Hi Alex, > On Sat, 9/23/2023 4:55 AM, Alex Williamson <alex.william...@redhat.com> wrote: > On Mon, 18 Sep 2023 05:45:05 -0400 > Jing Liu <jing2....@intel.com> 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 > ^^ ^^ > > s/to to/to/
Will change. > > > 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> > > --- > > Changes since v1: > > - Revise Qemu to QEMU. > > > > Changes since RFC v1: > > - Test vdev->msix->noresize to identify the allocation mode. (Alex) > > - Move defer_kvm_irq_routing test out and update nr_vectors in a > > common place before vfio_enable_vectors(). (Alex) > > - Revise the comments. (Alex) > > --- > > hw/vfio/pci.c | 44 +++++++++++++++++++++++++++----------------- > > 1 file changed, 27 insertions(+), 17 deletions(-) > > > > diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c index > > 60654ca28ab8..84987e46fd7a 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; > > + int old_nr_vecs = vdev->nr_vectors; > > Minor suggestion, it reads slightly better below if this were something > like: > > bool resizing = !!(vdev->nr_vectors < nr + 1); > > Then use the bool in place of the nr+1 tests below. Thanks, > Got it. This change makes it nice to read. Thanks for the advice. Will send v3 later. Thanks, Jing > Alex > > > > > 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) { > > vdev->nr_vectors = nr + 1; > > - if (!vdev->defer_kvm_irq_routing) { > > + } > > + > > + if (!vdev->defer_kvm_irq_routing) { > > + if (vdev->msix->noresize && (old_nr_vecs < nr + 1)) { > > 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); > > + } > > } > > } > >