On Mon, Oct 26, 2020 at 01:34:40PM +0000, Marc Zyngier wrote:
> On SMC trap, the prefered return address is set to that of the SMC
> instruction itself. It is thus wrong to tyr and roll it back when
Typo: s/tyr/try/
> an SError occurs while trapping on SMC. It is still necessary on
> HVC though, as HVC doesn't cause a trap, and sets ELR to returning
> *after* the HVC.
>
> It also became apparent that the is 16bit encoding for an AArch32
I guess s/that the is/that there is no/ ?
> HVC instruction, meaning that the displacement is always 4 bytes,
> no matter what the ISA is. Take this opportunity to simplify it.
>
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Assuming that there is no 16-bit HVC:
Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
Mark.
> ---
> arch/arm64/kvm/handle_exit.c | 16 ++++++++--------
> 1 file changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
> index 5d690d60ccad..79a720657c47 100644
> --- a/arch/arm64/kvm/handle_exit.c
> +++ b/arch/arm64/kvm/handle_exit.c
> @@ -245,15 +245,15 @@ int handle_exit(struct kvm_vcpu *vcpu, int exception_index)
> u8 esr_ec = ESR_ELx_EC(kvm_vcpu_get_esr(vcpu));
>
> /*
> - * HVC/SMC already have an adjusted PC, which we need
> - * to correct in order to return to after having
> - * injected the SError.
> + * 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 ||
> - esr_ec == ESR_ELx_EC_SMC32 || esr_ec == ESR_ELx_EC_SMC64) {
> - u32 adj = kvm_vcpu_trap_il_is32bit(vcpu) ? 4 : 2;
> - *vcpu_pc(vcpu) -= adj;
> - }
> + if (esr_ec == ESR_ELx_EC_HVC32 || esr_ec == ESR_ELx_EC_HVC64)
> + *vcpu_pc(vcpu) -= 4;
>
> return 1;
> }
> --
> 2.28.0
>
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