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Move the EDX initialization at vCPU RESET, which is now identical between
VMX and SVM, into common code.
No functional change intended.
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-20-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Consolidate the APIC base RESET logic, which is currently spread out
across both x86 and vendor code. For an in-kernel APIC, the vendor code
is redundant. But for a userspace APIC, KVM relies on the vendor code
to initialize vcpu->arch.apic_base. Hoist the vcpu->arch.apic_base
initialization above the !apic check so that it applies to both flavors
of APIC emulation, and delete the vendor code.
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-19-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Stuff vcpu->arch.apic_base and apic->base_address directly during APIC
reset, as opposed to bouncing through kvm_set_apic_base() while fudging
the ENABLE bit during creation to avoid the other, unwanted side effects.
This is a step towards consolidating the APIC RESET logic across x86,
VMX, and SVM.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-18-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Write vcpu->arch.apic_base directly instead of bouncing through
kvm_set_apic_base(). This is a glorified nop, and is a step towards
cleaning up the mess that is local APIC creation.
When using an in-kernel APIC, kvm_create_lapic() explicitly sets
vcpu->arch.apic_base to MSR_IA32_APICBASE_ENABLE to avoid its own
kvm_lapic_set_base() call in kvm_lapic_reset() from triggering state
changes. That call during RESET exists purely to set apic->base_address
to the default base value. As a result, by the time VMX gets control,
the only missing piece is the BSP bit being set for the reset BSP.
For a userspace APIC, there are no side effects to process (for the APIC).
In both cases, the call to kvm_update_cpuid_runtime() is a nop because
the vCPU hasn't yet been exposed to userspace, i.e. there can't be any
CPUID entries.
No functional change intended.
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-17-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Set the BSP bit appropriately during local APIC "reset" instead of
relying on vendor code to clean up at a later point. This is a step
towards consolidating the local APIC, VMX, and SVM xAPIC initialization
code.
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-16-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Don't set the BSP bit in vcpu->arch.apic_base when the local APIC is
managed by userspace. Forcing all vCPUs to be BSPs is non-sensical, and
was dead code when it was added by commit 97222cc83163 ("KVM: Emulate
local APIC in kernel"). At the time, kvm_lapic_set_base() was invoked
if and only if the local APIC was in-kernel (and it couldn't be called
before the vCPU created its APIC).
kvm_lapic_set_base() eventually gained generic usage, but the latent bug
escaped notice because the only true consumer would be the guest itself
in the form of an explicit RDMSRs on APs. Out of Linux, SeaBIOS, and
EDK2/OVMF, only OVMF consumes the BSP bit from the APIC_BASE MSR. For
the vast majority of usage in OVMF, BSP confusion would be benign.
OVMF's BSP election upon SMI rendezvous might be broken, but practically
no one runs KVM with an out-of-kernel local APIC, let alone does so while
utilizing SMIs with OVMF.
Fixes: 97222cc83163 ("KVM: Emulate local APIC in kernel")
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-15-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Make vcpu0 the arbitrary owner of the PIT, as was intended when PIT
migration was added by commit 2f5997140f22 ("KVM: migrate PIT timer").
The PIT was unintentionally turned into being owned by the BSP by commit
c5af89b68abb ("KVM: Introduce kvm_vcpu_is_bsp() function."), and was then
unintentionally converted to a shared ownership model when
kvm_vcpu_is_bsp() was modified to check the APIC base MSR instead of
hardcoding vcpu0 as the BSP.
Functionally, this just means the PIT's hrtimer is migrated less often.
The real motivation is to remove the usage of kvm_vcpu_is_bsp(), so that
more legacy/broken crud can be removed in a future patch.
Fixes: 58d269d8cccc ("KVM: x86: BSP in MSR_IA32_APICBASE is writable")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-14-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Remove a BSP APIC update in kvm_lapic_reset() that is a glorified and
confusing nop. When the code was originally added, kvm_vcpu_is_bsp()
queried kvm->arch.bsp_vcpu, i.e. the intent was to set the BSP bit in the
BSP vCPU's APIC. But, stuffing the BSP bit at INIT was wrong since the
guest can change its BSP(s); this was fixed by commit 58d269d8cccc ("KVM:
x86: BSP in MSR_IA32_APICBASE is writable").
