On Tue, 2011-11-29 at 13:01 +1100, Alexey Kardashevskiy wrote:
> Hi all,
>
> Another problem I hit on POWER - MSI interrupts allocation. The existing VFIO does not expect a PBH
> to support less interrupts that a device might request. In my case, PHB's limit is 8 interrupts
> while my test card (10Gb ethernet CXGB3) wants 9. Below are the patches to demonstrate the idea.
Seems reasonable. I assume we'd need similar for vfio_pci_setup_msi,
though I haven't seen anything use more than a single MSI interrupt.
Thanks,
Alex
> KERNEL patch:
>
> diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
> index 7d45c6b..d44b9bf 100644
> --- a/drivers/vfio/pci/vfio_pci_intrs.c
> +++ b/drivers/vfio/pci/vfio_pci_intrs.c
> @@ -458,17 +458,32 @@ int vfio_pci_setup_msix(struct vfio_pci_device *vdev, int nvec, int __user *inta
> vdev->msix[i].entry = i;
> vdev->ev_msix[i] = ctx;
> }
> - if (!ret)
> + if (!ret) {
> ret = pci_enable_msix(pdev, vdev->msix, nvec);
> + /*
> + The kernel is unable to allocate requested number of IRQs
> + and returned the available number.
> + */
> + if (0 < ret) {
> + ret = pci_enable_msix(pdev, vdev->msix, ret);
> + }
> + }
> vdev->msix_nvec = 0;
> - for (i = 0; i < nvec && !ret; i++) {
> - ret = request_irq(vdev->msix[i].vector, msihandler, 0,
> - "vfio", vdev->ev_msix[i]);
> - if (ret)
> - break;
> - vdev->msix_nvec = i+1;
> + if (0 == ret) {
> + vdev->msix_nvec = 0;
> + ret = 0;
> + for (i = 0; i < nvec && !ret; i++) {
> + ret = request_irq(vdev->msix[i].vector, msihandler, 0,
> + "vfio", vdev->ev_msix[i]);
> + if (ret)
> + break;
> + vdev->msix_nvec = i+1;
> + }
> + if ((0 == vdev->msix_nvec) && (0 != ret))
> + vfio_pci_drop_msix(vdev);
> + else
> + ret = vdev->msix_nvec;
> }
> - if (ret)
> - vfio_pci_drop_msix(vdev);
> +
> return ret;
> }
>
> === end ===
>
>
> QEMU patch:
>
> diff --git a/hw/vfio_pci.c b/hw/vfio_pci.c
> index 020961a..980eec7 100644
> --- a/hw/vfio_pci.c
> +++ b/hw/vfio_pci.c
> @@ -341,7 +341,8 @@ static void vfio_enable_msi(VFIODevice *vdev, bool msix)
> }
> }
>
> - if (ioctl(vdev->fd, VFIO_DEVICE_SET_IRQ_EVENTFDS, fds)) {
> + ret = ioctl(vdev->fd, VFIO_DEVICE_SET_IRQ_EVENTFDS, fds);
> + if (0 > ret) {
> fprintf(stderr, "vfio: Error: Failed to setup MSI/X fds %s\n",
> strerror(errno));
> for (i = 0; i < vdev->nr_vectors; i++) {
> @@ -355,6 +356,8 @@ static void vfio_enable_msi(VFIODevice *vdev, bool msix)
> qemu_free(vdev->msi_vectors);
> vdev->nr_vectors = 0;
> return;
> + } else if (0 < ret) {
> + vdev->nr_vectors = ret;
> }
>
> vdev->interrupt = msix ? INT_MSIX : INT_MSI;
>
>
> === end ===
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