On Wed, Jul 08, 2015 at 05:19:06PM +0100, Marc Zyngier wrote:
> Add a new ARM64_HAS_VIRT_HOST_EXTN features to indicate that the
> CPU has the ARMv8,1 VHE capability.
Nit: s/,/./
It's probably worth mentioning somewhere that we have to check CurrentEL
rather than a feature register in case some prior software dropped us to
EL1N (e.g. if we're a guest under this scheme).
Mark.
>
> This will be used to trigger kernel patching in KVM.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
> ---
> arch/arm64/include/asm/cpufeature.h | 3 ++-
> arch/arm64/kernel/cpufeature.c | 11 +++++++++++
> 2 files changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
> index c104421..6c3742d 100644
> --- a/arch/arm64/include/asm/cpufeature.h
> +++ b/arch/arm64/include/asm/cpufeature.h
> @@ -25,8 +25,9 @@
> #define ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE 1
> #define ARM64_WORKAROUND_845719 2
> #define ARM64_HAS_SYSREG_GIC_CPUIF 3
> +#define ARM64_HAS_VIRT_HOST_EXTN 4
>
> -#define ARM64_NCAPS 4
> +#define ARM64_NCAPS 5
>
> #ifndef __ASSEMBLY__
>
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 5ad86ce..e1dcd63 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -21,6 +21,7 @@
> #include <linux/types.h>
> #include <asm/cpu.h>
> #include <asm/cpufeature.h>
> +#include <asm/virt.h>
>
> static bool
> has_id_aa64pfr0_feature(const struct arm64_cpu_capabilities *entry)
> @@ -31,6 +32,11 @@ has_id_aa64pfr0_feature(const struct arm64_cpu_capabilities *entry)
> return (val & entry->register_mask) == entry->register_value;
> }
>
> +static bool runs_at_el2(const struct arm64_cpu_capabilities *entry)
> +{
> + return is_kernel_in_hyp_mode();
> +}
> +
> static const struct arm64_cpu_capabilities arm64_features[] = {
> {
> .desc = "GIC system register CPU interface",
> @@ -39,6 +45,11 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
> .register_mask = (0xf << 24),
> .register_value = (1 << 24),
> },
> + {
> + .desc = "Virtualization Host Extensions",
> + .capability = ARM64_HAS_VIRT_HOST_EXTN,
> + .matches = runs_at_el2,
> + },
> {},
> };
>
> --
> 2.1.4
>
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>
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