[PATCH 5.15 02/11] x86/speculation/mmio: Enumerate Processor MMIO Stale Data bug

Greg Kroah-Hartman
2022-06-14T18:49:57Z

From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>

commit 51802186158c74a0304f51ab963e7c2b3a2b046f upstream

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>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/include/asm/cpufeatures.h | 1
arch/x86/include/asm/msr-index.h | 19 +++++++++++++
arch/x86/kernel/cpu/common.c | 43 +++++++++++++++++++++++++++++--
tools/arch/x86/include/asm/cpufeatures.h | 1
tools/arch/x86/include/asm/msr-index.h | 19 +++++++++++++
5 files changed, 81 insertions(+), 2 deletions(-)

--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -436,5 +436,6 @@
#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 */
--- 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) /*
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1101,18 +1101,39 @@ static const __initconst struct x86_cpu_
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),
{}
};

@@ -1133,6 +1154,13 @@ 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();
@@ -1192,6 +1220,17 @@ static void __init cpu_set_bug_bits(stru
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;

--- a/tools/arch/x86/include/asm/cpufeatures.h
+++ b/tools/arch/x86/include/asm/cpufeatures.h
@@ -436,5 +436,6 @@
#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 */
--- 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) /*