virtio_blk: add SECURE ERASE command support

Support for the VIRTIO_BLK_F_SECURE_ERASE VirtIO feature.

A device that offers this feature can receive VIRTIO_BLK_T_SECURE_ERASE
commands.

A device which supports this feature has the following fields in the
virtio config:

- max_secure_erase_sectors
- max_secure_erase_seg
- secure_erase_sector_alignment

max_secure_erase_sectors and secure_erase_sector_alignment are expressed
in 512-byte units.

Every secure erase command has the following fields:

- sectors: The starting offset in 512-byte units.
- num_sectors: The number of sectors.

Signed-off-by: Alvaro Karsz <alvaro.karsz@solid-run.com>
Message-Id: <20220921082729.2516779-1-alvaro.karsz@solid-run.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

drivers/block/virtio_blk.c

@@ -130,7 +130,7 @@ static int virtblk_add_req(struct virtqueue *vq, struct virtblk_req *vbr)
 	return virtqueue_add_sgs(vq, sgs, num_out, num_in, vbr, GFP_ATOMIC);
 }
 
-static int virtblk_setup_discard_write_zeroes(struct request *req, bool unmap)
+static int virtblk_setup_discard_write_zeroes_erase(struct request *req, bool unmap)
 {
 	unsigned short segments = blk_rq_nr_discard_segments(req);
 	unsigned short n = 0;
@@ -240,6 +240,9 @@ static blk_status_t virtblk_setup_cmd(struct virtio_device *vdev,
 		type = VIRTIO_BLK_T_WRITE_ZEROES;
 		unmap = !(req->cmd_flags & REQ_NOUNMAP);
 		break;
+	case REQ_OP_SECURE_ERASE:
+		type = VIRTIO_BLK_T_SECURE_ERASE;
+		break;
 	case REQ_OP_DRV_IN:
 		type = VIRTIO_BLK_T_GET_ID;
 		break;
@@ -251,8 +254,9 @@ static blk_status_t virtblk_setup_cmd(struct virtio_device *vdev,
 	vbr->out_hdr.type = cpu_to_virtio32(vdev, type);
 	vbr->out_hdr.ioprio = cpu_to_virtio32(vdev, req_get_ioprio(req));
 
-	if (type == VIRTIO_BLK_T_DISCARD || type == VIRTIO_BLK_T_WRITE_ZEROES) {
+	if (type == VIRTIO_BLK_T_DISCARD || type == VIRTIO_BLK_T_WRITE_ZEROES ||
-		if (virtblk_setup_discard_write_zeroes(req, unmap))
+	    type == VIRTIO_BLK_T_SECURE_ERASE) {
+		if (virtblk_setup_discard_write_zeroes_erase(req, unmap))
 			return BLK_STS_RESOURCE;
 	}
 
@@ -888,6 +892,8 @@ static int virtblk_probe(struct virtio_device *vdev)
 	int err, index;
 
 	u32 v, blk_size, max_size, sg_elems, opt_io_size;
+	u32 max_discard_segs = 0;
+	u32 discard_granularity = 0;
 	u16 min_io_size;
 	u8 physical_block_exp, alignment_offset;
 	unsigned int queue_depth;
@@ -1045,27 +1051,14 @@ static int virtblk_probe(struct virtio_device *vdev)
 
 	if (virtio_has_feature(vdev, VIRTIO_BLK_F_DISCARD)) {
 		virtio_cread(vdev, struct virtio_blk_config,
-			     discard_sector_alignment, &v);
+			     discard_sector_alignment, &discard_granularity);
-		if (v)
-			q->limits.discard_granularity = v << SECTOR_SHIFT;
-		else
-			q->limits.discard_granularity = blk_size;
 
 		virtio_cread(vdev, struct virtio_blk_config,
 			     max_discard_sectors, &v);
 		blk_queue_max_discard_sectors(q, v ? v : UINT_MAX);
 
 		virtio_cread(vdev, struct virtio_blk_config, max_discard_seg,
-			     &v);
+			     &max_discard_segs);
-
-		/*
-		 * max_discard_seg == 0 is out of spec but we always
-		 * handled it.
-		 */
-		if (!v)
-			v = sg_elems;
-		blk_queue_max_discard_segments(q,
-					       min(v, MAX_DISCARD_SEGMENTS));
 	}
 
 	if (virtio_has_feature(vdev, VIRTIO_BLK_F_WRITE_ZEROES)) {
@@ -1074,6 +1067,85 @@ static int virtblk_probe(struct virtio_device *vdev)
 		blk_queue_max_write_zeroes_sectors(q, v ? v : UINT_MAX);
 	}
 
