cxlflash: Virtual LUN support

Add support for physical LUN segmentation (virtual LUNs) to device
driver supporting the IBM CXL Flash adapter. This patch allows user
space applications to virtually segment a physical LUN into N virtual
LUNs, taking advantage of the translation features provided by this
adapter.

Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>
Reviewed-by: Michael Neuling <mikey@neuling.org>
Reviewed-by: Wen Xiong <wenxiong@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>

1 files changed, 1243 insertions, 0 deletions

diff --git a/drivers/scsi/cxlflash/vlun.c b/drivers/scsi/cxlflash/vlun.c
new file mode 100644
index 000000000000..6155cb1d4ed3
--- /dev/null
+++ b/drivers/scsi/cxlflash/vlun.c
@@ -0,0 +1,1243 @@
+/*
+ * CXL Flash Device Driver
+ *
+ * Written by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>, IBM Corporation
+ *             Matthew R. Ochs <mrochs@linux.vnet.ibm.com>, IBM Corporation
+ *
+ * Copyright (C) 2015 IBM Corporation
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/syscalls.h>
+#include <misc/cxl.h>
+#include <asm/unaligned.h>
+#include <asm/bitsperlong.h>
+
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_host.h>
+#include <uapi/scsi/cxlflash_ioctl.h>
+
+#include "sislite.h"
+#include "common.h"
+#include "vlun.h"
+#include "superpipe.h"
+
+/**
+ * marshal_virt_to_resize() - translate uvirtual to resize structure
+ * @virt:	Source structure from which to translate/copy.
+ * @resize:	Destination structure for the translate/copy.
+ */
+static void marshal_virt_to_resize(struct dk_cxlflash_uvirtual *virt,
+				   struct dk_cxlflash_resize *resize)
+{
+	resize->hdr = virt->hdr;
+	resize->context_id = virt->context_id;
+	resize->rsrc_handle = virt->rsrc_handle;
+	resize->req_size = virt->lun_size;
+	resize->last_lba = virt->last_lba;
+}
+
+/**
+ * marshal_clone_to_rele() - translate clone to release structure
+ * @clone:	Source structure from which to translate/copy.
+ * @rele:	Destination structure for the translate/copy.
+ */
+static void marshal_clone_to_rele(struct dk_cxlflash_clone *clone,
+				  struct dk_cxlflash_release *release)
+{
+	release->hdr = clone->hdr;
+	release->context_id = clone->context_id_dst;
+}
+
+/**
+ * ba_init() - initializes a block allocator
+ * @ba_lun:	Block allocator to initialize.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static int ba_init(struct ba_lun *ba_lun)
+{
+	struct ba_lun_info *bali = NULL;
+	int lun_size_au = 0, i = 0;
+	int last_word_underflow = 0;
+	u64 *lam;
+
+	pr_debug("%s: Initializing LUN: lun_id = %llX, "
+		 "ba_lun->lsize = %lX, ba_lun->au_size = %lX\n",
+		__func__, ba_lun->lun_id, ba_lun->lsize, ba_lun->au_size);
+
+	/* Calculate bit map size */
+	lun_size_au = ba_lun->lsize / ba_lun->au_size;
+	if (lun_size_au == 0) {
+		pr_debug("%s: Requested LUN size of 0!\n", __func__);
+		return -EINVAL;
+	}
+
+	/* Allocate lun information container */
+	bali = kzalloc(sizeof(struct ba_lun_info), GFP_KERNEL);
+	if (unlikely(!bali)) {
+		pr_err("%s: Failed to allocate lun_info for lun_id %llX\n",
+		       __func__, ba_lun->lun_id);
+		return -ENOMEM;
+	}
+
+	bali->total_aus = lun_size_au;
+	bali->lun_bmap_size = lun_size_au / BITS_PER_LONG;
+
+	if (lun_size_au % BITS_PER_LONG)
+		bali->lun_bmap_size++;
+
+	/* Allocate bitmap space */
+	bali->lun_alloc_map = kzalloc((bali->lun_bmap_size * sizeof(u64)),
+				      GFP_KERNEL);
+	if (unlikely(!bali->lun_alloc_map)) {
+		pr_err("%s: Failed to allocate lun allocation map: "
+		       "lun_id = %llX\n", __func__, ba_lun->lun_id);
+		kfree(bali);
+		return -ENOMEM;
+	}
+
+	/* Initialize the bit map size and set all bits to '1' */
+	bali->free_aun_cnt = lun_size_au;
+
+	for (i = 0; i < bali->lun_bmap_size; i++)
+		bali->lun_alloc_map[i] = 0xFFFFFFFFFFFFFFFFULL;
+
+	/* If the last word not fully utilized, mark extra bits as allocated */
+	last_word_underflow = (bali->lun_bmap_size * BITS_PER_LONG);
+	last_word_underflow -= bali->free_aun_cnt;
+	if (last_word_underflow > 0) {
+		lam = &bali->lun_alloc_map[bali->lun_bmap_size - 1];
+		for (i = (HIBIT - last_word_underflow + 1);
+		     i < BITS_PER_LONG;
+		     i++)
+			clear_bit(i, (ulong *)lam);
+	}
+
+	/* Initialize high elevator index, low/curr already at 0 from kzalloc */
+	bali->free_high_idx = bali->lun_bmap_size;
+
+	/* Allocate clone map */
+	bali->aun_clone_map = kzalloc((bali->total_aus * sizeof(u8)),
+				      GFP_KERNEL);
+	if (unlikely(!bali->aun_clone_map)) {
+		pr_err("%s: Failed to allocate clone map: lun_id = %llX\n",
+		       __func__, ba_lun->lun_id);
+		kfree(bali->lun_alloc_map);
+		kfree(bali);
+		return -ENOMEM;
+	}
+
+	/* Pass the allocated lun info as a handle to the user */
+	ba_lun->ba_lun_handle = bali;
+
+	pr_debug("%s: Successfully initialized the LUN: "
+		 "lun_id = %llX, bitmap size = %X, free_aun_cnt = %llX\n",
+		__func__, ba_lun->lun_id, bali->lun_bmap_size,
+		bali->free_aun_cnt);
+	return 0;
+}
+
+/**
+ * find_free_range() - locates a free bit within the block allocator
+ * @low:	First word in block allocator to start search.
