Commit 41cff026 authored by Dongli Zhang's avatar Dongli Zhang Committed by Michael S. Tsirkin
Browse files

vhost: modify vhost_log_write() for broader users 



Currently, the only user of vhost_log_write() is vhost-net. The 'len'
argument prevents logging of pages that are not tainted by the RX path.

Adjustments are needed since more drivers (i.e. vhost-scsi) begin using
vhost_log_write(). So far vhost-net RX path may only partially use pages
shared via the last vring descriptor. Unlike vhost-net, vhost-scsi always
logs all pages shared via vring descriptors. To accommodate this,
use (len == U64_MAX) to indicate whether the driver would log all pages of
vring descriptors, or only pages that are tainted by the driver.

In addition, removes BUG().

Suggested-by: default avatarJoao Martins <joao.m.martins@oracle.com>
Signed-off-by: default avatarDongli Zhang <dongli.zhang@oracle.com>
Message-Id: <20250403063028.16045-5-dongli.zhang@oracle.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent a5806cd5

drivers/vhost/vhost.c

+20 −8
Original line number Diff line number Diff line
@@ -2304,6 +2304,19 @@ static int log_used(struct vhost_virtqueue *vq, u64 used_offset, u64 len) 
	return 0;

}



/*

 * vhost_log_write() - Log in dirty page bitmap

 * @vq:      vhost virtqueue.

 * @log:     Array of dirty memory in GPA.

 * @log_num: Size of vhost_log arrary.

 * @len:     The total length of memory buffer to log in the dirty bitmap.

 *	     Some drivers may only partially use pages shared via the last

 *	     vring descriptor (i.e. vhost-net RX buffer).

 *	     Use (len == U64_MAX) to indicate the driver would log all

 *           pages of vring descriptors.

 * @iov:     Array of dirty memory in HVA.

 * @count:   Size of iovec array.

 */

int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,

		    unsigned int log_num, u64 len, struct iovec *iov, int count)

{
@@ -2327,15 +2340,14 @@ int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, 
		r = log_write(vq->log_base, log[i].addr, l);

		if (r < 0)

			return r;



		if (len != U64_MAX)

			len -= l;

		if (!len) {

	}



	if (vq->log_ctx)

		eventfd_signal(vq->log_ctx);

			return 0;

		}

	}

	/* Length written exceeds what we have stored. This is a bug. */

	BUG();



	return 0;

}

EXPORT_SYMBOL_GPL(vhost_log_write);