Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 TSX Async Abort and iTLB Multihit mitigations from Thomas Gleixner:
 "The performance deterioration departement is not proud at all of
  presenting the seventh installment of speculation mitigations and
  hardware misfeature workarounds:

   1) TSX Async Abort (TAA) - 'The Annoying Affair'

      TAA is a hardware vulnerability that allows unprivileged
      speculative access to data which is available in various CPU
      internal buffers by using asynchronous aborts within an Intel TSX
      transactional region.

      The mitigation depends on a microcode update providing a new MSR
      which allows to disable TSX in the CPU. CPUs which have no
      microcode update can be mitigated by disabling TSX in the BIOS if
      the BIOS provides a tunable.

      Newer CPUs will have a bit set which indicates that the CPU is not
      vulnerable, but the MSR to disable TSX will be available
      nevertheless as it is an architected MSR. That means the kernel
      provides the ability to disable TSX on the kernel command line,
      which is useful as TSX is a truly useful mechanism to accelerate
      side channel attacks of all sorts.

   2) iITLB Multihit (NX) - 'No eXcuses'

      iTLB Multihit is an erratum where some Intel processors may incur
      a machine check error, possibly resulting in an unrecoverable CPU
      lockup, when an instruction fetch hits multiple entries in the
      instruction TLB. This can occur when the page size is changed
      along with either the physical address or cache type. A malicious
      guest running on a virtualized system can exploit this erratum to
      perform a denial of service attack.

      The workaround is that KVM marks huge pages in the extended page
      tables as not executable (NX). If the guest attempts to execute in
      such a page, the page is broken down into 4k pages which are
      marked executable. The workaround comes with a mechanism to
      recover these shattered huge pages over time.

  Both issues come with full documentation in the hardware
  vulnerabilities section of the Linux kernel user's and administrator's
  guide.

  Thanks to all patch authors and reviewers who had the extraordinary
  priviledge to be exposed to this nuisance.

  Special thanks to Borislav Petkov for polishing the final TAA patch
  set and to Paolo Bonzini for shepherding the KVM iTLB workarounds and
  providing also the backports to stable kernels for those!"

* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/speculation/taa: Fix printing of TAA_MSG_SMT on IBRS_ALL CPUs
  Documentation: Add ITLB_MULTIHIT documentation
  kvm: x86: mmu: Recovery of shattered NX large pages
  kvm: Add helper function for creating VM worker threads
  kvm: mmu: ITLB_MULTIHIT mitigation
  cpu/speculation: Uninline and export CPU mitigations helpers
  x86/cpu: Add Tremont to the cpu vulnerability whitelist
  x86/bugs: Add ITLB_MULTIHIT bug infrastructure
  x86/tsx: Add config options to set tsx=on|off|auto
  x86/speculation/taa: Add documentation for TSX Async Abort
  x86/tsx: Add "auto" option to the tsx= cmdline parameter
  kvm/x86: Export MDS_NO=0 to guests when TSX is enabled
  x86/speculation/taa: Add sysfs reporting for TSX Async Abort
  x86/speculation/taa: Add mitigation for TSX Async Abort
  x86/cpu: Add a "tsx=" cmdline option with TSX disabled by default
  x86/cpu: Add a helper function x86_read_arch_cap_msr()
  x86/msr: Add the IA32_TSX_CTRL MSR

5 files changed, 33 insertions, 2 deletions

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 0652d3eed9bd..c4fbe379cc0b 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -399,5 +399,7 @@
 #define X86_BUG_MDS			X86_BUG(19) /* CPU is affected by Microarchitectural data sampling */
 #define X86_BUG_MSBDS_ONLY		X86_BUG(20) /* CPU is only affected by the  MSDBS variant of BUG_MDS */
 #define X86_BUG_SWAPGS			X86_BUG(21) /* CPU is affected by speculation through SWAPGS */
+#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 */
 
 #endif /* _ASM_X86_CPUFEATURES_H */
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 24d6598dea29..4fc61483919a 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -312,9 +312,12 @@ struct kvm_rmap_head {
 struct kvm_mmu_page {
 	struct list_head link;
 	struct hlist_node hash_link;
+	struct list_head lpage_disallowed_link;
+
 	bool unsync;
 	u8 mmu_valid_gen;
 	bool mmio_cached;
+	bool lpage_disallowed; /* Can't be replaced by an equiv large page */
 