+ * @high:	Last word in block allocator to search.
+ * @bali:	LUN information structure owning the block allocator to search.
+ * @bit_word:	Passes back the word in the block allocator owning the free bit.
+ *
+ * Return: The bit position within the passed back word, -1 on failure
+ */
+static int find_free_range(u32 low,
+			   u32 high,
+			   struct ba_lun_info *bali, int *bit_word)
+{
+	int i;
+	u64 bit_pos = -1;
+	ulong *lam, num_bits;
+
+	for (i = low; i < high; i++)
+		if (bali->lun_alloc_map[i] != 0) {
+			lam = (ulong *)&bali->lun_alloc_map[i];
+			num_bits = (sizeof(*lam) * BITS_PER_BYTE);
+			bit_pos = find_first_bit(lam, num_bits);
+
+			pr_devel("%s: Found free bit %llX in lun "
+				 "map entry %llX at bitmap index = %X\n",
+				 __func__, bit_pos, bali->lun_alloc_map[i],
+				 i);
+
+			*bit_word = i;
+			bali->free_aun_cnt--;
+			clear_bit(bit_pos, lam);
+			break;
+		}
+
+	return bit_pos;
+}
+
+/**
+ * ba_alloc() - allocates a block from the block allocator
+ * @ba_lun:	Block allocator from which to allocate a block.
+ *
+ * Return: The allocated block, -1 on failure
+ */
+static u64 ba_alloc(struct ba_lun *ba_lun)
+{
+	u64 bit_pos = -1;
+	int bit_word = 0;
+	struct ba_lun_info *bali = NULL;
+
+	bali = ba_lun->ba_lun_handle;
+
+	pr_debug("%s: Received block allocation request: "
+		 "lun_id = %llX, free_aun_cnt = %llX\n",
+		 __func__, ba_lun->lun_id, bali->free_aun_cnt);
+
+	if (bali->free_aun_cnt == 0) {
+		pr_debug("%s: No space left on LUN: lun_id = %llX\n",
+			 __func__, ba_lun->lun_id);
+		return -1ULL;
+	}
+
+	/* Search to find a free entry, curr->high then low->curr */
+	bit_pos = find_free_range(bali->free_curr_idx,
+				  bali->free_high_idx, bali, &bit_word);
+	if (bit_pos == -1) {
+		bit_pos = find_free_range(bali->free_low_idx,
+					  bali->free_curr_idx,
+					  bali, &bit_word);
+		if (bit_pos == -1) {
+			pr_debug("%s: Could not find an allocation unit on LUN:"
+				 " lun_id = %llX\n", __func__, ba_lun->lun_id);
+			return -1ULL;
+		}
+	}
+
+	/* Update the free_curr_idx */
+	if (bit_pos == HIBIT)
+		bali->free_curr_idx = bit_word + 1;
+	else
+		bali->free_curr_idx = bit_word;
+
+	pr_debug("%s: Allocating AU number %llX, on lun_id %llX, "
+		 "free_aun_cnt = %llX\n", __func__,
+		 ((bit_word * BITS_PER_LONG) + bit_pos), ba_lun->lun_id,
+		 bali->free_aun_cnt);
+
+	return (u64) ((bit_word * BITS_PER_LONG) + bit_pos);
+}
+
+/**
+ * validate_alloc() - validates the specified block has been allocated
+ * @ba_lun_info:	LUN info owning the block allocator.
+ * @aun:		Block to validate.
+ *
+ * Return: 0 on success, -1 on failure
+ */
+static int validate_alloc(struct ba_lun_info *bali, u64 aun)
+{
+	int idx = 0, bit_pos = 0;
+
+	idx = aun / BITS_PER_LONG;
+	bit_pos = aun % BITS_PER_LONG;
+
+	if (test_bit(bit_pos, (ulong *)&bali->lun_alloc_map[idx]))
+		return -1;
+
+	return 0;
+}
+
+/**
+ * ba_free() - frees a block from the block allocator
+ * @ba_lun:	Block allocator from which to allocate a block.
+ * @to_free:	Block to free.
+ *
+ * Return: 0 on success, -1 on failure
+ */
+static int ba_free(struct ba_lun *ba_lun, u64 to_free)
+{
+	int idx = 0, bit_pos = 0;
+	struct ba_lun_info *bali = NULL;
+
+	bali = ba_lun->ba_lun_handle;
+
+	if (validate_alloc(bali, to_free)) {
+		pr_debug("%s: The AUN %llX is not allocated on lun_id %llX\n",
+			 __func__, to_free, ba_lun->lun_id);
+		return -1;
+	}
+
+	pr_debug("%s: Received a request to free AU %llX on lun_id %llX, "
+		 "free_aun_cnt = %llX\n", __func__, to_free, ba_lun->lun_id,
+		 bali->free_aun_cnt);
+
+	if (bali->aun_clone_map[to_free] > 0) {
+		pr_debug("%s: AUN %llX on lun_id %llX has been cloned. Clone "
+			 "count = %X\n", __func__, to_free, ba_lun->lun_id,
+			 bali->aun_clone_map[to_free]);
+		bali->aun_clone_map[to_free]--;
+		return 0;
+	}
+
+	idx = to_free / BITS_PER_LONG;
+	bit_pos = to_free % BITS_PER_LONG;
+
+	set_bit(bit_pos, (ulong *)&bali->lun_alloc_map[idx]);
+	bali->free_aun_cnt++;
+
+	if (idx < bali->free_low_idx)
+		bali->free_low_idx = idx;
+	else if (idx > bali->free_high_idx)
+		bali->free_high_idx = idx;
+
+	pr_debug("%s: Successfully freed AU at bit_pos %X, bit map index %X on "
+		 "lun_id %llX, free_aun_cnt = %llX\n", __func__, bit_pos, idx,
+		 ba_lun->lun_id, bali->free_aun_cnt);
+
+	return 0;
+}
+
+/**
+ * ba_clone() - Clone a chunk of the block allocation table
+ * @ba_lun:	Block allocator from which to allocate a block.
