On 7/27/23 09:24, Jing Liu wrote:
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 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 <jing2....@intel.com> Tested-by: Reinette Chatre <reinette.cha...@intel.com> --- hw/vfio/pci.c | 40 +++++++++++++++++++++++++++------------- 1 file changed, 27 insertions(+), 13 deletions(-) diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c index 0c4ac0873d40..8c485636445c 100644 --- a/hw/vfio/pci.c +++ b/hw/vfio/pci.c @@ -512,12 +512,20 @@ 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. + * And nr_vectors stands for the number of vectors being allocated. + * + * When dynamic allocation is supported, let the host only allocate + * and enable a vector when it is in use in guest. nr_vectors stands + * for the upper bound of vectors being enabled (but not all of the + * ranges is allocated or enabled). */ - if (vdev->nr_vectors < nr + 1) { + if ((vdev->msix->irq_info_flags & VFIO_IRQ_INFO_NORESIZE) &&
I would add a small helper for this test: vfio_msix_can_alloc_dyn(vdev) Thanks, C.
+ (vdev->nr_vectors < nr + 1)) { vdev->nr_vectors = nr + 1; + if (!vdev->defer_kvm_irq_routing) { vfio_disable_irqindex(&vdev->vbasedev, VFIO_PCI_MSIX_IRQ_INDEX); ret = vfio_enable_vectors(vdev, true); @@ -529,16 +537,22 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, unsigned int nr, 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); - } + if (!vdev->defer_kvm_irq_routing) { + 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); + 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); + } + } + /* Increase for dynamic allocation case. */ + if (vdev->nr_vectors < nr + 1) { + vdev->nr_vectors = nr + 1; } }
