On Fri, Mar 22, 2019 at 01:23:08PM +0800, Leo Yan wrote:
> If MSI doesn't support per-vector masking capability and
> PCI_MSI_FLAGS_MASKBIT isn't set in message control field, the function
> vfio_pci_msi_vector_write() will directly bail out for this case and
> every vector's 'virt_state' keeps setting bit VFIO_PCI_MSI_STATE_MASKED.
>
> This results in the state maintained in 'virt_state' cannot really
> reflect the MSI hardware state; finally it will mislead the function
> vfio_pci_update_msi_entry() to skip IRQ forwarding with below flow:
>
> vfio_pci_update_msi_entry() {
>
> [...]
>
> if (msi_is_masked(entry->virt_state) == msi_is_masked(entry->phys_state))
> return 0; ==> skip IRQ forwarding
>
> [...]
> }
>
> To fix this issue, when detect PCI_MSI_FLAGS_MASKBIT is not set in the
> message control field, this patch simply clears bit
> VFIO_PCI_MSI_STATE_MASKED for all vectors 'virt_state'; at the end
> vfio_pci_update_msi_entry() can forward MSI IRQ successfully.
Just remind, this patch is for kvmtool but not for kernel. Sorry I
forget to add it in subject.
Thanks,
Leo Yan
> Signed-off-by: Leo Yan <[email protected]>
> ---
> vfio/pci.c | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/vfio/pci.c b/vfio/pci.c
> index ba971eb..4fd24ac 100644
> --- a/vfio/pci.c
> +++ b/vfio/pci.c
> @@ -363,8 +363,18 @@ static int vfio_pci_msi_vector_write(struct kvm *kvm,
> struct vfio_device *vdev,
> struct vfio_pci_device *pdev = &vdev->pci;
> struct msi_cap_64 *msi_cap_64 = PCI_CAP(&pdev->hdr, pdev->msi.pos);
>
> - if (!(msi_cap_64->ctrl & PCI_MSI_FLAGS_MASKBIT))
> + if (!(msi_cap_64->ctrl & PCI_MSI_FLAGS_MASKBIT)) {
> + /*
> + * If MSI doesn't support per-vector masking capability,
> + * simply unmask for all vectors.
> + */
> + for (i = 0; i < pdev->msi.nr_entries; i++) {
> + entry = &pdev->msi.entries[i];
> + msi_set_masked(entry->virt_state, false);
> + }
> +
> return 0;
> + }
>
> if (msi_cap_64->ctrl & PCI_MSI_FLAGS_64BIT)
> mask_pos = PCI_MSI_MASK_64;
> --
> 2.19.1
>
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