+ * @to_free:	Block to free.
+ *
+ * Return: 0 on success, -1 on failure
+ */
+static int ba_clone(struct ba_lun *ba_lun, u64 to_clone)
+{
+	struct ba_lun_info *bali = ba_lun->ba_lun_handle;
+
+	if (validate_alloc(bali, to_clone)) {
+		pr_debug("%s: AUN %llX is not allocated on lun_id %llX\n",
+			 __func__, to_clone, ba_lun->lun_id);
+		return -1;
+	}
+
+	pr_debug("%s: Received a request to clone AUN %llX on lun_id %llX\n",
+		 __func__, to_clone, ba_lun->lun_id);
+
+	if (bali->aun_clone_map[to_clone] == MAX_AUN_CLONE_CNT) {
+		pr_debug("%s: AUN %llX on lun_id %llX hit max clones already\n",
+			 __func__, to_clone, ba_lun->lun_id);
+		return -1;
+	}
+
+	bali->aun_clone_map[to_clone]++;
+
+	return 0;
+}
+
+/**
+ * ba_space() - returns the amount of free space left in the block allocator
+ * @ba_lun:	Block allocator.
+ *
+ * Return: Amount of free space in block allocator
+ */
+static u64 ba_space(struct ba_lun *ba_lun)
+{
+	struct ba_lun_info *bali = ba_lun->ba_lun_handle;
+
+	return bali->free_aun_cnt;
+}
+
+/**
+ * cxlflash_ba_terminate() - frees resources associated with the block allocator
+ * @ba_lun:	Block allocator.
+ *
+ * Safe to call in a partially allocated state.
+ */
+void cxlflash_ba_terminate(struct ba_lun *ba_lun)
+{
+	struct ba_lun_info *bali = ba_lun->ba_lun_handle;
+
+	if (bali) {
+		kfree(bali->aun_clone_map);
+		kfree(bali->lun_alloc_map);
+		kfree(bali);
+		ba_lun->ba_lun_handle = NULL;
+	}
+}
+
+/**
+ * init_vlun() - initializes a LUN for virtual use
+ * @lun_info:	LUN information structure that owns the block allocator.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static int init_vlun(struct llun_info *lli)
+{
+	int rc = 0;
+	struct glun_info *gli = lli->parent;
+	struct blka *blka = &gli->blka;
+
+	memset(blka, 0, sizeof(*blka));
+	mutex_init(&blka->mutex);
+
+	/* LUN IDs are unique per port, save the index instead */
+	blka->ba_lun.lun_id = lli->lun_index;
+	blka->ba_lun.lsize = gli->max_lba + 1;
+	blka->ba_lun.lba_size = gli->blk_len;
+
+	blka->ba_lun.au_size = MC_CHUNK_SIZE;
+	blka->nchunk = blka->ba_lun.lsize / MC_CHUNK_SIZE;
+
+	rc = ba_init(&blka->ba_lun);
+	if (unlikely(rc))
+		pr_debug("%s: cannot init block_alloc, rc=%d\n", __func__, rc);
+
+	pr_debug("%s: returning rc=%d lli=%p\n", __func__, rc, lli);
+	return rc;
+}
+
+/**
+ * write_same16() - sends a SCSI WRITE_SAME16 (0) command to specified LUN
+ * @sdev:	SCSI device associated with LUN.
+ * @lba:	Logical block address to start write same.
+ * @nblks:	Number of logical blocks to write same.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static int write_same16(struct scsi_device *sdev,
+			u64 lba,
+			u32 nblks)
+{
+	u8 *cmd_buf = NULL;
+	u8 *scsi_cmd = NULL;
+	u8 *sense_buf = NULL;
+	int rc = 0;
+	int result = 0;
+	int ws_limit = SISLITE_MAX_WS_BLOCKS;
+	u64 offset = lba;
+	int left = nblks;
+	u32 tout = sdev->request_queue->rq_timeout;
+	struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
+	struct device *dev = &cfg->dev->dev;
+
+	cmd_buf = kzalloc(CMD_BUFSIZE, GFP_KERNEL);
+	scsi_cmd = kzalloc(MAX_COMMAND_SIZE, GFP_KERNEL);
+	sense_buf = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL);
+	if (unlikely(!cmd_buf || !scsi_cmd || !sense_buf)) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	while (left > 0) {
+
+		scsi_cmd[0] = WRITE_SAME_16;
+		put_unaligned_be64(offset, &scsi_cmd[2]);
+		put_unaligned_be32(ws_limit < left ? ws_limit : left,
+				   &scsi_cmd[10]);
+
+		result = scsi_execute(sdev, scsi_cmd, DMA_TO_DEVICE, cmd_buf,
+				      CMD_BUFSIZE, sense_buf, tout, 5, 0, NULL);
+		if (result) {
+			dev_err_ratelimited(dev, "%s: command failed for "
+					    "offset %lld result=0x%x\n",
+					    __func__, offset, result);
+			rc = -EIO;
+			goto out;
+		}
+		left -= ws_limit;
+		offset += ws_limit;
+	}
+
+out:
+	kfree(cmd_buf);
+	kfree(scsi_cmd);
+	kfree(sense_buf);
+	pr_debug("%s: returning rc=%d\n", __func__, rc);
+	return rc;
+}
+
+/**
+ * grow_lxt() - expands the translation table associated with the specified RHTE
+ * @afu:	AFU associated with the host.
+ * @sdev:	SCSI device associated with LUN.
+ * @ctxid:	Context ID of context owning the RHTE.
+ * @rhndl:	Resource handle associated with the RHTE.
+ * @rhte:	Resource handle entry (RHTE).
+ * @new_size:	Number of translation entries associated with RHTE.
