1 files changed, 28 insertions, 16 deletions

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 11472178e17f..f125bf7ecb6f 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1022,6 +1022,7 @@ static void identify_cpu_without_cpuid(struct cpuinfo_x86 *c)
 #define NO_L1TF         BIT(3)
 #define NO_MDS          BIT(4)
 #define MSBDS_ONLY      BIT(5)
+#define NO_SWAPGS       BIT(6)
 
 #define VULNWL(_vendor, _family, _model, _whitelist)    \
         { X86_VENDOR_##_vendor, _family, _model, X86_FEATURE_ANY, _whitelist }
@@ -1048,30 +1049,38 @@ static const __initconst struct x86_cpu_id cpu_vuln_whitelist[] = {
         VULNWL_INTEL(ATOM_BONNELL,              NO_SPECULATION),
         VULNWL_INTEL(ATOM_BONNELL_MID,          NO_SPECULATION),
 
-        VULNWL_INTEL(ATOM_SILVERMONT,           NO_SSB | NO_L1TF | MSBDS_ONLY),
-        VULNWL_INTEL(ATOM_SILVERMONT_X,         NO_SSB | NO_L1TF | MSBDS_ONLY),
-        VULNWL_INTEL(ATOM_SILVERMONT_MID,       NO_SSB | NO_L1TF | MSBDS_ONLY),
-        VULNWL_INTEL(ATOM_AIRMONT,              NO_SSB | NO_L1TF | MSBDS_ONLY),
-        VULNWL_INTEL(XEON_PHI_KNL,              NO_SSB | NO_L1TF | MSBDS_ONLY),
-        VULNWL_INTEL(XEON_PHI_KNM,              NO_SSB | NO_L1TF | MSBDS_ONLY),
+        VULNWL_INTEL(ATOM_SILVERMONT,           NO_SSB | NO_L1TF | MSBDS_ONLY | NO_SWAPGS),
+        VULNWL_INTEL(ATOM_SILVERMONT_X,         NO_SSB | NO_L1TF | MSBDS_ONLY | NO_SWAPGS),
+        VULNWL_INTEL(ATOM_SILVERMONT_MID,       NO_SSB | NO_L1TF | MSBDS_ONLY | NO_SWAPGS),
+        VULNWL_INTEL(ATOM_AIRMONT,              NO_SSB | NO_L1TF | MSBDS_ONLY | NO_SWAPGS),
+        VULNWL_INTEL(XEON_PHI_KNL,              NO_SSB | NO_L1TF | MSBDS_ONLY | NO_SWAPGS),
+        VULNWL_INTEL(XEON_PHI_KNM,              NO_SSB | NO_L1TF | MSBDS_ONLY | NO_SWAPGS),
 
         VULNWL_INTEL(CORE_YONAH,                NO_SSB),
 
-        VULNWL_INTEL(ATOM_AIRMONT_MID,          NO_L1TF | MSBDS_ONLY),
+        VULNWL_INTEL(ATOM_AIRMONT_MID,          NO_L1TF | MSBDS_ONLY | NO_SWAPGS),
 
-        VULNWL_INTEL(ATOM_GOLDMONT,             NO_MDS | NO_L1TF),
-        VULNWL_INTEL(ATOM_GOLDMONT_X,           NO_MDS | NO_L1TF),
-        VULNWL_INTEL(ATOM_GOLDMONT_PLUS,        NO_MDS | NO_L1TF),
+        VULNWL_INTEL(ATOM_GOLDMONT,             NO_MDS | NO_L1TF | NO_SWAPGS),
+        VULNWL_INTEL(ATOM_GOLDMONT_X,           NO_MDS | NO_L1TF | NO_SWAPGS),
+        VULNWL_INTEL(ATOM_GOLDMONT_PLUS,        NO_MDS | NO_L1TF | NO_SWAPGS),
+
+        /*
+         * Technically, swapgs isn't serializing on AMD (despite it previously
+         * being documented as such in the APM).  But according to AMD, %gs is
+         * updated non-speculatively, and the issuing of %gs-relative memory
+         * operands will be blocked until the %gs update completes, which is
+         * good enough for our purposes.
+         */
 
         /* AMD Family 0xf - 0x12 */
-        VULNWL_AMD(0x0f,        NO_MELTDOWN | NO_SSB | NO_L1TF | NO_MDS),
-        VULNWL_AMD(0x10,        NO_MELTDOWN | NO_SSB | NO_L1TF | NO_MDS),
-        VULNWL_AMD(0x11,        NO_MELTDOWN | NO_SSB | NO_L1TF | NO_MDS),
-        VULNWL_AMD(0x12,        NO_MELTDOWN | NO_SSB | NO_L1TF | NO_MDS),
+        VULNWL_AMD(0x0f,        NO_MELTDOWN | NO_SSB | NO_L1TF | NO_MDS | NO_SWAPGS),
+        VULNWL_AMD(0x10,        NO_MELTDOWN | NO_SSB | NO_L1TF | NO_MDS | NO_SWAPGS),
+        VULNWL_AMD(0x11,        NO_MELTDOWN | NO_SSB | NO_L1TF | NO_MDS | NO_SWAPGS),
+        VULNWL_AMD(0x12,        NO_MELTDOWN | NO_SSB | NO_L1TF | NO_MDS | NO_SWAPGS),
 
         /* FAMILY_ANY must be last, otherwise 0x0f - 0x12 matches won't work */
-        VULNWL_AMD(X86_FAMILY_ANY,      NO_MELTDOWN | NO_L1TF | NO_MDS),
-        VULNWL_HYGON(X86_FAMILY_ANY,    NO_MELTDOWN | NO_L1TF | NO_MDS),
+        VULNWL_AMD(X86_FAMILY_ANY,      NO_MELTDOWN | NO_L1TF | NO_MDS | NO_SWAPGS),
+        VULNWL_HYGON(X86_FAMILY_ANY,    NO_MELTDOWN | NO_L1TF | NO_MDS | NO_SWAPGS),
         {}
 };
 
@@ -1108,6 +1117,9 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
                         setup_force_cpu_bug(X86_BUG_MSBDS_ONLY);
         }
 
+        if (!cpu_matches(NO_SWAPGS))
+                setup_force_cpu_bug(X86_BUG_SWAPGS);
+
         if (cpu_matches(NO_MELTDOWN))
                 return;