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SubjectRe: [PATCH v2 05/17] arm64: Helper for parange to PASize
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Hi Suzuki,

On 27/03/18 14:15, Suzuki K Poulose wrote:
> Add a helper to convert ID_AA64MMFR0_EL1:PARange to they physical
> size shift. Limit the size to the maximum supported by the kernel.
> We are about to move the user of this code and this helps to
> keep the changes cleaner.

It is probably worth to mention that you are also adding 52-bit support
in the patch.

Cheers,

>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Cc: Christoffer Dall <cdall@kernel.org>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> ---
> arch/arm64/include/asm/cpufeature.h | 16 ++++++++++++++++
> arch/arm64/kvm/hyp/s2-setup.c | 28 +++++-----------------------
> 2 files changed, 21 insertions(+), 23 deletions(-)
>
> diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
> index fbf0aab..1f2a5dd 100644
> --- a/arch/arm64/include/asm/cpufeature.h
> +++ b/arch/arm64/include/asm/cpufeature.h
> @@ -311,6 +311,22 @@ static inline u64 read_zcr_features(void)
> return zcr;
> }
>
> +static inline u32 id_aa64mmfr0_parange_to_phys_shift(int parange)
> +{
> + switch (parange) {
> + case 0: return 32;
> + case 1: return 36;
> + case 2: return 40;
> + case 3: return 42;
> + case 4: return 44;
> + /* Report 48 bit if the kernel doesn't support 52bit */
> + default:
> + case 5: return 48;
> +#ifdef CONFIG_ARM64_PA_BITS_52
> + case 6: return 52;
> +#endif
> + }
> +}
> #endif /* __ASSEMBLY__ */
>
> #endif
> diff --git a/arch/arm64/kvm/hyp/s2-setup.c b/arch/arm64/kvm/hyp/s2-setup.c
> index 603e1ee..b1129c8 100644
> --- a/arch/arm64/kvm/hyp/s2-setup.c
> +++ b/arch/arm64/kvm/hyp/s2-setup.c
> @@ -19,11 +19,13 @@
> #include <asm/kvm_arm.h>
> #include <asm/kvm_asm.h>
> #include <asm/kvm_hyp.h>
> +#include <asm/cpufeature.h>
>
> u32 __hyp_text __init_stage2_translation(void)
> {
> u64 val = VTCR_EL2_FLAGS;
> u64 parange;
> + u32 phys_shift;
> u64 tmp;
>
> /*
> @@ -37,27 +39,7 @@ u32 __hyp_text __init_stage2_translation(void)
> val |= parange << 16;
>
> /* Compute the actual PARange... */
> - switch (parange) {
> - case 0:
> - parange = 32;
> - break;
> - case 1:
> - parange = 36;
> - break;
> - case 2:
> - parange = 40;
> - break;
> - case 3:
> - parange = 42;
> - break;
> - case 4:
> - parange = 44;
> - break;
> - case 5:
> - default:
> - parange = 48;
> - break;
> - }
> + phys_shift = id_aa64mmfr0_parange_to_phys_shift(parange);
>
> /*
> * ... and clamp it to 40 bits, unless we have some braindead
> @@ -65,7 +47,7 @@ u32 __hyp_text __init_stage2_translation(void)
> * return that value for the rest of the kernel to decide what
> * to do.
> */
> - val |= 64 - (parange > 40 ? 40 : parange);
> + val |= 64 - (phys_shift > 40 ? 40 : phys_shift);
>
> /*
> * Check the availability of Hardware Access Flag / Dirty Bit
> @@ -86,5 +68,5 @@ u32 __hyp_text __init_stage2_translation(void)
>
> write_sysreg(val, vtcr_el2);
>
> - return parange;
> + return phys_shift;
> }
>

--
Julien Grall

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