+ *
+ * By design, this routine employs a 'best attempt' allocation and will
+ * truncate the requested size down if there is not sufficient space in
+ * the block allocator to satisfy the request but there does exist some
+ * amount of space. The user is made aware of this by returning the size
+ * allocated.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static int grow_lxt(struct afu *afu,
+		    struct scsi_device *sdev,
+		    ctx_hndl_t ctxid,
+		    res_hndl_t rhndl,
+		    struct sisl_rht_entry *rhte,
+		    u64 *new_size)
+{
+	struct sisl_lxt_entry *lxt = NULL, *lxt_old = NULL;
+	struct llun_info *lli = sdev->hostdata;
+	struct glun_info *gli = lli->parent;
+	struct blka *blka = &gli->blka;
+	u32 av_size;
+	u32 ngrps, ngrps_old;
+	u64 aun;		/* chunk# allocated by block allocator */
+	u64 delta = *new_size - rhte->lxt_cnt;
+	u64 my_new_size;
+	int i, rc = 0;
+
+	/*
+	 * Check what is available in the block allocator before re-allocating
+	 * LXT array. This is done up front under the mutex which must not be
+	 * released until after allocation is complete.
+	 */
+	mutex_lock(&blka->mutex);
+	av_size = ba_space(&blka->ba_lun);
+	if (unlikely(av_size <= 0)) {
+		pr_debug("%s: ba_space error: av_size %d\n", __func__, av_size);
+		mutex_unlock(&blka->mutex);
+		rc = -ENOSPC;
+		goto out;
+	}
+
+	if (av_size < delta)
+		delta = av_size;
+
+	lxt_old = rhte->lxt_start;
+	ngrps_old = LXT_NUM_GROUPS(rhte->lxt_cnt);
+	ngrps = LXT_NUM_GROUPS(rhte->lxt_cnt + delta);
+
+	if (ngrps != ngrps_old) {
+		/* reallocate to fit new size */
+		lxt = kzalloc((sizeof(*lxt) * LXT_GROUP_SIZE * ngrps),
+			      GFP_KERNEL);
+		if (unlikely(!lxt)) {
+			mutex_unlock(&blka->mutex);
+			rc = -ENOMEM;
+			goto out;
+		}
+
+		/* copy over all old entries */
+		memcpy(lxt, lxt_old, (sizeof(*lxt) * rhte->lxt_cnt));
+	} else
+		lxt = lxt_old;
+
+	/* nothing can fail from now on */
+	my_new_size = rhte->lxt_cnt + delta;
+
+	/* add new entries to the end */
+	for (i = rhte->lxt_cnt; i < my_new_size; i++) {
+		/*
+		 * Due to the earlier check of available space, ba_alloc
+		 * cannot fail here. If it did due to internal error,
+		 * leave a rlba_base of -1u which will likely be a
+		 * invalid LUN (too large).
+		 */
+		aun = ba_alloc(&blka->ba_lun);
+		if ((aun == -1ULL) || (aun >= blka->nchunk))
+			pr_debug("%s: ba_alloc error: allocated chunk# %llX, "
+				 "max %llX\n", __func__, aun, blka->nchunk - 1);
+
+		/* select both ports, use r/w perms from RHT */
+		lxt[i].rlba_base = ((aun << MC_CHUNK_SHIFT) |
+				    (lli->lun_index << LXT_LUNIDX_SHIFT) |
+				    (RHT_PERM_RW << LXT_PERM_SHIFT |
+				     lli->port_sel));
+	}
+
+	mutex_unlock(&blka->mutex);
+
+	/*
+	 * The following sequence is prescribed in the SISlite spec
+	 * for syncing up with the AFU when adding LXT entries.
+	 */
+	dma_wmb(); /* Make LXT updates are visible */
+
+	rhte->lxt_start = lxt;
+	dma_wmb(); /* Make RHT entry's LXT table update visible */
+
+	rhte->lxt_cnt = my_new_size;
+	dma_wmb(); /* Make RHT entry's LXT table size update visible */
+
+	cxlflash_afu_sync(afu, ctxid, rhndl, AFU_LW_SYNC);
+
+	/* free old lxt if reallocated */
+	if (lxt != lxt_old)
+		kfree(lxt_old);
+	*new_size = my_new_size;
+out:
+	pr_debug("%s: returning rc=%d\n", __func__, rc);
+	return rc;
+}
+
+/**
+ * shrink_lxt() - reduces translation table associated with the specified RHTE
+ * @afu:	AFU associated with the host.
+ * @sdev:	SCSI device associated with LUN.
+ * @rhndl:	Resource handle associated with the RHTE.
+ * @rhte:	Resource handle entry (RHTE).
+ * @ctxi:	Context owning resources.
+ * @new_size:	Number of translation entries associated with RHTE.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static int shrink_lxt(struct afu *afu,
+		      struct scsi_device *sdev,
+		      res_hndl_t rhndl,
+		      struct sisl_rht_entry *rhte,
+		      struct ctx_info *ctxi,
+		      u64 *new_size)
+{
+	struct sisl_lxt_entry *lxt, *lxt_old;
+	struct llun_info *lli = sdev->hostdata;
+	struct glun_info *gli = lli->parent;
+	struct blka *blka = &gli->blka;
+	ctx_hndl_t ctxid = DECODE_CTXID(ctxi->ctxid);
+	bool needs_ws = ctxi->rht_needs_ws[rhndl];
+	bool needs_sync = !ctxi->err_recovery_active;
+	u32 ngrps, ngrps_old;
+	u64 aun;		/* chunk# allocated by block allocator */
+	u64 delta = rhte->lxt_cnt - *new_size;
+	u64 my_new_size;
+	int i, rc = 0;
+
+	lxt_old = rhte->lxt_start;
+	ngrps_old = LXT_NUM_GROUPS(rhte->lxt_cnt);
+	ngrps = LXT_NUM_GROUPS(rhte->lxt_cnt - delta);
+
+	if (ngrps != ngrps_old) {
+		/* Reallocate to fit new size unless new size is 0 */
+		if (ngrps) {
+			lxt = kzalloc((sizeof(*lxt) * LXT_GROUP_SIZE * ngrps),
+				      GFP_KERNEL);
+			if (unlikely(!lxt)) {
+				rc = -ENOMEM;
+				goto out;
+			}
+
+			/* Copy over old entries that will remain */
+			memcpy(lxt, lxt_old,
+			       (sizeof(*lxt) * (rhte->lxt_cnt - delta)));
+		} else
+			lxt = NULL;
+	} else
+		lxt = lxt_old;
+
+	/* Nothing can fail from now on */
+	my_new_size = rhte->lxt_cnt - delta;
+
+	/*
+	 * The following sequence is prescribed in the SISlite spec
+	 * for syncing up with the AFU when removing LXT entries.
