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KVM: nSVM: Expose SVM features to L1 iff nested is enabled

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Set SVM feature bits in KVM capabilities if and only if nested=true, KVM
shouldn't advertise features that realistically can't be used.  Use
kvm_cpu_cap_has(X86_FEATURE_SVM) to indirectly query "nested" in
svm_set_supported_cpuid() in anticipation of moving CPUID 0x8000000A
adjustments into common x86 code.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2020-03-02 15:57:07 -08:00 committed by Paolo Bonzini
parent 91661989d1
commit a50718cc3f
1 changed files with 13 additions and 9 deletions
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22
arch/x86/kvm/svm.c
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@ -1371,21 +1371,21 @@ static __init void svm_set_cpu_caps(void)
{
kvm_set_cpu_caps();
/* CPUID 0x80000001 */
if (nested)
/* CPUID 0x80000001 and 0x8000000A (SVM features) */
if (nested) {
kvm_cpu_cap_set(X86_FEATURE_SVM);
if (boot_cpu_has(X86_FEATURE_NRIPS))
kvm_cpu_cap_set(X86_FEATURE_NRIPS);
if (npt_enabled)
kvm_cpu_cap_set(X86_FEATURE_NPT);
}
/* CPUID 0x80000008 */
if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) ||
boot_cpu_has(X86_FEATURE_AMD_SSBD))
kvm_cpu_cap_set(X86_FEATURE_VIRT_SSBD);
/* CPUID 0x8000000A */
/* Support next_rip if host supports it */
kvm_cpu_cap_check_and_set(X86_FEATURE_NRIPS);
if (npt_enabled)
kvm_cpu_cap_set(X86_FEATURE_NPT);
}
static __init int svm_hardware_setup(void)
@ -6055,6 +6055,10 @@ static void svm_set_supported_cpuid(struct kvm_cpuid_entry2 *entry)
{
switch (entry->function) {
case 0x8000000A:
if (!kvm_cpu_cap_has(X86_FEATURE_SVM)) {
entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
break;
}
entry->eax = 1; /* SVM revision 1 */
entry->ebx = 8; /* Lets support 8 ASIDs in case we add proper
ASID emulation to nested SVM */