linux-kernel - [PATCH] irqchip/gic-v3-its: fix raw_local_irq

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Message-Id: <20241230134903.84613-1-krckatom@amazon.de>
Date: Mon, 30 Dec 2024 13:49:03 +0000
From: Tomas Krcka <tomas.krcka@...il.com>
To: linux-arm-kernel@...ts.infradead.org
Cc: nh-open-source@...zon.com,
	Tomas Krcka <krckatom@...zon.de>,
	Marc Zyngier <maz@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Hagar Hemdan <hagarhem@...zon.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] irqchip/gic-v3-its: fix raw_local_irq_restore() called with IRQs enabled

The following call-chain leads to misuse of spinlock_irq
when spinlock_irqsave was hold.

irq_set_vcpu_affinity
  -> irq_get_desc_lock (spinlock_irqsave)
   -> its_irq_set_vcpu_affinity
    -> guard(raw_spin_lock_irq) <--- this enables interrupts
  -> irq_put_desc_unlock // <--- WARN IRQs enabled

Fix the issue by using guard(raw_spinlock), since the function is
already called with irqsave and raw_spin_lock was used before the commit
b97e8a2f7130 ("irqchip/gic-v3-its: Fix potential race condition in its_vlpi_prop_update()")
introducing the guard as well.

This was discovered through the lock debugging, and the corresponding
log is as follows:

raw_local_irq_restore() called with IRQs enabled
WARNING: CPU: 38 PID: 444 at kernel/locking/irqflag-debug.c:10 warn_bogus_irq_restore+0x2c/0x38
 Call trace:
  warn_bogus_irq_restore+0x2c/0x38
   _raw_spin_unlock_irqrestore+0x68/0x88
   __irq_put_desc_unlock+0x1c/0x48
   irq_set_vcpu_affinity+0x74/0xc0
   its_map_vlpi+0x44/0x88
   kvm_vgic_v4_set_forwarding+0x148/0x230
   kvm_arch_irq_bypass_add_producer+0x20/0x28
   __connect+0x98/0xb8
   irq_bypass_register_consumer+0x150/0x178
   kvm_irqfd+0x6dc/0x744
   kvm_vm_ioctl+0xe44/0x16b0

Fixes: b97e8a2f7130 ("irqchip/gic-v3-its: Fix potential race condition in its_vlpi_prop_update()")
Signed-off-by: Tomas Krcka <krckatom@...zon.de>
---
 drivers/irqchip/irq-gic-v3-its.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 92244cfa0464..8c3ec5734f1e 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -2045,7 +2045,7 @@ static int its_irq_set_vcpu_affinity(struct irq_data *d, void *vcpu_info)
 	if (!is_v4(its_dev->its))
 		return -EINVAL;
 
-	guard(raw_spinlock_irq)(&its_dev->event_map.vlpi_lock);
+	guard(raw_spinlock)(&its_dev->event_map.vlpi_lock);
 
 	/* Unmap request? */
 	if (!info)
-- 
2.40.1