+	 */
+	rhte->lxt_cnt = my_new_size;
+	dma_wmb(); /* Make RHT entry's LXT table size update visible */
+
+	rhte->lxt_start = lxt;
+	dma_wmb(); /* Make RHT entry's LXT table update visible */
+
+	if (needs_sync)
+		cxlflash_afu_sync(afu, ctxid, rhndl, AFU_HW_SYNC);
+
+	if (needs_ws) {
+		/*
+		 * Mark the context as unavailable, so that we can release
+		 * the mutex safely.
+		 */
+		ctxi->unavail = true;
+		mutex_unlock(&ctxi->mutex);
+	}
+
+	/* Free LBAs allocated to freed chunks */
+	mutex_lock(&blka->mutex);
+	for (i = delta - 1; i >= 0; i--) {
+		/* Mask the higher 48 bits before shifting, even though
+		 * it is a noop
+		 */
+		aun = (lxt_old[my_new_size + i].rlba_base & SISL_ASTATUS_MASK);
+		aun = (aun >> MC_CHUNK_SHIFT);
+		if (needs_ws)
+			write_same16(sdev, aun, MC_CHUNK_SIZE);
+		ba_free(&blka->ba_lun, aun);
+	}
+	mutex_unlock(&blka->mutex);
+
+	if (needs_ws) {
+		/* Make the context visible again */
+		mutex_lock(&ctxi->mutex);
+		ctxi->unavail = false;
+	}
+
+	/* Free old lxt if reallocated */
+	if (lxt != lxt_old)
+		kfree(lxt_old);
+	*new_size = my_new_size;
+out:
+	pr_debug("%s: returning rc=%d\n", __func__, rc);
+	return rc;
+}
+
+/**
+ * _cxlflash_vlun_resize() - changes the size of a virtual lun
+ * @sdev:	SCSI device associated with LUN owning virtual LUN.
+ * @ctxi:	Context owning resources.
+ * @resize:	Resize ioctl data structure.
+ *
+ * On successful return, the user is informed of the new size (in blocks)
+ * of the virtual lun in last LBA format. When the size of the virtual
+ * lun is zero, the last LBA is reflected as -1. See comment in the
+ * prologue for _cxlflash_disk_release() regarding AFU syncs and contexts
+ * on the error recovery list.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+int _cxlflash_vlun_resize(struct scsi_device *sdev,
+			  struct ctx_info *ctxi,
+			  struct dk_cxlflash_resize *resize)
+{
+	struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
+	struct llun_info *lli = sdev->hostdata;
+	struct glun_info *gli = lli->parent;
+	struct afu *afu = cfg->afu;
+	bool put_ctx = false;
+
+	res_hndl_t rhndl = resize->rsrc_handle;
+	u64 new_size;
+	u64 nsectors;
+	u64 ctxid = DECODE_CTXID(resize->context_id),
+	    rctxid = resize->context_id;
+
+	struct sisl_rht_entry *rhte;
+
+	int rc = 0;
+
+	/*
+	 * The requested size (req_size) is always assumed to be in 4k blocks,
+	 * so we have to convert it here from 4k to chunk size.
+	 */
+	nsectors = (resize->req_size * CXLFLASH_BLOCK_SIZE) / gli->blk_len;
+	new_size = DIV_ROUND_UP(nsectors, MC_CHUNK_SIZE);
+
+	pr_debug("%s: ctxid=%llu rhndl=0x%llx, req_size=0x%llx,"
+		 "new_size=%llx\n", __func__, ctxid, resize->rsrc_handle,
+		 resize->req_size, new_size);
+
+	if (unlikely(gli->mode != MODE_VIRTUAL)) {
+		pr_debug("%s: LUN mode does not support resize! (%d)\n",
+			 __func__, gli->mode);
+		rc = -EINVAL;
+		goto out;
+
+	}
+
+	if (!ctxi) {
+		ctxi = get_context(cfg, rctxid, lli, CTX_CTRL_ERR_FALLBACK);
+		if (unlikely(!ctxi)) {
+			pr_debug("%s: Bad context! (%llu)\n", __func__, ctxid);
+			rc = -EINVAL;
+			goto out;
+		}
+
+		put_ctx = true;
+	}
+
+	rhte = get_rhte(ctxi, rhndl, lli);
+	if (unlikely(!rhte)) {
+		pr_debug("%s: Bad resource handle! (%u)\n", __func__, rhndl);
+		rc = -EINVAL;
+		goto out;
+	}
+
+	if (new_size > rhte->lxt_cnt)
+		rc = grow_lxt(afu, sdev, ctxid, rhndl, rhte, &new_size);
+	else if (new_size < rhte->lxt_cnt)
+		rc = shrink_lxt(afu, sdev, rhndl, rhte, ctxi, &new_size);
+
+	resize->hdr.return_flags = 0;
+	resize->last_lba = (new_size * MC_CHUNK_SIZE * gli->blk_len);
+	resize->last_lba /= CXLFLASH_BLOCK_SIZE;
+	resize->last_lba--;
+
+out:
+	if (put_ctx)
+		put_context(ctxi);
+	pr_debug("%s: resized to %lld returning rc=%d\n",
+		 __func__, resize->last_lba, rc);
+	return rc;
+}
+
+int cxlflash_vlun_resize(struct scsi_device *sdev,
+			 struct dk_cxlflash_resize *resize)
+{
+	return _cxlflash_vlun_resize(sdev, NULL, resize);
+}
+
+/**
+ * cxlflash_restore_luntable() - Restore LUN table to prior state
+ * @cfg:	Internal structure associated with the host.
