: ffffc90000731000 RCX: 0000000000000027 RDX: 0000000000000000 RSI: 00000000ffffdfff RDI: ffff888277c5b4c8 RBP: 0600000112400bf3 R08: ffff888277c5b4c0 R09: ffffc9000072f9a0 R10: 0000000000000001 R11: 0000000000000001 R12: 06000001126009f3 R13: 0000000000000002 R14: 0000000012600901 R15: 0000000012400b01 FS: 00007fba9f853740(0000) GS:ffff888277c40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000010aa7a003 CR4: 0000000000172ea0 Call Trace: <TASK> kvm_tdp_mmu_map+0x3b0/0x510 kvm_tdp_page_fault+0x10c/0x130 kvm_mmu_page_fault+0x103/0x680 vmx_handle_exit+0x132/0x5a0 [kvm_intel] vcpu_enter_guest+0x60c/0x16f0 kvm_arch_vcpu_ioctl_run+0x1e2/0x9d0 kvm_vcpu_ioctl+0x271/0x660 __x64_sys_ioctl+0x80/0xb0 do_syscall_64+0x2b/0x50 entry_SYSCALL_64_after_hwframe+0x46/0xb0 </TASK> Modules linked in: kvm_intel ---[ end trace 0000000000000000 ]--- Fixes: 63d28a25e04c ("KVM: x86/mmu: simplify kvm_tdp_mmu_map flow when guest has to retry") Cc: Robert Hoo <robert.hu@linux.intel.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221213033030.83345-3-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-23KVM: x86/mmu: Don't attempt to map leaf if target TDP MMU SPTE is frozenSean Christopherson
Hoist the is_removed_spte() check above the "level == goal_level" check when walking SPTEs during a TDP MMU page fault to avoid attempting to map a leaf entry if said entry is frozen by a different task/vCPU. ------------[ cut here ]------------ WARNING: CPU: 3 PID: 939 at arch/x86/kvm/mmu/tdp_mmu.c:653 kvm_tdp_mmu_map+0x269/0x4b0 Modules linked in: kvm_intel CPU: 3 PID: 939 Comm: nx_huge_pages_t Not tainted 6.1.0-rc4+ #67 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:kvm_tdp_mmu_map+0x269/0x4b0 RSP: 0018:ffffc9000068fba8 EFLAGS: 00010246 RAX: 00000000000005a0 RBX: ffffc9000068fcc0 RCX: 0000000000000005 RDX: ffff88810741f000 RSI: ffff888107f04600 RDI: ffffc900006a3000 RBP: 060000010b000bf3 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 000ffffffffff000 R12: 0000000000000005 R13: ffff888113670000 R14: ffff888107464958 R15: 0000000000000000 FS: 00007f01c942c740(0000) GS:ffff888277cc0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000117013006 CR4: 0000000000172ea0 Call Trace: <TASK> kvm_tdp_page_fault+0x10c/0x130 kvm_mmu_page_fault+0x103/0x680 vmx_handle_exit+0x132/0x5a0 [kvm_intel] vcpu_enter_guest+0x60c/0x16f0 kvm_arch_vcpu_ioctl_run+0x1e2/0x9d0 kvm_vcpu_ioctl+0x271/0x660 __x64_sys_ioctl+0x80/0xb0 do_syscall_64+0x2b/0x50 entry_SYSCALL_64_after_hwframe+0x46/0xb0 </TASK> ---[ end trace 0000000000000000 ]--- Fixes: 63d28a25e04c ("KVM: x86/mmu: simplify kvm_tdp_mmu_map flow when guest has to retry") Cc: Robert Hoo <robert.hu@linux.intel.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Robert Hoo <robert.hu@linux.intel.com> Message-Id: <20221213033030.83345-2-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-23KVM: nVMX: Don't stuff secondary execution control if it's not supportedSean Christopherson
When stuffing the allowed secondary execution controls for nested VMX in response to CPUID updates, don't set the allowed-1 bit for a feature that isn't supported by KVM, i.e. isn't allowed by the canonical vmcs_config. WARN if KVM attempts to manipulate a feature that isn't supported. All features that are currently stuffed are always advertised to L1 for nested VMX if they are supported in KVM's base configuration, and no additional features should ever be added to the CPUID-induced stuffing (updating VMX MSRs in response to CPUID updates is a long-standing KVM flaw that is slowly being fixed). Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221213062306.667649-3-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-23KVM: nVMX: Properly expose ENABLE_USR_WAIT_PAUSE control to L1Sean Christopherson
