xHCI: AMD isoc link TRB chain bit quirk

Setting the chain (CH) bit in the link TRB of isochronous transfer rings
is required by AMD 0.96 xHCI host controller to successfully transverse
multi-TRB TD that span through different memory segments.

When a Missed Service Error event occurs, if the chain bit is not set in
the link TRB and the host skips TDs which just across a link TRB, the
host may falsely recognize the link TRB as a normal TRB. You can see
this may cause big trouble - the host does not jump to the right address
which is pointed by the link TRB, but continue fetching the memory which
is after the link TRB address, which may not even belong to the host,
and the result cannot be predicted.

This causes some big problems. Without the former patch I sent: "xHCI:
prevent infinite loop when processing MSE event", the system may hang.
With that patch applied, system does not hang, but the host still access
wrong memory address and isoc transfer will fail. With this patch,
isochronous transfer works as expected.

This patch should be applied to kernels as old as 2.6.36, which was when
the first isochronous support was added for the xHCI host controller.

Signed-off-by: Andiry Xu <andiry.xu@amd.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 29 insertions, 24 deletions

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index a3679635382a..e4b7f003d702 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -185,7 +185,7 @@ static void inc_deq(struct xhci_hcd *xhci, struct xhci_ring *ring, bool consumer
  *			prepare_transfer()?
  */
 static void inc_enq(struct xhci_hcd *xhci, struct xhci_ring *ring,
-		bool consumer, bool more_trbs_coming)
+		bool consumer, bool more_trbs_coming, bool isoc)
 {
 	u32 chain;
 	union xhci_trb *next;
@@ -212,11 +212,13 @@ static void inc_enq(struct xhci_hcd *xhci, struct xhci_ring *ring,
 				if (!chain && !more_trbs_coming)
 					break;
 
-				/* If we're not dealing with 0.95 hardware,
+				/* If we're not dealing with 0.95 hardware or
+				 * isoc rings on AMD 0.96 host,
 				 * carry over the chain bit of the previous TRB
 				 * (which may mean the chain bit is cleared).
 				 */
-				if (!xhci_link_trb_quirk(xhci)) {
+				if (!(isoc && (xhci->quirks & XHCI_AMD_0x96_HOST))
+						&& !xhci_link_trb_quirk(xhci)) {
 					next->link.control &=
 						cpu_to_le32(~TRB_CHAIN);
 					next->link.control |=
@@ -2391,7 +2393,7 @@ irqreturn_t xhci_msi_irq(int irq, struct usb_hcd *hcd)
  *			prepare_transfer()?
  */
 static void queue_trb(struct xhci_hcd *xhci, struct xhci_ring *ring,
-		bool consumer, bool more_trbs_coming,
+		bool consumer, bool more_trbs_coming, bool isoc,
 		u32 field1, u32 field2, u32 field3, u32 field4)
 {
 	struct xhci_generic_trb *trb;
@@ -2401,7 +2403,7 @@ static void queue_trb(struct xhci_hcd *xhci, struct xhci_ring *ring,
 	trb->field[1] = cpu_to_le32(field2);
 	trb->field[2] = cpu_to_le32(field3);
 	trb->field[3] = cpu_to_le32(field4);
-	inc_enq(xhci, ring, consumer, more_trbs_coming);
+	inc_enq(xhci, ring, consumer, more_trbs_coming, isoc);
 }
 
 /*
@@ -2409,7 +2411,7 @@ static void queue_trb(struct xhci_hcd *xhci, struct xhci_ring *ring,
  * FIXME allocate segments if the ring is full.
  */
 static int prepare_ring(struct xhci_hcd *xhci, struct xhci_ring *ep_ring,
-		u32 ep_state, unsigned int num_trbs, gfp_t mem_flags)
+		u32 ep_state, unsigned int num_trbs, bool isoc, gfp_t mem_flags)
 {
 	/* Make sure the endpoint has been added to xHC schedule */
 	switch (ep_state) {
@@ -2451,10 +2453,11 @@ static int prepare_ring(struct xhci_hcd *xhci, struct xhci_ring *ep_ring,
 		next = ring->enqueue;
 
 		while (last_trb(xhci, ring, ring->enq_seg, next)) {
-			/* If we're not dealing with 0.95 hardware,
-			 * clear the chain bit.
+			/* If we're not dealing with 0.95 hardware or isoc rings
+			 * on AMD 0.96 host, clear the chain bit.
 			 */
-			if (!xhci_link_trb_quirk(xhci))
+			if (!xhci_link_trb_quirk(xhci) && !(isoc &&
+					(xhci->quirks & XHCI_AMD_0x96_HOST)))
 				next->link.control &= cpu_to_le32(~TRB_CHAIN);
 			else
 				next->link.control |= cpu_to_le32(TRB_CHAIN);
@@ -2487,6 +2490,7 @@ static int prepare_transfer(struct xhci_hcd *xhci,
 		unsigned int num_trbs,
 		struct urb *urb,
 		unsigned int td_index,
+		bool isoc,
 		gfp_t mem_flags)
 {
 	int ret;
@@ -2504,7 +2508,7 @@ static int prepare_transfer(struct xhci_hcd *xhci,
 
 	ret = prepare_ring(xhci, ep_ring,
 			   le32_to_cpu(ep_ctx->ep_info) & EP_STATE_MASK,
-			   num_trbs, mem_flags);
+			   num_trbs, isoc, mem_flags);
 	if (ret)
 		return ret;
 
