sfc: use 64-bit writes for PIO.

PATCH Superseded Shradha Shah 2 participants 5 messages May 28, 2014 1 message not in the archive

Subsystems (3)

Networking Network drivers Sfc network driver

lore

Share & tools

lore

Shradha Shah

author

2014-05-28 09:27 UTC #1 lore raw

PATCH v2 1/2 sfc: use 64-bit writes for PIO.

In reply to a message not in the archive

From: Jon Cooper <[email protected]>

Patch to open-code the memory copy routines. 32bit writes over the PCI bus causes data corruption.

Fixes ee45fd92c739db5b7950163d91dfe5f016af6d24

orig-hg-hash: 853f313def1e5e9c733f980f2b4e6330a7d063ef

Signed-off-by Shradha Shah <[email protected]>

---
 drivers/net/ethernet/sfc/tx.c | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

drivers/net/ethernet/sfc/tx.c +19 -5

index fa94753..bd6a4b8 100644
@@ -189,6 +189,20 @@ struct efx_short_copy_buffer {
 	u8 buf[L1_CACHE_BYTES];
 };
 
+/* Copy in explicit 64-bit writes. */
+static void efx_memcpy_64(void *dest, void *src, size_t len)
+{
+	uint64_t *src64 = src, *dest64 = dest;
+	size_t i, l64 = len / 8;
+
+	WARN_ON_ONCE(len % 8 != 0);
+	WARN_ON_ONCE(((u8 *)dest - (u8 *) 0) % 8 != 0);
+	BUILD_BUG_ON(sizeof(uint64_t) != 8);
+
+	for(i = 0; i < l64; ++i)
+		dest64[i] = src64[i];
+}
+
 /* Copy to PIO, respecting that writes to PIO buffers must be dword aligned.
  * Advances piobuf pointer. Leaves additional data in the copy buffer.
  */

@@ -198,7 +212,7 @@ static void efx_memcpy_toio_aligned(struct efx_nic *efx, u8 __iomem **piobuf,
 {
 	int block_len = len & ~(sizeof(copy_buf->buf) - 1);
 
-	memcpy_toio(*piobuf, data, block_len);
+	efx_memcpy_64(*piobuf, data, block_len);
 	*piobuf += block_len;
 	len -= block_len;

@@ -230,7 +244,7 @@ static void efx_memcpy_toio_aligned_cb(struct efx_nic *efx, u8 __iomem **piobuf,
 		if (copy_buf->used < sizeof(copy_buf->buf))
 			return;
 
-		memcpy_toio(*piobuf, copy_buf->buf, sizeof(copy_buf->buf));
+		efx_memcpy_64(*piobuf, copy_buf->buf, sizeof(copy_buf->buf));
 		*piobuf += sizeof(copy_buf->buf);
 		data += copy_to_buf;
 		len -= copy_to_buf;

@@ -245,7 +259,7 @@ static void efx_flush_copy_buffer(struct efx_nic *efx, u8 __iomem *piobuf,
 {
 	/* if there's anything in it, write the whole buffer, including junk */
 	if (copy_buf->used)
-		memcpy_toio(piobuf, copy_buf->buf, sizeof(copy_buf->buf));
+		efx_memcpy_64(piobuf, copy_buf->buf, sizeof(copy_buf->buf));
 }
 
 /* Traverse skb structure and copy fragments in to PIO buffer.

@@ -304,8 +318,8 @@ efx_enqueue_skb_pio(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
 		 */
 		BUILD_BUG_ON(L1_CACHE_BYTES >
 			     SKB_DATA_ALIGN(sizeof(struct skb_shared_info)));
-		memcpy_toio(tx_queue->piobuf, skb->data,
-			    ALIGN(skb->len, L1_CACHE_BYTES));
+		efx_memcpy_64(tx_queue->piobuf, skb->data,
+			      ALIGN(skb->len, L1_CACHE_BYTES));
 	}
 
 	EFX_POPULATE_QWORD_5(buffer->option,

Shradha Shah

author

2014-05-28 09:28 UTC #4 lore raw

PATCH v2 2/2 sfc: Restrict PIO to 64-bit architectures

In reply to a message not in the archive

From: Jon Cooper <[email protected]>

Enable PIO for x86_64 architecture only.
Not tested on platforms other than x86_64.