Set ENABLE_USR_WAIT_PAUSE in KVM's supported VMX MSR configuration if the feature is supported in hardware and enabled in KVM's base, non-nested configuration, i.e. expose ENABLE_USR_WAIT_PAUSE to L1 if it's supported. This fixes a bug where saving/restoring, i.e. migrating, a vCPU will fail if WAITPKG (the associated CPUID feature) is enabled for the vCPU, and obviously allows L1 to enable the feature for L2. KVM already effectively exposes ENABLE_USR_WAIT_PAUSE to L1 by stuffing the allowed-1 control ina vCPU's virtual MSR_IA32_VMX_PROCBASED_CTLS2 when updating secondary controls in response to KVM_SET_CPUID(2), but (a) that depends on flawed code (KVM shouldn't touch VMX MSRs in response to CPUID updates) and (b) runs afoul of vmx_restore_control_msr()'s restriction that the guest value must be a strict subset of the supported host value. Although no past commit explicitly enabled nested support for WAITPKG, doing so is safe and functionally correct from an architectural perspective as no additional KVM support is needed to virtualize TPAUSE, UMONITOR, and UMWAIT for L2 relative to L1, and KVM already forwards VM-Exits to L1 as necessary (commit bf653b78f960, "KVM: vmx: Introduce handle_unexpected_vmexit and handle WAITPKG vmexit"). Note, KVM always keeps the hosts MSR_IA32_UMWAIT_CONTROL resident in hardware, i.e. always runs both L1 and L2 with the host's power management settings for TPAUSE and UMWAIT. See commit bf09fb6cba4f ("KVM: VMX: Stop context switching MSR_IA32_UMWAIT_CONTROL") for more details. Fixes: e69e72faa3a0 ("KVM: x86: Add support for user wait instructions") Cc: stable@vger.kernel.org Reported-by: Aaron Lewis <aaronlewis@google.com> Reported-by: Yu Zhang <yu.c.zhang@linux.intel.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Jim Mattson <jmattson@google.com> Message-Id: <20221213062306.667649-2-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-23KVM: nVMX: Document that ignoring memory failures for VMCLEAR is deliberateSean Christopherson
Explicitly drop the result of kvm_vcpu_write_guest() when writing the "launch state" as part of VMCLEAR emulation, and add a comment to call out that KVM's behavior is architecturally valid. Intel's pseudocode effectively says that VMCLEAR is a nop if the target VMCS address isn't in memory, e.g. if the address points at MMIO. Add a FIXME to call out that suppressing failures on __copy_to_user() is wrong, as memory (a memslot) does exist in that case. Punt the issue to the future as open coding kvm_vcpu_write_guest() just to make sure the guest dies with -EFAULT isn't worth the extra complexity. The flaw will need to be addressed if KVM ever does something intelligent on uaccess failures, e.g. to support post-copy demand paging, but in that case KVM will need a more thorough overhaul, i.e. VMCLEAR shouldn't need to open code a core KVM helper. No functional change intended. Reported-by: coverity-bot <keescook+coverity-bot@chromium.org> Addresses-Coverity-ID: 1527765 ("Error handling issues") Fixes: 587d7e72aedc ("kvm: nVMX: VMCLEAR should not cause the vCPU to shut down") Cc: Jim Mattson <jmattson@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221220154224.526568-1-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-23KVM: x86: Sanity check inputs to kvm_handle_memory_failure()Sean Christopherson
Add a sanity check in kvm_handle_memory_failure() to assert that a valid x86_exception structure is provided if the memory "failure" wants to propagate a fault into the guest. If a memory failure happens during a direct guest physical memory access, e.g. for nested VMX, KVM hardcodes the failure to X86EMUL_IO_NEEDED and doesn't provide an exception pointer (because the exception struct would just be filled with garbage). Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221220153427.514032-1-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-23KVM: x86: Simplify kvm_apic_hw_enabledPeng Hao
