On Mon, Oct 26, 2020 at 01:34:43PM +0000, Marc Zyngier wrote:
> Instead of handling the "PC rollback on SError during HVC" at EL1 (which
> requires disclosing PC to a potentially untrusted kernel), let's move
> this fixup to ... fixup_guest_exit(), which is where we do all fixups.
>
> Isn't that neat?
>
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
Mark.
> ---
> arch/arm64/kvm/handle_exit.c | 17 -----------------
> arch/arm64/kvm/hyp/include/hyp/switch.h | 15 +++++++++++++++
> 2 files changed, 15 insertions(+), 17 deletions(-)
>
> diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
> index d4e00a864ee6..f79137ee4274 100644
> --- a/arch/arm64/kvm/handle_exit.c
> +++ b/arch/arm64/kvm/handle_exit.c
> @@ -241,23 +241,6 @@ int handle_exit(struct kvm_vcpu *vcpu, int exception_index)
> {
> struct kvm_run *run = vcpu->run;
>
> - if (ARM_SERROR_PENDING(exception_index)) {
> - u8 esr_ec = ESR_ELx_EC(kvm_vcpu_get_esr(vcpu));
> -
> - /*
> - * HVC already have an adjusted PC, which we need to
> - * correct in order to return to after having injected
> - * the SError.
> - *
> - * SMC, on the other hand, is *trapped*, meaning its
> - * preferred return address is the SMC itself.
> - */
> - if (esr_ec == ESR_ELx_EC_HVC32 || esr_ec == ESR_ELx_EC_HVC64)
> - *vcpu_pc(vcpu) -= 4;
> -
> - return 1;
> - }
> -
> exception_index = ARM_EXCEPTION_CODE(exception_index);
>
> switch (exception_index) {
> diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
> index d687e574cde5..668f02c7b0b3 100644
> --- a/arch/arm64/kvm/hyp/include/hyp/switch.h
> +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
> @@ -411,6 +411,21 @@ static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
> if (ARM_EXCEPTION_CODE(*exit_code) != ARM_EXCEPTION_IRQ)
> vcpu->arch.fault.esr_el2 = read_sysreg_el2(SYS_ESR);
>
> + if (ARM_SERROR_PENDING(*exit_code)) {
> + u8 esr_ec = kvm_vcpu_trap_get_class(vcpu);
> +
> + /*
> + * HVC already have an adjusted PC, which we need to
> + * correct in order to return to after having injected
> + * the SError.
> + *
> + * SMC, on the other hand, is *trapped*, meaning its
> + * preferred return address is the SMC itself.
> + */
> + if (esr_ec == ESR_ELx_EC_HVC32 || esr_ec == ESR_ELx_EC_HVC64)
> + *vcpu_pc(vcpu) -= 4;
> + }
> +
> /*
> * We're using the raw exception code in order to only process
> * the trap if no SError is pending. We will come back to the
> --
> 2.28.0
>
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