linux-kernel - [PATCH 3/7] KVM: VMX: Always inline eVMCS read/write helpers

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Date:   Tue, 13 Dec 2022 06:09:08 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 3/7] KVM: VMX: Always inline eVMCS read/write helpers

Tag all evmcs_{read,write}() helpers __always_inline so that they can be
freely used in noinstr sections, e.g. to get the VM-Exit reason in
vcpu_vmx_enter_exit() (in a future patch).  For consistency and to avoid
more spot fixes in the future, e.g. see commit 010050a86393 ("x86/kvm:
Always inline evmcs_write64()"), tag all accessors even though
evmcs_read32() is the only anticipated use case in the near future.  In
practice, non-KASAN builds are all but guaranteed to inline the helpers
anyways.

  vmlinux.o: warning: objtool: vmx_vcpu_enter_exit+0x107: call to evmcs_read32()
                               leaves .noinstr.text section

Reported-by: kernel test robot <lkp@...el.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/vmx/hyperv.h | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kvm/vmx/hyperv.h b/arch/x86/kvm/vmx/hyperv.h
index 571e7929d14e..3f4049e4f35d 100644
--- a/arch/x86/kvm/vmx/hyperv.h
+++ b/arch/x86/kvm/vmx/hyperv.h
@@ -136,7 +136,7 @@ static __always_inline void evmcs_write64(unsigned long field, u64 value)
 	current_evmcs->hv_clean_fields &= ~clean_field;
 }
 
-static inline void evmcs_write32(unsigned long field, u32 value)
+static __always_inline void evmcs_write32(unsigned long field, u32 value)
 {
 	u16 clean_field;
 	int offset = get_evmcs_offset(field, &clean_field);
@@ -148,7 +148,7 @@ static inline void evmcs_write32(unsigned long field, u32 value)
 	current_evmcs->hv_clean_fields &= ~clean_field;
 }
 
-static inline void evmcs_write16(unsigned long field, u16 value)
+static __always_inline void evmcs_write16(unsigned long field, u16 value)
 {
 	u16 clean_field;
 	int offset = get_evmcs_offset(field, &clean_field);
@@ -160,7 +160,7 @@ static inline void evmcs_write16(unsigned long field, u16 value)
 	current_evmcs->hv_clean_fields &= ~clean_field;
 }
 
-static inline u64 evmcs_read64(unsigned long field)
+static __always_inline u64 evmcs_read64(unsigned long field)
 {
 	int offset = get_evmcs_offset(field, NULL);
 
@@ -170,7 +170,7 @@ static inline u64 evmcs_read64(unsigned long field)
 	return *(u64 *)((char *)current_evmcs + offset);
 }
 
-static inline u32 evmcs_read32(unsigned long field)
+static __always_inline u32 evmcs_read32(unsigned long field)
 {
 	int offset = get_evmcs_offset(field, NULL);
 
@@ -180,7 +180,7 @@ static inline u32 evmcs_read32(unsigned long field)
 	return *(u32 *)((char *)current_evmcs + offset);
 }
 
-static inline u16 evmcs_read16(unsigned long field)
+static __always_inline u16 evmcs_read16(unsigned long field)
 {
 	int offset = get_evmcs_offset(field, NULL);
 
@@ -213,11 +213,11 @@ static inline void evmcs_load(u64 phys_addr)
 
 #else /* !IS_ENABLED(CONFIG_HYPERV) */
 static __always_inline void evmcs_write64(unsigned long field, u64 value) {}
-static inline void evmcs_write32(unsigned long field, u32 value) {}
-static inline void evmcs_write16(unsigned long field, u16 value) {}
-static inline u64 evmcs_read64(unsigned long field) { return 0; }
-static inline u32 evmcs_read32(unsigned long field) { return 0; }
-static inline u16 evmcs_read16(unsigned long field) { return 0; }
+static __always_inline void evmcs_write32(unsigned long field, u32 value) {}
+static __always_inline void evmcs_write16(unsigned long field, u16 value) {}
+static __always_inline u64 evmcs_read64(unsigned long field) { return 0; }
+static __always_inline u32 evmcs_read32(unsigned long field) { return 0; }
+static __always_inline u16 evmcs_read16(unsigned long field) { return 0; }
 static inline void evmcs_load(u64 phys_addr) {}
 static inline void evmcs_touch_msr_bitmap(void) {}
 #endif /* IS_ENABLED(CONFIG_HYPERV) */
-- 
2.39.0.rc1.256.g54fd8350bd-goog