@@ -33,6 +33,8 @@ typedef struct VhostShadowVirtqueue {
EventNotifier svq_call;
} VhostShadowVirtqueue;
+bool vhost_svq_valid_features(uint64_t features, Error **errp);
+
void vhost_svq_set_svq_kick_fd(VhostShadowVirtqueue *svq, int svq_kick_fd);
void vhost_svq_set_svq_call_fd(VhostShadowVirtqueue *svq, int call_fd);
@@ -11,9 +11,53 @@
#include "hw/virtio/vhost-shadow-virtqueue.h"
#include "qemu/error-report.h"
+#include "qapi/error.h"
#include "qemu/main-loop.h"
#include "linux-headers/linux/vhost.h"
+/**
+ * Validate the transport device features that both guests can use with the SVQ
+ * and SVQs can use with the device.
+ *
+ * @dev_features: The features
+ * @errp: Error pointer
+ */
+bool vhost_svq_valid_features(uint64_t features, Error **errp)
+{
+ bool ok = true;
+ uint64_t svq_features = features;
+
+ for (uint64_t b = VIRTIO_TRANSPORT_F_START; b <= VIRTIO_TRANSPORT_F_END;
+ ++b) {
+ switch (b) {
+ case VIRTIO_F_ANY_LAYOUT:
+ continue;
+
+ case VIRTIO_F_ACCESS_PLATFORM:
+ /* SVQ trust in the host's IOMMU to translate addresses */
+ case VIRTIO_F_VERSION_1:
+ /* SVQ trust that the guest vring is little endian */
+ if (!(svq_features & BIT_ULL(b))) {
+ set_bit(b, &svq_features);
+ ok = false;
+ }
+ continue;
+
+ default:
+ if (svq_features & BIT_ULL(b)) {
+ clear_bit(b, &svq_features);
+ ok = false;
+ }
+ }
+ }
+
+ if (ok) {
+ error_setg(errp, "SVQ Invalid device feature flags, offer: 0x%"PRIx64
+ ", ok: 0x%"PRIx64, features, svq_features);
+ }
+ return ok;
+}
+
/**
* Forward guest notifications.
*
@@ -348,11 +348,26 @@ static int vhost_vdpa_init_svq(struct vhost_dev *hdev, struct vhost_vdpa *v,
Error **errp)
{
g_autoptr(GPtrArray) shadow_vqs = NULL;
+ uint64_t dev_features, svq_features;
+ int r;
+ bool ok;
if (!v->shadow_vqs_enabled) {
return 0;
}
+ r = hdev->vhost_ops->vhost_get_features(hdev, &dev_features);
+ if (r != 0) {
+ error_setg_errno(errp, -r, "Can't get vdpa device features");
+ return r;
+ }
+
+ svq_features = dev_features;
+ ok = vhost_svq_valid_features(svq_features, errp);
+ if (unlikely(!ok)) {
+ return -1;
+ }
+
shadow_vqs = g_ptr_array_new_full(hdev->nvqs, vhost_svq_free);
for (unsigned n = 0; n < hdev->nvqs; ++n) {
g_autoptr(VhostShadowVirtqueue) svq = vhost_svq_new();
This allows SVQ to negotiate features with the guest and the device. For the device, SVQ is a driver. While this function bypasses all non-transport features, it needs to disable the features that SVQ does not support when forwarding buffers. This includes packed vq layout, indirect descriptors or event idx. Future changes can add support to offer more features to the guest, since the use of VirtQueue gives this for free. This is left out at the moment for simplicity. Signed-off-by: Eugenio PĂ©rez <eperezma@redhat.com> --- hw/virtio/vhost-shadow-virtqueue.h | 2 ++ hw/virtio/vhost-shadow-virtqueue.c | 44 ++++++++++++++++++++++++++++++ hw/virtio/vhost-vdpa.c | 15 ++++++++++ 3 files changed, 61 insertions(+)