On Thu, Nov 06, 2014 at 12:11:45PM +0000, Andre Przywara wrote:
> Currently we mangle the endianness of the guest's register even on an
> MMIO _read_, where it is completely useless, because we will not use
> the value of that register.
> Rework the io_mem_abort() function to clearly separate between reads
> and writes and only do the endianness mangling on MMIO writes.
>
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
> ---
> arch/arm/kvm/mmio.c | 15 +++++++++------
> 1 file changed, 9 insertions(+), 6 deletions(-)
>
> Hi,
>
> I found this while investigating bi-endianness for MMIO. Not sure if
> it's really useful, but I found it more clearer this way.
>
> Cheers,
> Andre.
>
> diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c
> index 4cb5a93..5d3bfc0 100644
> --- a/arch/arm/kvm/mmio.c
> +++ b/arch/arm/kvm/mmio.c
> @@ -187,15 +187,18 @@ int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
> }
>
> rt = vcpu->arch.mmio_decode.rt;
> - data = vcpu_data_guest_to_host(vcpu, *vcpu_reg(vcpu, rt), mmio.len);
>
> - trace_kvm_mmio((mmio.is_write) ? KVM_TRACE_MMIO_WRITE :
> - KVM_TRACE_MMIO_READ_UNSATISFIED,
> - mmio.len, fault_ipa,
> - (mmio.is_write) ? data : 0);
> + if (mmio.is_write) {
> + data = vcpu_data_guest_to_host(vcpu, *vcpu_reg(vcpu, rt),
> + mmio.len);
>
> - if (mmio.is_write)
> + trace_kvm_mmio(KVM_TRACE_MMIO_WRITE, mmio.len,
> + fault_ipa, data);
> mmio_write_buf(mmio.data, mmio.len, data);
> + } else {
> + trace_kvm_mmio(KVM_TRACE_MMIO_READ_UNSATISFIED, mmio.len,
> + fault_ipa, 0);
> + }
>
> if (vgic_handle_mmio(vcpu, run, &mmio))
> return 1;
> --
> 1.7.9.5
>
Looks good to me:
Acked-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
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