Add shared memory BAR support to vhost-user-device-pci
to enable direct file mapping for VIRTIO Shared
Memory Regions.
The implementation creates a consolidated shared
memory BAR that contains all VIRTIO Shared
Memory Regions as subregions. Each region is
configured with its proper shmid, size, and
offset within the BAR. The number and size of
regions are retrieved via VHOST_USER_GET_SHMEM_CONFIG
message sent by vhost-user-base during realization
after virtio_init().
Specifically, it uses BAR 4 to avoid conflicts, as
it is currently unused.
The shared memory BAR is only created when the
backend supports VHOST_USER_PROTOCOL_F_SHMEM and
has configured shared memory regions. This maintains
backward compatibility with backends that do not
support shared memory functionality.
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Albert Esteve <aesteve@redhat.com>
---
hw/virtio/vhost-user-base.c | 46 ++++++++++++++++++++++++--
hw/virtio/vhost-user-test-device-pci.c | 42 +++++++++++++++++++++--
2 files changed, 83 insertions(+), 5 deletions(-)
diff --git a/hw/virtio/vhost-user-base.c b/hw/virtio/vhost-user-base.c
index 01ab9ca56b..de42ea46e5 100644
--- a/hw/virtio/vhost-user-base.c
+++ b/hw/virtio/vhost-user-base.c
@@ -16,6 +16,7 @@
#include "hw/virtio/virtio-bus.h"
#include "hw/virtio/vhost-user-base.h"
#include "qemu/error-report.h"
+#include "migration/blocker.h"
static void vub_start(VirtIODevice *vdev)
{
@@ -276,7 +277,8 @@ static void vub_device_realize(DeviceState *dev, Error **errp)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VHostUserBase *vub = VHOST_USER_BASE(dev);
- int ret;
+ uint64_t memory_sizes[VIRTIO_MAX_SHMEM_REGIONS];
+ int i, ret, nregions, regions_processed = 0;
if (!vub->chardev.chr) {
error_setg(errp, "vhost-user-base: missing chardev");
@@ -319,7 +321,7 @@ static void vub_device_realize(DeviceState *dev, Error **errp)
/* Allocate queues */
vub->vqs = g_ptr_array_sized_new(vub->num_vqs);
- for (int i = 0; i < vub->num_vqs; i++) {
+ for (i = 0; i < vub->num_vqs; i++) {
g_ptr_array_add(vub->vqs,
virtio_add_queue(vdev, vub->vq_size,
vub_handle_output));
@@ -333,11 +335,49 @@ static void vub_device_realize(DeviceState *dev, Error **errp)
VHOST_BACKEND_TYPE_USER, 0, errp);
if (ret < 0) {
- do_vhost_user_cleanup(vdev, vub);
+ goto err;
+ }
+
+ ret = vub->vhost_dev.vhost_ops->vhost_get_shmem_config(&vub->vhost_dev,
+ &nregions,
+ memory_sizes,
+ errp);
+
+ if (ret < 0) {
+ goto err;
+ }
+
+ for (i = 0; i < VIRTIO_MAX_SHMEM_REGIONS && regions_processed < nregions; i++) {
+ if (memory_sizes[i]) {
+ regions_processed++;
+ if (vub->vhost_dev.migration_blocker == NULL) {
+ error_setg(&vub->vhost_dev.migration_blocker,
+ "Migration disabled: devices with VIRTIO Shared Memory "
+ "Regions do not support migration yet.");
+ ret = migrate_add_blocker_normal(
+ &vub->vhost_dev.migration_blocker,
+ errp);
+
+ if (ret < 0) {
+ goto err;
+ }
+ }
+
+ if (memory_sizes[i] % qemu_real_host_page_size() != 0) {
+ error_setg(errp, "Shared memory %d size must be a multiple of "
+ "the host page size", i);
+ goto err;
+ }
+
+ virtio_new_shmem_region(vdev, i, memory_sizes[i]);
+ }
}
qemu_chr_fe_set_handlers(&vub->chardev, NULL, NULL, vub_event, NULL,
dev, NULL, true);
+ return;
+err:
+ do_vhost_user_cleanup(vdev, vub);
}
static void vub_device_unrealize(DeviceState *dev)
diff --git a/hw/virtio/vhost-user-test-device-pci.c b/hw/virtio/vhost-user-test-device-pci.c
index 7f6d751690..2106557ed8 100644
--- a/hw/virtio/vhost-user-test-device-pci.c
+++ b/hw/virtio/vhost-user-test-device-pci.c
@@ -12,10 +12,13 @@
#include "hw/virtio/vhost-user-base.h"
#include "hw/virtio/virtio-pci.h"
+#define VIRTIO_DEVICE_PCI_SHMEM_BAR 4
+
struct VHostUserDevicePCI {
VirtIOPCIProxy parent_obj;
VHostUserBase vub;
+ MemoryRegion shmembar;
};
#define TYPE_VHOST_USER_TEST_DEVICE_PCI "vhost-user-test-device-pci-base"
@@ -25,10 +28,45 @@ OBJECT_DECLARE_SIMPLE_TYPE(VHostUserDevicePCI, VHOST_USER_TEST_DEVICE_PCI)
static void vhost_user_device_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
{
VHostUserDevicePCI *dev = VHOST_USER_TEST_DEVICE_PCI(vpci_dev);
- DeviceState *vdev = DEVICE(&dev->vub);
+ DeviceState *dev_state = DEVICE(&dev->vub);
+ VirtIODevice *vdev = VIRTIO_DEVICE(dev_state);
+ VirtioSharedMemory *shmem;
+ uint64_t offset = 0, shmem_size = 0;
+ /* Keep modern 64-bit BARs (2 slots) away from the shared memory BAR. */
+ vpci_dev->modern_mem_bar_idx = 2;
vpci_dev->nvectors = 1;
- qdev_realize(vdev, BUS(&vpci_dev->bus), errp);
+ if (!qdev_realize(dev_state, BUS(&vpci_dev->bus), errp)) {
+ return;
+ }
+
+ QSIMPLEQ_FOREACH(shmem, &vdev->shmem_list, entry) {
+ if (memory_region_size(&shmem->mr) > UINT64_MAX - shmem_size) {
+ error_setg(errp, "Total shared memory required overflow");
+ return;
+ }
+ shmem_size = shmem_size + memory_region_size(&shmem->mr);
+ }
+ if (shmem_size) {
+ if (vpci_dev->flags & VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY) {
+ error_setg(errp, "modern-pio-notify is not supported due to PCI BAR layout limitations");
+ return;
+ }
+ memory_region_init(&dev->shmembar, OBJECT(vpci_dev),
+ "vhost-device-pci-shmembar", shmem_size);
+ QSIMPLEQ_FOREACH(shmem, &vdev->shmem_list, entry) {
+ memory_region_add_subregion(&dev->shmembar, offset, &shmem->mr);
+ virtio_pci_add_shm_cap(vpci_dev, VIRTIO_DEVICE_PCI_SHMEM_BAR,
+ offset, memory_region_size(&shmem->mr),
+ shmem->shmid);
+ offset = offset + memory_region_size(&shmem->mr);
+ }
+ pci_register_bar(&vpci_dev->pci_dev, VIRTIO_DEVICE_PCI_SHMEM_BAR,
+ PCI_BASE_ADDRESS_SPACE_MEMORY |
+ PCI_BASE_ADDRESS_MEM_PREFETCH |
+ PCI_BASE_ADDRESS_MEM_TYPE_64,
+ &dev->shmembar);
+ }
}
static void vhost_user_device_pci_class_init(ObjectClass *klass,
--
2.52.0