KVM: selftests: Add helpers for safe and safe+forced RDMSR, RDPMC, and XGETBV

Add helpers for safe and safe-with-forced-emulations versions of RDMSR,
RDPMC, and XGETBV.  Use macro shenanigans to eliminate the rather large
amount of boilerplate needed to get values in and out of registers.

Tested-by: Dapeng Mi <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Sean Christopherson <[email protected]>

Author: sean-jc

tools/testing/selftests/kvm/include/x86_64/processor.h

@@ -1216,20 +1216,34 @@ void vm_install_exception_handler(struct kvm_vm *vm, int vector,
 	vector;								\
 })
 
-static inline uint8_t rdmsr_safe(uint32_t msr, uint64_t *val)
-{
-	uint64_t error_code;
-	uint8_t vector;
-	uint32_t a, d;
+#define BUILD_READ_U64_SAFE_HELPER(insn, _fep, _FEP)			\
+static inline uint8_t insn##_safe ##_fep(uint32_t idx, uint64_t *val)	\
+{									\
+	uint64_t error_code;						\
+	uint8_t vector;							\
+	uint32_t a, d;							\
+									\
+	asm volatile(KVM_ASM_SAFE##_FEP(#insn)				\
+		     : "=a"(a), "=d"(d),				\
+		       KVM_ASM_SAFE_OUTPUTS(vector, error_code)		\
+		     : "c"(idx)						\
+		     : KVM_ASM_SAFE_CLOBBERS);				\
+									\
+	*val = (uint64_t)a | ((uint64_t)d << 32);			\
+	return vector;							\
+}
 
-	asm volatile(KVM_ASM_SAFE("rdmsr")
-		     : "=a"(a), "=d"(d), KVM_ASM_SAFE_OUTPUTS(vector, error_code)
-		     : "c"(msr)
-		     : KVM_ASM_SAFE_CLOBBERS);
+/*
+ * Generate {insn}_safe() and {insn}_safe_fep() helpers for instructions that
+ * use ECX as in input index, and EDX:EAX as a 64-bit output.
+ */
+#define BUILD_READ_U64_SAFE_HELPERS(insn)				\
+	BUILD_READ_U64_SAFE_HELPER(insn, , )				\
+	BUILD_READ_U64_SAFE_HELPER(insn, _fep, _FEP)			\
 
-	*val = (uint64_t)a | ((uint64_t)d << 32);
-	return vector;
-}
+BUILD_READ_U64_SAFE_HELPERS(rdmsr)
+BUILD_READ_U64_SAFE_HELPERS(rdpmc)
+BUILD_READ_U64_SAFE_HELPERS(xgetbv)
 
 static inline uint8_t wrmsr_safe(uint32_t msr, uint64_t val)
 {