Merge tag 'x86-bugs-2022-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 MMIO stale data fixes from Thomas Gleixner:
 "Yet another hw vulnerability with a software mitigation: Processor
  MMIO Stale Data.

  They are a class of MMIO-related weaknesses which can expose stale
  data by propagating it into core fill buffers. Data which can then be
  leaked using the usual speculative execution methods.

  Mitigations include this set along with microcode updates and are
  similar to MDS and TAA vulnerabilities: VERW now clears those buffers
  too"

* tag 'x86-bugs-2022-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/speculation/mmio: Print SMT warning
  KVM: x86/speculation: Disable Fill buffer clear within guests
  x86/speculation/mmio: Reuse SRBDS mitigation for SBDS
  x86/speculation/srbds: Update SRBDS mitigation selection
  x86/speculation/mmio: Add sysfs reporting for Processor MMIO Stale Data
  x86/speculation/mmio: Enable CPU Fill buffer clearing on idle
  x86/bugs: Group MDS, TAA & Processor MMIO Stale Data mitigations
  x86/speculation/mmio: Add mitigation for Processor MMIO Stale Data
  x86/speculation: Add a common function for MD_CLEAR mitigation update
  x86/speculation/mmio: Enumerate Processor MMIO Stale Data bug
  Documentation: Add documentation for Processor MMIO Stale Data

2 files changed, 26 insertions, 0 deletions

diff --git a/tools/arch/x86/include/asm/cpufeatures.h b/tools/arch/x86/include/asm/cpufeatures.h
index 73e643ae94b6..e17de69faa54 100644
--- 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 403e83b4adc8..d27e0581b777 100644
--- a/tools/arch/x86/include/asm/msr-index.h
+++ b/tools/arch/x86/include/asm/msr-index.h
@@ -116,6 +116,30 @@
 						 * 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 ARCH_CAP_FB_CLEAR_CTRL		BIT(18)	/*
+						 * MSR_IA32_MCU_OPT_CTRL[FB_CLEAR_DIS]
+						 * bit available to control VERW
+						 * behavior.
+						 */
 
 #define MSR_IA32_FLUSH_CMD		0x0000010b
 #define L1D_FLUSH			BIT(0)	/*
@@ -133,6 +157,7 @@
 #define MSR_IA32_MCU_OPT_CTRL		0x00000123
 #define RNGDS_MITG_DIS			BIT(0)	/* SRBDS support */
 #define RTM_ALLOW			BIT(1)	/* TSX development mode */
+#define FB_CLEAR_DIS			BIT(3)	/* CPU Fill buffer clear disable */
 
 #define MSR_IA32_SYSENTER_CS		0x00000174
 #define MSR_IA32_SYSENTER_ESP		0x00000175