[PATCH 5.10 047/103] powerpc/xive: Discard disabled interrupts in get_irqchip_state()

Greg Kroah-Hartman
2021-10-18T13:45:57Z

From: Cédric Le Goater <clg@kaod.org>

commit 6f779e1d359b8d5801f677c1d49dcfa10bf95674 upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/powerpc/sysdev/xive/common.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/powerpc/sysdev/xive/common.c
+++ b/arch/powerpc/sysdev/xive/common.c
@@ -997,7 +997,8 @@ static int xive_get_irqchip_state(struct
* 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;