1 files changed, 342 insertions, 176 deletions

diff --git a/fs/verity/verify.c b/fs/verity/verify.c
index 0adb970f4e73..86067c8b40cf 100644
--- a/fs/verity/verify.c
+++ b/fs/verity/verify.c
@@ -1,220 +1,398 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
- * Data verification functions, i.e. hooks for ->readpages()
+ * Data verification functions, i.e. hooks for ->readahead()
  *
  * Copyright 2019 Google LLC
  */
 
 #include "fsverity_private.h"
 
-#include <crypto/hash.h>
 #include <linux/bio.h>
-#include <linux/ratelimit.h>
+#include <linux/export.h>
 
-static struct workqueue_struct *fsverity_read_workqueue;
-
-/**
- * hash_at_level() - compute the location of the block's hash at the given level
- *
- * @params:	(in) the Merkle tree parameters
- * @dindex:	(in) the index of the data block being verified
- * @level:	(in) the level of hash we want (0 is leaf level)
- * @hindex:	(out) the index of the hash block containing the wanted hash
- * @hoffset:	(out) the byte offset to the wanted hash within the hash block
- */
-static void hash_at_level(const struct merkle_tree_params *params,
-			  pgoff_t dindex, unsigned int level, pgoff_t *hindex,
-			  unsigned int *hoffset)
-{
-	pgoff_t position;
+#define FS_VERITY_MAX_PENDING_BLOCKS 2
 
-	/* Offset of the hash within the level's region, in hashes */
-	position = dindex >> (level * params->log_arity);
+struct fsverity_pending_block {
+	const void *data;
+	u64 pos;
+	u8 real_hash[FS_VERITY_MAX_DIGEST_SIZE];
+};
 
-	/* Index of the hash block in the tree overall */
-	*hindex = params->level_start[level] + (position >> params->log_arity);
+struct fsverity_verification_context {
+	struct inode *inode;
+	struct fsverity_info *vi;
+	unsigned long max_ra_pages;
 
-	/* Offset of the wanted hash (in bytes) within the hash block */
-	*hoffset = (position & ((1 << params->log_arity) - 1)) <<
-		   (params->log_blocksize - params->log_arity);
-}
-
-/* Extract a hash from a hash page */
-static void extract_hash(struct page *hpage, unsigned int hoffset,
-			 unsigned int hsize, u8 *out)
-{
-	void *virt = kmap_atomic(hpage);
+	/*
+	 * This is the queue of data blocks that are pending verification.  When
+	 * the crypto layer supports interleaved hashing, we allow multiple
+	 * blocks to be queued up in order to utilize it.  This can improve
+	 * performance significantly vs. sequential hashing of each block.
+	 */
+	int num_pending;
+	int max_pending;
+	struct fsverity_pending_block
+		pending_blocks[FS_VERITY_MAX_PENDING_BLOCKS];
+};
 
-	memcpy(out, virt + hoffset, hsize);
-	kunmap_atomic(virt);
-}
+static struct workqueue_struct *fsverity_read_workqueue;
 
-static inline int cmp_hashes(const struct fsverity_info *vi,
-			     const u8 *want_hash, const u8 *real_hash,
-			     pgoff_t index, int level)
+/*
+ * Returns true if the hash block with index @hblock_idx in the tree, located in
+ * @hpage, has already been verified.
+ */
+static bool is_hash_block_verified(struct fsverity_info *vi, struct page *hpage,
+				   unsigned long hblock_idx)
 {
-	const unsigned int hsize = vi->tree_params.digest_size;
+	unsigned int blocks_per_page;
+	unsigned int i;
 
