On 5/3/24 18:31, Joey Gouly wrote:
> FEAT_ATS1E1A introduces a new instruction: `at s1e1a`.
> This is an address translation, without permission checks.
>
> POE allows read permissions to be removed from S1 by the guest. This means
> that an `at` instruction could fail, and not get the IPA.
>
> Switch to using `at s1e1a` so that KVM can get the IPA regardless of S1
> permissions.
>
> Signed-off-by: Joey Gouly <joey.gouly@xxxxxxx>
> Cc: Marc Zyngier <maz@xxxxxxxxxx>
> Cc: Oliver Upton <oliver.upton@xxxxxxxxx>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Will Deacon <will@xxxxxxxxxx>
> ---
> arch/arm64/kvm/hyp/include/hyp/fault.h | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/hyp/include/hyp/fault.h b/arch/arm64/kvm/hyp/include/hyp/fault.h
> index 487c06099d6f..17df94570f03 100644
> --- a/arch/arm64/kvm/hyp/include/hyp/fault.h
> +++ b/arch/arm64/kvm/hyp/include/hyp/fault.h
> @@ -14,6 +14,7 @@
>
> static inline bool __translate_far_to_hpfar(u64 far, u64 *hpfar)
> {
> + int ret;
> u64 par, tmp;
>
> /*
> @@ -27,7 +28,9 @@ static inline bool __translate_far_to_hpfar(u64 far, u64 *hpfar)
> * saved the guest context yet, and we may return early...
> */
> par = read_sysreg_par();
> - if (!__kvm_at(OP_AT_S1E1R, far))
> + ret = system_supports_poe() ? __kvm_at(OP_AT_S1E1A, far) :
> + __kvm_at(OP_AT_S1E1R, far);
> + if (!ret)
> tmp = read_sysreg_par();
> else
> tmp = SYS_PAR_EL1_F; /* back to the guest */
Since the idea is to get the IPA, using OP_AT_S1E1A instead, makes sense
when POE is enabled.
Reviewed-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