In other words, kvm_vcpu_is_bsp() is now purely a reflection of
vcpu->arch.apic_base.MSR_IA32_APICBASE_BSP, thus the update will always
set the current value and kvm_lapic_set_base() is effectively a nop if
the new and old values match. The RESET case, which does need to stuff
the BSP for the reset vCPU, is handled by vendor code (though this will
soon be moved to common code).
No functional change intended.
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-13-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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WARN if KVM ends up in a state where it thinks its APIC map needs to be
recalculated, but KVM is not emulating the local APIC. This is mostly
to document KVM's "rules" in order to provide clarity in future cleanups.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-12-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Drop an explicit MMU reset in SVM's vCPU RESET/INIT flow now that the
common x86 path correctly handles conditional MMU resets, e.g. if INIT
arrives while the vCPU is in 64-bit mode.
This reverts commit ebae871a509d ("kvm: svm: reset mmu on VCPU reset").
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Drop an explicit MMU reset when entering emulated real mode now that the
vCPU INIT/RESET path correctly handles conditional MMU resets, e.g. if
INIT arrives while the vCPU is in 64-bit mode.
Note, while there are multiple other direct calls to vmx_set_cr0(), i.e.
paths that change CR0 without invoking kvm_post_set_cr0(), only the INIT
emulation can reach enter_rmode(). CLTS emulation only toggles CR.TS,
VM-Exit (and late VM-Fail) emulation cannot architecturally transition to
Real Mode, and VM-Enter to Real Mode is possible if and only if
Unrestricted Guest is enabled (exposed to L1).
This effectively reverts commit 8668a3c468ed ("KVM: VMX: Reset mmu
context when entering real mode")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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At vCPU RESET/INIT (mostly RESET), stuff EDX with KVM's hardcoded,
default Family-Model-Stepping ID of 0x600 if CPUID.0x1 isn't defined.
At RESET, the CPUID lookup is guaranteed to "miss" because KVM emulates
RESET before exposing the vCPU to userspace, i.e. userspace can't
possibly have done set the vCPU's CPUID model, and thus KVM will always
write '0'. At INIT, using 0x600 is less bad than using '0'.
While initializing EDX to '0' is _extremely_ unlikely to be noticed by
the guest, let alone break the guest, and can be overridden by
userspace for the RESET case, using 0x600 is preferable as it will allow
consolidating the relevant VMX and SVM RESET/INIT logic in the future.
And, digging through old specs suggests that neither Intel nor AMD have
ever shipped a CPU that initialized EDX to '0' at RESET.
Regarding 0x600 as KVM's default Family, it is a sane default and in
many ways the most appropriate. Prior to the 386 implementations, DX
was undefined at RESET. With the 386, 486, 586/P5, and 686/P6/Athlon,
both Intel and AMD set EDX to 3, 4, 5, and 6 respectively. AMD switched
to using '15' as its primary Family with the introduction of AMD64, but
Intel has continued using '6' for the last few decades.
So, '6' is a valid Family for both Intel and AMD CPUs, is compatible
with both 32-bit and 64-bit CPUs (albeit not a perfect fit for 64-bit
AMD), and of the common Families (3 - 6), is the best fit with respect to
KVM's virtual CPU model. E.g. prior to the P6, Intel CPUs did not have a
STI window. Modern operating systems, Linux included, rely on the STI
window, e.g. for "safe halt", and KVM unconditionally assumes the virtual
CPU has an STI window. Thus enumerating a Family ID of 3, 4, or 5 would
be provably wrong.
Opportunistically remove a stale comment.
Fixes: 66f7b72e1171 ("KVM: x86: Make register state after reset conform to specification")
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Do not allow an inexact CPUID "match" when querying the guest's CPUID.0x1
to stuff EDX during INIT. In the common case, where the guest CPU model
is an AMD variant, allowing an inexact match is a nop since KVM doesn't
emulate Intel's goofy "out-of-range" logic for AMD and Hygon. If the
vCPU model happens to be an Intel variant, an inexact match is possible
if and only if the max CPUID leaf is precisely '0'. Aside from the fact
that there's probably no CPU in existence with a single CPUID leaf, if
the max CPUID leaf is '0', that means that CPUID.0.EAX is '0', and thus
an inexact match for CPUID.0x1.EAX will also yield '0'.