Fixes ee45fd92c739db5b7950163d91dfe5f016af6d24

orig-hg-hash: 53dc43553d9bbe1c5a64c49e580ca571ddc470ae

Signed-off-by Shradha Shah <[email protected]>

---
 drivers/net/ethernet/sfc/io.h | 8 ++++++++
 1 file changed, 8 insertions(+)

drivers/net/ethernet/sfc/io.h +8 -0

index 4d3f119..adadcf0 100644
@@ -66,10 +66,18 @@
 #define EFX_USE_QWORD_IO 1
 #endif
 
+/* PIO only works on 64-bit architectures */
+#if BITS_PER_LONG == 64
+/* not strictly necessary to restrict to x86 arch, but done for safety
+ * since unusual write combining behaviour can break PIO.
+ */
+#ifdef CONFIG_X86_64
 /* PIO is a win only if write-combining is possible */
 #ifdef ARCH_HAS_IOREMAP_WC
 #define EFX_USE_PIO 1
 #endif
+#endif
+#endif
 
 #ifdef EFX_USE_QWORD_IO
 static inline void _efx_writeq(struct efx_nic *efx, __le64 value,

Shradha Shah

author

2014-05-28 09:32 UTC #2 lore raw

In reply to Shradha Shah

Please ignore this patch.

I have sent out the correct patch with a cover letter.

My Apologies for duplication

Regards,
Shradha

Quoted 77 lines · Shradha Shah

From: Jon Cooper <[email protected]>

Patch to open-code the memory copy routines. 32bit writes over the PCI bus causes data corruption.

Fixes ee45fd92c739db5b7950163d91dfe5f016af6d24

orig-hg-hash: 853f313def1e5e9c733f980f2b4e6330a7d063ef

Signed-off-by Shradha Shah <[email protected]>

---
 drivers/net/ethernet/sfc/tx.c | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

drivers/net/ethernet/sfc/tx.c +19 -5

index fa94753..bd6a4b8 100644
@@ -189,6 +189,20 @@ struct efx_short_copy_buffer {
 	u8 buf[L1_CACHE_BYTES];
 };
 
+/* Copy in explicit 64-bit writes. */
+static void efx_memcpy_64(void *dest, void *src, size_t len)
+{
+	uint64_t *src64 = src, *dest64 = dest;
+	size_t i, l64 = len / 8;
+
+	WARN_ON_ONCE(len % 8 != 0);
+	WARN_ON_ONCE(((u8 *)dest - (u8 *) 0) % 8 != 0);
+	BUILD_BUG_ON(sizeof(uint64_t) != 8);
+
+	for(i = 0; i < l64; ++i)
+		dest64[i] = src64[i];
+}
+
 /* Copy to PIO, respecting that writes to PIO buffers must be dword aligned.
  * Advances piobuf pointer. Leaves additional data in the copy buffer.
  */

@@ -198,7 +212,7 @@ static void efx_memcpy_toio_aligned(struct efx_nic *efx, u8 __iomem **piobuf,
 {
 	int block_len = len & ~(sizeof(copy_buf->buf) - 1);
 
-	memcpy_toio(*piobuf, data, block_len);
+	efx_memcpy_64(*piobuf, data, block_len);
 	*piobuf += block_len;
 	len -= block_len;

@@ -230,7 +244,7 @@ static void efx_memcpy_toio_aligned_cb(struct efx_nic *efx, u8 __iomem **piobuf,
 		if (copy_buf->used < sizeof(copy_buf->buf))
 			return;
 
-		memcpy_toio(*piobuf, copy_buf->buf, sizeof(copy_buf->buf));
+		efx_memcpy_64(*piobuf, copy_buf->buf, sizeof(copy_buf->buf));
 		*piobuf += sizeof(copy_buf->buf);
 		data += copy_to_buf;
 		len -= copy_to_buf;

@@ -245,7 +259,7 @@ static void efx_flush_copy_buffer(struct efx_nic *efx, u8 __iomem *piobuf,
 {
 	/* if there's anything in it, write the whole buffer, including junk */
 	if (copy_buf->used)
-		memcpy_toio(piobuf, copy_buf->buf, sizeof(copy_buf->buf));
+		efx_memcpy_64(piobuf, copy_buf->buf, sizeof(copy_buf->buf));
 }
 
 /* Traverse skb structure and copy fragments in to PIO buffer.

