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 d19d1f965904a533998739698020ff4ee8a103da)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index a20fe265735e99000550fc7d0a9be86eb00c1278..2f5263e22f01f201a654c7c081e3e320622e30f8 100644 (file)
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -510,7 +510,7 @@ 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 1b219fafc499c273198563e803eb76252fd9d935..970ab96e543427b33d7b6901029592686217ce1c 100644 (file)
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -684,6 +684,7 @@ 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)