[kvm-unit-tests PATCH 05/10] x86: Provide result of RDMSR from "safe" variant

[Sean Christopherson <seanjc@google.com>]

Provide the result of RDMSR from rdmsr_safe() so that it can be used by
tests that are unsure whether or not RDMSR will fault, but want the value
if it doesn't fault.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 lib/x86/processor.h | 9 +++++++--
 x86/msr.c           | 3 ++-
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/lib/x86/processor.h b/lib/x86/processor.h
index bc6c8d94..82f8df58 100644
--- a/lib/x86/processor.h
+++ b/lib/x86/processor.h
@@ -360,12 +360,17 @@ static inline void wrmsr(u32 index, u64 val)
 	asm volatile ("wrmsr" : : "a"(a), "d"(d), "c"(index) : "memory");
 }
 
-static inline int rdmsr_safe(u32 index)
+static inline int rdmsr_safe(u32 index, uint64_t *val)
 {
+	uint32_t a, d;
+
 	asm volatile (ASM_TRY("1f")
 		      "rdmsr\n\t"
 		      "1:"
-		      : : "c"(index) : "memory", "eax", "edx");
+		      : "=a"(a), "=d"(d)
+		      : "c"(index) : "memory");
+
+	*val = (uint64_t)a | ((uint64_t)d << 32);
 	return exception_vector();
 }
 
diff --git a/x86/msr.c b/x86/msr.c
index eaca19ed..ee1d3984 100644
--- a/x86/msr.c
+++ b/x86/msr.c
@@ -81,7 +81,8 @@ static void test_wrmsr_fault(struct msr_info *msr, unsigned long long val)
 
 static void test_rdmsr_fault(struct msr_info *msr)
 {
-	unsigned char vector = rdmsr_safe(msr->index);
+	uint64_t ignored;
+	unsigned char vector = rdmsr_safe(msr->index, &ignored);
 
 	report(vector == GP_VECTOR,
 	       "Expected #GP on RDSMR(%s), got vector %d", msr->name, vector);
-- 
2.36.1.255.ge46751e96f-goog