KVM: arm64: use `at s1e1a` for POE

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@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240822151113.1479789-10-joey.gouly@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/kvm/hyp/include/hyp/fault.h b/arch/arm64/kvm/hyp/include/hyp/fault.h
index 487c06099d6fc1e01e1f5218916038cd83010056..17df94570f03a55315d37087a041e3e1242bfb0f 100644 (file)
--- 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 */