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powerpc/xive: Discard disabled interrupts in get_irqchip_state()

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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
This commit is contained in:
Cédric Le Goater 2021-10-11 09:02:03 +02:00 committed by Michael Ellerman
parent eb8257a121
commit 6f779e1d35
1 changed files with 2 additions and 1 deletions
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3
arch/powerpc/sysdev/xive/common.c
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@ -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;