diff options
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 46 | ||||
| -rw-r--r-- | arch/x86/kvm/cpuid.c | 14 | ||||
| -rw-r--r-- | arch/x86/kvm/cpuid.h | 10 | ||||
| -rw-r--r-- | arch/x86/kvm/reverse_cpuid.h | 17 |
4 files changed, 45 insertions, 42 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index f076df9f18be..81ce8cd5814a 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -739,6 +739,23 @@ struct kvm_queued_exception { bool has_payload; }; +/* + * Hardware-defined CPUID leafs that are either scattered by the kernel or are + * unknown to the kernel, but need to be directly used by KVM. Note, these + * word values conflict with the kernel's "bug" caps, but KVM doesn't use those. + */ +enum kvm_only_cpuid_leafs { + CPUID_12_EAX = NCAPINTS, + CPUID_7_1_EDX, + CPUID_8000_0007_EDX, + CPUID_8000_0022_EAX, + CPUID_7_2_EDX, + CPUID_24_0_EBX, + NR_KVM_CPU_CAPS, + + NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS, +}; + struct kvm_vcpu_arch { /* * rip and regs accesses must go through @@ -857,23 +874,20 @@ struct kvm_vcpu_arch { bool is_amd_compatible; /* - * FIXME: Drop this macro and use KVM_NR_GOVERNED_FEATURES directly - * when "struct kvm_vcpu_arch" is no longer defined in an - * arch/x86/include/asm header. The max is mostly arbitrary, i.e. - * can be increased as necessary. - */ -#define KVM_MAX_NR_GOVERNED_FEATURES BITS_PER_LONG - - /* - * Track whether or not the guest is allowed to use features that are - * governed by KVM, where "governed" means KVM needs to manage state - * and/or explicitly enable the feature in hardware. Typically, but - * not always, governed features can be used by the guest if and only - * if both KVM and userspace want to expose the feature to the guest. + * cpu_caps holds the effective guest capabilities, i.e. the features + * the vCPU is allowed to use. Typically, but not always, features can + * be used by the guest if and only if both KVM and userspace want to + * expose the feature to the guest. + * + * A common exception is for virtualization holes, i.e. when KVM can't + * prevent the guest from using a feature, in which case the vCPU "has" + * the feature regardless of what KVM or userspace desires. + * + * Note, features that don't require KVM involvement in any way are + * NOT enforced/sanitized by KVM, i.e. are taken verbatim from the + * guest CPUID provided by userspace. */ - struct { - DECLARE_BITMAP(enabled, KVM_MAX_NR_GOVERNED_FEATURES); - } governed_features; + u32 cpu_caps[NR_KVM_CPU_CAPS]; u64 reserved_gpa_bits; int maxphyaddr; diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 42d05bb73e5b..29a9562031f4 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -360,9 +360,7 @@ void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) 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); + memset(vcpu->arch.cpu_caps, 0, sizeof(vcpu->arch.cpu_caps)); kvm_update_cpuid_runtime(vcpu); @@ -446,6 +444,7 @@ u64 kvm_vcpu_reserved_gpa_bits_raw(struct kvm_vcpu *vcpu) static int kvm_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2, int nent) { + u32 vcpu_caps[NR_KVM_CPU_CAPS]; int r; /* @@ -453,10 +452,18 @@ static int kvm_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2, * order to massage the new entries, e.g. to account for dynamic bits * that KVM controls, without clobbering the current guest CPUID, which * KVM needs to preserve in order to unwind on failure. + * + * Similarly, save the vCPU's current cpu_caps so that the capabilities + * can be updated alongside the CPUID entries when performing runtime + * updates. Full initialization is done if and only if the vCPU hasn't + * run, i.e. only if userspace is potentially changing CPUID features. */ swap(vcpu->arch.cpuid_entries, e2); swap(vcpu->arch.cpuid_nent, nent); + memcpy(vcpu_caps, vcpu->arch.cpu_caps, sizeof(vcpu_caps)); + BUILD_BUG_ON(sizeof(vcpu_caps) != sizeof(vcpu->arch.cpu_caps)); + /* * KVM does not correctly handle changing guest CPUID after KVM_RUN, as * MAXPHYADDR, GBPAGES support, AMD reserved bit behavior, etc.. aren't @@ -497,6 +504,7 @@ success: return 0; err: + memcpy(vcpu->arch.cpu_caps, vcpu_caps, sizeof(vcpu_caps)); swap(vcpu->arch.cpuid_entries, e2); swap(vcpu->arch.cpuid_nent, nent); return r; diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h index 8fe0c1772f19..486cb1429998 100644 --- a/arch/x86/kvm/cpuid.h +++ b/arch/x86/kvm/cpuid.h @@ -241,10 +241,9 @@ static __always_inline bool kvm_is_governed_feature(unsigned int x86_feature) static __always_inline void guest_cpu_cap_set(struct kvm_vcpu *vcpu, unsigned int x86_feature) { - BUILD_BUG_ON(!kvm_is_governed_feature(x86_feature)); + unsigned int x86_leaf = __feature_leaf(x86_feature); - __set_bit(kvm_governed_feature_index(x86_feature), - vcpu->arch.governed_features.enabled); + vcpu->arch.cpu_caps[x86_leaf] |= __feature_bit(x86_feature); } static __always_inline void guest_cpu_cap_check_and_set(struct kvm_vcpu *vcpu, @@ -257,10 +256,9 @@ static __always_inline void guest_cpu_cap_check_and_set(struct kvm_vcpu *vcpu, static __always_inline bool guest_cpu_cap_has(struct kvm_vcpu *vcpu, unsigned int x86_feature) { - BUILD_BUG_ON(!kvm_is_governed_feature(x86_feature)); + unsigned int x86_leaf = __feature_leaf(x86_feature); - return test_bit(kvm_governed_feature_index(x86_feature), - vcpu->arch.governed_features.enabled); + return vcpu->arch.cpu_caps[x86_leaf] & __feature_bit(x86_feature); } static inline bool kvm_vcpu_is_legal_cr3(struct kvm_vcpu *vcpu, unsigned long cr3) diff --git a/arch/x86/kvm/reverse_cpuid.h b/arch/x86/kvm/reverse_cpuid.h index 1d2db9d529ff..fde0ae986003 100644 --- a/arch/x86/kvm/reverse_cpuid.h +++ b/arch/x86/kvm/reverse_cpuid.h @@ -7,23 +7,6 @@ #include <asm/cpufeatures.h> /* - * Hardware-defined CPUID leafs that are either scattered by the kernel or are - * unknown to the kernel, but need to be directly used by KVM. Note, these - * word values conflict with the kernel's "bug" caps, but KVM doesn't use those. - */ -enum kvm_only_cpuid_leafs { - CPUID_12_EAX = NCAPINTS, - CPUID_7_1_EDX, - CPUID_8000_0007_EDX, - CPUID_8000_0022_EAX, - CPUID_7_2_EDX, - CPUID_24_0_EBX, - NR_KVM_CPU_CAPS, - - NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS, -}; - -/* * Define a KVM-only feature flag. * * For features that are scattered by cpufeatures.h, __feature_translate() also |