@@ -304,8 +318,8 @@ efx_enqueue_skb_pio(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
 		 */
 		BUILD_BUG_ON(L1_CACHE_BYTES >
 			     SKB_DATA_ALIGN(sizeof(struct skb_shared_info)));
-		memcpy_toio(tx_queue->piobuf, skb->data,
-			    ALIGN(skb->len, L1_CACHE_BYTES));
+		efx_memcpy_64(tx_queue->piobuf, skb->data,
+			      ALIGN(skb->len, L1_CACHE_BYTES));
 	}
 
 	EFX_POPULATE_QWORD_5(buffer->option,

Signature · 3 lines

Many Thanks,
Regards,
Shradha Shah

Sergei Shtylyov

2014-05-28 14:45 UTC #5 lore raw

Re: [PATCH net v2 2/2] sfc: Restrict PIO to 64-bit architectures

In reply to Shradha Shah

Hello.

Quoted 6 lines · Shradha Shah

From: Jon Cooper <[email protected]>
Enable PIO for x86_64 architecture only.
Not tested on platforms other than x86_64.
Fixes ee45fd92c739db5b7950163d91dfe5f016af6d24

12 digits is enough. And please specify that commit's summary enclosed in
parens and quotes.

Quoted 5 lines

orig-hg-hash: 53dc43553d9bbe1c5a64c49e580ca571ddc470ae
Signed-off-by Shradha Shah <[email protected]>
---
  drivers/net/ethernet/sfc/io.h | 8 ++++++++
  1 file changed, 8 insertions(+)

WBR, Sergei

Sergei Shtylyov

2014-05-28 14:48 UTC #3 lore raw

In reply to Shradha Shah

Quoted 6 lines · Shradha Shah

From: Jon Cooper <[email protected]>
Patch to open-code the memory copy routines. 32bit writes over the PCI bus causes data corruption.
Fixes ee45fd92c739db5b7950163d91dfe5f016af6d24

Same comment as in the patch #2

Quoted 1 line

orig-hg-hash: 853f313def1e5e9c733f980f2b4e6330a7d063ef

What's this?

Quoted 11 lines

Signed-off-by Shradha Shah <[email protected]>

---
  drivers/net/ethernet/sfc/tx.c | 24 +++++++++++++++++++-----
  1 file changed, 19 insertions(+), 5 deletions(-)

drivers/net/ethernet/sfc/tx.c +0 -0

index fa94753..bd6a4b8 100644
@@ -189,6 +189,20 @@ struct efx_short_copy_buffer {
  	u8 buf[L1_CACHE_BYTES];

drivers/net/ethernet/sfc/tx.c struct efx_short_copy_buffer { · line 199

Quoted 10 lines

drivers/net/ethernet/sfc/tx.c +8 -0

  };
 
+/* Copy in explicit 64-bit writes. */
+static void efx_memcpy_64(void *dest, void *src, size_t len)
+{
+	uint64_t *src64 = src, *dest64 = dest;
+	size_t i, l64 = len / 8;
+
+	WARN_ON_ONCE(len % 8 != 0);
+	WARN_ON_ONCE(((u8 *)dest - (u8 *) 0) % 8 != 0);

Be consistent with spaces after a typecast, please.

drivers/net/ethernet/sfc/tx.c struct efx_short_copy_buffer { · line 208

Quoted 9 lines

drivers/net/ethernet/sfc/tx.c +6 -0

+	BUILD_BUG_ON(sizeof(uint64_t) != 8);
+
+	for(i = 0; i < l64; ++i)
+		dest64[i] = src64[i];
+}
+
  /* Copy to PIO, respecting that writes to PIO buffers must be dword aligned.
   * Advances piobuf pointer. Leaves additional data in the copy buffer.
   */

[...]

WBR, Sergei