On 2/5/2025 11:48 AM, Cédric Le Goater wrote:
On 1/29/25 15:43, Steve Sistare wrote:
Save the MSI message area as part of vfio-pci vmstate, and preserve the
interrupt and notifier eventfd's. migrate_incoming loads the MSI data,
then the vfio-pci post_load handler finds the eventfds in CPR state,
rebuilds vector data structures, and attaches the interrupts to the new
KVM instance.
Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
---
hw/vfio/pci.c | 117 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 116 insertions(+), 1 deletion(-)
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index fa77c36..df6e298 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -56,11 +56,37 @@ static void vfio_disable_interrupts(VFIOPCIDevice *vdev);
static void vfio_mmap_set_enabled(VFIOPCIDevice *vdev, bool enabled);
static void vfio_msi_disable_common(VFIOPCIDevice *vdev);
+#define EVENT_FD_NAME(vdev, name) \
+ g_strdup_printf("%s_%s", (vdev)->vbasedev.name, (name))
hmm, this helper could lead to memory leaks if not used as done below.
Being explict would be safer.
How about renaming it ALLOC_EVENT_FD_NAME?
If not, I will uses g_strdup_printf at the call sites but define a symbol
for the format string.
+static void save_event_fd(VFIOPCIDevice *vdev, const char *name, int nr,
+ EventNotifier *ev)
+{
+ int fd = event_notifier_get_fd(ev);
+
+ if (fd >= 0) {
+ g_autofree char *fdname = EVENT_FD_NAME(vdev, name);
+ cpr_resave_fd(fdname, nr, fd);
+ }
+}
+
+static int load_event_fd(VFIOPCIDevice *vdev, const char *name, int nr)
+{
+ g_autofree char *fdname = EVENT_FD_NAME(vdev, name);
+ return cpr_find_fd(fdname, nr);
+}
+
+static void delete_event_fd(VFIOPCIDevice *vdev, const char *name, int nr)
+{
+ g_autofree char *fdname = EVENT_FD_NAME(vdev, name);
+ cpr_delete_fd(fdname, nr);
+}
+
please move these helpers to a cpr file. They are not strictly VFIO
related too. So they could me moved outside of hw/vfio.
OK. Moving to migration/cpr.c.
/* Create new or reuse existing eventfd */
static int vfio_notifier_init(VFIOPCIDevice *vdev, EventNotifier *e,
const char *name, int nr)
{
- int fd = -1; /* placeholder until a subsequent patch */
+ int fd = load_event_fd(vdev, name, nr);
int ret = 0;
if (fd >= 0) {
@@ -71,6 +97,8 @@ static int vfio_notifier_init(VFIOPCIDevice *vdev,
EventNotifier *e,
Error *err = NULL;
error_setg_errno(&err, -ret, "vfio_notifier_init %s failed",
name);
error_report_err(err);
+ } else {
+ save_event_fd(vdev, name, nr, e);
I'd rather move the CPR related fd handling which is done in
vfio_notifier_init() in a cpr routine which vfio_notifier_init()
would call. This comment applies to all the series. Anything
related to CPR should be handled explicitely :
if (cpr_in_progress) {
cpr_do_cpr_related_stuff()
}
It will ease reading and long term maintenance.
That design pattern does not apply to this call site. The event fd must
be saved unconditionally, in case a cpr operation is performed later.
}
}
return ret;
@@ -79,6 +107,7 @@ static int vfio_notifier_init(VFIOPCIDevice *vdev,
EventNotifier *e,
static void vfio_notifier_cleanup(VFIOPCIDevice *vdev, EventNotifier *e,
const char *name, int nr)
{
+ delete_event_fd(vdev, name, nr);
event_notifier_cleanup(e);
}
@@ -561,6 +590,15 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev,
unsigned int nr,
int ret;
bool resizing = !!(vdev->nr_vectors < nr + 1);
+ /*
+ * Ignore the callback from msix_set_vector_notifiers during resume.
+ * The necessary subset of these actions is called from vfio_claim_vectors
+ * during post load.
+ */
+ if (vdev->vbasedev.reused) {
+ return 0;
+ }
again, I would prefer some explicit CPR test. Same below.
