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 <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20230211003534.564198-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 11 insertions, 11 deletions

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);