Re: [PATCH v2 07/14] arm64: Make the PHYS_MASK_SHIFT dynamic

Catalin Marinas
2024-05-13T16:38:59Z

On Fri, Apr 12, 2024 at 09:42:06AM +0100, Steven Price wrote:
> diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
> index e01bb5ca13b7..9944aca348bd 100644
> --- a/arch/arm64/include/asm/kvm_arm.h
> +++ b/arch/arm64/include/asm/kvm_arm.h
> @@ -398,7 +398,7 @@
> * bits in PAR are res0.
> */
> #define PAR_TO_HPFAR(par) \
> - (((par) & GENMASK_ULL(52 - 1, 12)) >> 8)
> + (((par) & GENMASK_ULL(MAX_PHYS_MASK_SHIFT - 1, 12)) >> 8)

Why does this need to be changed? It's still a constant not dependent on
the new dynamic IPA size.

> diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
> index ef207a0d4f0d..90dc292bed5f 100644
> --- a/arch/arm64/include/asm/pgtable-hwdef.h
> +++ b/arch/arm64/include/asm/pgtable-hwdef.h
> @@ -206,8 +206,8 @@
> /*
> * Highest possible physical address supported.
> */
> -#define PHYS_MASK_SHIFT (CONFIG_ARM64_PA_BITS)
> -#define PHYS_MASK ((UL(1) << PHYS_MASK_SHIFT) - 1)
> +#define MAX_PHYS_MASK_SHIFT (CONFIG_ARM64_PA_BITS)
> +#define MAX_PHYS_MASK ((UL(1) << PHYS_MASK_SHIFT) - 1)

I prefer to have MAX as suffix in those definitions, it matches other
places like TASK_SIZE_MAX, PHYS_ADDR_MAX (I know PHYS_MASK_MAX doesn't
roll off the tongue easily but very few people tend to read the kernel
aloud ;)).

--
Catalin