So, with lots of twisty logic, no functional change intended.
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Set EDX at RESET/INIT based on the userspace-defined CPUID model when
possible, i.e. when CPUID.0x1.EAX is defind by userspace. At RESET/INIT,
all CPUs that support CPUID set EDX to the FMS enumerated in
CPUID.0x1.EAX. If no CPUID match is found, fall back to KVM's default
of 0x600 (Family '6'), which is the least awful approximation of KVM's
virtual CPU model.
Fixes: 6aa8b732ca01 ("[PATCH] kvm: userspace interface")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Explicitly set GDTR.base and IDTR.base to zero when intializing the VMCB.
Functionally this only affects INIT, as the bases are implicitly set to
zero on RESET by virtue of the VMCB being zero allocated.
Per AMD's APM, GDTR.base and IDTR.base are zeroed after RESET and INIT.
Fixes: 04d2cc7780d4 ("KVM: Move main vcpu loop into subarch independent code")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Set L1's LDTR on VM-Exit per the Intel SDM:
The host-state area does not contain a selector field for LDTR. LDTR is
established as follows on all VM exits: the selector is cleared to
0000H, the segment is marked unusable and is otherwise undefined
(although the base address is always canonical).
This is likely a benign bug since the LDTR is unusable, as it means the
L1 VMM is conditioned to reload its LDTR in order to function properly on
bare metal.
Fixes: 4704d0befb07 ("KVM: nVMX: Exiting from L2 to L1")
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Flush the guest's TLB on INIT, as required by Intel's SDM. Although
AMD's APM states that the TLBs are unchanged by INIT, it's not clear that
that's correct as the APM also states that the TLB is flush on "External
initialization of the processor." Regardless, relying on the guest to be
paranoid is unnecessarily risky, while an unnecessary flush is benign
from a functional perspective and likely has no measurable impact on
guest performance.
Note, as of the April 2021 version of Intels' SDM, it also contradicts
itself with respect to TLB flushing. The overview of INIT explicitly
calls out the TLBs as being invalidated, while a table later in the same
section says they are unchanged.
9.1 INITIALIZATION OVERVIEW:
The major difference is that during an INIT, the internal caches, MSRs,
MTRRs, and x87 FPU state are left unchanged (although, the TLBs and BTB
are invalidated as with a hardware reset)
Table 9-1:
Register Power up Reset INIT
Data and Code Cache, TLBs: Invalid[6] Invalid[6] Unchanged
Given Core2's erratum[*] about global TLB entries not being flush on INIT,
it's safe to assume that the table is simply wrong.
AZ28. INIT Does Not Clear Global Entries in the TLB
Problem: INIT may not flush a TLB entry when:
• The processor is in protected mode with paging enabled and the page global enable
flag is set (PGE bit of CR4 register)
• G bit for the page table entry is set
• TLB entry is present in TLB when INIT occurs
• Software may encounter unexpected page fault or incorrect address translation due
to a TLB entry erroneously left in TLB after INIT.
Workaround: Write to CR3, CR4 (setting bits PSE, PGE or PAE) or CR0 (setting
bits PG or PE) registers before writing to memory early in BIOS
code to clear all the global entries from TLB.
Status: For the steppings affected, see the Summary Tables of Changes.
[*] https://www.intel.com/content/dam/support/us/en/documents/processors/mobile/celeron/sb/320121.pdf
Fixes: 6aa8b732ca01 ("[PATCH] kvm: userspace interface")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Special case of disabling the APICv on the current vCPU right away in
kvm_request_apicv_update doesn't bring much benefit vs raising
KVM_REQ_APICV_UPDATE on it instead, since this request will be processed
on the next entry to the guest.
(the comment about having another #VMEXIT is wrong).
It also hides various assumptions that APIVc enable state matches
the APICv inhibit state, as this special case only makes those states
match on the current vCPU.
Previous patches fixed few such assumptions so now it should be safe
to drop this special case.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210713142023.106183-5-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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With the addition of fast page fault support, the TDP-specific MMU has reached
feature parity with the original MMU. All my testing in the last few months
has been done with the TDP MMU; switch the default on 64-bit machines.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Make fast_page_fault interoperate with the TDP MMU by leveraging
walk_shadow_page_lockless_{begin,end} to acquire the RCU read lock and
introducing a new helper function kvm_tdp_mmu_fast_pf_get_last_sptep to
grab the lowest level sptep.
