crypto: crypto4xx - add backlog queue support

Previously, If the crypto4xx driver used all available
security contexts, it would simply refuse new requests
with -EAGAIN. CRYPTO_TFM_REQ_MAY_BACKLOG was ignored.

in case of dm-crypt.c's crypt_convert() function this was
causing the following errors to manifest, if the system was
pushed hard enough:

| EXT4-fs warning (dm-1): ext4_end_bio:314: I/O error -5 writing to ino ..
| EXT4-fs warning (dm-1): ext4_end_bio:314: I/O error -5 writing to ino ..
| EXT4-fs warning (dm-1): ext4_end_bio:314: I/O error -5 writing to ino ..
| JBD2: Detected IO errors while flushing file data on dm-1-8
| Aborting journal on device dm-1-8.
| EXT4-fs error : ext4_journal_check_start:56: Detected aborted journal
| EXT4-fs (dm-1): Remounting filesystem read-only
| EXT4-fs : ext4_writepages: jbd2_start: 2048 pages, inode 498...; err -30

(This did cause corruptions due to failed writes)

To fix this mess, the crypto4xx driver needs to notifiy the
user to slow down. This can be achieved by returning -EBUSY
on requests, once the crypto hardware was falling behind.

Note: -EBUSY has two different meanings. Setting the flag
CRYPTO_TFM_REQ_MAY_BACKLOG implies that the request was
successfully queued, by the crypto driver. To achieve this
requirement, the implementation introduces a threshold check and
adds logic to the completion routines in much the same way as
AMD's Cryptographic Coprocessor (CCP) driver do.

Note2: Tests showed that dm-crypt starved ipsec traffic.
Under load, ipsec links dropped to 0 Kbits/s. This is because
dm-crypt's callback would instantly queue the next request.
In order to not starve ipsec, the driver reserves a small
portion of the available crypto contexts for this purpose.

Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/drivers/crypto/amcc/crypto4xx_core.c b/drivers/crypto/amcc/crypto4xx_core.c
index cb45365166ae554dd39f430a31eb8cb16a2f7d28..abdf1db9b0ebae3ffcba636a7d7a0b49b60856f8 100644 (file)
--- a/drivers/crypto/amcc/crypto4xx_core.c
+++ b/drivers/crypto/amcc/crypto4xx_core.c
@@ -39,6 +39,7 @@
 #include <crypto/ctr.h>
 #include <crypto/sha.h>
 #include <crypto/scatterwalk.h>
+#include <crypto/internal/skcipher.h>
 #include "crypto4xx_reg_def.h"
 #include "crypto4xx_core.h"
 #include "crypto4xx_sa.h"
@@ -573,8 +574,10 @@ static u32 crypto4xx_ablkcipher_done(struct crypto4xx_device *dev,
                                    dst->offset, dst->length, DMA_FROM_DEVICE);
        }
        crypto4xx_ret_sg_desc(dev, pd_uinfo);
-       if (ablk_req->base.complete != NULL)
-               ablk_req->base.complete(&ablk_req->base, 0);
+
+       if (pd_uinfo->state & PD_ENTRY_BUSY)
+               ablkcipher_request_complete(ablk_req, -EINPROGRESS);
+       ablkcipher_request_complete(ablk_req, 0);
 
        return 0;
 }
@@ -591,9 +594,10 @@ static u32 crypto4xx_ahash_done(struct crypto4xx_device *dev,
        crypto4xx_copy_digest_to_dst(pd_uinfo,
                                     crypto_tfm_ctx(ahash_req->base.tfm));
        crypto4xx_ret_sg_desc(dev, pd_uinfo);
-       /* call user provided callback function x */
-       if (ahash_req->base.complete != NULL)
-               ahash_req->base.complete(&ahash_req->base, 0);
+
+       if (pd_uinfo->state & PD_ENTRY_BUSY)
+               ahash_request_complete(ahash_req, -EINPROGRESS);
+       ahash_request_complete(ahash_req, 0);
 
        return 0;
 }
@@ -704,6 +708,7 @@ u32 crypto4xx_build_pd(struct crypto_async_request *req,
        struct pd_uinfo *pd_uinfo = NULL;
        unsigned int nbytes = datalen, idx;
        u32 gd_idx = 0;
+       bool is_busy;
 
