linux-kernel - RE: [PATCH v2 vfio 1/3] pds/vfio: Fix spinlock bad magic BUG

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Date:   Thu, 12 Oct 2023 08:44:46 +0000
From:   Shameerali Kolothum Thodi <shameerali.kolothum.thodi@...wei.com>
To:     Brett Creeley <brett.creeley@....com>,
        "jgg@...pe.ca" <jgg@...pe.ca>,
        "yishaih@...dia.com" <yishaih@...dia.com>,
        "kevin.tian@...el.com" <kevin.tian@...el.com>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "dan.carpenter@...aro.org" <dan.carpenter@...aro.org>
CC:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "shannon.nelson@....com" <shannon.nelson@....com>
Subject: RE: [PATCH v2 vfio 1/3] pds/vfio: Fix spinlock bad magic BUG



> -----Original Message-----
> From: Brett Creeley [mailto:brett.creeley@....com]
> Sent: 12 October 2023 00:01
> To: jgg@...pe.ca; yishaih@...dia.com; Shameerali Kolothum Thodi
> <shameerali.kolothum.thodi@...wei.com>; kevin.tian@...el.com;
> alex.williamson@...hat.com; dan.carpenter@...aro.org
> Cc: kvm@...r.kernel.org; linux-kernel@...r.kernel.org;
> brett.creeley@....com; shannon.nelson@....com
> Subject: [PATCH v2 vfio 1/3] pds/vfio: Fix spinlock bad magic BUG
> 
> The following BUG was found when running on a kernel with
> CONFIG_DEBUG_SPINLOCK=y set:
> 
> BUG: spinlock bad magic on CPU#2, bash/2481
>  lock: 0xffff8d6052a88f50, .magic: 00000000, .owner:
> <none>/-1, .owner_cpu: 0
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0x36/0x50
>  do_raw_spin_lock+0x79/0xc0
>  pds_vfio_reset+0x1d/0x60 [pds_vfio_pci]
>  pci_reset_function+0x4b/0x70
>  reset_store+0x5b/0xa0
>  kernfs_fop_write_iter+0x137/0x1d0
>  vfs_write+0x2de/0x410
>  ksys_write+0x5d/0xd0
>  do_syscall_64+0x3b/0x90
>  entry_SYSCALL_64_after_hwframe+0x6e/0xd8
> 
> As shown, the .magic: 00000000, does not match the expected value. This
> is because spin_lock_init() is never called for the reset_lock. Fix
> this by calling spin_lock_init(&pds_vfio->reset_lock) when initializing
> the device.
> 
> Signed-off-by: Brett Creeley <brett.creeley@....com>
> Reviewed-by: Shannon Nelson <shannon.nelson@....com>

Reviewed-by: Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>

I think this needs to be fixed in HiSilicon driver as well. I will send out a 
patch.

Thanks,
Shameer

> ---
>  drivers/vfio/pci/pds/vfio_dev.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/vfio/pci/pds/vfio_dev.c b/drivers/vfio/pci/pds/vfio_dev.c
> index 649b18ee394b..c351f588fa13 100644
> --- a/drivers/vfio/pci/pds/vfio_dev.c
> +++ b/drivers/vfio/pci/pds/vfio_dev.c
> @@ -155,6 +155,8 @@ static int pds_vfio_init_device(struct vfio_device
> *vdev)
> 
>  	pds_vfio->vf_id = vf_id;
> 
> +	spin_lock_init(&pds_vfio->reset_lock);
> +
>  	vdev->migration_flags = VFIO_MIGRATION_STOP_COPY |
> VFIO_MIGRATION_P2P;
>  	vdev->mig_ops = &pds_vfio_lm_ops;
>  	vdev->log_ops = &pds_vfio_log_ops;
> --
> 2.17.1