Suggested-by: Ben Gardon <bgardon@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20210713220957.3493520-5-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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the TDP MMU
Acquire the RCU read lock in walk_shadow_page_lockless_begin and release
it in walk_shadow_page_lockless_end when the TDP MMU is enabled. This
should not introduce any functional changes but is used in the following
commit to make fast_page_fault interoperate with the TDP MMU.
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20210713220957.3493520-4-dmatlack@google.com>
[Use if...else instead of if(){return;}]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Enum values have to be exported to userspace since the formatting is not
done in the kernel. Without doing this perf maps RET_PF_FIXED and
RET_PF_SPURIOUS to 0, which results in incorrect output:
$ perf record -a -e kvmmmu:fast_page_fault --filter "ret==3" -- ./access_tracking_perf_test
$ perf script | head -1
[...] new 610006048d25877 spurious 0 fixed 0 <------ should be 1
Fix this by exporting the enum values to userspace with TRACE_DEFINE_ENUM.
Fixes: c4371c2a682e ("KVM: x86/mmu: Return unique RET_PF_* values if the fault was fixed")
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20210713220957.3493520-3-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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fast_page_fault is only called from direct_page_fault where we know the
address is a gpa.
Fixes: 736c291c9f36 ("KVM: x86: Use gpa_t for cr2/gpa to fix TDP support on 32-bit KVM")
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20210713220957.3493520-2-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The file has been moved to arch/x86 long time ago. Time to get rid of
non-x86 stuff.
Signed-off-by: Juergen Gross <jgross@suse.com>
Message-Id: <20210701154105.23215-3-jgross@suse.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Add a new statistic max_mmu_rmap_size, which stores the maximum size of rmap
for the vm.
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20210625153214.43106-2-peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Return the old SPTE when clearing a SPTE and push the "old SPTE present"
check to the caller. Private shadow page support will use the old SPTE
in rmap_remove() to determine whether or not there is a linked private
shadow page.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <b16bac1fd1357aaf39e425aab2177d3f89ee8318.1625186503.git.isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Employ a 'continue' to reduce the indentation for linking a new shadow
page during __direct_map() in preparation for linking private pages.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <702419686d5700373123f6ea84e7a946c2cad8b4.1625186503.git.isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Move the kvm_dirty_regs vs. KVM_SYNC_X86_VALID_FIELDS check out of
sync_regs() and into its sole caller, kvm_arch_vcpu_ioctl_run(). This
allows a future patch to allow synchronizing select state for protected
VMs.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <889017a8d31cea46472e0c64b234ef5919278ed9.1625186503.git.isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <298980aa5fc5707184ac082287d13a800cd9c25f.1625186503.git.isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <0e8760a26151f47dc47052b25ca8b84fffe0641e.1625186503.git.isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Once an exception has been injected, any side effects related to
the exception (such as setting CR2 or DR6) have been taked place.
Therefore, once KVM sets the VM-entry interruption information
field or the AMD EVENTINJ field, the next VM-entry must deliver that
exception.
Pending interrupts are processed after injected exceptions, so
in theory it would not be a problem to use KVM_INTERRUPT when
an injected exception is present. However, DOSEMU is using
run->ready_for_interrupt_injection to detect interrupt windows
and then using KVM_SET_SREGS/KVM_SET_REGS to inject the
interrupt manually. For this to work, the interrupt window
must be delayed after the completion of the previous event
injection.
Cc: stable@vger.kernel.org
Reported-by: Stas Sergeev <stsp2@yandex.ru>
Tested-by: Stas Sergeev <stsp2@yandex.ru>
Fixes: 71cc849b7093 ("KVM: x86: Fix split-irqchip vs interrupt injection window request")
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Currently when SVM is enabled in guest CPUID, AVIC is inhibited as soon
as the guest CPUID is set.
AVIC happens to be fully disabled on all vCPUs by the time any guest
entry starts (if after migration the entry can be nested).
The reason is that currently we disable avic right away on vCPU from which
the kvm_request_apicv_update was called and for this case, it happens to be
called on all vCPUs (by svm_vcpu_after_set_cpuid).
