From: Cédric Le Goater clg@kaod.org
[ Upstream commit 237aed48c642328ff0ab19b63423634340224a06 ]
When a vCPU is brought done, the XIVE VP (Virtual Processor) 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 (Event Notification Descriptor) 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.
Fixes: 90c73795afa2 ("KVM: PPC: Book3S HV: Add a new KVM device for the XIVE native exploitation mode") Fixes: 5af50993850a ("KVM: PPC: Book3S HV: Native usage of the XIVE interrupt controller") Cc: stable@vger.kernel.org # v4.12+ Signed-off-by: Cédric Le Goater clg@kaod.org Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20190806172538.5087-1-clg@kaod.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/kvm/book3s_xive.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c index 3c75eee45edf9..46f99fc1901c8 100644 --- a/arch/powerpc/kvm/book3s_xive.c +++ b/arch/powerpc/kvm/book3s_xive.c @@ -1001,20 +1001,22 @@ void kvmppc_xive_cleanup_vcpu(struct kvm_vcpu *vcpu) /* Mask the VP IPI */ xive_vm_esb_load(&xc->vp_ipi_data, XIVE_ESB_SET_PQ_01);
- /* Disable the VP */ - xive_native_disable_vp(xc->vp_id); - - /* Free the queues & associated interrupts */ + /* Free escalations */ for (i = 0; i < KVMPPC_XIVE_Q_COUNT; i++) { - struct xive_q *q = &xc->queues[i]; - - /* Free the escalation irq */ if (xc->esc_virq[i]) { free_irq(xc->esc_virq[i], vcpu); irq_dispose_mapping(xc->esc_virq[i]); kfree(xc->esc_virq_names[i]); } - /* Free the queue */ + } + + /* Disable the VP */ + xive_native_disable_vp(xc->vp_id); + + /* Free the queues */ + for (i = 0; i < KVMPPC_XIVE_Q_COUNT; i++) { + struct xive_q *q = &xc->queues[i]; + xive_native_disable_queue(xc->vp_id, q, i); if (q->qpage) { free_pages((unsigned long)q->qpage,