linux-kernel - [PATCH 5.4 37/69] powerpc/xive: Discard disabled interrupts in get_irqchip

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Message-Id: <20211018132330.707750916@linuxfoundation.org>
Date:   Mon, 18 Oct 2021 15:24:35 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Cédric Le Goater <clg@...d.org>,
        seeteena <s1seetee@...ux.vnet.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>
Subject: [PATCH 5.4 37/69] powerpc/xive: Discard disabled interrupts in get_irqchip_state()

From: Cédric Le Goater <clg@...d.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@...r.kernel.org #v5.4+
Signed-off-by: Cédric Le Goater <clg@...d.org>
Tested-by: seeteena <s1seetee@...ux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Link: https://lore.kernel.org/r/20211011070203.99726-1-clg@kaod.org
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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
@@ -990,7 +990,8 @@ 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;