kvm_apic_hw_enabled() only needs to return bool, there is no place to use the return value of MSR_IA32_APICBASE_ENABLE. Signed-off-by: Peng Hao <flyingpeng@tencent.com> Message-Id: <CAPm50aJ=BLXNWT11+j36Dd6d7nz2JmOBk4u7o_NPQ0N61ODu1g@mail.gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-23KVM: x86: hyper-v: Fix 'using uninitialized value' Coverity warningVitaly Kuznetsov
In kvm_hv_flush_tlb(), 'data_offset' and 'consumed_xmm_halves' variables are used in a mutually exclusive way: in 'hc->fast' we count in 'XMM halves' and increase 'data_offset' otherwise. Coverity discovered, that in one case both variables are incremented unconditionally. This doesn't seem to cause any issues as the only user of 'data_offset'/'consumed_xmm_halves' data is kvm_hv_get_tlb_flush_entries() -> kvm_hv_get_hc_data() which also takes into account 'hc->fast' but is still worth fixing. To make things explicit, put 'data_offset' and 'consumed_xmm_halves' to 'struct kvm_hv_hcall' as a union and use at call sites. This allows to remove explicit 'data_offset'/'consumed_xmm_halves' parameters from kvm_hv_get_hc_data()/kvm_get_sparse_vp_set()/kvm_hv_get_tlb_flush_entries() helpers. Note: 'struct kvm_hv_hcall' is allocated on stack in kvm_hv_hypercall() and is not zeroed, consumers are supposed to initialize the appropriate field if needed. Reported-by: coverity-bot <keescook+coverity-bot@chromium.org> Addresses-Coverity-ID: 1527764 ("Uninitialized variables") Fixes: 260970862c88 ("KVM: x86: hyper-v: Handle HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST{,EX} calls gently") Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221208102700.959630-1-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-23KVM: x86: ioapic: Fix level-triggered EOI and userspace I/OAPIC reconfigure raceAdamos Ttofari
When scanning userspace I/OAPIC entries, intercept EOI for level-triggered IRQs if the current vCPU has a pending and/or in-service IRQ for the vector in its local API, even if the vCPU doesn't match the new entry's destination. This fixes a race between userspace I/OAPIC reconfiguration and IRQ delivery that results in the vector's bit being left set in the remote IRR due to the eventual EOI not being forwarded to the userspace I/OAPIC. Commit 0fc5a36dd6b3 ("KVM: x86: ioapic: Fix level-triggered EOI and IOAPIC reconfigure race") fixed the in-kernel IOAPIC, but not the userspace IOAPIC configuration, which has a similar race. Fixes: 0fc5a36dd6b3 ("KVM: x86: ioapic: Fix level-triggered EOI and IOAPIC reconfigure race") Signed-off-by: Adamos Ttofari <attofari@amazon.de> Reviewed-by: Sean Christopherson <seanjc@google.com> Message-Id: <20221208094415.12723-1-attofari@amazon.de> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-23KVM: x86/pmu: Prevent zero period event from being repeatedly releasedLike Xu
The current vPMU can reuse the same pmc->perf_event for the same hardware event via pmc_pause/resume_counter(), but this optimization does not apply to a portion of the TSX events (e.g., "event=0x3c,in_tx=1, in_tx_cp=1"), where event->attr.sample_period is legally zero at creation, thus making the perf call to perf_event_period() meaningless (no need to adjust sample period in this case), and instead causing such reusable perf_events to be repeatedly released and created. Avoid releasing zero sample_period events by checking is_sampling_event() to follow the previously enable/disable optimization. Signed-off-by: Like Xu <likexu@tencent.com> Message-Id: <20221207071506.15733-2-likexu@tencent.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
generated by cgit (git 2.34.1) at 2025-04-15 06:41:51 +0000