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SubjectRe: iommu/vt-d: Cure VF irqdomain hickup
Date
Hi Thomas,

On 2020/11/13 3:15, Thomas Gleixner wrote:
> The recent changes to store the MSI irqdomain pointer in struct device
> missed that Intel DMAR does not register virtual function devices. Due to
> that a VF device gets the plain PCI-MSI domain assigned and then issues
> compat MSI messages which get caught by the interrupt remapping unit.
>
> Cure that by inheriting the irq domain from the physical function
> device.
>
> That's a temporary workaround. The correct fix is to inherit the irq domain
> from the bus, but that's a larger effort which needs quite some other
> changes to the way how x86 manages PCI and MSI domains.
>
> Fixes: 85a8dfc57a0b ("iommm/vt-d: Store irq domain in struct device")
> Reported-by: Jason Gunthorpe <jgg@nvidia.com>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> drivers/iommu/intel/dmar.c | 19 ++++++++++++++++++-
> 1 file changed, 18 insertions(+), 1 deletion(-)
>
> --- a/drivers/iommu/intel/dmar.c
> +++ b/drivers/iommu/intel/dmar.c
> @@ -333,6 +333,11 @@ static void dmar_pci_bus_del_dev(struct
> dmar_iommu_notify_scope_dev(info);
> }
>
> +static inline void vf_inherit_msi_domain(struct pci_dev *pdev)
> +{
> + dev_set_msi_domain(&pdev->dev, dev_get_msi_domain(&pdev->physfn->dev));
> +}
> +
> static int dmar_pci_bus_notifier(struct notifier_block *nb,
> unsigned long action, void *data)
> {
> @@ -342,8 +347,20 @@ static int dmar_pci_bus_notifier(struct
> /* Only care about add/remove events for physical functions.
> * For VFs we actually do the lookup based on the corresponding
> * PF in device_to_iommu() anyway. */
> - if (pdev->is_virtfn)
> + if (pdev->is_virtfn) {
> + /*
> + * Note: This is a horrible hack and needs to be cleaned
> + * up by assigning the domain to the bus, but that's too
> + * big of a change for post rc3.
> + *
> + * Ensure that the VF device inherits the irq domain of the
> + * PF device:
> + */
> + if (action == BUS_NOTIFY_ADD_DEVICE)
> + vf_inherit_msi_domain(pdev);
> return NOTIFY_DONE;
> + }
> +
> if (action != BUS_NOTIFY_ADD_DEVICE &&
> action != BUS_NOTIFY_REMOVED_DEVICE)
> return NOTIFY_DONE;

We also encountered this problem in internal testing. This patch can
solve the problem.

Acked-by: Lu Baolu <baolu.lu@linux.intel.com>

Best regards,
baolu

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