 	/*
 	 * The following two entries are used to key the shadow page in the
@@ -859,6 +862,7 @@ struct kvm_arch {
 	 */
 	struct list_head active_mmu_pages;
 	struct list_head zapped_obsolete_pages;
+	struct list_head lpage_disallowed_mmu_pages;
 	struct kvm_page_track_notifier_node mmu_sp_tracker;
 	struct kvm_page_track_notifier_head track_notifier_head;
 
@@ -933,6 +937,7 @@ struct kvm_arch {
 	bool exception_payload_enabled;
 
 	struct kvm_pmu_event_filter *pmu_event_filter;
+	struct task_struct *nx_lpage_recovery_thread;
 };
 
 struct kvm_vm_stat {
@@ -946,6 +951,7 @@ struct kvm_vm_stat {
 	ulong mmu_unsync;
 	ulong remote_tlb_flush;
 	ulong lpages;
+	ulong nx_lpage_splits;
 	ulong max_mmu_page_hash_collisions;
 };
 
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 20ce682a2540..6a3124664289 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -93,6 +93,18 @@
 						  * Microarchitectural Data
 						  * Sampling (MDS) vulnerabilities.
 						  */
+#define ARCH_CAP_PSCHANGE_MC_NO		BIT(6)	 /*
+						  * The processor is not susceptible to a
+						  * machine check error due to modifying the
+						  * code page size along with either the
+						  * physical address or cache type
+						  * without TLB invalidation.
+						  */
+#define ARCH_CAP_TSX_CTRL_MSR		BIT(7)	/* MSR for TSX control is available. */
+#define ARCH_CAP_TAA_NO			BIT(8)	/*
+						 * Not susceptible to
+						 * TSX Async Abort (TAA) vulnerabilities.
+						 */
 
 #define MSR_IA32_FLUSH_CMD		0x0000010b
 #define L1D_FLUSH			BIT(0)	/*
@@ -103,6 +115,10 @@
 #define MSR_IA32_BBL_CR_CTL		0x00000119
 #define MSR_IA32_BBL_CR_CTL3		0x0000011e
 
+#define MSR_IA32_TSX_CTRL		0x00000122
+#define TSX_CTRL_RTM_DISABLE		BIT(0)	/* Disable RTM feature */
+#define TSX_CTRL_CPUID_CLEAR		BIT(1)	/* Disable TSX enumeration */
+
 #define MSR_IA32_SYSENTER_CS		0x00000174
 #define MSR_IA32_SYSENTER_ESP		0x00000175
 #define MSR_IA32_SYSENTER_EIP		0x00000176
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index 80bc209c0708..5c24a7b35166 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -314,7 +314,7 @@ DECLARE_STATIC_KEY_FALSE(mds_idle_clear);
 #include <asm/segment.h>
 
 /**
- * mds_clear_cpu_buffers - Mitigation for MDS vulnerability
+ * mds_clear_cpu_buffers - Mitigation for MDS and TAA vulnerability
  *
  * This uses the otherwise unused and obsolete VERW instruction in
  * combination with microcode which triggers a CPU buffer flush when the
@@ -337,7 +337,7 @@ static inline void mds_clear_cpu_buffers(void)
 }
 
 /**
- * mds_user_clear_cpu_buffers - Mitigation for MDS vulnerability
+ * mds_user_clear_cpu_buffers - Mitigation for MDS and TAA vulnerability
  *
  * Clear CPU buffers if the corresponding static key is enabled
  */
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 6e0a3b43d027..54f5d54280f6 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -988,4 +988,11 @@ enum mds_mitigations {
 	MDS_MITIGATION_VMWERV,
 };
 
+enum taa_mitigations {
+	TAA_MITIGATION_OFF,
+	TAA_MITIGATION_UCODE_NEEDED,
+	TAA_MITIGATION_VERW,
+	TAA_MITIGATION_TSX_DISABLED,
+};
+
 #endif /* _ASM_X86_PROCESSOR_H */