Commit 7392079c authored Mar 02, 2020 by Sean Christopherson Committed by Paolo Bonzini Mar 16, 2020

KVM: x86: Clear output regs for CPUID 0x14 if PT isn't exposed to guest

Clear the output regs for the main CPUID 0x14 leaf (index=0) if Intel PT
isn't exposed to the guest. Leaf 0x14 enumerates Intel PT capabilities
and should return zeroes if PT is not supported. Incorrectly reporting
PT capabilities is essentially a cosmetic error, i.e. doesn't negatively
affect any known userspace/kernel, as the existence of PT itself is
correctly enumerated via CPUID 0x7.

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent 615a4ae1

arch/x86/kvm/cpuid.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -663,8 +663,10 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
		break;
		/* Intel PT */
		case 0x14:
		if (!f_intel_pt)
		if (!f_intel_pt) {
		entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
		break;
		}

		for (i = 1, max_idx = entry->eax; i <= max_idx; ++i) {
		if (!do_host_cpuid(array, function, i))

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