After we stop doing this, AVIC will end up being disabled only when
KVM_REQ_APICV_UPDATE is processed which is after we done switching to the
nested guest.
Fix this by just using vmcb01 in svm_refresh_apicv_exec_ctrl for avic
(which is a right thing to do anyway).
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210713142023.106183-4-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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It is possible that AVIC was requested to be disabled but
not yet disabled, e.g if the nested entry is done right
after svm_vcpu_after_set_cpuid.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210713142023.106183-3-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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deactivated
It is possible for AVIC inhibit and AVIC active state to be mismatched.
Currently we disable AVIC right away on vCPU which started the AVIC inhibit
request thus this warning doesn't trigger but at least in theory,
if svm_set_vintr is called at the same time on multiple vCPUs,
the warning can happen.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210713142023.106183-2-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Right now, svm_hv_vmcb_dirty_nested_enlightenments has an incorrect
dereference of vmcb->control.reserved_sw before the vmcb is checked
for being non-NULL. The compiler is usually sinking the dereference
after the check; instead of doing this ourselves in the source,
ensure that svm_hv_vmcb_dirty_nested_enlightenments is only called
with a non-NULL VMCB.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Vineeth Pillai <viremana@linux.microsoft.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[Untested for now due to issues with my AMD machine. - Paolo]
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KVM_MAX_VCPU_ID is the maximum vcpu-id of a guest, and not the number
of vcpu-ids. Fix array indexed by vcpu-id to have KVM_MAX_VCPU_ID+1
elements.
Note that this is currently no real problem, as KVM_MAX_VCPU_ID is
an odd number, resulting in always enough padding being available at
the end of those arrays.
Nevertheless this should be fixed in order to avoid rare problems in
case someone is using an even number for KVM_MAX_VCPU_ID.
Signed-off-by: Juergen Gross <jgross@suse.com>
Message-Id: <20210701154105.23215-2-jgross@suse.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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MSR_KVM_ASYNC_PF_ACK MSR is part of interrupt based asynchronous page fault
interface and not the original (deprecated) KVM_FEATURE_ASYNC_PF. This is
stated in Documentation/virt/kvm/msr.rst.
Fixes: 66570e966dd9 ("kvm: x86: only provide PV features if enabled in guest's CPUID")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Oliver Upton <oupton@google.com>
Message-Id: <20210722123018.260035-1-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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svm_copy_vmrun_state()/svm_copy_vmloadsave_state()
Make svm_copy_vmrun_state()/svm_copy_vmloadsave_state() interface match
'memcpy(dest, src)' to avoid any confusion.
No functional change intended.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210719090322.625277-1-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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To match svm_copy_vmrun_state(), rename nested_svm_vmloadsave() to
svm_copy_vmloadsave_state().
Opportunistically add missing braces to 'else' branch in
vmload_vmsave_interception().
No functional change intended.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210716144104.465269-1-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Pull kvm fixes from Paolo Bonzini:
- Allow again loading KVM on 32-bit non-PAE builds
- Fixes for host SMIs on AMD
- Fixes for guest SMIs on AMD
- Fixes for selftests on s390 and ARM
- Fix memory leak
- Enforce no-instrumentation area on vmentry when hardware breakpoints
are in use.
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (25 commits)
KVM: selftests: smm_test: Test SMM enter from L2
KVM: nSVM: Restore nested control upon leaving SMM
KVM: nSVM: Fix L1 state corruption upon return from SMM
KVM: nSVM: Introduce svm_copy_vmrun_state()
KVM: nSVM: Check that VM_HSAVE_PA MSR was set before VMRUN
KVM: nSVM: Check the value written to MSR_VM_HSAVE_PA
KVM: SVM: Fix sev_pin_memory() error checks in SEV migration utilities
KVM: SVM: Return -EFAULT if copy_to_user() for SEV mig packet header fails
KVM: SVM: add module param to control the #SMI interception
KVM: SVM: remove INIT intercept handler
KVM: SVM: #SMI interception must not skip the instruction
KVM: VMX: Remove vmx_msr_index from vmx.h
KVM: X86: Disable hardware breakpoints unconditionally before kvm_x86->run()
KVM: selftests: Address extra memslot parameters in vm_vaddr_alloc
kvm: debugfs: fix memory leak in kvm_create_vm_debugfs
KVM: x86/pmu: Clear anythread deprecated bit when 0xa leaf is unsupported on the SVM
KVM: mmio: Fix use-after-free Read in kvm_vm_ioctl_unregister_coalesced_mmio
KVM: SVM: Revert clearing of C-bit on GPA in #NPF handler
KVM: x86/mmu: Do not apply HPA (memory encryption) mask to GPAs
KVM: x86: Use kernel's x86_phys_bits to handle reduced MAXPHYADDR
...
