diff options
| author | Sean Christopherson <seanjc@google.com> | 2023-08-15 13:36:40 -0700 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2023-08-17 11:38:27 -0700 |
| commit | ccf31d6e6cc53e50cc42845061174082fd229c79 (patch) | |
| tree | 897c6203c7b1eb636b13fec237772ff0ba480afc /arch/x86/kvm/cpuid.c | |
| parent | 42764413d19585caff1321823b376c0bd0a597af (diff) | |
KVM: x86/mmu: Use KVM-governed feature framework to track "GBPAGES enabled"
Use the governed feature framework to track whether or not the guest can
use 1GiB pages, and drop the one-off helper that wraps the surprisingly
non-trivial logic surrounding 1GiB page usage in the guest.
No functional change intended.
Reviewed-by: Yuan Yao <yuan.yao@intel.com>
Link: https://lore.kernel.org/r/20230815203653.519297-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'arch/x86/kvm/cpuid.c')
| -rw-r--r-- | arch/x86/kvm/cpuid.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 4ba43ae008cb..67e9f79fe059 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -312,11 +312,28 @@ static void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) { struct kvm_lapic *apic = vcpu->arch.apic; struct kvm_cpuid_entry2 *best; + bool allow_gbpages; BUILD_BUG_ON(KVM_NR_GOVERNED_FEATURES > KVM_MAX_NR_GOVERNED_FEATURES); bitmap_zero(vcpu->arch.governed_features.enabled, KVM_MAX_NR_GOVERNED_FEATURES); + /* + * If TDP is enabled, let the guest use GBPAGES if they're supported in + * hardware. The hardware page walker doesn't let KVM disable GBPAGES, + * i.e. won't treat them as reserved, and KVM doesn't redo the GVA->GPA + * walk for performance and complexity reasons. Not to mention KVM + * _can't_ solve the problem because GVA->GPA walks aren't visible to + * KVM once a TDP translation is installed. Mimic hardware behavior so + * that KVM's is at least consistent, i.e. doesn't randomly inject #PF. + * If TDP is disabled, honor *only* guest CPUID as KVM has full control + * and can install smaller shadow pages if the host lacks 1GiB support. + */ + allow_gbpages = tdp_enabled ? boot_cpu_has(X86_FEATURE_GBPAGES) : + guest_cpuid_has(vcpu, X86_FEATURE_GBPAGES); + if (allow_gbpages) + kvm_governed_feature_set(vcpu, X86_FEATURE_GBPAGES); + best = kvm_find_cpuid_entry(vcpu, 1); if (best && apic) { if (cpuid_entry_has(best, X86_FEATURE_TSC_DEADLINE_TIMER)) |