Re: [Qemu-devel] [PATCH v3 18/20] kvm: arm64: Add support for handling 52bit IPA

[Marc Zyngier]

On 29/06/18 12:15, Suzuki K Poulose wrote:
> Add support for handling the 52bit IPA. 52bit IPA
> support needs changes to the following :
> 
>  1) Page-table entries - We use kernel page table helpers for setting
>  up the stage2. Hence we don't explicit changes here
> 
>  2) VTTBR:BADDR - This is already supported with :
>    commit 529c4b05a3cb2f324aa ("arm64: handle 52-bit addresses in TTBR")
> 
>  3) VGIC support for 52bit: Supported with a patch in this series.
> 
> That leaves us with the handling for PAR and HPAR. This patch adds

HPFAR?

> support for handling the 52bit addresses in PAR and HPFAR,
> which are used while handling the permission faults in stage1.

Overall, this is a pretty confusing commit message. Can you just call it:

KVM/arm64: Add 52bit support for PAR to HPFAR conversion

and just describe that it now uses PHYS_MASK_SHIFT instead of a
hardcoded constant?

> 
> Cc: Marc Zyngier <address@hidden>
> Cc: Kristina Martsenko <address@hidden>
> Cc: Christoffer Dall <address@hidden>
> Signed-off-by: Suzuki K Poulose <address@hidden>
> ---
>  arch/arm64/include/asm/kvm_arm.h | 7 +++++++
>  arch/arm64/kvm/hyp/switch.c      | 2 +-
>  2 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/include/asm/kvm_arm.h 
> b/arch/arm64/include/asm/kvm_arm.h
> index 2e90942..cb6a2ee 100644
> --- a/arch/arm64/include/asm/kvm_arm.h
> +++ b/arch/arm64/include/asm/kvm_arm.h
> @@ -301,6 +301,13 @@
>  
>  /* Hyp Prefetch Fault Address Register (HPFAR/HDFAR) */
>  #define HPFAR_MASK   (~UL(0xf))
> +/*
> + * We have
> + *   PAR     [PA_Shift - 1   : 12] = PA      [PA_Shift - 1 : 12]
> + *   HPFAR   [PA_Shift - 9   : 4]  = FIPA    [PA_Shift - 1 : 12]
> + */
> +#define PAR_TO_HPFAR(par)            \
> +     (((par) & GENMASK_ULL(PHYS_MASK_SHIFT - 1, 12)) >> 8)
>  
>  #define kvm_arm_exception_type       \
>       {0, "IRQ" },            \
> diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
> index 355fb25..fb66320 100644
> --- a/arch/arm64/kvm/hyp/switch.c
> +++ b/arch/arm64/kvm/hyp/switch.c
> @@ -260,7 +260,7 @@ static bool __hyp_text __translate_far_to_hpfar(u64 far, 
> u64 *hpfar)
>               return false; /* Translation failed, back to guest */
>  
>       /* Convert PAR to HPFAR format */
> -     *hpfar = ((tmp >> 12) & ((1UL << 36) - 1)) << 4;
> +     *hpfar = PAR_TO_HPFAR(tmp);
>       return true;
>  }
>  
> 

Otherwise:

Acked-by: Marc Zyngier <address@hidden>

        M.
-- 
Jazz is not dead. It just smells funny...