+ */
+void cxlflash_restore_luntable(struct cxlflash_cfg *cfg)
+{
+	struct llun_info *lli, *temp;
+	u32 chan;
+	u32 lind;
+	struct afu *afu = cfg->afu;
+	struct sisl_global_map *agm = &afu->afu_map->global;
+
+	mutex_lock(&global.mutex);
+
+	list_for_each_entry_safe(lli, temp, &cfg->lluns, list) {
+		if (!lli->in_table)
+			continue;
+
+		lind = lli->lun_index;
+
+		if (lli->port_sel == BOTH_PORTS) {
+			writeq_be(lli->lun_id[0], &agm->fc_port[0][lind]);
+			writeq_be(lli->lun_id[1], &agm->fc_port[1][lind]);
+			pr_debug("%s: Virtual LUN on slot %d  id0=%llx, "
+				 "id1=%llx\n", __func__, lind,
+				 lli->lun_id[0], lli->lun_id[1]);
+		} else {
+			chan = PORT2CHAN(lli->port_sel);
+			writeq_be(lli->lun_id[chan], &agm->fc_port[chan][lind]);
+			pr_debug("%s: Virtual LUN on slot %d chan=%d, "
+				 "id=%llx\n", __func__, lind, chan,
+				 lli->lun_id[chan]);
+		}
+	}
+
+	mutex_unlock(&global.mutex);
+}
+
+/**
+ * init_luntable() - write an entry in the LUN table
+ * @cfg:	Internal structure associated with the host.
+ * @lli:	Per adapter LUN information structure.
+ *
+ * On successful return, a LUN table entry is created.
+ * At the top for LUNs visible on both ports.
+ * At the bottom for LUNs visible only on one port.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static int init_luntable(struct cxlflash_cfg *cfg, struct llun_info *lli)
+{
+	u32 chan;
+	u32 lind;
+	int rc = 0;
+	struct afu *afu = cfg->afu;
+	struct sisl_global_map *agm = &afu->afu_map->global;
+
+	mutex_lock(&global.mutex);
+
+	if (lli->in_table)
+		goto out;
+
+	if (lli->port_sel == BOTH_PORTS) {
+		/*
+		 * If this LUN is visible from both ports, we will put
+		 * it in the top half of the LUN table.
+		 */
+		if ((cfg->promote_lun_index == cfg->last_lun_index[0]) ||
+		    (cfg->promote_lun_index == cfg->last_lun_index[1])) {
+			rc = -ENOSPC;
+			goto out;
+		}
+
+		lind = lli->lun_index = cfg->promote_lun_index;
+		writeq_be(lli->lun_id[0], &agm->fc_port[0][lind]);
+		writeq_be(lli->lun_id[1], &agm->fc_port[1][lind]);
+		cfg->promote_lun_index++;
+		pr_debug("%s: Virtual LUN on slot %d  id0=%llx, id1=%llx\n",
+			 __func__, lind, lli->lun_id[0], lli->lun_id[1]);
+	} else {
+		/*
+		 * If this LUN is visible only from one port, we will put
+		 * it in the bottom half of the LUN table.
+		 */
+		chan = PORT2CHAN(lli->port_sel);
+		if (cfg->promote_lun_index == cfg->last_lun_index[chan]) {
+			rc = -ENOSPC;
+			goto out;
+		}
+
+		lind = lli->lun_index = cfg->last_lun_index[chan];
+		writeq_be(lli->lun_id[chan], &agm->fc_port[chan][lind]);
+		cfg->last_lun_index[chan]--;
+		pr_debug("%s: Virtual LUN on slot %d  chan=%d, id=%llx\n",
+			 __func__, lind, chan, lli->lun_id[chan]);
+	}
+
+	lli->in_table = true;
+out:
+	mutex_unlock(&global.mutex);
+	pr_debug("%s: returning rc=%d\n", __func__, rc);
+	return rc;
+}
+
+/**
+ * cxlflash_disk_virtual_open() - open a virtual disk of specified size
+ * @sdev:	SCSI device associated with LUN owning virtual LUN.
+ * @arg:	UVirtual ioctl data structure.
