From: Marc Zyngier marc.zyngier@arm.com
commit 94a9e04aa16abd1194d9b4158c618ba87f5d01e6 upstream.
Add a new item to the feature set (ARM64_HAS_SYSREG_GIC_CPUIF) to indicate that we have a system register GIC CPU interface
This will help KVM switching to alternative instruction patching.
Reviewed-by: Andre Przywara andre.przywara@arm.com Reviewed-by: Christoffer Dall christoffer.dall@linaro.org Acked-by: Will Deacon will.deacon@arm.com Signed-off-by: Marc Zyngier marc.zyngier@arm.com Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: David Brown david.brown@linaro.org --- arch/arm64/include/asm/cpufeature.h | 8 +++++++- arch/arm64/kernel/cpufeature.c | 16 ++++++++++++++++ 2 files changed, 23 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index 82cb9f9..c104421 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -24,8 +24,9 @@ #define ARM64_WORKAROUND_CLEAN_CACHE 0 #define ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE 1 #define ARM64_WORKAROUND_845719 2 +#define ARM64_HAS_SYSREG_GIC_CPUIF 3
-#define ARM64_NCAPS 3 +#define ARM64_NCAPS 4
#ifndef __ASSEMBLY__
@@ -38,6 +39,11 @@ struct arm64_cpu_capabilities { u32 midr_model; u32 midr_range_min, midr_range_max; }; + + struct { /* Feature register checking */ + u64 register_mask; + u64 register_value; + }; }; };
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 3d9967e..5ad86ce 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -22,7 +22,23 @@ #include <asm/cpu.h> #include <asm/cpufeature.h>
+static bool +has_id_aa64pfr0_feature(const struct arm64_cpu_capabilities *entry) +{ + u64 val; + + val = read_cpuid(id_aa64pfr0_el1); + return (val & entry->register_mask) == entry->register_value; +} + static const struct arm64_cpu_capabilities arm64_features[] = { + { + .desc = "GIC system register CPU interface", + .capability = ARM64_HAS_SYSREG_GIC_CPUIF, + .matches = has_id_aa64pfr0_feature, + .register_mask = (0xf << 24), + .register_value = (1 << 24), + }, {}, };