On Mon, Feb 04, 2019 at 08:07:20PM +0100, Cédric Le Goater wrote:
> On 2/4/19 5:57 AM, David Gibson wrote:
> > On Mon, Jan 07, 2019 at 07:43:21PM +0100, Cédric Le Goater wrote:
[snip]
> >> + sb = kvmppc_xive_create_src_block(xive, irq);
> >> + if (!sb) {
> >> + pr_err("Failed to create block...\n");
> >> + return -ENOMEM;
> >> + }
> >> + }
> >> + state = &sb->irq_state[idx];
> >> +
> >> + if (get_user(val, ubufp)) {
> >> + pr_err("fault getting user info !\n");
> >> + return -EFAULT;
> >> + }
> >> +
> >> + /*
> >> + * If the source doesn't already have an IPI, allocate
> >> + * one and get the corresponding data
> >> + */
> >> + if (!state->ipi_number) {
> >> + state->ipi_number = xive_native_alloc_irq();
> >> + if (state->ipi_number == 0) {
> >> + pr_err("Failed to allocate IRQ !\n");
> >> + return -ENOMEM;
> >> + }
> >
> > Am I right in thinking this is the point at which a specific guest irq
> > number gets bound to a specific host irq number?
>
> yes. the XIVE IRQ state caches this information and 'state' should be
> protected before being assigned, indeed ... The XICS-over-XIVE device
> also has the same race issue.
>
> It's not showing because where initializing the KVM device sequentially
> from QEMU and only once.
Ok.
So, for the passthrough case, what's the point at which we know that a
particular guest interrupt needs to be bound to a specific real
hardware interrupt, rather than a generic IPI?
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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