+ *
+ * On successful return, the user is informed of the resource handle
+ * to be used to identify the virtual lun and the size (in blocks) of
+ * the virtual lun in last LBA format. When the size of the virtual lun
+ * is zero, the last LBA is reflected as -1.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+int cxlflash_disk_virtual_open(struct scsi_device *sdev, void *arg)
+{
+	struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
+	struct device *dev = &cfg->dev->dev;
+	struct llun_info *lli = sdev->hostdata;
+	struct glun_info *gli = lli->parent;
+
+	struct dk_cxlflash_uvirtual *virt = (struct dk_cxlflash_uvirtual *)arg;
+	struct dk_cxlflash_resize resize;
+
+	u64 ctxid = DECODE_CTXID(virt->context_id),
+	    rctxid = virt->context_id;
+	u64 lun_size = virt->lun_size;
+	u64 last_lba = 0;
+	u64 rsrc_handle = -1;
+
+	int rc = 0;
+
+	struct ctx_info *ctxi = NULL;
+	struct sisl_rht_entry *rhte = NULL;
+
+	pr_debug("%s: ctxid=%llu ls=0x%llx\n", __func__, ctxid, lun_size);
+
+	mutex_lock(&gli->mutex);
+	if (gli->mode == MODE_NONE) {
+		/* Setup the LUN table and block allocator on first call */
+		rc = init_luntable(cfg, lli);
+		if (rc) {
+			dev_err(dev, "%s: call to init_luntable failed "
+				"rc=%d!\n", __func__, rc);
+			goto err0;
+		}
+
+		rc = init_vlun(lli);
+		if (rc) {
+			dev_err(dev, "%s: call to init_vlun failed rc=%d!\n",
+				__func__, rc);
+			rc = -ENOMEM;
+			goto err0;
+		}
+	}
+
+	rc = cxlflash_lun_attach(gli, MODE_VIRTUAL, true);
+	if (unlikely(rc)) {
+		dev_err(dev, "%s: Failed to attach to LUN! (VIRTUAL)\n",
+			__func__);
+		goto err0;
+	}
+	mutex_unlock(&gli->mutex);
+
+	ctxi = get_context(cfg, rctxid, lli, 0);
+	if (unlikely(!ctxi)) {
+		dev_err(dev, "%s: Bad context! (%llu)\n", __func__, ctxid);
+		rc = -EINVAL;
+		goto err1;
+	}
+
+	rhte = rhte_checkout(ctxi, lli);
+	if (unlikely(!rhte)) {
+		dev_err(dev, "%s: too many opens for this context\n", __func__);
+		rc = -EMFILE;	/* too many opens  */
+		goto err1;
+	}
+
+	rsrc_handle = (rhte - ctxi->rht_start);
+
+	/* Populate RHT format 0 */
+	rhte->nmask = MC_RHT_NMASK;
+	rhte->fp = SISL_RHT_FP(0U, ctxi->rht_perms);
+
+	/* Resize even if requested size is 0 */
+	marshal_virt_to_resize(virt, &resize);
+	resize.rsrc_handle = rsrc_handle;
+	rc = _cxlflash_vlun_resize(sdev, ctxi, &resize);
+	if (rc) {
+		dev_err(dev, "%s: resize failed rc %d\n", __func__, rc);
+		goto err2;
+	}
+	last_lba = resize.last_lba;
+
+	if (virt->hdr.flags & DK_CXLFLASH_UVIRTUAL_NEED_WRITE_SAME)
+		ctxi->rht_needs_ws[rsrc_handle] = true;
+
+	virt->hdr.return_flags = 0;
+	virt->last_lba = last_lba;
+	virt->rsrc_handle = rsrc_handle;
+
+out:
+	if (likely(ctxi))
+		put_context(ctxi);
+	pr_debug("%s: returning handle 0x%llx rc=%d llba %lld\n",
+		 __func__, rsrc_handle, rc, last_lba);
+	return rc;
+
+err2:
+	rhte_checkin(ctxi, rhte);
+err1:
+	cxlflash_lun_detach(gli);
+	goto out;
+err0:
+	/* Special common cleanup prior to successful LUN attach */
+	cxlflash_ba_terminate(&gli->blka.ba_lun);
+	mutex_unlock(&gli->mutex);
+	goto out;
+}
+
+/**
+ * clone_lxt() - copies translation tables from source to destination RHTE
+ * @afu:	AFU associated with the host.
+ * @blka:	Block allocator associated with LUN.
+ * @ctxid:	Context ID of context owning the RHTE.
+ * @rhndl:	Resource handle associated with the RHTE.
+ * @rhte:	Destination resource handle entry (RHTE).
+ * @rhte_src:	Source resource handle entry (RHTE).
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static int clone_lxt(struct afu *afu,
+		     struct blka *blka,
+		     ctx_hndl_t ctxid,
+		     res_hndl_t rhndl,
+		     struct sisl_rht_entry *rhte,
+		     struct sisl_rht_entry *rhte_src)
+{
+	struct sisl_lxt_entry *lxt;
+	u32 ngrps;
+	u64 aun;		/* chunk# allocated by block allocator */
+	int i, j;
+
+	ngrps = LXT_NUM_GROUPS(rhte_src->lxt_cnt);
+
+	if (ngrps) {
+		/* allocate new LXTs for clone */
+		lxt = kzalloc((sizeof(*lxt) * LXT_GROUP_SIZE * ngrps),
+				GFP_KERNEL);
+		if (unlikely(!lxt))
+			return -ENOMEM;
+
+		/* copy over */
+		memcpy(lxt, rhte_src->lxt_start,
+		       (sizeof(*lxt) * rhte_src->lxt_cnt));
+
+		/* clone the LBAs in block allocator via ref_cnt */
+		mutex_lock(&blka->mutex);
+		for (i = 0; i < rhte_src->lxt_cnt; i++) {
+			aun = (lxt[i].rlba_base >> MC_CHUNK_SHIFT);
+			if (ba_clone(&blka->ba_lun, aun) == -1ULL) {
+				/* free the clones already made */
+				for (j = 0; j < i; j++) {
+					aun = (lxt[j].rlba_base >>
+					       MC_CHUNK_SHIFT);
+					ba_free(&blka->ba_lun, aun);
+				}
+
+				mutex_unlock(&blka->mutex);
+				kfree(lxt);
+				return -EIO;
+			}
+		}
+		mutex_unlock(&blka->mutex);
+	} else {
+		lxt = NULL;
+	}
+
+	/*
+	 * The following sequence is prescribed in the SISlite spec
+	 * for syncing up with the AFU when adding LXT entries.
+	 */
+	dma_wmb(); /* Make LXT updates are visible */
+
+	rhte->lxt_start = lxt;
+	dma_wmb(); /* Make RHT entry's LXT table update visible */
+
+	rhte->lxt_cnt = rhte_src->lxt_cnt;
+	dma_wmb(); /* Make RHT entry's LXT table size update visible */
+
+	cxlflash_afu_sync(afu, ctxid, rhndl, AFU_LW_SYNC);
+
+	pr_debug("%s: returning\n", __func__);
+	return 0;
+}
+
+/**
+ * cxlflash_disk_clone() - clone a context by making snapshot of another
+ * @sdev:	SCSI device associated with LUN owning virtual LUN.
+ * @clone:	Clone ioctl data structure.
