Merge tag 'tsa_x86_bugs_for_6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull CPU speculation fixes from Borislav Petkov:
 "Add the mitigation logic for Transient Scheduler Attacks (TSA)

  TSA are new aspeculative side channel attacks related to the execution
  timing of instructions under specific microarchitectural conditions.
  In some cases, an attacker may be able to use this timing information
  to infer data from other contexts, resulting in information leakage.

  Add the usual controls of the mitigation and integrate it into the
  existing speculation bugs infrastructure in the kernel"

* tag 'tsa_x86_bugs_for_6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/process: Move the buffer clearing before MONITOR
  x86/microcode/AMD: Add TSA microcode SHAs
  KVM: SVM: Advertise TSA CPUID bits to guests
  x86/bugs: Add a Transient Scheduler Attacks mitigation
  x86/bugs: Rename MDS machinery to something more generic

4 files changed, 19 insertions, 7 deletions

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index bf85f4de6862..ab8cd337f43a 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -584,6 +584,7 @@ What:		/sys/devices/system/cpu/vulnerabilities
 		/sys/devices/system/cpu/vulnerabilities/spectre_v1
 		/sys/devices/system/cpu/vulnerabilities/spectre_v2
 		/sys/devices/system/cpu/vulnerabilities/srbds
+		/sys/devices/system/cpu/vulnerabilities/tsa
 		/sys/devices/system/cpu/vulnerabilities/tsx_async_abort
 Date:		January 2018
 Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
diff --git a/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst b/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst
index 1302fd1b55e8..6dba18dbb9ab 100644
--- a/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst
+++ b/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst
@@ -157,9 +157,7 @@ This is achieved by using the otherwise unused and obsolete VERW instruction in
 combination with a microcode update. The microcode clears the affected CPU
 buffers when the VERW instruction is executed.
 
-Kernel reuses the MDS function to invoke the buffer clearing:
-
-	mds_clear_cpu_buffers()
+Kernel does the buffer clearing with x86_clear_cpu_buffers().
 
 On MDS affected CPUs, the kernel already invokes CPU buffer clear on
 kernel/userspace, hypervisor/guest and C-state (idle) transitions. No
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index f1f2c0874da9..07e22ba5bfe3 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -7488,6 +7488,19 @@
 			having this key zero'ed is acceptable. E.g. in testing
 			scenarios.
 
+	tsa=		[X86] Control mitigation for Transient Scheduler
+			Attacks on AMD CPUs. Search the following in your
+			favourite search engine for more details:
+
+			"Technical guidance for mitigating transient scheduler
+			attacks".
+
+			off		- disable the mitigation
+			on		- enable the mitigation (default)
+			user		- mitigate only user/kernel transitions
+			vm		- mitigate only guest/host transitions
+
+
 	tsc=		Disable clocksource stability checks for TSC.
 			Format: <string>
 			[x86] reliable: mark tsc clocksource as reliable, this
diff --git a/Documentation/arch/x86/mds.rst b/Documentation/arch/x86/mds.rst
index 5a2e6c0ef04a..3518671e1a85 100644
--- a/Documentation/arch/x86/mds.rst
+++ b/Documentation/arch/x86/mds.rst
@@ -93,7 +93,7 @@ enters a C-state.
 
 The kernel provides a function to invoke the buffer clearing:
 
-    mds_clear_cpu_buffers()
+    x86_clear_cpu_buffers()
 
 Also macro CLEAR_CPU_BUFFERS can be used in ASM late in exit-to-user path.
 Other than CFLAGS.ZF, this macro doesn't clobber any registers.
@@ -185,9 +185,9 @@ Mitigation points
    idle clearing would be a window dressing exercise and is therefore not
    activated.
 
-   The invocation is controlled by the static key mds_idle_clear which is
-   switched depending on the chosen mitigation mode and the SMT state of
-   the system.
+   The invocation is controlled by the static key cpu_buf_idle_clear which is
+   switched depending on the chosen mitigation mode and the SMT state of the
+   system.
 
    The buffer clear is only invoked before entering the C-State to prevent
    that stale data from the idling CPU from spilling to the Hyper-Thread