x86/speculation/mmio: Enumerate Processor MMIO Stale Data bug

Processor MMIO Stale Data is a class of vulnerabilities that may
expose data after an MMIO operation. For more details please refer to
Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst

Add the Processor MMIO Stale Data bug enumeration. A microcode update
adds new bits to the MSR IA32_ARCH_CAPABILITIES, define them.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 73e643ae94b6f2206d8dac0fdd10477e7c1eb8df..e17de69faa5432dbf288ec846dba2745468aeb7e 100644 (file)
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -443,5 +443,6 @@
 #define X86_BUG_TAA                    X86_BUG(22) /* CPU is affected by TSX Async Abort(TAA) */
 #define X86_BUG_ITLB_MULTIHIT          X86_BUG(23) /* CPU may incur MCE during certain page attribute changes */
 #define X86_BUG_SRBDS                  X86_BUG(24) /* CPU may leak RNG bits if not mitigated */
+#define X86_BUG_MMIO_STALE_DATA                X86_BUG(25) /* CPU is affected by Processor MMIO Stale Data vulnerabilities */
 
 #endif /* _ASM_X86_CPUFEATURES_H */

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index ee15311b6be1d99e2bea11bd4c03a8a36fd8c706..12976405441b7bd6cb098a0f491ce94da48a430a 100644 (file)
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -114,6 +114,25 @@
                                                 * Not susceptible to
                                                 * TSX Async Abort (TAA) vulnerabilities.
                                                 */
+#define ARCH_CAP_SBDR_SSDP_NO          BIT(13) /*
+                                                * Not susceptible to SBDR and SSDP
+                                                * variants of Processor MMIO stale data
+                                                * vulnerabilities.
+                                                */
+#define ARCH_CAP_FBSDP_NO              BIT(14) /*
+                                                * Not susceptible to FBSDP variant of
+                                                * Processor MMIO stale data
+                                                * vulnerabilities.
+                                                */
+#define ARCH_CAP_PSDP_NO               BIT(15) /*
+                                                * Not susceptible to PSDP variant of
+                                                * Processor MMIO stale data
+                                                * vulnerabilities.
+                                                */
+#define ARCH_CAP_FB_CLEAR              BIT(17) /*
+                                                * VERW clears CPU fill buffer
+                                                * even on MDS_NO CPUs.
+                                                */
 
 #define MSR_IA32_FLUSH_CMD             0x0000010b
 #define L1D_FLUSH                      BIT(0)  /*

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index e342ae4db3c4de5e88456b72e727cc0def5e6978..f7757409e1338c07f3d433fd008dbe0b6210235b 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1237,18 +1237,39 @@ static const __initconst struct x86_cpu_id cpu_vuln_whitelist[] = {
                                            X86_FEATURE_ANY, issues)
 
 #define SRBDS          BIT(0)
+/* CPU is affected by X86_BUG_MMIO_STALE_DATA */
+#define MMIO           BIT(1)
 
 static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = {
        VULNBL_INTEL_STEPPINGS(IVYBRIDGE,       X86_STEPPING_ANY,               SRBDS),
        VULNBL_INTEL_STEPPINGS(HASWELL,         X86_STEPPING_ANY,               SRBDS),
        VULNBL_INTEL_STEPPINGS(HASWELL_L,       X86_STEPPING_ANY,               SRBDS),
        VULNBL_INTEL_STEPPINGS(HASWELL_G,       X86_STEPPING_ANY,               SRBDS),
+       VULNBL_INTEL_STEPPINGS(HASWELL_X,       BIT(2) | BIT(4),                MMIO),
+       VULNBL_INTEL_STEPPINGS(BROADWELL_D,     X86_STEPPINGS(0x3, 0x5),        MMIO),
        VULNBL_INTEL_STEPPINGS(BROADWELL_G,     X86_STEPPING_ANY,               SRBDS),
+       VULNBL_INTEL_STEPPINGS(BROADWELL_X,     X86_STEPPING_ANY,               MMIO),
        VULNBL_INTEL_STEPPINGS(BROADWELL,       X86_STEPPING_ANY,               SRBDS),
+       VULNBL_INTEL_STEPPINGS(SKYLAKE_L,       X86_STEPPINGS(0x3, 0x3),        SRBDS | MMIO),
        VULNBL_INTEL_STEPPINGS(SKYLAKE_L,       X86_STEPPING_ANY,               SRBDS),
+       VULNBL_INTEL_STEPPINGS(SKYLAKE_X,       BIT(3) | BIT(4) | BIT(6) |
+                                               BIT(7) | BIT(0xB),              MMIO),
+       VULNBL_INTEL_STEPPINGS(SKYLAKE,         X86_STEPPINGS(0x3, 0x3),        SRBDS | MMIO),
        VULNBL_INTEL_STEPPINGS(SKYLAKE,         X86_STEPPING_ANY,               SRBDS),
-       VULNBL_INTEL_STEPPINGS(KABYLAKE_L,      X86_STEPPINGS(0x0, 0xC),        SRBDS),
-       VULNBL_INTEL_STEPPINGS(KABYLAKE,        X86_STEPPINGS(0x0, 0xD),        SRBDS),
+       VULNBL_INTEL_STEPPINGS(KABYLAKE_L,      X86_STEPPINGS(0x9, 0xC),        SRBDS | MMIO),
+       VULNBL_INTEL_STEPPINGS(KABYLAKE_L,      X86_STEPPINGS(0x0, 0x8),        SRBDS),
+       VULNBL_INTEL_STEPPINGS(KABYLAKE,        X86_STEPPINGS(0x9, 0xD),        SRBDS | MMIO),
+       VULNBL_INTEL_STEPPINGS(KABYLAKE,        X86_STEPPINGS(0x0, 0x8),        SRBDS),
+       VULNBL_INTEL_STEPPINGS(ICELAKE_L,       X86_STEPPINGS(0x5, 0x5),        MMIO),
+       VULNBL_INTEL_STEPPINGS(ICELAKE_D,       X86_STEPPINGS(0x1, 0x1),        MMIO),
+       VULNBL_INTEL_STEPPINGS(ICELAKE_X,       X86_STEPPINGS(0x4, 0x6),        MMIO),
+       VULNBL_INTEL_STEPPINGS(COMETLAKE,       BIT(2) | BIT(3) | BIT(5),       MMIO),
+       VULNBL_INTEL_STEPPINGS(COMETLAKE_L,     X86_STEPPINGS(0x0, 0x1),        MMIO),
+       VULNBL_INTEL_STEPPINGS(LAKEFIELD,       X86_STEPPINGS(0x1, 0x1),        MMIO),
+       VULNBL_INTEL_STEPPINGS(ROCKETLAKE,      X86_STEPPINGS(0x1, 0x1),        MMIO),
+       VULNBL_INTEL_STEPPINGS(ATOM_TREMONT,    X86_STEPPINGS(0x1, 0x1),        MMIO),
+       VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_D,  X86_STEPPING_ANY,               MMIO),
+       VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_L,  X86_STEPPINGS(0x0, 0x0),        MMIO),
        {}
 };
 