+ *
+ * This routine effectively performs cxlflash_disk_open operation for each
+ * in-use virtual resource in the source context. Note that the destination
+ * context must be in pristine state and cannot have any resource handles
+ * open at the time of the clone.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+int cxlflash_disk_clone(struct scsi_device *sdev,
+			struct dk_cxlflash_clone *clone)
+{
+	struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)sdev->host->hostdata;
+	struct llun_info *lli = sdev->hostdata;
+	struct glun_info *gli = lli->parent;
+	struct blka *blka = &gli->blka;
+	struct afu *afu = cfg->afu;
+	struct dk_cxlflash_release release = { { 0 }, 0 };
+
+	struct ctx_info *ctxi_src = NULL,
+			*ctxi_dst = NULL;
+	struct lun_access *lun_access_src, *lun_access_dst;
+	u32 perms;
+	u64 ctxid_src = DECODE_CTXID(clone->context_id_src),
+	    ctxid_dst = DECODE_CTXID(clone->context_id_dst),
+	    rctxid_src = clone->context_id_src,
+	    rctxid_dst = clone->context_id_dst;
+	int adap_fd_src = clone->adap_fd_src;
+	int i, j;
+	int rc = 0;
+	bool found;
+	LIST_HEAD(sidecar);
+
+	pr_debug("%s: ctxid_src=%llu ctxid_dst=%llu adap_fd_src=%d\n",
+		 __func__, ctxid_src, ctxid_dst, adap_fd_src);
+
+	/* Do not clone yourself */
+	if (unlikely(rctxid_src == rctxid_dst)) {
+		rc = -EINVAL;
+		goto out;
+	}
+
+	if (unlikely(gli->mode != MODE_VIRTUAL)) {
+		rc = -EINVAL;
+		pr_debug("%s: Clone not supported on physical LUNs! (%d)\n",
+			 __func__, gli->mode);
+		goto out;
+	}
+
+	ctxi_src = get_context(cfg, rctxid_src, lli, CTX_CTRL_CLONE);
+	ctxi_dst = get_context(cfg, rctxid_dst, lli, 0);
+	if (unlikely(!ctxi_src || !ctxi_dst)) {
+		pr_debug("%s: Bad context! (%llu,%llu)\n", __func__,
+			 ctxid_src, ctxid_dst);
+		rc = -EINVAL;
+		goto out;
+	}
+
+	if (unlikely(adap_fd_src != ctxi_src->lfd)) {
+		pr_debug("%s: Invalid source adapter fd! (%d)\n",
+			 __func__, adap_fd_src);
+		rc = -EINVAL;
+		goto out;
+	}
+
+	/* Verify there is no open resource handle in the destination context */
+	for (i = 0; i < MAX_RHT_PER_CONTEXT; i++)
+		if (ctxi_dst->rht_start[i].nmask != 0) {
+			rc = -EINVAL;
+			goto out;
+		}
+
+	/* Clone LUN access list */
+	list_for_each_entry(lun_access_src, &ctxi_src->luns, list) {
+		found = false;
+		list_for_each_entry(lun_access_dst, &ctxi_dst->luns, list)
+			if (lun_access_dst->sdev == lun_access_src->sdev) {
+				found = true;
+				break;
+			}
+
+		if (!found) {
+			lun_access_dst = kzalloc(sizeof(*lun_access_dst),
+						 GFP_KERNEL);
+			if (unlikely(!lun_access_dst)) {
+				pr_err("%s: Unable to allocate lun_access!\n",
+				       __func__);
+				rc = -ENOMEM;
+				goto out;
+			}
+
+			*lun_access_dst = *lun_access_src;
+			list_add(&lun_access_dst->list, &sidecar);
+		}
+	}
+
+	if (unlikely(!ctxi_src->rht_out)) {
+		pr_debug("%s: Nothing to clone!\n", __func__);
+		goto out_success;
+	}
+
+	/* User specified permission on attach */
+	perms = ctxi_dst->rht_perms;
+
+	/*
+	 * Copy over checked-out RHT (and their associated LXT) entries by
+	 * hand, stopping after we've copied all outstanding entries and
+	 * cleaning up if the clone fails.
+	 *
+	 * Note: This loop is equivalent to performing cxlflash_disk_open and
+	 * cxlflash_vlun_resize. As such, LUN accounting needs to be taken into
+	 * account by attaching after each successful RHT entry clone. In the
+	 * event that a clone failure is experienced, the LUN detach is handled
+	 * via the cleanup performed by _cxlflash_disk_release.
+	 */
+	for (i = 0; i < MAX_RHT_PER_CONTEXT; i++) {
+		if (ctxi_src->rht_out == ctxi_dst->rht_out)
+			break;
+		if (ctxi_src->rht_start[i].nmask == 0)
+			continue;
+
+		/* Consume a destination RHT entry */
+		ctxi_dst->rht_out++;
+		ctxi_dst->rht_start[i].nmask = ctxi_src->rht_start[i].nmask;
+		ctxi_dst->rht_start[i].fp =
+		    SISL_RHT_FP_CLONE(ctxi_src->rht_start[i].fp, perms);
+		ctxi_dst->rht_lun[i] = ctxi_src->rht_lun[i];
+
+		rc = clone_lxt(afu, blka, ctxid_dst, i,
+			       &ctxi_dst->rht_start[i],
+			       &ctxi_src->rht_start[i]);
+		if (rc) {
+			marshal_clone_to_rele(clone, &release);
+			for (j = 0; j < i; j++) {
+				release.rsrc_handle = j;
+				_cxlflash_disk_release(sdev, ctxi_dst,
+						       &release);
+			}
+
+			/* Put back the one we failed on */
+			rhte_checkin(ctxi_dst, &ctxi_dst->rht_start[i]);
+			goto err;
+		}
+
+		cxlflash_lun_attach(gli, gli->mode, false);
+	}
+
+out_success:
+	list_splice(&sidecar, &ctxi_dst->luns);
+	sys_close(adap_fd_src);
+
+	/* fall through */
+out:
+	if (ctxi_src)
+		put_context(ctxi_src);
+	if (ctxi_dst)
+		put_context(ctxi_dst);
+	pr_debug("%s: returning rc=%d\n", __func__, rc);
+	return rc;
+
+err:
+	list_for_each_entry_safe(lun_access_src, lun_access_dst, &sidecar, list)
+		kfree(lun_access_src);
+	goto out;
+}