Re: [Qemu-devel] [PATCH for-2.12] hw/intc/arm_gicv3: Fix secure-GIC NS ICC_PMR and ICC_RPR accesses

[Peter Maydell <peter.maydell@linaro.org>]

On 22 March 2018 at 14:23, Andrew Jones <drjones@redhat.com> wrote:
> On Thu, Mar 15, 2018 at 01:34:41PM +0000, Peter Maydell wrote:
>> If the GIC has the security extension support enabled, then a
>> non-secure access to ICC_PMR must take account of the non-secure
>> view of interrupt priorities, where real priorities 0..0x7f
>> are secure-only and not visible to the non-secure guest, and
>> priorities 0x80..0xff are shown to the guest as if they were
>> 0x00..0xff. We had the logic here wrong:
>
> 0x00..0x7f

I think 0x00..0xff is correct. The conversion from actual
priority value to the NS-view is
   if (prio & 0x80 == 0) {
       nsview = 0;
   } else {
       nsview = (prio << 1) & 0xff;
   }

so:
   real priority     NS view
    0x80              0x00
    0x90              0x20
    0xa0              0x40
    0xb0              0x60
    0xc0              0x80
    0xd0              0xa0
    0xe0              0xc0
    0xf0              0xe0

the NS view covers the whole 0x00..0xff range, but more sparsely.
(OK, technically you can't ever read 0xff, only 0xfe.)

> Reviewed-by: Andrew Jones <drjones@redhat.com>

Thanks for the review.

-- PMM