Message-Id: <20250704042323.10318-12-kanchana.p.sridhar@intel.com>
Date: Thu,  3 Jul 2025 21:23:09 -0700
From: Kanchana P Sridhar <kanchana.p.sridhar@...el.com>
To: linux-kernel@...r.kernel.org,
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Cc: wajdi.k.feghali@...el.com,
	vinodh.gopal@...el.com,
	kanchana.p.sridhar@...el.com
Subject: [PATCH v10 11/25] crypto: iaa - Enablers for submitting descriptors then polling for completion.

This patch adds capabilities in the IAA driver for kernel users to avail
of the benefits of compressing/decompressing multiple jobs in parallel
using IAA hardware acceleration, without the use of interrupts. Instead,
this is accomplished using an async "submit-poll" mechanism.

To achieve this, we break down a compress/decompress job into two
separate activities if the driver is configured for non-irq async mode:

1) Submit a descriptor after caching the "idxd_desc" descriptor in the
   req->drv_data, and return -EINPROGRESS.
2) Poll: Given a request, retrieve the descriptor and poll its completion
   status for success/error.

This is enabled by the following additions in the driver:

1) The idxd_desc is cached in the "drv_data" member of "struct iaa_req".

2) IAA_REQ_POLL_FLAG: if set in the iaa_req's flags, this tells
   the driver that it should submit the descriptor and return
   -EINPROGRESS. If not set, the driver will proceed to call
   check_completion() in fully synchronous mode, until the hardware
   returns a completion status.

3) iaa_comp_poll() procedure: This routine is intended to be called
   after submission returns -EINPROGRESS. It will check the completion
   status once, and return -EAGAIN if the job has not completed. If the
   job has completed, it will return the completion status.

The purpose of this commit is to allow kernel users of iaa_crypto, such
as zswap, to be able to invoke the crypto_acomp_compress() API in fully
synchronous mode for sequential/non-batching use cases (i.e. today's
status-quo), wherein zswap calls:

  crypto_wait_req(crypto_acomp_compress(req), wait);

and to non-instrusively invoke the fully asynchronous batch
compress/decompress functionality that will be introduced in subsequent
patches. Both use cases need to reuse same code paths in the driver to
interface with hardware: the IAA_REQ_POLL_FLAG allows this
shared code to determine whether we need to process an iaa_req
synchronously/asynchronously. The idea is to simplify iaa_crypto's
sequential/batching interfaces for use by zswap and zram.

Thus, regardless of the iaa_crypto driver's 'sync_mode' setting, it
can still be forced to use synchronous mode by *not setting* the
IAA_REQ_POLL_FLAG in iaa_req->flags: this is the default to support
sequential use cases in zswap today.

When IAA batching functionality is introduced subsequently, it will set
the IAA_REQ_POLL_FLAG for the requests in a batch. We will submit the
descriptors for each request in the batch in iaa_[de]compress(), and
return -EINPROGRESS. The hardware will begin processing each request as
soon as it is submitted, essentially all compress/decompress jobs will
be parallelized. The polling function, "iaa_comp_poll()", will retrieve
the descriptor from each iaa_req->drv_data to check its completion
status. This enables the iaa_crypto driver to implement true async
"submit-polling" for parallel compressions and decompressions in the IAA
hardware accelerator.

Both these conditions need to be met for a request to be processed in
fully async submit-poll mode:

 1) use_irq should be "false"
 2) iaa_req->flags & IAA_REQ_POLL_FLAG should be "true"

Signed-off-by: Kanchana P Sridhar <kanchana.p.sridhar@...el.com>
---
 drivers/crypto/intel/iaa/iaa_crypto.h      |  6 ++
 drivers/crypto/intel/iaa/iaa_crypto_main.c | 71 +++++++++++++++++++++-
 2 files changed, 75 insertions(+), 2 deletions(-)

diff --git a/drivers/crypto/intel/iaa/iaa_crypto.h b/drivers/crypto/intel/iaa/iaa_crypto.h
index 190157967e3ba..1cc383c94fb80 100644
--- a/drivers/crypto/intel/iaa/iaa_crypto.h
+++ b/drivers/crypto/intel/iaa/iaa_crypto.h
@@ -41,6 +41,12 @@
 					 IAA_DECOMP_CHECK_FOR_EOB | \
 					 IAA_DECOMP_STOP_ON_EOB)
 