@@ -1269,6 +1290,13 @@ u64 x86_read_arch_cap_msr(void)
        return ia32_cap;
 }
 
+static bool arch_cap_mmio_immune(u64 ia32_cap)
+{
+       return (ia32_cap & ARCH_CAP_FBSDP_NO &&
+               ia32_cap & ARCH_CAP_PSDP_NO &&
+               ia32_cap & ARCH_CAP_SBDR_SSDP_NO);
+}
+
 static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
 {
        u64 ia32_cap = x86_read_arch_cap_msr();
@@ -1328,6 +1356,17 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
            cpu_matches(cpu_vuln_blacklist, SRBDS))
                    setup_force_cpu_bug(X86_BUG_SRBDS);
 
+       /*
+        * Processor MMIO Stale Data bug enumeration
+        *
+        * Affected CPU list is generally enough to enumerate the vulnerability,
+        * but for virtualization case check for ARCH_CAP MSR bits also, VMM may
+        * not want the guest to enumerate the bug.
+        */
+       if (cpu_matches(cpu_vuln_blacklist, MMIO) &&
+           !arch_cap_mmio_immune(ia32_cap))
+               setup_force_cpu_bug(X86_BUG_MMIO_STALE_DATA);
+
        if (cpu_matches(cpu_vuln_whitelist, NO_MELTDOWN))
                return;
 

diff --git a/tools/arch/x86/include/asm/cpufeatures.h b/tools/arch/x86/include/asm/cpufeatures.h
index 73e643ae94b6f2206d8dac0fdd10477e7c1eb8df..e17de69faa5432dbf288ec846dba2745468aeb7e 100644 (file)
--- a/tools/arch/x86/include/asm/cpufeatures.h
+++ b/tools/arch/x86/include/asm/cpufeatures.h
@@ -443,5 +443,6 @@
 #define X86_BUG_TAA                    X86_BUG(22) /* CPU is affected by TSX Async Abort(TAA) */
 #define X86_BUG_ITLB_MULTIHIT          X86_BUG(23) /* CPU may incur MCE during certain page attribute changes */
 #define X86_BUG_SRBDS                  X86_BUG(24) /* CPU may leak RNG bits if not mitigated */
+#define X86_BUG_MMIO_STALE_DATA                X86_BUG(25) /* CPU is affected by Processor MMIO Stale Data vulnerabilities */
 
 #endif /* _ASM_X86_CPUFEATURES_H */

diff --git a/tools/arch/x86/include/asm/msr-index.h b/tools/arch/x86/include/asm/msr-index.h
index ee15311b6be1d99e2bea11bd4c03a8a36fd8c706..12976405441b7bd6cb098a0f491ce94da48a430a 100644 (file)
--- a/tools/arch/x86/include/asm/msr-index.h
+++ b/tools/arch/x86/include/asm/msr-index.h
@@ -114,6 +114,25 @@
                                                 * Not susceptible to
                                                 * TSX Async Abort (TAA) vulnerabilities.
                                                 */
+#define ARCH_CAP_SBDR_SSDP_NO          BIT(13) /*
+                                                * Not susceptible to SBDR and SSDP
+                                                * variants of Processor MMIO stale data
+                                                * vulnerabilities.
+                                                */
+#define ARCH_CAP_FBSDP_NO              BIT(14) /*
+                                                * Not susceptible to FBSDP variant of
+                                                * Processor MMIO stale data
+                                                * vulnerabilities.
+                                                */
+#define ARCH_CAP_PSDP_NO               BIT(15) /*
+                                                * Not susceptible to PSDP variant of
+                                                * Processor MMIO stale data
+                                                * vulnerabilities.
+                                                */
+#define ARCH_CAP_FB_CLEAR              BIT(17) /*
+                                                * VERW clears CPU fill buffer
+                                                * even on MDS_NO CPUs.
+                                                */
 
 #define MSR_IA32_FLUSH_CMD             0x0000010b
 #define L1D_FLUSH                      BIT(0)  /*