Re: [PATCH v2] irqchip/gic-v3-its: fix raw_local_irq_restore() called with IRQs enabled

[Krcka, Tomas]

Ping for this one.

> On 30. Dec 2024, at 16:08, Tomas Krcka <krckatom@xxxxxxxxx> wrote:
> 
> 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@xxxxxxxxx>
> Reviewed-by: Marc Zyngier <maz@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> 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
>