Commit 43bb9e00 authored by Sean Christopherson's avatar Sean Christopherson
Browse files

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



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: bfbcc81b ("KVM: x86: Add a quirk for KVM's "MONITOR/MWAIT are NOPs!" behavior")
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20220711225753.1073989-4-seanjc@google.com
parent 14fd95bf

Documentation/virt/kvm/api.rst

+1 −1
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@@ -7523,7 +7523,7 @@ The valid bits in cap.args[0] are: 
                                    incorrect hypercall instruction will

                                    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

                                    whether or not MONITOR/MWAIT are supported

                                    according to guest CPUID.  When this quirk

arch/x86/include/asm/kvm_host.h

+1 −1
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@@ -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_MISC_ENABLE_NO_MWAIT |	\

	 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 */

arch/x86/include/uapi/asm/kvm.h

+1 −1
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@@ -439,7 +439,7 @@ struct kvm_sync_regs { 
#define KVM_X86_QUIRK_OUT_7E_INC_RIP		(1 << 3)

#define KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT	(1 << 4)

#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_SVM	1

arch/x86/kvm/x86.c

+1 −1
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@@ -2046,7 +2046,7 @@ EXPORT_SYMBOL_GPL(kvm_handle_invalid_op); 


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))

		return kvm_handle_invalid_op(vcpu);

tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c

+1 −1
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@@ -113,7 +113,7 @@ int main(int argc, char *argv[]) 


		disabled_quirks = 0;

		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)

			disabled_quirks |= KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT;

		vm_enable_cap(vm, KVM_CAP_DISABLE_QUIRKS2, disabled_quirks);