On Fri, Nov 09, 2018 at 03:07:10PM +0000, Mark Rutland wrote:
> When we emulate an MMIO instruction, we advance the CPU state within
> decode_hsr(), before emulating the instruction effects.
>
> Having this logic in decode_hsr() is opaque, and advancing the state
> before emulation is problematic. It gets in the way of applying
> consistent single-step logic, and it prevents us from being able to fail
> an MMIO instruction with a synchronous exception.
>
> Clean this up by only advancing the CPU state *after* the effects of the
> instruction are emulated.
>
> Signed-off-by: Mark Rutland <mark.rutl...@arm.com>
> Cc: Alex Bennée <alex.ben...@linaro.org>
> Cc: Christoffer Dall <christoffer.d...@arm.com>
> Cc: Marc Zyngier <marc.zyng...@arm.com>
> Cc: Peter Maydell <peter.mayd...@linaro.org>
> ---
> virt/kvm/arm/mmio.c | 11 ++++++-----
> 1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/virt/kvm/arm/mmio.c b/virt/kvm/arm/mmio.c
> index dac7ceb1a677..08443a15e6be 100644
> --- a/virt/kvm/arm/mmio.c
> +++ b/virt/kvm/arm/mmio.c
> @@ -117,6 +117,12 @@ int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct
> kvm_run *run)
> vcpu_set_reg(vcpu, vcpu->arch.mmio_decode.rt, data);
> }
>
> + /*
> + * The MMIO instruction is emulated and should not be re-executed
> + * in the guest.
> + */
> + kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
> +
> return 0;
> }
>
> @@ -144,11 +150,6 @@ static int decode_hsr(struct kvm_vcpu *vcpu, bool
> *is_write, int *len)
> vcpu->arch.mmio_decode.sign_extend = sign_extend;
> vcpu->arch.mmio_decode.rt = rt;
>
> - /*
> - * The MMIO instruction is emulated and should not be re-executed
> - * in the guest.
> - */
> - kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
> return 0;
> }
>
> --
> 2.11.0
>
Reviewed-by: Christoffer Dall <christoffer.d...@arm.com>
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