On Mon, Oct 21, 2019 at 10:57 PM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
>
> On 16/10/19 18:12, Anup Patel wrote:
> > + /* Read current VSIP and VSIE CSRs */
> > + vsip = csr_read(CSR_VSIP);
> > + csr->vsie = csr_read(CSR_VSIE);
> > +
> > + /* Sync-up VSIP.SSIP bit changes does by Guest */
> > + if ((csr->vsip ^ vsip) & (1UL << IRQ_S_SOFT)) {
> > + if (!test_and_set_bit(IRQ_S_SOFT, &v->irqs_pending_mask)) {
> > + if (vsip & (1UL << IRQ_S_SOFT))
> > + set_bit(IRQ_S_SOFT, &v->irqs_pending);
> > + else
> > + clear_bit(IRQ_S_SOFT, &v->irqs_pending);
> > + }
>
> Looks good, but I wonder if this could just be "csr->vsip =
> csr_read(CSR_VSIP)", which will be fixed up by flush_interrupts on the
> next entry.
It's not just "csr->vsip = csr_read(CSR_VSIP" because "irqs_pending"
bitmap has to be in-sync with Guest updates to VSIP because WFI
trap-n-emulate will check for pending interrupts which in-turn checks
"irqs_pending" bitmap.
Regards,
Anup
