From d9e6710d7d59c1f774bfb49f3b1c2b5ee06ed33e Mon Sep 17 00:00:00 2001 From: Jing Liu Date: Mon, 25 Sep 2023 22:14:05 -0400 Subject: [PATCH] vfio/pci: enable vector on dynamic MSI-X allocation MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The vector_use callback is used to enable vector that is unmasked in guest. The kernel used to only support static MSI-X allocation. When allocating a new interrupt using "static MSI-X allocation" kernels, QEMU first disables all previously allocated vectors and then re-allocates all including the new one. The nr_vectors of VFIOPCIDevice indicates that all vectors from 0 to nr_vectors are allocated (and may be enabled), which is used to loop all the possibly used vectors when e.g., disabling MSI-X interrupts. Extend the vector_use function to support dynamic MSI-X allocation when host supports the capability. QEMU therefore can individually allocate and enable a new interrupt without affecting others or causing interrupts lost during runtime. Utilize nr_vectors to calculate the upper bound of enabled vectors in dynamic MSI-X allocation mode since looping all msix_entries_nr is not efficient and unnecessary. Signed-off-by: Jing Liu Tested-by: Reinette Chatre Reviewed-by: Alex Williamson Signed-off-by: Cédric Le Goater --- hw/vfio/pci.c | 46 ++++++++++++++++++++++++++++------------------ 1 file changed, 28 insertions(+), 18 deletions(-) diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c index 86c92c51a4..eb7627c5f9 100644 --- a/hw/vfio/pci.c +++ b/hw/vfio/pci.c @@ -470,6 +470,7 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, unsigned int nr, VFIOPCIDevice *vdev = VFIO_PCI(pdev); VFIOMSIVector *vector; int ret; + bool resizing = !!(vdev->nr_vectors < nr + 1); trace_vfio_msix_vector_do_use(vdev->vbasedev.name, nr); @@ -512,33 +513,42 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, unsigned int nr, } /* - * We don't want to have the host allocate all possible MSI vectors - * for a device if they're not in use, so we shutdown and incrementally - * increase them as needed. + * When dynamic allocation is not supported, we don't want to have the + * host allocate all possible MSI vectors for a device if they're not + * in use, so we shutdown and incrementally increase them as needed. + * nr_vectors represents the total number of vectors allocated. + * + * When dynamic allocation is supported, let the host only allocate + * and enable a vector when it is in use in guest. nr_vectors represents + * the upper bound of vectors being enabled (but not all of the ranges + * is allocated or enabled). */ - if (vdev->nr_vectors < nr + 1) { + if (resizing) { vdev->nr_vectors = nr + 1; - if (!vdev->defer_kvm_irq_routing) { + } + + if (!vdev->defer_kvm_irq_routing) { + if (vdev->msix->noresize && resizing) { vfio_disable_irqindex(&vdev->vbasedev, VFIO_PCI_MSIX_IRQ_INDEX); ret = vfio_enable_vectors(vdev, true); if (ret) { error_report("vfio: failed to enable vectors, %d", ret); } - } - } else { - Error *err = NULL; - int32_t fd; - - if (vector->virq >= 0) { - fd = event_notifier_get_fd(&vector->kvm_interrupt); } else { - fd = event_notifier_get_fd(&vector->interrupt); - } + Error *err = NULL; + int32_t fd; - if (vfio_set_irq_signaling(&vdev->vbasedev, - VFIO_PCI_MSIX_IRQ_INDEX, nr, - VFIO_IRQ_SET_ACTION_TRIGGER, fd, &err)) { - error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name); + if (vector->virq >= 0) { + fd = event_notifier_get_fd(&vector->kvm_interrupt); + } else { + fd = event_notifier_get_fd(&vector->interrupt); + } + + if (vfio_set_irq_signaling(&vdev->vbasedev, + VFIO_PCI_MSIX_IRQ_INDEX, nr, + VFIO_IRQ_SET_ACTION_TRIGGER, fd, &err)) { + error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name); + } } } -- 2.11.4.GIT