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KVM: x86: Tweak name of MONITOR/MWAIT #UD quirk to make it #UD specific

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Add a "UD" clause to KVM_X86_QUIRK_MWAIT_NEVER_FAULTS to make it clear
that the quirk only controls the #UD behavior of MONITOR/MWAIT.  KVM
doesn't currently enforce fault checks when MONITOR/MWAIT are supported,
but that could change in the future.  SVM also has a virtualization hole
in that it checks all faults before intercepts, and so "never faults" is
already a lie when running on SVM.

Fixes: bfbcc81bb8 ("KVM: x86: Add a quirk for KVM's "MONITOR/MWAIT are NOPs!" behavior")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20220711225753.1073989-4-seanjc@google.com
This commit is contained in:
Sean Christopherson 2022-07-11 22:57:53 +00:00
parent 14fd95bf14
commit 43bb9e000e
5 changed files with 5 additions and 5 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

2
Documentation/virt/kvm/api.rst
View file

@ -7523,7 +7523,7 @@ The valid bits in cap.args[0] are:
incorrect hypercall instruction will incorrect hypercall instruction will
generate a #UD within the guest. generate a #UD within the guest.
KVM_X86_QUIRK_MWAIT_NEVER_FAULTS By default, KVM emulates MONITOR/MWAIT (if KVM_X86_QUIRK_MWAIT_NEVER_UD_FAULTS By default, KVM emulates MONITOR/MWAIT (if
they are intercepted) as NOPs regardless of they are intercepted) as NOPs regardless of
whether or not MONITOR/MWAIT are supported whether or not MONITOR/MWAIT are supported
according to guest CPUID. When this quirk according to guest CPUID. When this quirk

2
arch/x86/include/asm/kvm_host.h
View file

@ -2096,6 +2096,6 @@ int memslot_rmap_alloc(struct kvm_memory_slot *slot, unsigned long npages);
KVM_X86_QUIRK_OUT_7E_INC_RIP | \ KVM_X86_QUIRK_OUT_7E_INC_RIP | \
KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT | \ KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT | \
KVM_X86_QUIRK_FIX_HYPERCALL_INSN | \ KVM_X86_QUIRK_FIX_HYPERCALL_INSN | \
KVM_X86_QUIRK_MWAIT_NEVER_FAULTS) KVM_X86_QUIRK_MWAIT_NEVER_UD_FAULTS)
#endif /* _ASM_X86_KVM_HOST_H */ #endif /* _ASM_X86_KVM_HOST_H */

2
arch/x86/include/uapi/asm/kvm.h
View file

@ -439,7 +439,7 @@ struct kvm_sync_regs {
#define KVM_X86_QUIRK_OUT_7E_INC_RIP (1 << 3) #define KVM_X86_QUIRK_OUT_7E_INC_RIP (1 << 3)
#define KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT (1 << 4) #define KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT (1 << 4)
#define KVM_X86_QUIRK_FIX_HYPERCALL_INSN (1 << 5) #define KVM_X86_QUIRK_FIX_HYPERCALL_INSN (1 << 5)
#define KVM_X86_QUIRK_MWAIT_NEVER_FAULTS (1 << 6) #define KVM_X86_QUIRK_MWAIT_NEVER_UD_FAULTS (1 << 6)
#define KVM_STATE_NESTED_FORMAT_VMX 0 #define KVM_STATE_NESTED_FORMAT_VMX 0
#define KVM_STATE_NESTED_FORMAT_SVM 1 #define KVM_STATE_NESTED_FORMAT_SVM 1

2
arch/x86/kvm/x86.c
View file

@ -2046,7 +2046,7 @@ EXPORT_SYMBOL_GPL(kvm_handle_invalid_op);
static int kvm_emulate_monitor_mwait(struct kvm_vcpu *vcpu, const char *insn) static int kvm_emulate_monitor_mwait(struct kvm_vcpu *vcpu, const char *insn)
{ {
if (!kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_MWAIT_NEVER_FAULTS) && if (!kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_MWAIT_NEVER_UD_FAULTS) &&
!guest_cpuid_has(vcpu, X86_FEATURE_MWAIT)) !guest_cpuid_has(vcpu, X86_FEATURE_MWAIT))
return kvm_handle_invalid_op(vcpu); return kvm_handle_invalid_op(vcpu);

2
tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c
View file

@ -113,7 +113,7 @@ int main(int argc, char *argv[])
disabled_quirks = 0; disabled_quirks = 0;
if (testcase & MWAIT_QUIRK_DISABLED) if (testcase & MWAIT_QUIRK_DISABLED)
disabled_quirks |= KVM_X86_QUIRK_MWAIT_NEVER_FAULTS; disabled_quirks |= KVM_X86_QUIRK_MWAIT_NEVER_UD_FAULTS;
if (testcase & MISC_ENABLES_QUIRK_DISABLED) if (testcase & MISC_ENABLES_QUIRK_DISABLED)
disabled_quirks |= KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT; disabled_quirks |= KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT;
vm_enable_cap(vm, KVM_CAP_DISABLE_QUIRKS2, disabled_quirks); vm_enable_cap(vm, KVM_CAP_DISABLE_QUIRKS2, disabled_quirks);