-	if (memcmp(want_hash, real_hash, hsize) == 0)
-		return 0;
+	/*
+	 * When the Merkle tree block size and page size are the same, then the
+	 * ->hash_block_verified bitmap isn't allocated, and we use PG_checked
+	 * to directly indicate whether the page's block has been verified.
+	 *
+	 * Using PG_checked also guarantees that we re-verify hash pages that
+	 * get evicted and re-instantiated from the backing storage, as new
+	 * pages always start out with PG_checked cleared.
+	 */
+	if (!vi->hash_block_verified)
+		return PageChecked(hpage);
 
-	fsverity_err(vi->inode,
-		     "FILE CORRUPTED! index=%lu, level=%d, want_hash=%s:%*phN, real_hash=%s:%*phN",
-		     index, level,
-		     vi->tree_params.hash_alg->name, hsize, want_hash,
-		     vi->tree_params.hash_alg->name, hsize, real_hash);
-	return -EBADMSG;
+	/*
+	 * When the Merkle tree block size and page size differ, we use a bitmap
+	 * to indicate whether each hash block has been verified.
+	 *
+	 * However, we still need to ensure that hash pages that get evicted and
+	 * re-instantiated from the backing storage are re-verified.  To do
+	 * this, we use PG_checked again, but now it doesn't really mean
+	 * "checked".  Instead, now it just serves as an indicator for whether
+	 * the hash page is newly instantiated or not.  If the page is new, as
+	 * indicated by PG_checked=0, we clear the bitmap bits for the page's
+	 * blocks since they are untrustworthy, then set PG_checked=1.
+	 * Otherwise we return the bitmap bit for the requested block.
+	 *
+	 * Multiple threads may execute this code concurrently on the same page.
+	 * This is safe because we use memory barriers to ensure that if a
+	 * thread sees PG_checked=1, then it also sees the associated bitmap
+	 * clearing to have occurred.  Also, all writes and their corresponding
+	 * reads are atomic, and all writes are safe to repeat in the event that
+	 * multiple threads get into the PG_checked=0 section.  (Clearing a
+	 * bitmap bit again at worst causes a hash block to be verified
+	 * redundantly.  That event should be very rare, so it's not worth using
+	 * a lock to avoid.  Setting PG_checked again has no effect.)
+	 */
+	if (PageChecked(hpage)) {
+		/*
+		 * A read memory barrier is needed here to give ACQUIRE
+		 * semantics to the above PageChecked() test.
+		 */
+		smp_rmb();
+		return test_bit(hblock_idx, vi->hash_block_verified);
+	}
+	blocks_per_page = vi->tree_params.blocks_per_page;
+	hblock_idx = round_down(hblock_idx, blocks_per_page);
+	for (i = 0; i < blocks_per_page; i++)
+		clear_bit(hblock_idx + i, vi->hash_block_verified);
+	/*
+	 * A write memory barrier is needed here to give RELEASE semantics to
+	 * the below SetPageChecked() operation.
+	 */
+	smp_wmb();
+	SetPageChecked(hpage);
+	return false;
 }
 
