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Commit 5dade710 authored by Nicholas Bellinger's avatar Nicholas Bellinger
Browse files

tcm_vhost: Avoid VIRTIO_RING_F_EVENT_IDX feature bit 



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: default avatarMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: default avatarAsias He <asias@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 8f27d487

drivers/vhost/tcm_vhost.c

+11 −2
Original line number Original line Diff line number Diff line
@@ -60,6 +60,15 @@ enum { 
	VHOST_SCSI_VQ_IO = 2,

	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_TARGET	256

#define VHOST_SCSI_MAX_VQ	128

#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)

static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)

{

{

	if (features & ~VHOST_FEATURES)

	if (features & ~VHOST_SCSI_FEATURES)

		return -EOPNOTSUPP;

		return -EOPNOTSUPP;





	mutex_lock(&vs->dev.mutex);

	mutex_lock(&vs->dev.mutex);
@@ -992,7 +1001,7 @@ static long vhost_scsi_ioctl(struct file *f, unsigned int ioctl, 
			return -EFAULT;

			return -EFAULT;

		return 0;

		return 0;

	case VHOST_GET_FEATURES:

	case VHOST_GET_FEATURES:

		features = VHOST_FEATURES;

		features = VHOST_SCSI_FEATURES;

		if (copy_to_user(featurep, &features, sizeof features))

		if (copy_to_user(featurep, &features, sizeof features))

			return -EFAULT;

			return -EFAULT;

		return 0;

		return 0;