[PATCH] KVM: PPC: Book3S HV: XIVE: Free escalation interrupts before disabling the VP

[Michael Ellerman]

On Tue, 2019-08-06 at 17:25:38 UTC, =?utf-8?q?C=C3=A9dric_Le_Goater?= wrote:
> When a vCPU is brought done, the XIVE VP is first disabled and then
> the event notification queues are freed. When freeing the queues, we
> check for possible escalation interrupts and free them also.
> 
> But when a XIVE VP is disabled, the underlying XIVE ENDs also are
> disabled in OPAL. When an END is disabled, its ESB pages (ESn and ESe)
> are disabled and loads return all 1s. Which means that any access on
> the ESB page of the escalation interrupt will return invalid values.
> 
> When an interrupt is freed, the shutdown handler computes a 'saved_p'
> field from the value returned by a load in xive_do_source_set_mask().
> This value is incorrect for escalation interrupts for the reason
> described above.
> 
> This has no impact on Linux/KVM today because we don't make use of it
> but we will introduce in future changes a xive_get_irqchip_state()
> handler. This handler will use the 'saved_p' field to return the state
> of an interrupt and 'saved_p' being incorrect, softlockup will occur.
> 
> Fix the vCPU cleanup sequence by first freeing the escalation
> interrupts if any, then disable the XIVE VP and last free the queues.
> 
> Signed-off-by: Cédric Le Goater <clg at kaod.org>

Applied to powerpc topic/ppc-kvm, thanks.

https://git.kernel.org/powerpc/c/237aed48c642328ff0ab19b63423634340224a06

cheers