From 19f10315fd53599d8186aa46a0363b233292eb3d Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Sat, 11 Feb 2023 00:35:33 +0000 Subject: [PATCH] KVM: VMX: Stub out enable_evmcs static key for CONFIG_HYPERV=n Wrap enable_evmcs in a helper and stub it out when CONFIG_HYPERV=n in order to eliminate the static branch nop placeholders. clang-14 is clever enough to elide the nop, but gcc-12 is not. Stubbing out the key reduces the size of kvm-intel.ko by ~7.5% (200KiB) when compiled with gcc-12 (there are a _lot_ of VMCS accesses throughout KVM). Reviewed-by: Vitaly Kuznetsov Signed-off-by: Sean Christopherson Message-Id: <20230211003534.564198-3-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx/hyperv.c | 4 ++-- arch/x86/kvm/vmx/hyperv.h | 10 ++++++++-- arch/x86/kvm/vmx/vmx.c | 15 +++++++-------- arch/x86/kvm/vmx/vmx_ops.h | 22 +++++++++++----------- 4 files changed, 28 insertions(+), 23 deletions(-) diff --git a/arch/x86/kvm/vmx/hyperv.c b/arch/x86/kvm/vmx/hyperv.c index b6748055c586..274fbd38c64e 100644 --- a/arch/x86/kvm/vmx/hyperv.c +++ b/arch/x86/kvm/vmx/hyperv.c @@ -118,8 +118,6 @@ #define EVMCS1_SUPPORTED_VMFUNC (0) -DEFINE_STATIC_KEY_FALSE(enable_evmcs); - #define EVMCS1_OFFSET(x) offsetof(struct hv_enlightened_vmcs, x) #define EVMCS1_FIELD(number, name, clean_field)[ROL16(number, 6)] = \ {EVMCS1_OFFSET(name), clean_field} @@ -611,6 +609,8 @@ int nested_evmcs_check_controls(struct vmcs12 *vmcs12) } #if IS_ENABLED(CONFIG_HYPERV) +DEFINE_STATIC_KEY_FALSE(enable_evmcs); + /* * KVM on Hyper-V always uses the latest known eVMCSv1 revision, the assumption * is: in case a feature has corresponding fields in eVMCS described and it was diff --git a/arch/x86/kvm/vmx/hyperv.h b/arch/x86/kvm/vmx/hyperv.h index 1299143d00df..a54a2fdf0a5b 100644 --- a/arch/x86/kvm/vmx/hyperv.h +++ b/arch/x86/kvm/vmx/hyperv.h @@ -16,8 +16,6 @@ struct vmcs_config; -DECLARE_STATIC_KEY_FALSE(enable_evmcs); - #define current_evmcs ((struct hv_enlightened_vmcs *)this_cpu_read(current_vmcs)) #define KVM_EVMCS_VERSION 1 @@ -69,6 +67,13 @@ static inline u64 evmcs_read_any(struct hv_enlightened_vmcs *evmcs, #if IS_ENABLED(CONFIG_HYPERV) +DECLARE_STATIC_KEY_FALSE(enable_evmcs); + +static __always_inline bool kvm_is_using_evmcs(void) +{ + return static_branch_unlikely(&enable_evmcs); +} + static __always_inline int get_evmcs_offset(unsigned long field, u16 *clean_field) { @@ -158,6 +163,7 @@ static inline void evmcs_load(u64 phys_addr) void evmcs_sanitize_exec_ctrls(struct vmcs_config *vmcs_conf); #else /* !IS_ENABLED(CONFIG_HYPERV) */ +static __always_inline bool kvm_is_using_evmcs(void) { return false; } static __always_inline void evmcs_write64(unsigned long field, u64 value) {} static __always_inline void evmcs_write32(unsigned long field, u32 value) {} static __always_inline void evmcs_write16(unsigned long field, u16 value) {} diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index d2d6e1b6c788..09e07fb83c37 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -595,7 +595,7 @@ static void hv_reset_evmcs(void) { struct hv_vp_assist_page *vp_ap; - if (!static_branch_unlikely(&enable_evmcs)) + if (!kvm_is_using_evmcs()) return; /* @@ -2816,8 +2816,7 @@ static int vmx_hardware_enable(void) * This can happen if we hot-added a CPU but failed to allocate * VP assist page for it. */ - if (static_branch_unlikely(&enable_evmcs) && - !hv_get_vp_assist_page(cpu)) + if (kvm_is_using_evmcs() && !hv_get_vp_assist_page(cpu)) return -EFAULT; intel_pt_handle_vmx(1); @@ -2869,7 +2868,7 @@ struct vmcs *alloc_vmcs_cpu(bool shadow, int cpu, gfp_t flags) memset(vmcs, 0, vmcs_config.size); /* KVM supports Enlightened VMCS v1 only */ - if (static_branch_unlikely(&enable_evmcs)) + if (kvm_is_using_evmcs()) vmcs->hdr.revision_id = KVM_EVMCS_VERSION; else vmcs->hdr.revision_id = vmcs_config.revision_id; @@ -2964,7 +2963,7 @@ static __init int alloc_kvm_area(void) * still be marked with revision_id reported by * physical CPU. */ - if (static_branch_unlikely(&enable_evmcs)) + if (kvm_is_using_evmcs()) vmcs->hdr.revision_id = vmcs_config.revision_id; per_cpu(vmxarea, cpu) = vmcs; @@ -3931,7 +3930,7 @@ static void vmx_msr_bitmap_l01_changed(struct vcpu_vmx *vmx) * 'Enlightened MSR Bitmap' feature L0 needs to know that MSR * bitmap has changed. */ - if (IS_ENABLED(CONFIG_HYPERV) && static_branch_unlikely(&enable_evmcs)) { + if (kvm_is_using_evmcs()) { struct hv_enlightened_vmcs *evmcs = (void *)vmx->vmcs01.vmcs; if (evmcs->hv_enlightenments_control.msr_bitmap) @@ -7310,7 +7309,7 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu) vmx_vcpu_enter_exit(vcpu, __vmx_vcpu_run_flags(vmx)); /* All fields are clean at this point */ - if (static_branch_unlikely(&enable_evmcs)) { + if (kvm_is_using_evmcs()) { current_evmcs->hv_clean_fields |= HV_VMX_ENLIGHTENED_CLEAN_FIELD_ALL; @@ -7440,7 +7439,7 @@ static int vmx_vcpu_create(struct kvm_vcpu *vcpu) * feature only for vmcs01, KVM currently isn't equipped to realize any * performance benefits from enabling it for vmcs02. */ - if (IS_ENABLED(CONFIG_HYPERV) && static_branch_unlikely(&enable_evmcs) && + if (kvm_is_using_evmcs() && (ms_hyperv.nested_features & HV_X64_NESTED_MSR_BITMAP)) { struct hv_enlightened_vmcs *evmcs = (void *)vmx->vmcs01.vmcs; diff --git a/arch/x86/kvm/vmx/vmx_ops.h b/arch/x86/kvm/vmx/vmx_ops.h index db95bde52998..ce47dc265f89 100644 --- a/arch/x86/kvm/vmx/vmx_ops.h +++ b/arch/x86/kvm/vmx/vmx_ops.h @@ -147,7 +147,7 @@ do_exception: static __always_inline u16 vmcs_read16(unsigned long field) { vmcs_check16(field); - if (static_branch_unlikely(&enable_evmcs)) + if (kvm_is_using_evmcs()) return evmcs_read16(field); return __vmcs_readl(field); } @@ -155,7 +155,7 @@ static __always_inline u16 vmcs_read16(unsigned long field) static __always_inline u32 vmcs_read32(unsigned long field) { vmcs_check32(field); - if (static_branch_unlikely(&enable_evmcs)) + if (kvm_is_using_evmcs()) return evmcs_read32(field); return __vmcs_readl(field); } @@ -163,7 +163,7 @@ static __always_inline u32 vmcs_read32(unsigned long field) static __always_inline u64 vmcs_read64(unsigned long field) { vmcs_check64(field); - if (static_branch_unlikely(&enable_evmcs)) + if (kvm_is_using_evmcs()) return evmcs_read64(field); #ifdef CONFIG_X86_64 return __vmcs_readl(field); @@ -175,7 +175,7 @@ static __always_inline u64 vmcs_read64(unsigned long field) static __always_inline unsigned long vmcs_readl(unsigned long field) { vmcs_checkl(field); - if (static_branch_unlikely(&enable_evmcs)) + if (kvm_is_using_evmcs()) return evmcs_read64(field); return __vmcs_readl(field); } @@ -222,7 +222,7 @@ static __always_inline void __vmcs_writel(unsigned long field, unsigned long val static __always_inline void vmcs_write16(unsigned long field, u16 value) { vmcs_check16(field); - if (static_branch_unlikely(&enable_evmcs)) + if (kvm_is_using_evmcs()) return evmcs_write16(field, value); __vmcs_writel(field, value); @@ -231,7 +231,7 @@ static __always_inline void vmcs_write16(unsigned long field, u16 value) static __always_inline void vmcs_write32(unsigned long field, u32 value) { vmcs_check32(field); - if (static_branch_unlikely(&enable_evmcs)) + if (kvm_is_using_evmcs()) return evmcs_write32(field, value); __vmcs_writel(field, value); @@ -240,7 +240,7 @@ static __always_inline void vmcs_write32(unsigned long field, u32 value) static __always_inline void vmcs_write64(unsigned long field, u64 value) { vmcs_check64(field); - if (static_branch_unlikely(&enable_evmcs)) + if (kvm_is_using_evmcs()) return evmcs_write64(field, value); __vmcs_writel(field, value); @@ -252,7 +252,7 @@ static __always_inline void vmcs_write64(unsigned long field, u64 value) static __always_inline void vmcs_writel(unsigned long field, unsigned long value) { vmcs_checkl(field); - if (static_branch_unlikely(&enable_evmcs)) + if (kvm_is_using_evmcs()) return evmcs_write64(field, value); __vmcs_writel(field, value); @@ -262,7 +262,7 @@ static __always_inline void vmcs_clear_bits(unsigned long field, u32 mask) { BUILD_BUG_ON_MSG(__builtin_constant_p(field) && ((field) & 0x6000) == 0x2000, "vmcs_clear_bits does not support 64-bit fields"); - if (static_branch_unlikely(&enable_evmcs)) + if (kvm_is_using_evmcs()) return evmcs_write32(field, evmcs_read32(field) & ~mask); __vmcs_writel(field, __vmcs_readl(field) & ~mask); @@ -272,7 +272,7 @@ static __always_inline void vmcs_set_bits(unsigned long field, u32 mask) { BUILD_BUG_ON_MSG(__builtin_constant_p(field) && ((field) & 0x6000) == 0x2000, "vmcs_set_bits does not support 64-bit fields"); - if (static_branch_unlikely(&enable_evmcs)) + if (kvm_is_using_evmcs()) return evmcs_write32(field, evmcs_read32(field) | mask); __vmcs_writel(field, __vmcs_readl(field) | mask); @@ -289,7 +289,7 @@ static inline void vmcs_load(struct vmcs *vmcs) { u64 phys_addr = __pa(vmcs); - if (static_branch_unlikely(&enable_evmcs)) + if (kvm_is_using_evmcs()) return evmcs_load(phys_addr); vmx_asm1(vmptrld, "m"(phys_addr), vmcs, phys_addr); -- 2.25.1