Reused is an explicit cpr test, true iff an incoming cpr operation is in
progress. I prefer the short name, but if it would help you to see cpr
leap off the page, I'll rename it cpr_reused.
trace_vfio_msix_vector_do_use(vdev->vbasedev.name, nr);
vector = &vdev->msi_vectors[nr];
@@ -2896,6 +2934,11 @@ static void vfio_register_err_notifier(VFIOPCIDevice
*vdev)
fd = event_notifier_get_fd(&vdev->err_notifier);
qemu_set_fd_handler(fd, vfio_err_notifier_handler, NULL, vdev);
+ /* Do not alter irq_signaling during vfio_realize for cpr */
+ if (vdev->vbasedev.reused) {
+ return;
+ }
+
if (!vfio_set_irq_signaling(&vdev->vbasedev, VFIO_PCI_ERR_IRQ_INDEX, 0,
VFIO_IRQ_SET_ACTION_TRIGGER, fd, &err)) {
error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name);
@@ -2960,6 +3003,12 @@ static void vfio_register_req_notifier(VFIOPCIDevice
*vdev)
fd = event_notifier_get_fd(&vdev->req_notifier);
qemu_set_fd_handler(fd, vfio_req_notifier_handler, NULL, vdev);
+ /* Do not alter irq_signaling during vfio_realize for cpr */
+ if (vdev->vbasedev.reused) {
+ vdev->req_enabled = true;
+ return;
+ }
+
if (!vfio_set_irq_signaling(&vdev->vbasedev, VFIO_PCI_REQ_IRQ_INDEX, 0,
VFIO_IRQ_SET_ACTION_TRIGGER, fd, &err)) {
error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name);
@@ -3454,6 +3503,46 @@ static void vfio_pci_set_fd(Object *obj, const char
*str, Error **errp)
}
#endif
+static void vfio_claim_vectors(VFIOPCIDevice *vdev, int nr_vectors, bool msix)
+{
+ int i, fd;
+ bool pending = false;
+ PCIDevice *pdev = &vdev->pdev;
+
+ vdev->nr_vectors = nr_vectors;
+ vdev->msi_vectors = g_new0(VFIOMSIVector, nr_vectors);
+ vdev->interrupt = msix ? VFIO_INT_MSIX : VFIO_INT_MSI;
+
+ vfio_prepare_kvm_msi_virq_batch(vdev);
+
+ for (i = 0; i < nr_vectors; i++) {
+ VFIOMSIVector *vector = &vdev->msi_vectors[i];
+
+ fd = load_event_fd(vdev, "interrupt", i);
+ if (fd >= 0) {
+ vfio_vector_init(vdev, i);
+ qemu_set_fd_handler(fd, vfio_msi_interrupt, NULL, vector);
+ }
+
+ if (load_event_fd(vdev, "kvm_interrupt", i) >= 0) {
+ vfio_add_kvm_msi_virq(vdev, vector, i, msix);
+ } else {
+ vdev->msi_vectors[i].virq = -1;
+ }
+
+ if (msix && msix_is_pending(pdev, i) && msix_is_masked(pdev, i)) {
+ set_bit(i, vdev->msix->pending);
+ pending = true;
+ }
+ }
+
+ vfio_commit_kvm_msi_virq_batch(vdev);
+
+ if (msix) {
+ memory_region_set_enabled(&pdev->msix_pba_mmio, pending);
+ }
+}
move to a cpr file please. We can have a vfio-pci lib/common file
for external users. It will take more work to get the interface right
but it will benefit other proposals. I think vfio-user as more or less
the same needs.
OK.
+
/*
* The kernel may change non-emulated config bits. Exclude them from the
* changed-bits check in get_pci_config_device.
@@ -3472,13 +3561,39 @@ static int vfio_pci_pre_load(void *opaque)
return 0;
}
+static int vfio_pci_post_load(void *opaque, int version_id)
+{
+ VFIOPCIDevice *vdev = opaque;
+ PCIDevice *pdev = &vdev->pdev;
+ int nr_vectors;
+
+ if (msix_enabled(pdev)) {
+ msix_set_vector_notifiers(pdev, vfio_msix_vector_use,
+ vfio_msix_vector_release, NULL);
+ nr_vectors = vdev->msix->entries;
+ vfio_claim_vectors(vdev, nr_vectors, true);
+
+ } else if (msi_enabled(pdev)) {
+ nr_vectors = msi_nr_vectors_allocated(pdev);
+ vfio_claim_vectors(vdev, nr_vectors, false);
+
+ } else if (vfio_pci_read_config(pdev, PCI_INTERRUPT_PIN, 1)) {
+ g_assert_not_reached(); /* completed in a subsequent patch */
+ }
+
+ return 0;
+}
+
static const VMStateDescription vfio_pci_vmstate = {
.name = "vfio-pci",
.version_id = 0,
.minimum_version_id = 0,
.pre_load = vfio_pci_pre_load,
+ .post_load = vfio_pci_post_load,
.needed = cpr_needed_for_reuse,
.fields = (VMStateField[]) {
+ VMSTATE_PCI_DEVICE(pdev, VFIOPCIDevice),
+ VMSTATE_MSIX_TEST(pdev, VFIOPCIDevice, vfio_msix_present),
VMSTATE_END_OF_LIST()
}
};
I think you can move vfio_pci_vmstate out of hw/vfio/pci.c too. Only
cpr needs it.
OK.
- Steve