+	/* The discard and secure erase limits are combined since the Linux
+	 * block layer uses the same limit for both commands.
+	 *
+	 * If both VIRTIO_BLK_F_SECURE_ERASE and VIRTIO_BLK_F_DISCARD features
+	 * are negotiated, we will use the minimum between the limits.
+	 *
+	 * discard sector alignment is set to the minimum between discard_sector_alignment
+	 * and secure_erase_sector_alignment.
+	 *
+	 * max discard sectors is set to the minimum between max_discard_seg and
+	 * max_secure_erase_seg.
+	 */
+	if (virtio_has_feature(vdev, VIRTIO_BLK_F_SECURE_ERASE)) {
+
+		virtio_cread(vdev, struct virtio_blk_config,
+			     secure_erase_sector_alignment, &v);
+
+		/* secure_erase_sector_alignment should not be zero, the device should set a
+		 * valid number of sectors.
+		 */
+		if (!v) {
+			dev_err(&vdev->dev,
+				"virtio_blk: secure_erase_sector_alignment can't be 0\n");
+			err = -EINVAL;
+			goto out_cleanup_disk;
+		}
+
+		discard_granularity = min_not_zero(discard_granularity, v);
+
+		virtio_cread(vdev, struct virtio_blk_config,
+			     max_secure_erase_sectors, &v);
+
+		/* max_secure_erase_sectors should not be zero, the device should set a
+		 * valid number of sectors.
+		 */
+		if (!v) {
+			dev_err(&vdev->dev,
+				"virtio_blk: max_secure_erase_sectors can't be 0\n");
+			err = -EINVAL;
+			goto out_cleanup_disk;
+		}
+
+		blk_queue_max_secure_erase_sectors(q, v);
+
+		virtio_cread(vdev, struct virtio_blk_config,
+			     max_secure_erase_seg, &v);
+
+		/* max_secure_erase_seg should not be zero, the device should set a
+		 * valid number of segments
+		 */
+		if (!v) {
+			dev_err(&vdev->dev,
+				"virtio_blk: max_secure_erase_seg can't be 0\n");
+			err = -EINVAL;
+			goto out_cleanup_disk;
+		}
+
+		max_discard_segs = min_not_zero(max_discard_segs, v);
+	}
+
+	if (virtio_has_feature(vdev, VIRTIO_BLK_F_DISCARD) ||
+	    virtio_has_feature(vdev, VIRTIO_BLK_F_SECURE_ERASE)) {
+		/* max_discard_seg and discard_granularity will be 0 only
+		 * if max_discard_seg and discard_sector_alignment fields in the virtio
+		 * config are 0 and VIRTIO_BLK_F_SECURE_ERASE feature is not negotiated.
+		 * In this case, we use default values.
+		 */
+		if (!max_discard_segs)
+			max_discard_segs = sg_elems;
+
+		blk_queue_max_discard_segments(q,
+					       min(max_discard_segs, MAX_DISCARD_SEGMENTS));
+
+		if (discard_granularity)
+			q->limits.discard_granularity = discard_granularity << SECTOR_SHIFT;
+		else
+			q->limits.discard_granularity = blk_size;
+	}
+
 	virtblk_update_capacity(vblk, false);
 	virtio_device_ready(vdev);
 
@@ -1169,6 +1241,7 @@ static unsigned int features_legacy[] = {
 	VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
 	VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
 	VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES,
+	VIRTIO_BLK_F_SECURE_ERASE,
 }
 ;
 static unsigned int features[] = {
@@ -1176,6 +1249,7 @@ static unsigned int features[] = {
 	VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
 	VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
 	VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES,
+	VIRTIO_BLK_F_SECURE_ERASE,
 };
 
 static struct virtio_driver virtio_blk = {

include/uapi/linux/virtio_blk.h

@@ -40,6 +40,7 @@
 #define VIRTIO_BLK_F_MQ		12	/* support more than one vq */
 #define VIRTIO_BLK_F_DISCARD	13	/* DISCARD is supported */
 #define VIRTIO_BLK_F_WRITE_ZEROES	14	/* WRITE ZEROES is supported */
+#define VIRTIO_BLK_F_SECURE_ERASE	16 /* Secure Erase is supported */
 
 /* Legacy feature bits */
 #ifndef VIRTIO_BLK_NO_LEGACY
@@ -121,6 +122,21 @@ struct virtio_blk_config {
 	__u8 write_zeroes_may_unmap;
 
 	__u8 unused1[3];
+
+	/* the next 3 entries are guarded by VIRTIO_BLK_F_SECURE_ERASE */
+	/*
+	 * The maximum secure erase sectors (in 512-byte sectors) for
+	 * one segment.
+	 */
+	__virtio32 max_secure_erase_sectors;
+	/*
+	 * The maximum number of secure erase segments in a
+	 * secure erase command.
+	 */
+	__virtio32 max_secure_erase_seg;
+	/* Secure erase commands must be aligned to this number of sectors. */
+	__virtio32 secure_erase_sector_alignment;
+
 } __attribute__((packed));
 
 /*
@@ -155,6 +171,9 @@ struct virtio_blk_config {
 /* Write zeroes command */
 #define VIRTIO_BLK_T_WRITE_ZEROES	13
 
+/* Secure erase command */
+#define VIRTIO_BLK_T_SECURE_ERASE	14
+
 #ifndef VIRTIO_BLK_NO_LEGACY
 /* Barrier before this op. */
 #define VIRTIO_BLK_T_BARRIER	0x80000000