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If the VM was migrated while in SMM, no nested state was saved/restored,
and therefore svm_leave_smm has to load both save and control area
of the vmcb12. Save area is already loaded from HSAVE area,
so now load the control area as well from the vmcb12.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210628104425.391276-6-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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VMCB split commit 4995a3685f1b ("KVM: SVM: Use a separate vmcb for the
nested L2 guest") broke return from SMM when we entered there from guest
(L2) mode. Gen2 WS2016/Hyper-V is known to do this on boot. The problem
manifests itself like this:
kvm_exit: reason EXIT_RSM rip 0x7ffbb280 info 0 0
kvm_emulate_insn: 0:7ffbb280: 0f aa
kvm_smm_transition: vcpu 0: leaving SMM, smbase 0x7ffb3000
kvm_nested_vmrun: rip: 0x000000007ffbb280 vmcb: 0x0000000008224000
nrip: 0xffffffffffbbe119 int_ctl: 0x01020000 event_inj: 0x00000000
npt: on
kvm_nested_intercepts: cr_read: 0000 cr_write: 0010 excp: 40060002
intercepts: fd44bfeb 0000217f 00000000
kvm_entry: vcpu 0, rip 0xffffffffffbbe119
kvm_exit: reason EXIT_NPF rip 0xffffffffffbbe119 info
200000006 1ab000
kvm_nested_vmexit: vcpu 0 reason npf rip 0xffffffffffbbe119 info1
0x0000000200000006 info2 0x00000000001ab000 intr_info 0x00000000
error_code 0x00000000
kvm_page_fault: address 1ab000 error_code 6
kvm_nested_vmexit_inject: reason EXIT_NPF info1 200000006 info2 1ab000
int_info 0 int_info_err 0
kvm_entry: vcpu 0, rip 0x7ffbb280
kvm_exit: reason EXIT_EXCP_GP rip 0x7ffbb280 info 0 0
kvm_emulate_insn: 0:7ffbb280: 0f aa
kvm_inj_exception: #GP (0x0)
Note: return to L2 succeeded but upon first exit to L1 its RIP points to
'RSM' instruction but we're not in SMM.
The problem appears to be that VMCB01 gets irreversibly destroyed during
SMM execution. Previously, we used to have 'hsave' VMCB where regular
(pre-SMM) L1's state was saved upon nested_svm_vmexit() but now we just
switch to VMCB01 from VMCB02.
Pre-split (working) flow looked like:
- SMM is triggered during L2's execution
- L2's state is pushed to SMRAM
- nested_svm_vmexit() restores L1's state from 'hsave'
- SMM -> RSM
- enter_svm_guest_mode() switches to L2 but keeps 'hsave' intact so we have
pre-SMM (and pre L2 VMRUN) L1's state there
- L2's state is restored from SMRAM
- upon first exit L1's state is restored from L1.
This was always broken with regards to svm_get_nested_state()/
svm_set_nested_state(): 'hsave' was never a part of what's being
save and restored so migration happening during SMM triggered from L2 would
never restore L1's state correctly.
Post-split flow (broken) looks like:
- SMM is triggered during L2's execution
- L2's state is pushed to SMRAM
- nested_svm_vmexit() switches to VMCB01 from VMCB02
- SMM -> RSM
- enter_svm_guest_mode() switches from VMCB01 to VMCB02 but pre-SMM VMCB01
is already lost.
- L2's state is restored from SMRAM
- upon first exit L1's state is restored from VMCB01 but it is corrupted
(reflects the state during 'RSM' execution).
VMX doesn't have this problem because unlike VMCB, VMCS keeps both guest
and host state so when we switch back to VMCS02 L1's state is intact there.
