powerpc/xive: Discard disabled interrupts in get_irqchip_state()

When an interrupt is passed through, the KVM XIVE device calls the
set_vcpu_affinity() handler which raises the P bit to mask the
interrupt and to catch any in-flight interrupts while routing the
interrupt to the guest.

On the guest side, drivers (like some Intels) can request at probe
time some MSIs and call synchronize_irq() to check that there are no
in flight interrupts. This will call the XIVE get_irqchip_state()
handler which will always return true as the interrupt P bit has been
set on the host side and lock the CPU in an infinite loop.

Fix that by discarding disabled interrupts in get_irqchip_state().

Fixes: da15c03b047d ("powerpc/xive: Implement get_irqchip_state method for XIVE to fix shutdown race")
Cc: stable@vger.kernel.org #v5.4+
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Tested-by: seeteena <s1seetee@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211011070203.99726-1-clg@kaod.org

diff --git a/arch/powerpc/sysdev/xive/common.c b/arch/powerpc/sysdev/xive/common.c
index c732ce5a3e1a500746feb41649d78b8a164ae354..c5d75c02ad8b512d51b13eb0c4a7baf7bec3524e 100644 (file)
--- a/arch/powerpc/sysdev/xive/common.c
+++ b/arch/powerpc/sysdev/xive/common.c
@@ -945,7 +945,8 @@ static int xive_get_irqchip_state(struct irq_data *data,
                 * interrupt to be inactive in that case.
                 */
                *state = (pq != XIVE_ESB_INVALID) && !xd->stale_p &&
-                       (xd->saved_p || !!(pq & XIVE_ESB_VAL_P));
+                       (xd->saved_p || (!!(pq & XIVE_ESB_VAL_P) &&
+                        !irqd_irq_disabled(data)));
                return 0;
        default:
                return -EINVAL;