From 9b58b9857f221e4f7149a22727ef61d0c141f56b Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Mon, 2 Mar 2020 15:56:42 -0800 Subject: [PATCH] KVM: SVM: Convert feature updates from CPUID to KVM cpu caps Use the recently introduced KVM CPU caps to propagate SVM-only (kernel) settings to supported CPUID flags. Note, there are a few subtleties: - Setting a flag based on a *different* feature is effectively emulation, and must be done at runtime via ->set_supported_cpuid(). - CPUID 0x8000000A.EDX is a feature leaf that was previously not adjusted by kvm_cpu_cap_mask() because all features are hidden by default. Opportunistically add a technically unnecessary break and fix an indentation issue in svm_set_supported_cpuid(). No functional change intended. Reviewed-by: Vitaly Kuznetsov Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- arch/x86/kvm/cpuid.c | 6 ++++++ arch/x86/kvm/svm.c | 46 +++++++++++++++++++++++++++++--------------- 2 files changed, 36 insertions(+), 16 deletions(-) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 31ea934d9b49..a5aed82d9ffa 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -370,6 +370,12 @@ void kvm_set_cpu_caps(void) F(AMD_SSB_NO) | F(AMD_STIBP) | F(AMD_STIBP_ALWAYS_ON) ); + /* + * Hide all SVM features by default, SVM will set the cap bits for + * features it emulates and/or exposes for L1. + */ + kvm_cpu_cap_mask(CPUID_8000_000A_EDX, 0); + kvm_cpu_cap_mask(CPUID_C000_0001_EDX, F(XSTORE) | F(XSTORE_EN) | F(XCRYPT) | F(XCRYPT_EN) | F(ACE2) | F(ACE2_EN) | F(PHE) | F(PHE_EN) | diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index aae5e3eff48d..61333c8306b0 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1367,6 +1367,23 @@ static void svm_hardware_teardown(void) iopm_base = 0; } +static __init void svm_set_cpu_caps(void) +{ + kvm_set_cpu_caps(); + + /* CPUID 0x80000001 */ + if (nested) + kvm_cpu_cap_set(X86_FEATURE_SVM); + + /* CPUID 0x8000000A */ + /* Support next_rip if host supports it */ + if (boot_cpu_has(X86_FEATURE_NRIPS)) + kvm_cpu_cap_set(X86_FEATURE_NRIPS); + + if (npt_enabled) + kvm_cpu_cap_set(X86_FEATURE_NPT); +} + static __init int svm_hardware_setup(void) { int cpu; @@ -1479,7 +1496,7 @@ static __init int svm_hardware_setup(void) pr_info("Virtual GIF supported\n"); } - kvm_set_cpu_caps(); + svm_set_cpu_caps(); return 0; @@ -6035,16 +6052,20 @@ static void svm_cpuid_update(struct kvm_vcpu *vcpu) APICV_INHIBIT_REASON_NESTED); } +/* + * Vendor specific emulation must be handled via ->set_supported_cpuid(), not + * svm_set_cpu_caps(), as capabilities configured during hardware_setup() are + * masked against hardware/kernel support, i.e. they'd be lost. + * + * Note, setting a flag based on a *different* feature, e.g. setting VIRT_SSBD + * if LS_CFG_SSBD or AMD_SSBD is supported, is effectively emulation. + */ static void svm_set_supported_cpuid(struct kvm_cpuid_entry2 *entry) { switch (entry->function) { - case 0x80000001: - if (nested) - cpuid_entry_set(entry, X86_FEATURE_SVM); - break; case 0x80000008: if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) || - boot_cpu_has(X86_FEATURE_AMD_SSBD)) + boot_cpu_has(X86_FEATURE_AMD_SSBD)) cpuid_entry_set(entry, X86_FEATURE_VIRT_SSBD); break; case 0x8000000A: @@ -6052,16 +6073,9 @@ static void svm_set_supported_cpuid(struct kvm_cpuid_entry2 *entry) entry->ebx = 8; /* Lets support 8 ASIDs in case we add proper ASID emulation to nested SVM */ entry->ecx = 0; /* Reserved */ - entry->edx = 0; /* Per default do not support any - additional features */ - - /* Support next_rip if host supports it */ - if (boot_cpu_has(X86_FEATURE_NRIPS)) - cpuid_entry_set(entry, X86_FEATURE_NRIPS); - - /* Support NPT for the guest if enabled */ - if (npt_enabled) - cpuid_entry_set(entry, X86_FEATURE_NPT); + /* Note, 0x8000000A.EDX is managed via kvm_cpu_caps. */; + cpuid_entry_mask(entry, CPUID_8000_000A_EDX); + break; } }