[PATCH 25/31] arm64: Add workaround for Cavium Thunder erratum 30115

[Marc Zyngier]

From: David Daney <david.daney at cavium.com>

Some Cavium Thunder CPUs suffer a problem where a KVM guest may
inadvertently cause the host kernel to quit receiving interrupts.

Use the Group-0/1 trapping in order to deal with it.

[maz]: Adapted patch to the Group-0/1 trapping, reworked commit log

Signed-off-by: David Daney <david.daney at cavium.com>
Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
---
 Documentation/arm64/silicon-errata.txt |  1 +
 arch/arm64/Kconfig                     | 11 +++++++++++
 arch/arm64/include/asm/cpucaps.h       |  3 ++-
 arch/arm64/kernel/cpu_errata.c         | 21 +++++++++++++++++++++
 virt/kvm/arm/vgic/vgic-v3.c            |  7 +++++++
 5 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/Documentation/arm64/silicon-errata.txt b/Documentation/arm64/silicon-errata.txt
index 10f2dddbf449..f5f93dca54b7 100644
--- a/Documentation/arm64/silicon-errata.txt
+++ b/Documentation/arm64/silicon-errata.txt
@@ -62,6 +62,7 @@ stable kernels.
 | Cavium         | ThunderX GICv3  | #23154          | CAVIUM_ERRATUM_23154        |
 | Cavium         | ThunderX Core   | #27456          | CAVIUM_ERRATUM_27456        |
 | Cavium         | ThunderX SMMUv2 | #27704          | N/A                         |
+| Cavium         | ThunderX Core   | #30115          | CAVIUM_ERRATUM_30115        |
 |                |                 |                 |                             |
 | Freescale/NXP  | LS2080A/LS1043A | A-008585        | FSL_ERRATUM_A008585         |
 |                |                 |                 |                             |
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 3dcd7ec69bca..0950b21e4d17 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -480,6 +480,17 @@ config CAVIUM_ERRATUM_27456
 
 	  If unsure, say Y.
 
+config CAVIUM_ERRATUM_30115
+	bool "Cavium erratum 30115: Guest may disable interrupts in host"
+	default y
+	help
+	  On ThunderX T88 pass 1.x through 2.2, T81 pass 1.0 through
+	  1.2, and T83 Pass 1.0, KVM guest execution may disable
+	  interrupts in host. Trapping GICv3 group-1 accesses sidesteps
+	  the issue.
+
+	  If unsure, say Y.
+
 config QCOM_FALKOR_ERRATUM_1003
 	bool "Falkor E1003: Incorrect translation due to ASID change"
 	default y
diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index b3aab8a17868..8d2272c6822c 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -38,7 +38,8 @@
 #define ARM64_WORKAROUND_REPEAT_TLBI		17
 #define ARM64_WORKAROUND_QCOM_FALKOR_E1003	18
 #define ARM64_WORKAROUND_858921			19
+#define ARM64_WORKAROUND_CAVIUM_30115		20
 
-#define ARM64_NCAPS				20
+#define ARM64_NCAPS				21
 
 #endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 2ed2a7657711..0e27f86ee709 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -133,6 +133,27 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
 		MIDR_RANGE(MIDR_THUNDERX_81XX, 0x00, 0x00),
 	},
 #endif
+#ifdef CONFIG_CAVIUM_ERRATUM_30115
+	{
+	/* Cavium ThunderX, T88 pass 1.x - 2.2 */
+		.desc = "Cavium erratum 30115",
+		.capability = ARM64_WORKAROUND_CAVIUM_30115,
+		MIDR_RANGE(MIDR_THUNDERX, 0x00,
+			   (1 << MIDR_VARIANT_SHIFT) | 2),
+	},
+	{
+	/* Cavium ThunderX, T81 pass 1.0 - 1.2 */
+		.desc = "Cavium erratum 30115",
+		.capability = ARM64_WORKAROUND_CAVIUM_30115,
+		MIDR_RANGE(MIDR_THUNDERX_81XX, 0x00, 0x02),
+	},
+	{
+	/* Cavium ThunderX, T83 pass 1.0 */
+		.desc = "Cavium erratum 30115",
+		.capability = ARM64_WORKAROUND_CAVIUM_30115,
+		MIDR_RANGE(MIDR_THUNDERX_83XX, 0x00, 0x00),
+	},
+#endif
 	{
 		.desc = "Mismatched cache line size",
 		.capability = ARM64_MISMATCHED_CACHE_LINE_SIZE,
diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
index 7c82c586d44a..445e86c8b00c 100644
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -390,6 +390,13 @@ int vgic_v3_probe(const struct gic_kvm_info *info)
 	if (kvm_vgic_global_state.vcpu_base == 0)
 		kvm_info("disabling GICv2 emulation\n");
 
+#ifdef CONFIG_ARM64
+	if (cpus_have_const_cap(ARM64_WORKAROUND_CAVIUM_30115)) {
+		group0_trap = true;
+		group1_trap = true;
+	}
+#endif
+
 	if (group0_trap || group1_trap) {
 		kvm_info("GICv3 sysreg trapping enabled (reduced performance)\n");
 		static_branch_enable(&vgic_v3_cpuif_trap);
-- 
2.11.0