 /*
- * Verify a single data page against the file's Merkle tree.
+ * Verify the hash of a single data block against the file's Merkle tree.
  *
  * In principle, we need to verify the entire path to the root node.  However,
- * for efficiency the filesystem may cache the hash pages.  Therefore we need
- * only ascend the tree until an already-verified page is seen, as indicated by
- * the PageChecked bit being set; then verify the path to that page.
- *
- * This code currently only supports the case where the verity block size is
- * equal to PAGE_SIZE.  Doing otherwise would be possible but tricky, since we
- * wouldn't be able to use the PageChecked bit.
- *
- * Note that multiple processes may race to verify a hash page and mark it
- * Checked, but it doesn't matter; the result will be the same either way.
+ * for efficiency the filesystem may cache the hash blocks.  Therefore we need
+ * only ascend the tree until an already-verified hash block is seen, and then
+ * verify the path to that block.
  *
- * Return: true if the page is valid, else false.
+ * Return: %true if the data block is valid, else %false.
  */
-static bool verify_page(struct inode *inode, const struct fsverity_info *vi,
-			struct ahash_request *req, struct page *data_page,
-			unsigned long level0_ra_pages)
+static bool verify_data_block(struct inode *inode, struct fsverity_info *vi,
+			      const struct fsverity_pending_block *dblock,
+			      unsigned long max_ra_pages)
 {
+	const u64 data_pos = dblock->pos;
 	const struct merkle_tree_params *params = &vi->tree_params;
 	const unsigned int hsize = params->digest_size;
-	const pgoff_t index = data_page->index;
 	int level;
 	u8 _want_hash[FS_VERITY_MAX_DIGEST_SIZE];
 	const u8 *want_hash;
 	u8 real_hash[FS_VERITY_MAX_DIGEST_SIZE];
-	struct page *hpages[FS_VERITY_MAX_LEVELS];
-	unsigned int hoffsets[FS_VERITY_MAX_LEVELS];
-	int err;
+	/* The hash blocks that are traversed, indexed by level */
+	struct {
+		/* Page containing the hash block */
+		struct page *page;
+		/* Mapped address of the hash block (will be within @page) */
+		const void *addr;
+		/* Index of the hash block in the tree overall */
+		unsigned long index;
+		/* Byte offset of the wanted hash relative to @addr */
+		unsigned int hoffset;
+	} hblocks[FS_VERITY_MAX_LEVELS];
+	/*
+	 * The index of the previous level's block within that level; also the
+	 * index of that block's hash within the current level.
+	 */
+	u64 hidx = data_pos >> params->log_blocksize;
 
-	if (WARN_ON_ONCE(!PageLocked(data_page) || PageUptodate(data_page)))
-		return false;
+	/*
+	 * Up to FS_VERITY_MAX_PENDING_BLOCKS + FS_VERITY_MAX_LEVELS pages may
+	 * be mapped at once.
+	 */
+	static_assert(FS_VERITY_MAX_PENDING_BLOCKS + FS_VERITY_MAX_LEVELS <=
+		      KM_MAX_IDX);
 
-	pr_debug_ratelimited("Verifying data page %lu...\n", index);
+	if (unlikely(data_pos >= inode->i_size)) {
+		/*
+		 * This can happen in the data page spanning EOF when the Merkle
+		 * tree block size is less than the page size.  The Merkle tree
+		 * doesn't cover data blocks fully past EOF.  But the entire
+		 * page spanning EOF can be visible to userspace via a mmap, and
+		 * any part past EOF should be all zeroes.  Therefore, we need
+		 * to verify that any data blocks fully past EOF are all zeroes.
+		 */
+		if (memchr_inv(dblock->data, 0, params->block_size)) {
+			fsverity_err(inode,
+				     "FILE CORRUPTED!  Data past EOF is not zeroed");
+			return false;
+		}
+		return true;
+	}
 
 	/*
-	 * Starting at the leaf level, ascend the tree saving hash pages along
-	 * the way until we find a verified hash page, indicated by PageChecked;
-	 * or until we reach the root.
+	 * Starting at the leaf level, ascend the tree saving hash blocks along
+	 * the way until we find a hash block that has already been verified, or
+	 * until we reach the root.
 	 */
 	for (level = 0; level < params->num_levels; level++) {
-		pgoff_t hindex;
+		unsigned long next_hidx;
+		unsigned long hblock_idx;
+		pgoff_t hpage_idx;
+		unsigned int hblock_offset_in_page;
 		unsigned int hoffset;
 		struct page *hpage;
+		const void *haddr;
+
+		/*
+		 * The index of the block in the current level; also the index
+		 * of that block's hash within the next level.
+		 */
+		next_hidx = hidx >> params->log_arity;
+
+		/* Index of the hash block in the tree overall */
+		hblock_idx = params->level_start[level] + next_hidx;
 
-		hash_at_level(params, index, level, &hindex, &hoffset);
+		/* Index of the hash page in the tree overall */
+		hpage_idx = hblock_idx >> params->log_blocks_per_page;
 
