tcm_vhost: Avoid VIRTIO_RING_F_EVENT_IDX feature bit (5dade710) · Commits · 戴 / test

This patch adds a VHOST_SCSI_FEATURES mask minus VIRTIO_RING_F_EVENT_IDX so that vhost-scsi-pci userspace will strip this feature bit once GET_FEATURES reports it as being unsupported on the host. This is to avoid a bug where ->handle_kicks() are missed when EVENT_IDX is enabled by default in userspace code. (mst: Rename to VHOST_SCSI_FEATURES + add comment) Acked-by:

Michael S. Tsirkin <mst@redhat.com> Reviewed-by:

Asias He <asias@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by:

Nicholas Bellinger <nab@linux-iscsi.org>

drivers/vhost/tcm_vhost.c

+11 −2

Original line number	Diff line number	Diff line
		@@ -60,6 +60,15 @@ enum {
		VHOST_SCSI_VQ_IO = 2,
		};

		/*
		* VIRTIO_RING_F_EVENT_IDX seems broken. Not sure the bug is in
		* kernel but disabling it helps.
		* TODO: debug and remove the workaround.
		*/
		enum {
		VHOST_SCSI_FEATURES = VHOST_FEATURES & (~VIRTIO_RING_F_EVENT_IDX)
		};

		#define VHOST_SCSI_MAX_TARGET 256
		#define VHOST_SCSI_MAX_VQ 128

		@@ -946,7 +955,7 @@ static void vhost_scsi_flush(struct vhost_scsi *vs)

		static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
		{
		if (features & ~VHOST_FEATURES)
		if (features & ~VHOST_SCSI_FEATURES)
		return -EOPNOTSUPP;

		mutex_lock(&vs->dev.mutex);
		@@ -992,7 +1001,7 @@ static long vhost_scsi_ioctl(struct file *f, unsigned int ioctl,
		return -EFAULT;
		return 0;
		case VHOST_GET_FEATURES:
		features = VHOST_FEATURES;
		features = VHOST_SCSI_FEATURES;
		if (copy_to_user(featurep, &features, sizeof features))
		return -EFAULT;
		return 0;

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