arm64: errata: Expand speculative SSBS workaround (again)

A number of Arm Ltd CPUs suffer from errata whereby an MSR to the SSBS
special-purpose register does not affect subsequent speculative
instructions, permitting speculative store bypassing for a window of
time.

We worked around this for a number of CPUs in commits:

* 7187bb7d0b5c7dfa ("arm64: errata: Add workaround for Arm errata 3194386 and 3312417")
* 75b3c43eab594bfb ("arm64: errata: Expand speculative SSBS workaround")

Since then, similar errata have been published for a number of other Arm
Ltd CPUs, for which the same mitigation is sufficient. This is described
in their respective Software Developer Errata Notice (SDEN) documents:

* Cortex-A76 (MP052) SDEN v31.0, erratum 3324349
  https://developer.arm.com/documentation/SDEN-885749/3100/

* Cortex-A77 (MP074) SDEN v19.0, erratum 3324348
  https://developer.arm.com/documentation/SDEN-1152370/1900/

* Cortex-A78 (MP102) SDEN v21.0, erratum 3324344
  https://developer.arm.com/documentation/SDEN-1401784/2100/

* Cortex-A78C (MP138) SDEN v16.0, erratum 3324346
  https://developer.arm.com/documentation/SDEN-1707916/1600/

* Cortex-A78C (MP154) SDEN v10.0, erratum 3324347
  https://developer.arm.com/documentation/SDEN-2004089/1000/

* Cortex-A725 (MP190) SDEN v5.0, erratum 3456106
  https://developer.arm.com/documentation/SDEN-2832921/0500/

* Cortex-X1 (MP077) SDEN v21.0, erratum 3324344
  https://developer.arm.com/documentation/SDEN-1401782/2100/

* Cortex-X1C (MP136) SDEN v16.0, erratum 3324346
  https://developer.arm.com/documentation/SDEN-1707914/1600/

* Neoverse-N1 (MP050) SDEN v32.0, erratum 3324349
  https://developer.arm.com/documentation/SDEN-885747/3200/

* Neoverse-V1 (MP076) SDEN v19.0, erratum 3324341
  https://developer.arm.com/documentation/SDEN-1401781/1900/

Note that due to the manner in which Arm develops IP and tracks errata,
some CPUs share a common erratum number and some CPUs have multiple
erratum numbers for the same HW issue.

On parts without SB, it is necessary to use ISB for the workaround. The
spec_bar() macro used in the mitigation will expand to a "DSB SY; ISB"
sequence in this case, which is sufficient on all affected parts.

Enable the existing mitigation by adding the relevant MIDRs to
erratum_spec_ssbs_list. The list is sorted alphanumerically (involving
moving Neoverse-V3 after Neoverse-V2) so that this is easy to audit and
potentially extend again in future. The Kconfig text is also updated to
clarify the set of affected parts and the mitigation.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20240801101803.1982459-4-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

2 files changed, 26 insertions, 7 deletions

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index b3fc891f1544..a2f8ff354ca6 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1069,18 +1069,28 @@ config ARM64_ERRATUM_3117295
 	  If unsure, say Y.
 
 config ARM64_ERRATUM_3194386
-	bool "Cortex-{A720,X4,X925}/Neoverse-V3: workaround for MSR SSBS not self-synchronizing"
+	bool "Cortex-*/Neoverse-*: workaround for MSR SSBS not self-synchronizing"
 	default y
 	help
 	  This option adds the workaround for the following errata:
 
+	  * ARM Cortex-A76 erratum 3324349
+	  * ARM Cortex-A77 erratum 3324348
+	  * ARM Cortex-A78 erratum 3324344
+	  * ARM Cortex-A78C erratum 3324346
+	  * ARM Cortex-A78C erratum 3324347
 	  * ARM Cortex-A710 erratam 3324338
 	  * ARM Cortex-A720 erratum 3456091
+	  * ARM Cortex-A725 erratum 3456106
+	  * ARM Cortex-X1 erratum 3324344
+	  * ARM Cortex-X1C erratum 3324346
 	  * ARM Cortex-X2 erratum 3324338
 	  * ARM Cortex-X3 erratum 3324335
 	  * ARM Cortex-X4 erratum 3194386
 	  * ARM Cortex-X925 erratum 3324334
+	  * ARM Neoverse-N1 erratum 3324349
 	  * ARM Neoverse N2 erratum 3324339
+	  * ARM Neoverse-V1 erratum 3324341
 	  * ARM Neoverse V2 erratum 3324336
 	  * ARM Neoverse-V3 erratum 3312417
 
@@ -1088,11 +1098,11 @@ config ARM64_ERRATUM_3194386
 	  subsequent speculative instructions, which may permit unexepected
 	  speculative store bypassing.
 
-	  Work around this problem by placing a speculation barrier after
-	  kernel changes to SSBS. The presence of the SSBS special-purpose
-	  register is hidden from hwcaps and EL0 reads of ID_AA64PFR1_EL1, such
-	  that userspace will use the PR_SPEC_STORE_BYPASS prctl to change
-	  SSBS.
+	  Work around this problem by placing a Speculation Barrier (SB) or
+	  Instruction Synchronization Barrier (ISB) after kernel changes to
+	  SSBS. The presence of the SSBS special-purpose register is hidden
+	  from hwcaps and EL0 reads of ID_AA64PFR1_EL1, such that userspace
+	  will use the PR_SPEC_STORE_BYPASS prctl to change SSBS.
 
 	  If unsure, say Y.
 
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 617424b73f8c..f6b6b4507357 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -434,15 +434,24 @@ static const struct midr_range erratum_spec_unpriv_load_list[] = {
 
 #ifdef CONFIG_ARM64_ERRATUM_3194386
 static const struct midr_range erratum_spec_ssbs_list[] = {
+	MIDR_ALL_VERSIONS(MIDR_CORTEX_A76),
+	MIDR_ALL_VERSIONS(MIDR_CORTEX_A77),
+	MIDR_ALL_VERSIONS(MIDR_CORTEX_A78),
+	MIDR_ALL_VERSIONS(MIDR_CORTEX_A78C),
 	MIDR_ALL_VERSIONS(MIDR_CORTEX_A710),
 	MIDR_ALL_VERSIONS(MIDR_CORTEX_A720),
+	MIDR_ALL_VERSIONS(MIDR_CORTEX_A725),
+	MIDR_ALL_VERSIONS(MIDR_CORTEX_X1),
+	MIDR_ALL_VERSIONS(MIDR_CORTEX_X1C),
 	MIDR_ALL_VERSIONS(MIDR_CORTEX_X2),
 	MIDR_ALL_VERSIONS(MIDR_CORTEX_X3),
 	MIDR_ALL_VERSIONS(MIDR_CORTEX_X4),
 	MIDR_ALL_VERSIONS(MIDR_CORTEX_X925),
+	MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N1),
 	MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N2),
-	MIDR_ALL_VERSIONS(MIDR_NEOVERSE_V3),
+	MIDR_ALL_VERSIONS(MIDR_NEOVERSE_V1),
 	MIDR_ALL_VERSIONS(MIDR_NEOVERSE_V2),
+	MIDR_ALL_VERSIONS(MIDR_NEOVERSE_V3),
 	{}
 };
 #endif