-		pr_debug_ratelimited("Level %d: hindex=%lu, hoffset=%u\n",
-				     level, hindex, hoffset);
+		/* Byte offset of the hash block within the page */
+		hblock_offset_in_page =
+			(hblock_idx << params->log_blocksize) & ~PAGE_MASK;
 
-		hpage = inode->i_sb->s_vop->read_merkle_tree_page(inode, hindex,
-				level == 0 ? level0_ra_pages : 0);
+		/* Byte offset of the hash within the block */
+		hoffset = (hidx << params->log_digestsize) &
+			  (params->block_size - 1);
+
+		hpage = inode->i_sb->s_vop->read_merkle_tree_page(inode,
+				hpage_idx, level == 0 ? min(max_ra_pages,
+					params->tree_pages - hpage_idx) : 0);
 		if (IS_ERR(hpage)) {
-			err = PTR_ERR(hpage);
 			fsverity_err(inode,
-				     "Error %d reading Merkle tree page %lu",
-				     err, hindex);
-			goto out;
+				     "Error %ld reading Merkle tree page %lu",
+				     PTR_ERR(hpage), hpage_idx);
+			goto error;
 		}
-
-		if (PageChecked(hpage)) {
-			extract_hash(hpage, hoffset, hsize, _want_hash);
+		haddr = kmap_local_page(hpage) + hblock_offset_in_page;
+		if (is_hash_block_verified(vi, hpage, hblock_idx)) {
+			memcpy(_want_hash, haddr + hoffset, hsize);
 			want_hash = _want_hash;
+			kunmap_local(haddr);
 			put_page(hpage);
-			pr_debug_ratelimited("Hash page already checked, want %s:%*phN\n",
-					     params->hash_alg->name,
-					     hsize, want_hash);
 			goto descend;
 		}
-		pr_debug_ratelimited("Hash page not yet checked\n");
-		hpages[level] = hpage;
-		hoffsets[level] = hoffset;
+		hblocks[level].page = hpage;
+		hblocks[level].addr = haddr;
+		hblocks[level].index = hblock_idx;
+		hblocks[level].hoffset = hoffset;
+		hidx = next_hidx;
 	}
 
 	want_hash = vi->root_hash;
-	pr_debug("Want root hash: %s:%*phN\n",
-		 params->hash_alg->name, hsize, want_hash);
 descend:
-	/* Descend the tree verifying hash pages */
+	/* Descend the tree verifying hash blocks. */
 	for (; level > 0; level--) {
-		struct page *hpage = hpages[level - 1];
-		unsigned int hoffset = hoffsets[level - 1];
-
-		err = fsverity_hash_page(params, inode, req, hpage, real_hash);
-		if (err)
-			goto out;
-		err = cmp_hashes(vi, want_hash, real_hash, index, level - 1);
-		if (err)
-			goto out;
-		SetPageChecked(hpage);
-		extract_hash(hpage, hoffset, hsize, _want_hash);
+		struct page *hpage = hblocks[level - 1].page;
+		const void *haddr = hblocks[level - 1].addr;
+		unsigned long hblock_idx = hblocks[level - 1].index;
+		unsigned int hoffset = hblocks[level - 1].hoffset;
+
+		fsverity_hash_block(params, haddr, real_hash);
+		if (memcmp(want_hash, real_hash, hsize) != 0)
+			goto corrupted;
+		/*
+		 * Mark the hash block as verified.  This must be atomic and
+		 * idempotent, as the same hash block might be verified by
+		 * multiple threads concurrently.
+		 */
+		if (vi->hash_block_verified)
+			set_bit(hblock_idx, vi->hash_block_verified);
+		else
+			SetPageChecked(hpage);
+		memcpy(_want_hash, haddr + hoffset, hsize);
 		want_hash = _want_hash;
+		kunmap_local(haddr);
 		put_page(hpage);
-		pr_debug("Verified hash page at level %d, now want %s:%*phN\n",
-			 level - 1, params->hash_alg->name, hsize, want_hash);
 	}
 
