[Qemu-devel] [PATCH 1/3] i386: define the 'ssbd' CPUID feature bit (CVE-2018-3639)

["Daniel P. Berrangé" <berrange@redhat.com>]

New microcode introduces the "Speculative Store Bypass Disable"
CPUID feature bit. This needs to be exposed to guest OS to allow
them to protect against CVE-2018-3639.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 target/i386/cpu.c | 2 +-
 target/i386/cpu.h | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index e5e66a75d4..a1185b17d1 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -805,7 +805,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
             NULL, NULL, NULL, NULL,
             NULL, NULL, NULL, NULL,
             NULL, NULL, "spec-ctrl", NULL,
-            NULL, NULL, NULL, NULL,
+            NULL, NULL, NULL, "ssbd",
         },
         .cpuid_eax = 7,
         .cpuid_needs_ecx = true, .cpuid_ecx = 0,
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 8bc54d70bf..f0b68905de 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -685,6 +685,7 @@ typedef uint32_t FeatureWordArray[FEATURE_WORDS];
 #define CPUID_7_0_EDX_AVX512_4VNNIW (1U << 2) /* AVX512 Neural Network Instructions */
 #define CPUID_7_0_EDX_AVX512_4FMAPS (1U << 3) /* AVX512 Multiply Accumulation Single Precision */
 #define CPUID_7_0_EDX_SPEC_CTRL     (1U << 26) /* Speculation Control */
+#define CPUID_7_0_EDX_SPEC_CTRL_SSBD  (1U << 31) /* Speculative Store Bypass Disable */
 
 #define KVM_HINTS_DEDICATED (1U << 0)
 
-- 
2.17.0