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KVM: x86: Add return value to kvm_cpuid().

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Return false in kvm_cpuid() when it fails to find the cpuid
entry. Also, this routine(and its caller) is optimized with
a new argument - check_limit, so that the check_cpuid_limit()
fall back can be avoided.

Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Yu Zhang
2017-08-24 20:27:52 +08:00
committed by Paolo Bonzini
parent 3db134805c
commit e911eb3b34
7 changed files with 35 additions and 22 deletions
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19
arch/x86/kvm/cpuid.c
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@@ -853,16 +853,24 @@ static struct kvm_cpuid_entry2* check_cpuid_limit(struct kvm_vcpu *vcpu,
return kvm_find_cpuid_entry(vcpu, maxlevel->eax, index);
}
void kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx, u32 *ecx, u32 *edx)
bool kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx,
u32 *ecx, u32 *edx, bool check_limit)
{
u32 function = *eax, index = *ecx;
struct kvm_cpuid_entry2 *best;
bool entry_found = true;
best = kvm_find_cpuid_entry(vcpu, function, index);
if (!best)
best = check_cpuid_limit(vcpu, function, index);
if (!best) {
entry_found = false;
if (!check_limit)
goto out;
best = check_cpuid_limit(vcpu, function, index);
}
out:
if (best) {
*eax = best->eax;
*ebx = best->ebx;
@@ -870,7 +878,8 @@ void kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx, u32 *ecx, u32 *edx)
*edx = best->edx;
} else
*eax = *ebx = *ecx = *edx = 0;
trace_kvm_cpuid(function, *eax, *ebx, *ecx, *edx);
trace_kvm_cpuid(function, *eax, *ebx, *ecx, *edx, entry_found);
return entry_found;
}
EXPORT_SYMBOL_GPL(kvm_cpuid);
@@ -883,7 +892,7 @@ int kvm_emulate_cpuid(struct kvm_vcpu *vcpu)
eax = kvm_register_read(vcpu, VCPU_REGS_RAX);
ecx = kvm_register_read(vcpu, VCPU_REGS_RCX);
kvm_cpuid(vcpu, &eax, &ebx, &ecx, &edx);
kvm_cpuid(vcpu, &eax, &ebx, &ecx, &edx, true);
kvm_register_write(vcpu, VCPU_REGS_RAX, eax);
kvm_register_write(vcpu, VCPU_REGS_RBX, ebx);
kvm_register_write(vcpu, VCPU_REGS_RCX, ecx);