-	/* Finally, verify the data page */
-	err = fsverity_hash_page(params, inode, req, data_page, real_hash);
-	if (err)
-		goto out;
-	err = cmp_hashes(vi, want_hash, real_hash, index, -1);
-out:
-	for (; level > 0; level--)
-		put_page(hpages[level - 1]);
+	/* Finally, verify the hash of the data block. */
+	if (memcmp(want_hash, dblock->real_hash, hsize) != 0)
+		goto corrupted;
+	return true;
+
+corrupted:
+	fsverity_err(
+		inode,
+		"FILE CORRUPTED! pos=%llu, level=%d, want_hash=%s:%*phN, real_hash=%s:%*phN",
+		data_pos, level - 1, params->hash_alg->name, hsize, want_hash,
+		params->hash_alg->name, hsize,
+		level == 0 ? dblock->real_hash : real_hash);
+error:
+	for (; level > 0; level--) {
+		kunmap_local(hblocks[level - 1].addr);
+		put_page(hblocks[level - 1].page);
+	}
+	return false;
+}
+
+static void
+fsverity_init_verification_context(struct fsverity_verification_context *ctx,
+				   struct inode *inode,
+				   unsigned long max_ra_pages)
+{
+	struct fsverity_info *vi = *fsverity_info_addr(inode);
+
+	ctx->inode = inode;
+	ctx->vi = vi;
+	ctx->max_ra_pages = max_ra_pages;
+	ctx->num_pending = 0;
+	if (vi->tree_params.hash_alg->algo_id == HASH_ALGO_SHA256 &&
+	    sha256_finup_2x_is_optimized())
+		ctx->max_pending = 2;
+	else
+		ctx->max_pending = 1;
+}
+
+static void
+fsverity_clear_pending_blocks(struct fsverity_verification_context *ctx)
+{
+	int i;
+
+	for (i = ctx->num_pending - 1; i >= 0; i--) {
+		kunmap_local(ctx->pending_blocks[i].data);
+		ctx->pending_blocks[i].data = NULL;
+	}
+	ctx->num_pending = 0;
+}
+
+static bool
+fsverity_verify_pending_blocks(struct fsverity_verification_context *ctx)
+{
+	struct fsverity_info *vi = ctx->vi;
+	const struct merkle_tree_params *params = &vi->tree_params;
+	int i;
+
+	if (ctx->num_pending == 2) {
+		/* num_pending == 2 implies that the algorithm is SHA-256 */
+		sha256_finup_2x(params->hashstate ? &params->hashstate->sha256 :
+						    NULL,
+				ctx->pending_blocks[0].data,
+				ctx->pending_blocks[1].data, params->block_size,
+				ctx->pending_blocks[0].real_hash,
+				ctx->pending_blocks[1].real_hash);
+	} else {
+		for (i = 0; i < ctx->num_pending; i++)
+			fsverity_hash_block(params, ctx->pending_blocks[i].data,
+					    ctx->pending_blocks[i].real_hash);
+	}
+
+	for (i = 0; i < ctx->num_pending; i++) {
+		if (!verify_data_block(ctx->inode, vi, &ctx->pending_blocks[i],
+				       ctx->max_ra_pages))
+			return false;
+	}
+	fsverity_clear_pending_blocks(ctx);
+	return true;
+}
+
+static bool fsverity_add_data_blocks(struct fsverity_verification_context *ctx,
+				     struct folio *data_folio, size_t len,
+				     size_t offset)
+{
+	struct fsverity_info *vi = ctx->vi;
+	const struct merkle_tree_params *params = &vi->tree_params;
+	const unsigned int block_size = params->block_size;
+	u64 pos = (u64)data_folio->index << PAGE_SHIFT;
 