+/*
+ * If set, the driver must have a way to submit the req, then
+ * poll its completion status for success/error.
+ */
+#define IAA_REQ_POLL_FLAG		0x00000002
+
 /* Representation of IAA workqueue */
 struct iaa_wq {
 	struct list_head	list;
diff --git a/drivers/crypto/intel/iaa/iaa_crypto_main.c b/drivers/crypto/intel/iaa/iaa_crypto_main.c
index ecb737c70b53e..4b25235d6636c 100644
--- a/drivers/crypto/intel/iaa/iaa_crypto_main.c
+++ b/drivers/crypto/intel/iaa/iaa_crypto_main.c
@@ -1890,13 +1890,14 @@ static int iaa_compress(struct iaa_compression_ctx *ctx, struct iaa_req *req,
 					  ctx->mode, iaa_device->compression_modes[ctx->mode]);
 
 	if (likely(!ctx->use_irq)) {
+		req->drv_data = idxd_desc;
 		iaa_submit_desc_movdir64b(wq, idxd_desc);
 
 		/* Update stats */
 		update_total_comp_calls();
 		update_wq_comp_calls(wq);
 
-		if (ctx->async_mode)
+		if (req->flags & IAA_REQ_POLL_FLAG)
 			return -EINPROGRESS;
 
 		ret = check_completion(dev, idxd_desc->iax_completion, true, false);
@@ -1978,13 +1979,14 @@ static int iaa_decompress(struct iaa_compression_ctx *ctx, struct iaa_req *req,
 	desc = iaa_setup_decompress_hw_desc(idxd_desc, src_addr, slen, dst_addr, *dlen);
 
 	if (likely(!ctx->use_irq)) {
+		req->drv_data = idxd_desc;
 		iaa_submit_desc_movdir64b(wq, idxd_desc);
 
 		/* Update stats */
 		update_total_decomp_calls();
 		update_wq_decomp_calls(wq);
 
-		if (ctx->async_mode)
+		if (req->flags & IAA_REQ_POLL_FLAG)
 			return -EINPROGRESS;
 
 		ret = check_completion(dev, idxd_desc->iax_completion, false, false);
@@ -2187,6 +2189,71 @@ static int iaa_comp_adecompress(struct iaa_compression_ctx *ctx, struct iaa_req
 	return ret;
 }
 
+static int __maybe_unused iaa_comp_poll(struct iaa_compression_ctx *ctx, struct iaa_req *req)
+{
+	struct idxd_desc *idxd_desc;
+	struct idxd_device *idxd;
+	struct iaa_wq *iaa_wq;
+	struct pci_dev *pdev;
+	struct device *dev;
+	struct idxd_wq *wq;
+	bool compress_op;
+	int ret;
+
+	idxd_desc = req->drv_data;
+	if (!idxd_desc)
+		return -EAGAIN;
+
+	compress_op = (idxd_desc->iax_hw->opcode == IAX_OPCODE_COMPRESS);
+	wq = idxd_desc->wq;
+	iaa_wq = idxd_wq_get_private(wq);
+	idxd = iaa_wq->iaa_device->idxd;
+	pdev = idxd->pdev;
+	dev = &pdev->dev;
+
+	ret = check_completion(dev, idxd_desc->iax_completion, compress_op, true);
+	if (ret == -EAGAIN)
+		return ret;
+	if (ret)
+		goto out;
+
+	req->dlen = idxd_desc->iax_completion->output_size;
+
+	/* Update stats */
+	if (compress_op) {
+		update_total_comp_bytes_out(req->dlen);
+		update_wq_comp_bytes(wq, req->dlen);
+	} else {
+		update_total_decomp_bytes_in(req->slen);
+		update_wq_decomp_bytes(wq, req->slen);
+	}
+
+	if (compress_op && ctx->verify_compress) {
+		dma_addr_t src_addr, dst_addr;
+
+		req->compression_crc = idxd_desc->iax_completion->crc;
+
+		dma_sync_sg_for_device(dev, req->dst, 1, DMA_FROM_DEVICE);
+		dma_sync_sg_for_device(dev, req->src, 1, DMA_TO_DEVICE);
+
+		src_addr = sg_dma_address(req->src);
+		dst_addr = sg_dma_address(req->dst);
+
+		ret = iaa_compress_verify(ctx, req, wq, src_addr, req->slen,
+					  dst_addr, req->dlen);
+	}
+
+out:
+	/* caller doesn't call crypto_wait_req, so no acomp_request_complete() */
+	dma_unmap_sg(dev, req->dst, sg_nents(req->dst), DMA_FROM_DEVICE);
+	dma_unmap_sg(dev, req->src, sg_nents(req->src), DMA_TO_DEVICE);
+
+	idxd_free_desc(idxd_desc->wq, idxd_desc);
+	percpu_ref_put(&iaa_wq->ref);
+
+	return ret;
+}
+
 static void compression_ctx_init(struct iaa_compression_ctx *ctx, enum iaa_mode mode)
 {
 	ctx->mode = mode;
-- 
2.27.0

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