From cfc481810c903a5f74e5c7bf50ca8e28318dbc44 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Mon, 2 Mar 2020 15:56:23 -0800 Subject: [PATCH] KVM: x86: Calculate the supported xcr0 mask at load time Add a new global variable, supported_xcr0, to track which xcr0 bits can be exposed to the guest instead of calculating the mask on every call. The supported bits are constant for a given instance of KVM. This paves the way toward eliminating the ->mpx_supported() call in kvm_mpx_supported(), e.g. eliminates multiple retpolines in VMX's nested VM-Enter path, and eventually toward eliminating ->mpx_supported() altogether. No functional change intended. Reviewed-by: Xiaoyao Li Reviewed-by: Vitaly Kuznetsov Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- arch/x86/kvm/cpuid.c | 32 +++++++++----------------------- arch/x86/kvm/svm.c | 2 ++ arch/x86/kvm/vmx/vmx.c | 4 ++++ arch/x86/kvm/x86.c | 14 +++++++++++--- arch/x86/kvm/x86.h | 7 +------ 5 files changed, 27 insertions(+), 32 deletions(-) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 85f2920..1eb775c 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -52,16 +52,6 @@ bool kvm_mpx_supported(void) } EXPORT_SYMBOL_GPL(kvm_mpx_supported); -u64 kvm_supported_xcr0(void) -{ - u64 xcr0 = KVM_SUPPORTED_XCR0 & host_xcr0; - - if (!kvm_mpx_supported()) - xcr0 &= ~(XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR); - - return xcr0; -} - #define F feature_bit int kvm_update_cpuid(struct kvm_vcpu *vcpu) @@ -107,8 +97,7 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu) vcpu->arch.guest_xstate_size = XSAVE_HDR_SIZE + XSAVE_HDR_OFFSET; } else { vcpu->arch.guest_supported_xcr0 = - (best->eax | ((u64)best->edx << 32)) & - kvm_supported_xcr0(); + (best->eax | ((u64)best->edx << 32)) & supported_xcr0; vcpu->arch.guest_xstate_size = best->ebx = xstate_required_size(vcpu->arch.xcr0, false); } @@ -633,14 +622,12 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) goto out; } break; - case 0xd: { - u64 supported = kvm_supported_xcr0(); - - entry->eax &= supported; - entry->ebx = xstate_required_size(supported, false); + case 0xd: + entry->eax &= supported_xcr0; + entry->ebx = xstate_required_size(supported_xcr0, false); entry->ecx = entry->ebx; - entry->edx &= supported >> 32; - if (!supported) + entry->edx &= supported_xcr0 >> 32; + if (!supported_xcr0) break; entry = do_host_cpuid(array, function, 1); @@ -650,7 +637,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) entry->eax &= kvm_cpuid_D_1_eax_x86_features; cpuid_mask(&entry->eax, CPUID_D_1_EAX); if (entry->eax & (F(XSAVES)|F(XSAVEC))) - entry->ebx = xstate_required_size(supported, true); + entry->ebx = xstate_required_size(supported_xcr0, true); else entry->ebx = 0; /* Saving XSS controlled state via XSAVES isn't supported. */ @@ -658,7 +645,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) entry->edx = 0; for (i = 2; i < 64; ++i) { - if (!(supported & BIT_ULL(i))) + if (!(supported_xcr0 & BIT_ULL(i))) continue; entry = do_host_cpuid(array, function, i); @@ -666,7 +653,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) goto out; /* - * The @supported check above should have filtered out + * The supported check above should have filtered out * invalid sub-leafs as well as sub-leafs managed by * IA32_XSS MSR. Only XCR0-managed sub-leafs should * reach this point, and they should have a non-zero @@ -681,7 +668,6 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) entry->edx = 0; } break; - } /* Intel PT */ case 0x14: if (!f_intel_pt) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 7f32c40..5ba2ef1 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1385,6 +1385,8 @@ static __init int svm_hardware_setup(void) init_msrpm_offsets(); + supported_xcr0 &= ~(XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR); + if (boot_cpu_has(X86_FEATURE_NX)) kvm_enable_efer_bits(EFER_NX); diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index af2acf1..e03b4d0 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -7660,6 +7660,10 @@ static __init int hardware_setup(void) WARN_ONCE(host_bndcfgs, "KVM: BNDCFGS in host will be lost"); } + if (!kvm_mpx_supported()) + supported_xcr0 &= ~(XFEATURE_MASK_BNDREGS | + XFEATURE_MASK_BNDCSR); + if (!cpu_has_vmx_vpid() || !cpu_has_vmx_invvpid() || !(cpu_has_vmx_invvpid_single() || cpu_has_vmx_invvpid_global())) enable_vpid = 0; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a69f7bf..849957f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -181,6 +181,11 @@ struct kvm_shared_msrs { static struct kvm_shared_msrs_global __read_mostly shared_msrs_global; static struct kvm_shared_msrs __percpu *shared_msrs; +#define KVM_SUPPORTED_XCR0 (XFEATURE_MASK_FP | XFEATURE_MASK_SSE \ + | XFEATURE_MASK_YMM | XFEATURE_MASK_BNDREGS \ + | XFEATURE_MASK_BNDCSR | XFEATURE_MASK_AVX512 \ + | XFEATURE_MASK_PKRU) + static u64 __read_mostly host_xss; struct kvm_stats_debugfs_item debugfs_entries[] = { @@ -227,6 +232,8 @@ struct kvm_stats_debugfs_item debugfs_entries[] = { }; u64 __read_mostly host_xcr0; +u64 __read_mostly supported_xcr0; +EXPORT_SYMBOL_GPL(supported_xcr0); struct kmem_cache *x86_fpu_cache; EXPORT_SYMBOL_GPL(x86_fpu_cache); @@ -4114,8 +4121,7 @@ static int kvm_vcpu_ioctl_x86_set_xsave(struct kvm_vcpu *vcpu, * CPUID leaf 0xD, index 0, EDX:EAX. This is for compatibility * with old userspace. */ - if (xstate_bv & ~kvm_supported_xcr0() || - mxcsr & ~mxcsr_feature_mask) + if (xstate_bv & ~supported_xcr0 || mxcsr & ~mxcsr_feature_mask) return -EINVAL; load_xsave(vcpu, (u8 *)guest_xsave->region); } else { @@ -7352,8 +7358,10 @@ int kvm_arch_init(void *opaque) perf_register_guest_info_callbacks(&kvm_guest_cbs); - if (boot_cpu_has(X86_FEATURE_XSAVE)) + if (boot_cpu_has(X86_FEATURE_XSAVE)) { host_xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK); + supported_xcr0 = host_xcr0 & KVM_SUPPORTED_XCR0; + } kvm_lapic_init(); if (pi_inject_timer == -1) diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index f3c6e55..7a7dd5a 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -270,13 +270,8 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, int emulation_type, void *insn, int insn_len); enum exit_fastpath_completion handle_fastpath_set_msr_irqoff(struct kvm_vcpu *vcpu); -#define KVM_SUPPORTED_XCR0 (XFEATURE_MASK_FP | XFEATURE_MASK_SSE \ - | XFEATURE_MASK_YMM | XFEATURE_MASK_BNDREGS \ - | XFEATURE_MASK_BNDCSR | XFEATURE_MASK_AVX512 \ - | XFEATURE_MASK_PKRU) extern u64 host_xcr0; - -extern u64 kvm_supported_xcr0(void); +extern u64 supported_xcr0; extern unsigned int min_timer_period_us; -- 2.7.4