-	return err == 0;
+	if (WARN_ON_ONCE(len <= 0 || !IS_ALIGNED(len | offset, block_size)))
+		return false;
+	if (WARN_ON_ONCE(!folio_test_locked(data_folio) ||
+			 folio_test_uptodate(data_folio)))
+		return false;
+	do {
+		ctx->pending_blocks[ctx->num_pending].data =
+			kmap_local_folio(data_folio, offset);
+		ctx->pending_blocks[ctx->num_pending].pos = pos + offset;
+		if (++ctx->num_pending == ctx->max_pending &&
+		    !fsverity_verify_pending_blocks(ctx))
+			return false;
+		offset += block_size;
+		len -= block_size;
+	} while (len);
+	return true;
 }
 
 /**
- * fsverity_verify_page() - verify a data page
- * @page: the page to verity
+ * fsverity_verify_blocks() - verify data in a folio
+ * @folio: the folio containing the data to verify
+ * @len: the length of the data to verify in the folio
+ * @offset: the offset of the data to verify in the folio
  *
- * Verify a page that has just been read from a verity file.  The page must be a
- * pagecache page that is still locked and not yet uptodate.
+ * Verify data that has just been read from a verity file.  The data must be
+ * located in a pagecache folio that is still locked and not yet uptodate.  The
+ * length and offset of the data must be Merkle tree block size aligned.
  *
- * Return: true if the page is valid, else false.
+ * Return: %true if the data is valid, else %false.
  */
-bool fsverity_verify_page(struct page *page)
+bool fsverity_verify_blocks(struct folio *folio, size_t len, size_t offset)
 {
-	struct inode *inode = page->mapping->host;
-	const struct fsverity_info *vi = inode->i_verity_info;
-	struct ahash_request *req;
-	bool valid;
-
-	/* This allocation never fails, since it's mempool-backed. */
-	req = fsverity_alloc_hash_request(vi->tree_params.hash_alg, GFP_NOFS);
+	struct fsverity_verification_context ctx;
 
-	valid = verify_page(inode, vi, req, page, 0);
+	fsverity_init_verification_context(&ctx, folio->mapping->host, 0);
 
-	fsverity_free_hash_request(vi->tree_params.hash_alg, req);
-
-	return valid;
+	if (fsverity_add_data_blocks(&ctx, folio, len, offset) &&
+	    fsverity_verify_pending_blocks(&ctx))
+		return true;
+	fsverity_clear_pending_blocks(&ctx);
+	return false;
 }
-EXPORT_SYMBOL_GPL(fsverity_verify_page);
+EXPORT_SYMBOL_GPL(fsverity_verify_blocks);
 
 #ifdef CONFIG_BLOCK
 /**
  * fsverity_verify_bio() - verify a 'read' bio that has just completed
  * @bio: the bio to verify
  *
- * Verify a set of pages that have just been read from a verity file.  The pages
- * must be pagecache pages that are still locked and not yet uptodate.  Pages
- * that fail verification are set to the Error state.  Verification is skipped
- * for pages already in the Error state, e.g. due to fscrypt decryption failure.
+ * Verify the bio's data against the file's Merkle tree.  All bio data segments
+ * must be aligned to the file's Merkle tree block size.  If any data fails
+ * verification, then bio->bi_status is set to an error status.
  *
- * This is a helper function for use by the ->readpages() method of filesystems
+ * This is a helper function for use by the ->readahead() method of filesystems
  * that issue bios to read data directly into the page cache.  Filesystems that
  * populate the page cache without issuing bios (e.g. non block-based
  * filesystems) must instead call fsverity_verify_page() directly on each page.
@@ -222,17 +400,11 @@ EXPORT_SYMBOL_GPL(fsverity_verify_page);
  */
 void fsverity_verify_bio(struct bio *bio)
 {
-	struct inode *inode = bio_first_page_all(bio)->mapping->host;
-	const struct fsverity_info *vi = inode->i_verity_info;
-	const struct merkle_tree_params *params = &vi->tree_params;
-	struct ahash_request *req;
-	struct bio_vec *bv;
-	struct bvec_iter_all iter_all;
+	struct inode *inode = bio_first_folio_all(bio)->mapping->host;
+	struct fsverity_verification_context ctx;
+	struct folio_iter fi;
 	unsigned long max_ra_pages = 0;
 
