[PATCH] xen/arm: Add workaround for Cortex-A55 erratum #1530923

[Bertrand Marquis <bertrand.marquis@xxxxxxx>]

On the Cortex A55, TLB entries can be allocated by a speculative AT
instruction. If this is happening during a guest context switch with an
inconsistent page table state in the guest, TLBs with wrong values might
be allocated.
The ARM64_WORKAROUND_AT_SPECULATE workaround is used as for erratum
1165522 on Cortex A76 or Neoverse N1.

This change is also introducing the MIDR identifier for the Cortex-A55.

Signed-off-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
---
 docs/misc/arm/silicon-errata.txt | 1 +
 xen/arch/arm/cpuerrata.c         | 6 ++++++
 xen/include/asm-arm/processor.h  | 2 ++
 3 files changed, 9 insertions(+)

diff --git a/docs/misc/arm/silicon-errata.txt b/docs/misc/arm/silicon-errata.txt
index d183ba543f..27bf957ebf 100644
--- a/docs/misc/arm/silicon-errata.txt
+++ b/docs/misc/arm/silicon-errata.txt
@@ -45,6 +45,7 @@ stable hypervisors.
 | ARM            | Cortex-A53      | #827319         | ARM64_ERRATUM_827319    
|
 | ARM            | Cortex-A53      | #824069         | ARM64_ERRATUM_824069    
|
 | ARM            | Cortex-A53      | #819472         | ARM64_ERRATUM_819472    
|
+| ARM            | Cortex-A55      | #1530923        | N/A                     
|
 | ARM            | Cortex-A57      | #852523         | N/A                     
|
 | ARM            | Cortex-A57      | #832075         | ARM64_ERRATUM_832075    
|
 | ARM            | Cortex-A57      | #834220         | ARM64_ERRATUM_834220    
|
diff --git a/xen/arch/arm/cpuerrata.c b/xen/arch/arm/cpuerrata.c
index cb4795beec..b398d480f1 100644
--- a/xen/arch/arm/cpuerrata.c
+++ b/xen/arch/arm/cpuerrata.c
@@ -514,6 +514,12 @@ static const struct arm_cpu_capabilities arm_errata[] = {
         .capability = ARM64_WORKAROUND_AT_SPECULATE,
         MIDR_ALL_VERSIONS(MIDR_CORTEX_A57),
     },
+    {
+        /* Cortex-A55 (All versions as erratum is open in SDEN v14) */
+        .desc = "ARM erratum 1530923",
+        .capability = ARM64_WORKAROUND_AT_SPECULATE,
+        MIDR_ALL_VERSIONS(MIDR_CORTEX_A55),
+    },
     {},
 };
 
diff --git a/xen/include/asm-arm/processor.h b/xen/include/asm-arm/processor.h
index d3d12a9d19..87c8136022 100644
--- a/xen/include/asm-arm/processor.h
+++ b/xen/include/asm-arm/processor.h
@@ -53,6 +53,7 @@
 #define ARM_CPU_PART_CORTEX_A17     0xC0E
 #define ARM_CPU_PART_CORTEX_A15     0xC0F
 #define ARM_CPU_PART_CORTEX_A53     0xD03
+#define ARM_CPU_PART_CORTEX_A55     0xD05
 #define ARM_CPU_PART_CORTEX_A57     0xD07
 #define ARM_CPU_PART_CORTEX_A72     0xD08
 #define ARM_CPU_PART_CORTEX_A73     0xD09
@@ -64,6 +65,7 @@
 #define MIDR_CORTEX_A17 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, 
ARM_CPU_PART_CORTEX_A17)
 #define MIDR_CORTEX_A15 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, 
ARM_CPU_PART_CORTEX_A15)
 #define MIDR_CORTEX_A53 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, 
ARM_CPU_PART_CORTEX_A53)
+#define MIDR_CORTEX_A55 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, 
ARM_CPU_PART_CORTEX_A55)
 #define MIDR_CORTEX_A57 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, 
ARM_CPU_PART_CORTEX_A57)
 #define MIDR_CORTEX_A72 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, 
ARM_CPU_PART_CORTEX_A72)
 #define MIDR_CORTEX_A73 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, 
ARM_CPU_PART_CORTEX_A73)
-- 
2.17.1