KVM: arm64: Move GICv3 broken SEIS implementation detection to a CPU errrata

Using is_midr_in_range_list() in a noinstr function isn't a good idea.
And yet kvm_compute_ich_hcr_trap_bits() is doing that by calling
vgic_v3_broken_seis().

Move all the broken SEIS detection logic to the errata detection
framework, and use a new ARM64_WORKAROUND_GICv3_BROKEN_SEIS cap
to indicate that we're running on broken CPUs.

This reuses the MIDR list used for IMPDEF PMU detection, which
has a 100% overlap with the SEIS stuff...

Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://patch.msgid.link/20260721170754.3150521-3-maz@kernel.org
Signed-off-by: Oliver Upton <oupton@kernel.org>

3 files changed, 20 insertions, 26 deletions

diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 1995e1198648..78e4e105f6ab 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -272,7 +272,7 @@ has_neoverse_n1_erratum_1542419(const struct arm64_cpu_capabilities *entry,
 	return is_midr_in_range(&range) && has_dic;
 }
 
-static const struct midr_range impdef_pmuv3_cpus[] = {
+static const struct midr_range apple_cpus[] = {
 	MIDR_ALL_VERSIONS(MIDR_APPLE_M1_ICESTORM),
 	MIDR_ALL_VERSIONS(MIDR_APPLE_M1_FIRESTORM),
 	MIDR_ALL_VERSIONS(MIDR_APPLE_M1_ICESTORM_PRO),
@@ -301,7 +301,14 @@ static bool has_impdef_pmuv3(const struct arm64_cpu_capabilities *entry, int sco
 	if (pmuver != ID_AA64DFR0_EL1_PMUVer_IMP_DEF)
 		return false;
 
-	return is_midr_in_range_list(impdef_pmuv3_cpus);
+	return is_midr_in_range_list(apple_cpus);
+}
+
+static bool has_broken_gic_v3_seis(const struct arm64_cpu_capabilities *entry, int scope)
+{
+	return (is_kernel_in_hyp_mode() &&
+		is_midr_in_range_list(apple_cpus) &&
+		(read_sysreg_s(SYS_ICH_VTR_EL2) & ICH_VTR_EL2_SEIS));
 }
 
 static void cpu_enable_impdef_pmuv3_traps(const struct arm64_cpu_capabilities *__unused)
@@ -1010,5 +1017,11 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
 		.cpu_enable = cpu_enable_impdef_pmuv3_traps,
 	},
 	{
+		.desc = "Known broken GICv3 SEIS implementation",
+		.capability = ARM64_WORKAROUND_GICv3_BROKEN_SEIS,
+		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
+		.matches = has_broken_gic_v3_seis,
+	},
+	{
 	}
 };
diff --git a/arch/arm64/kvm/vgic/vgic-v3.c b/arch/arm64/kvm/vgic/vgic-v3.c
index 9e841e7afd4a..0991a649a5d1 100644
--- a/arch/arm64/kvm/vgic/vgic-v3.c
+++ b/arch/arm64/kvm/vgic/vgic-v3.c
@@ -809,27 +809,9 @@ static int __init early_gicv4_enable(char *buf)
 }
 early_param("kvm-arm.vgic_v4_enable", early_gicv4_enable);
 
-static const struct midr_range broken_seis[] = {
-	MIDR_ALL_VERSIONS(MIDR_APPLE_M1_ICESTORM),
-	MIDR_ALL_VERSIONS(MIDR_APPLE_M1_FIRESTORM),
-	MIDR_ALL_VERSIONS(MIDR_APPLE_M1_ICESTORM_PRO),
-	MIDR_ALL_VERSIONS(MIDR_APPLE_M1_FIRESTORM_PRO),
-	MIDR_ALL_VERSIONS(MIDR_APPLE_M1_ICESTORM_MAX),
-	MIDR_ALL_VERSIONS(MIDR_APPLE_M1_FIRESTORM_MAX),
-	MIDR_ALL_VERSIONS(MIDR_APPLE_M2_BLIZZARD),
-	MIDR_ALL_VERSIONS(MIDR_APPLE_M2_AVALANCHE),
-	MIDR_ALL_VERSIONS(MIDR_APPLE_M2_BLIZZARD_PRO),
-	MIDR_ALL_VERSIONS(MIDR_APPLE_M2_AVALANCHE_PRO),
-	MIDR_ALL_VERSIONS(MIDR_APPLE_M2_BLIZZARD_MAX),
-	MIDR_ALL_VERSIONS(MIDR_APPLE_M2_AVALANCHE_MAX),
-	{},
-};
-
-static bool vgic_v3_broken_seis(void)
-{
-	return (is_kernel_in_hyp_mode() &&
-		is_midr_in_range_list(broken_seis) &&
-		(read_sysreg_s(SYS_ICH_VTR_EL2) & ICH_VTR_EL2_SEIS));
+static __always_inline bool vgic_v3_broken_seis(void)
+{
+	return cpus_have_cap(ARM64_WORKAROUND_GICv3_BROKEN_SEIS);
 }
 
 void noinstr kvm_compute_ich_hcr_trap_bits(struct alt_instr *alt,
@@ -959,10 +941,8 @@ int vgic_v3_probe(const struct gic_kvm_info *info)
 	if (has_v2)
 		static_branch_enable(&vgic_v3_has_v2_compat);
 
-	if (vgic_v3_broken_seis()) {
-		kvm_info("GICv3 with broken locally generated SEI\n");
+	if (vgic_v3_broken_seis())
 		kvm_vgic_global_state.ich_vtr_el2 &= ~ICH_VTR_EL2_SEIS;
-	}
 
 	vgic_v3_enable_cpuif_traps();
 
diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
index 9b85a84f6fd4..50373264ecde 100644
--- a/arch/arm64/tools/cpucaps
+++ b/arch/arm64/tools/cpucaps
@@ -121,6 +121,7 @@ WORKAROUND_CAVIUM_TX2_219_TVM
 WORKAROUND_CLEAN_CACHE
 WORKAROUND_DEVICE_LOAD_ACQUIRE
 WORKAROUND_DISABLE_CNP
+WORKAROUND_GICv3_BROKEN_SEIS
 WORKAROUND_PMUV3_IMPDEF_TRAPS
 WORKAROUND_QCOM_FALKOR_E1003
 WORKAROUND_QCOM_ORYON_CNTVOFF