i386: define the 'ssbd' CPUID feature bit (CVE-2018-3639)

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> Message-Id: <20180521215424.13520-2-berrange@redhat.com> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> (cherry picked from commit d19d1f9) Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
qemu · Jun 21, 2018 · 4ce0b75 · 4ce0b75
1 parent 84cfae0
commit 4ce0b75
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Showing 2 changed files with 2 additions and 1 deletion.
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
@@ -459,7 +459,7 @@ 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
@@ -644,6 +644,7 @@ 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 CPUID_8000_0008_EBX_IBPB    (1U << 12) /* Indirect Branch Prediction Barrier */