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.liu@intel.com>
Tested-by: Reinette Chatre <reinette.chatre@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;
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);
+ }
}
}
--
2.27.0
On Mon, 18 Sep 2023 05:45:05 -0400 Jing Liu <jing2.liu@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/ > 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.liu@intel.com> > Tested-by: Reinette Chatre <reinette.chatre@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, 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); > + } > } > } >
Hi Alex, > On Sat, 9/23/2023 4:55 AM, Alex Williamson <alex.williamson@redhat.com> wrote: > On Mon, 18 Sep 2023 05:45:05 -0400 > Jing Liu <jing2.liu@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.liu@intel.com> > > Tested-by: Reinette Chatre <reinette.chatre@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); > > + } > > } > > } > >
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