arm64: Add workaround for Cavium Thunder erratum 30115

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
Tested-by: NAlexander Graf <agraf@suse.de>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Reviewed-by: NEric Auger <eric.auger@redhat.com>
Signed-off-by: NDavid Daney <david.daney@cavium.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <cdall@linaro.org>

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         |
 |                |                 |                 |                             |

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 both GICv3 group-0 and 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

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 */

arch/arm64/kernel/cpu_errata.c

@@ -132,6 +132,27 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
 		.capability = ARM64_WORKAROUND_CAVIUM_27456,
 		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",

virt/kvm/arm/vgic/vgic-v3.c

@@ -501,6 +501,13 @@ 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);