Hi Andre,
On 06/06/17 18:20, Andre Przywara wrote:
What about this one (in xen/arch/arm/vgic-v[23].c):
static int vgic_v2_distr_mmio_write(struct vcpu *v, ...
{
- uint32_t *ipriorityr;
+ uint32_t *ipriorityr, priority;
....
vgic_lock_rank(v, rank, flags);
ipriorityr = &rank->ipriorityr[REG_RANK_INDEX(8,
gicd_reg - GICD_IPRIORITYR,
DABT_WORD)];
- vgic_reg32_update(ipriorityr, r, info);
+ priority = ACCESS_ONCE(*ipriorityr);
+ vgic_reg32_update(&priority, r, info);
+ ACCESS_ONCE(*ipriorityr) = priority;
vgic_unlock_rank(v, rank, flags);
....
What you do is very similar to my patch but open-code it. It might be
possible to have other place which could take advantage of the a generic
solution, so I am not convinced this would be the right way.
My idea was to confine this fix to what we care for right now.
I guess eventually it doesn't matter as we will probably get rid of the
rank and its lock anyway.
That's a good point. So we may want to wait until the vGIC rework to see
what we can do here. Stefano, any opinion?
Cheers,
--
Julien Grall
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