        /* figure how many gd is needed */
        num_gd = sg_nents_for_len(src, datalen);
@@ -734,6 +739,31 @@ u32 crypto4xx_build_pd(struct crypto_async_request *req,
         * already got must be return the original place.
         */
        spin_lock_irqsave(&dev->core_dev->lock, flags);
+       /*
+        * Let the caller know to slow down, once more than 13/16ths = 81%
+        * of the available data contexts are being used simultaneously.
+        *
+        * With PPC4XX_NUM_PD = 256, this will leave a "backlog queue" for
+        * 31 more contexts. Before new requests have to be rejected.
+        */
+       if (req->flags & CRYPTO_TFM_REQ_MAY_BACKLOG) {
+               is_busy = ((dev->pdr_head - dev->pdr_tail) % PPC4XX_NUM_PD) >=
+                       ((PPC4XX_NUM_PD * 13) / 16);
+       } else {
+               /*
+                * To fix contention issues between ipsec (no blacklog) and
+                * dm-crypto (backlog) reserve 32 entries for "no backlog"
+                * data contexts.
+                */
+               is_busy = ((dev->pdr_head - dev->pdr_tail) % PPC4XX_NUM_PD) >=
+                       ((PPC4XX_NUM_PD * 15) / 16);
+
+               if (is_busy) {
+                       spin_unlock_irqrestore(&dev->core_dev->lock, flags);
+                       return -EBUSY;
+               }
+       }
+
        if (num_gd) {
                fst_gd = crypto4xx_get_n_gd(dev, num_gd);
                if (fst_gd == ERING_WAS_FULL) {
@@ -888,11 +918,12 @@ u32 crypto4xx_build_pd(struct crypto_async_request *req,
        sa->sa_command_1.bf.hash_crypto_offset = 0;
        pd->pd_ctl.w = ctx->pd_ctl;
        pd->pd_ctl_len.w = 0x00400000 | datalen;
-       pd_uinfo->state = PD_ENTRY_INUSE;
+       pd_uinfo->state = PD_ENTRY_INUSE | (is_busy ? PD_ENTRY_BUSY : 0);
+
        wmb();
        /* write any value to push engine to read a pd */
        writel(1, dev->ce_base + CRYPTO4XX_INT_DESCR_RD);
-       return -EINPROGRESS;
+       return is_busy ? -EBUSY : -EINPROGRESS;
 }
 
 /**
@@ -997,7 +1028,7 @@ static void crypto4xx_bh_tasklet_cb(unsigned long data)
                tail = core_dev->dev->pdr_tail;
                pd_uinfo = &core_dev->dev->pdr_uinfo[tail];
                pd = &core_dev->dev->pdr[tail];
-               if ((pd_uinfo->state == PD_ENTRY_INUSE) &&
+               if ((pd_uinfo->state & PD_ENTRY_INUSE) &&
                                   pd->pd_ctl.bf.pe_done &&
                                   !pd->pd_ctl.bf.host_ready) {
                        pd->pd_ctl.bf.pe_done = 0;

diff --git a/drivers/crypto/amcc/crypto4xx_core.h b/drivers/crypto/amcc/crypto4xx_core.h
index 27e439c1f5bf5c5bf6f766933650449446ca7d3c..dbe29043e0c5bc848627a7e112affe97aed5c21c 100644 (file)
--- a/drivers/crypto/amcc/crypto4xx_core.h
+++ b/drivers/crypto/amcc/crypto4xx_core.h
@@ -44,7 +44,8 @@
 #define PPC4XX_LAST_SD                         (PPC4XX_NUM_SD - 1)
 #define PPC4XX_SD_BUFFER_SIZE                  2048
 
-#define PD_ENTRY_INUSE                         1
+#define PD_ENTRY_BUSY                          BIT(1)
+#define PD_ENTRY_INUSE                         BIT(0)
 #define PD_ENTRY_FREE                          0
 #define ERING_WAS_FULL                         0xffffffff