-	/* This allocation never fails, since it's mempool-backed. */
-	req = fsverity_alloc_hash_request(params->hash_alg, GFP_NOFS);
-
 	if (bio->bi_opf & REQ_RAHEAD) {
 		/*
 		 * If this bio is for data readahead, then we also do readahead
@@ -243,23 +415,24 @@ void fsverity_verify_bio(struct bio *bio)
 		 * This improves sequential read performance, as it greatly
 		 * reduces the number of I/O requests made to the Merkle tree.
 		 */
-		bio_for_each_segment_all(bv, bio, iter_all)
-			max_ra_pages++;
-		max_ra_pages /= 4;
+		max_ra_pages = bio->bi_iter.bi_size >> (PAGE_SHIFT + 2);
 	}
 
-	bio_for_each_segment_all(bv, bio, iter_all) {
-		struct page *page = bv->bv_page;
-		unsigned long level0_index = page->index >> params->log_arity;
-		unsigned long level0_ra_pages =
-			min(max_ra_pages, params->level0_blocks - level0_index);
+	fsverity_init_verification_context(&ctx, inode, max_ra_pages);
 
-		if (!PageError(page) &&
-		    !verify_page(inode, vi, req, page, level0_ra_pages))
-			SetPageError(page);
+	bio_for_each_folio_all(fi, bio) {
+		if (!fsverity_add_data_blocks(&ctx, fi.folio, fi.length,
+					      fi.offset))
+			goto ioerr;
 	}
 
-	fsverity_free_hash_request(params->hash_alg, req);
+	if (!fsverity_verify_pending_blocks(&ctx))
+		goto ioerr;
+	return;
+
+ioerr:
+	fsverity_clear_pending_blocks(&ctx);
+	bio->bi_status = BLK_STS_IOERR;
 }
 EXPORT_SYMBOL_GPL(fsverity_verify_bio);
 #endif /* CONFIG_BLOCK */
@@ -276,26 +449,19 @@ void fsverity_enqueue_verify_work(struct work_struct *work)
 }
 EXPORT_SYMBOL_GPL(fsverity_enqueue_verify_work);
 
-int __init fsverity_init_workqueue(void)
+void __init fsverity_init_workqueue(void)
 {
 	/*
-	 * Use an unbound workqueue to allow bios to be verified in parallel
-	 * even when they happen to complete on the same CPU.  This sacrifices
-	 * locality, but it's worthwhile since hashing is CPU-intensive.
+	 * Use a high-priority workqueue to prioritize verification work, which
+	 * blocks reads from completing, over regular application tasks.
 	 *
-	 * Also use a high-priority workqueue to prioritize verification work,
-	 * which blocks reads from completing, over regular application tasks.
+	 * For performance reasons, don't use an unbound workqueue.  Using an
+	 * unbound workqueue for crypto operations causes excessive scheduler
+	 * latency on ARM64.
 	 */
 	fsverity_read_workqueue = alloc_workqueue("fsverity_read_queue",
-						  WQ_UNBOUND | WQ_HIGHPRI,
+						  WQ_HIGHPRI | WQ_PERCPU,
 						  num_online_cpus());
 	if (!fsverity_read_workqueue)
-		return -ENOMEM;
-	return 0;
-}
-
-void __init fsverity_exit_workqueue(void)
-{
-	destroy_workqueue(fsverity_read_workqueue);
-	fsverity_read_workqueue = NULL;
+		panic("failed to allocate fsverity_read_queue");
 }