diff options
Diffstat (limited to 'arch/x86/kvm/cpuid.c')
| -rw-r--r-- | arch/x86/kvm/cpuid.c | 40 |
1 files changed, 39 insertions, 1 deletions
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index d3432687c9e6..0544e30b4946 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -11,6 +11,7 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/kvm_host.h> +#include "linux/lockdep.h" #include <linux/export.h> #include <linux/vmalloc.h> #include <linux/uaccess.h> @@ -84,6 +85,18 @@ static inline struct kvm_cpuid_entry2 *cpuid_entry2_find( struct kvm_cpuid_entry2 *e; int i; + /* + * KVM has a semi-arbitrary rule that querying the guest's CPUID model + * with IRQs disabled is disallowed. The CPUID model can legitimately + * have over one hundred entries, i.e. the lookup is slow, and IRQs are + * typically disabled in KVM only when KVM is in a performance critical + * path, e.g. the core VM-Enter/VM-Exit run loop. Nothing will break + * if this rule is violated, this assertion is purely to flag potential + * performance issues. If this fires, consider moving the lookup out + * of the hotpath, e.g. by caching information during CPUID updates. + */ + lockdep_assert_irqs_enabled(); + for (i = 0; i < nent; i++) { e = &entries[i]; @@ -312,6 +325,27 @@ 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) { @@ -647,7 +681,8 @@ void kvm_set_cpu_caps(void) ); kvm_cpu_cap_init_kvm_defined(CPUID_7_1_EDX, - F(AVX_VNNI_INT8) | F(AVX_NE_CONVERT) | F(PREFETCHITI) + F(AVX_VNNI_INT8) | F(AVX_NE_CONVERT) | F(PREFETCHITI) | + F(AMX_COMPLEX) ); kvm_cpu_cap_mask(CPUID_D_1_EAX, @@ -1154,6 +1189,9 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) cpuid_entry_override(entry, CPUID_8000_0001_EDX); cpuid_entry_override(entry, CPUID_8000_0001_ECX); break; + case 0x80000005: + /* Pass host L1 cache and TLB info. */ + break; case 0x80000006: /* Drop reserved bits, pass host L2 cache and TLB info. */ entry->edx &= ~GENMASK(17, 16); |