To resolve the issue we need to save L1's state somewhere. We could've
created a third VMCB for SMM but that would require us to modify saved
state format. L1's architectural HSAVE area (pointed by MSR_VM_HSAVE_PA)
seems appropriate: L0 is free to save any (or none) of L1's state there.
Currently, KVM does 'none'.
Note, for nested state migration to succeed, both source and destination
hypervisors must have the fix. We, however, don't need to create a new
flag indicating the fact that HSAVE area is now populated as migration
during SMM triggered from L2 was always broken.
Fixes: 4995a3685f1b ("KVM: SVM: Use a separate vmcb for the nested L2 guest")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Separate the code setting non-VMLOAD-VMSAVE state from
svm_set_nested_state() into its own function. This is going to be
re-used from svm_enter_smm()/svm_leave_smm().
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210628104425.391276-4-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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APM states that "The address written to the VM_HSAVE_PA MSR, which holds
the address of the page used to save the host state on a VMRUN, must point
to a hypervisor-owned page. If this check fails, the WRMSR will fail with
a #GP(0) exception. Note that a value of 0 is not considered valid for the
VM_HSAVE_PA MSR and a VMRUN that is attempted while the HSAVE_PA is 0 will
fail with a #GP(0) exception."
svm_set_msr() already checks that the supplied address is valid, so only
check for '0' is missing. Add it to nested_svm_vmrun().
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210628104425.391276-3-vkuznets@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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APM states that #GP is raised upon write to MSR_VM_HSAVE_PA when
the supplied address is not page-aligned or is outside of "maximum
supported physical address for this implementation".
page_address_valid() check seems suitable. Also, forcefully page-align
the address when it's written from VMM.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210628104425.391276-2-vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
[Add comment about behavior for host-provided values. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Use IS_ERR() instead of checking for a NULL pointer when querying for
sev_pin_memory() failures. sev_pin_memory() always returns an error code
cast to a pointer, or a valid pointer; it never returns NULL.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Steve Rutherford <srutherford@google.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Ashish Kalra <ashish.kalra@amd.com>
Fixes: d3d1af85e2c7 ("KVM: SVM: Add KVM_SEND_UPDATE_DATA command")
Fixes: 15fb7de1a7f5 ("KVM: SVM: Add KVM_SEV_RECEIVE_UPDATE_DATA command")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210506175826.2166383-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Return -EFAULT if copy_to_user() fails; if accessing user memory faults,
copy_to_user() returns the number of bytes remaining, not an error code.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Steve Rutherford <srutherford@google.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Ashish Kalra <ashish.kalra@amd.com>
Fixes: d3d1af85e2c7 ("KVM: SVM: Add KVM_SEND_UPDATE_DATA command")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210506175826.2166383-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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In theory there are no side effects of not intercepting #SMI,
because then #SMI becomes transparent to the OS and the KVM.
Plus an observation on recent Zen2 CPUs reveals that these
CPUs ignore #SMI interception and never deliver #SMI VMexits.
This is also useful to test nested KVM to see that L1
handles #SMIs correctly in case when L1 doesn't intercept #SMI.
Finally the default remains the same, the SMI are intercepted
by default thus this patch doesn't have any effect unless
non default module param value is used.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210707125100.677203-4-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Kernel never sends real INIT even to CPUs, other than on boot.
Thus INIT interception is an error which should be caught
by a check for an unknown VMexit reason.
On top of that, the current INIT VM exit handler skips
the current instruction which is wrong.
That was added in commit 5ff3a351f687 ("KVM: x86: Move trivial
instruction-based exit handlers to common code").
Fixes: 5ff3a351f687 ("KVM: x86: Move trivial instruction-based exit handlers to common code")
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210707125100.677203-3-mlevitsk@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Commit 5ff3a351f687 ("KVM: x86: Move trivial instruction-based
exit handlers to common code"), unfortunately made a mistake of
treating nop_on_interception and nop_interception in the same way.
Former does truly nothing while the latter skips the instruction.
SMI VM exit handler should do nothing.
(SMI itself is handled by the host when we do STGI)
Fixes: 5ff3a351f687 ("KVM: x86: Move trivial instruction-based exit handlers to common code")
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210707125100.677203-2-mlevitsk@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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