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Date:   Tue, 22 Aug 2023 01:22:17 +0000
From:   Wei Liu <wei.liu@kernel.org>
To:     "Michael Kelley (LINUX)" <mikelley@microsoft.com>
Cc:     Dexuan Cui <decui@microsoft.com>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
        "jgg@ziepe.ca" <jgg@ziepe.ca>,
        "bhelgaas@google.com" <bhelgaas@google.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        "kw@linux.com" <kw@linux.com>, KY Srinivasan <kys@microsoft.com>,
        "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
        "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
        "lpieralisi@kernel.org" <lpieralisi@kernel.org>,
        "robh@kernel.org" <robh@kernel.org>,
        "wei.liu@kernel.org" <wei.liu@kernel.org>,
        "helgaas@kernel.org" <helgaas@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] PCI: hv: Fix a crash in hv_pci_restore_msi_msg()
 during hibernation
Message-ID: <ZOQNyVtQ9Cilfk92@liuwe-devbox-debian-v2>
References: <20230816175939.21566-1-decui@microsoft.com>
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On Wed, Aug 16, 2023 at 08:10:25PM +0000, Michael Kelley (LINUX) wrote:
> From: Dexuan Cui <decui@microsoft.com> Sent: Wednesday, August 16, 2023 11:00 AM
> > 
> > When a Linux VM with an assigned PCI device runs on Hyper-V, if the PCI
> > device driver is not loaded yet (i.e. MSI-X/MSI is not enabled on the
> > device yet), doing a VM hibernation triggers a panic in
> > hv_pci_restore_msi_msg() -> msi_lock_descs(&pdev->dev), because
> > pdev->dev.msi.data is still NULL.
> > 
> > Avoid the panic by checking if MSI-X/MSI is enabled.
> > 
> > Fixes: dc2b453290c4 ("PCI: hv: Rework MSI handling")
> > Signed-off-by: Dexuan Cui <decui@microsoft.com>
> > ---
> > 
> > Changes in v2:
> >     Replaced the test "if (!pdev->dev.msi.data)" with
> > 		      "if (!pdev->msi_enabled && !pdev->msix_enabled)".
> >       Thanks Michael!
> >     Updated the changelog accordingly.
> > 
> >  drivers/pci/controller/pci-hyperv.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> > index 2d93d0c4f10d..bed3cefdaf19 100644
> > --- a/drivers/pci/controller/pci-hyperv.c
> > +++ b/drivers/pci/controller/pci-hyperv.c
> > @@ -3983,6 +3983,9 @@ static int hv_pci_restore_msi_msg(struct pci_dev *pdev, void *arg)
> >  	struct msi_desc *entry;
> >  	int ret = 0;
> > 
> > +	if (!pdev->msi_enabled && !pdev->msix_enabled)
> > +		return 0;
> > +
> >  	msi_lock_descs(&pdev->dev);
> >  	msi_for_each_desc(entry, &pdev->dev, MSI_DESC_ASSOCIATED) {
> >  		irq_data = irq_get_irq_data(entry->irq);
> > --
> > 2.25.1
> 
> Reviewed-by: Michael Kelley <mikelley@microsoft.com>
> 
> 

I expect this to go through the PCI tree. Just let me know if I should
pick this up.

Thanks,
Wei.