@@ -2727,7 +2731,7 @@ static int queue_bulk_sg_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 
 	trb_buff_len = prepare_transfer(xhci, xhci->devs[slot_id],
 			ep_index, urb->stream_id,
-			num_trbs, urb, 0, mem_flags);
+			num_trbs, urb, 0, false, mem_flags);
 	if (trb_buff_len < 0)
 		return trb_buff_len;
 
@@ -2822,7 +2826,7 @@ static int queue_bulk_sg_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 			more_trbs_coming = true;
 		else
 			more_trbs_coming = false;
-		queue_trb(xhci, ep_ring, false, more_trbs_coming,
+		queue_trb(xhci, ep_ring, false, more_trbs_coming, false,
 				lower_32_bits(addr),
 				upper_32_bits(addr),
 				length_field,
@@ -2913,7 +2917,7 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 
 	ret = prepare_transfer(xhci, xhci->devs[slot_id],
 			ep_index, urb->stream_id,
-			num_trbs, urb, 0, mem_flags);
+			num_trbs, urb, 0, false, mem_flags);
 	if (ret < 0)
 		return ret;
 
@@ -2985,7 +2989,7 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 			more_trbs_coming = true;
 		else
 			more_trbs_coming = false;
-		queue_trb(xhci, ep_ring, false, more_trbs_coming,
+		queue_trb(xhci, ep_ring, false, more_trbs_coming, false,
 				lower_32_bits(addr),
 				upper_32_bits(addr),
 				length_field,
@@ -3045,7 +3049,7 @@ int xhci_queue_ctrl_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 		num_trbs++;
 	ret = prepare_transfer(xhci, xhci->devs[slot_id],
 			ep_index, urb->stream_id,
-			num_trbs, urb, 0, mem_flags);
+			num_trbs, urb, 0, false, mem_flags);
 	if (ret < 0)
 		return ret;
 
@@ -3078,7 +3082,7 @@ int xhci_queue_ctrl_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 		}
 	}
 
-	queue_trb(xhci, ep_ring, false, true,
+	queue_trb(xhci, ep_ring, false, true, false,
 		  setup->bRequestType | setup->bRequest << 8 | le16_to_cpu(setup->wValue) << 16,
 		  le16_to_cpu(setup->wIndex) | le16_to_cpu(setup->wLength) << 16,
 		  TRB_LEN(8) | TRB_INTR_TARGET(0),
@@ -3098,7 +3102,7 @@ int xhci_queue_ctrl_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 	if (urb->transfer_buffer_length > 0) {
 		if (setup->bRequestType & USB_DIR_IN)
 			field |= TRB_DIR_IN;
-		queue_trb(xhci, ep_ring, false, true,
+		queue_trb(xhci, ep_ring, false, true, false,
 				lower_32_bits(urb->transfer_dma),
 				upper_32_bits(urb->transfer_dma),
 				length_field,
@@ -3114,7 +3118,7 @@ int xhci_queue_ctrl_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 		field = 0;
 	else
 		field = TRB_DIR_IN;
-	queue_trb(xhci, ep_ring, false, false,
+	queue_trb(xhci, ep_ring, false, false, false,
 			0,
 			0,
 			TRB_INTR_TARGET(0),
@@ -3263,7 +3267,8 @@ static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 		trbs_per_td = count_isoc_trbs_needed(xhci, urb, i);
 
 		ret = prepare_transfer(xhci, xhci->devs[slot_id], ep_index,
-				urb->stream_id, trbs_per_td, urb, i, mem_flags);
+				urb->stream_id, trbs_per_td, urb, i, true,
+				mem_flags);
 		if (ret < 0) {
 			if (i == 0)
 				return ret;
@@ -3333,7 +3338,7 @@ static int xhci_queue_isoc_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 				remainder |
 				TRB_INTR_TARGET(0);
 
-			queue_trb(xhci, ep_ring, false, more_trbs_coming,
+			queue_trb(xhci, ep_ring, false, more_trbs_coming, true,
 				lower_32_bits(addr),
 				upper_32_bits(addr),
 				length_field,
@@ -3415,7 +3420,7 @@ int xhci_queue_isoc_tx_prepare(struct xhci_hcd *xhci, gfp_t mem_flags,
 	 * Do not insert any td of the urb to the ring if the check failed.
 	 */
 	ret = prepare_ring(xhci, ep_ring, le32_to_cpu(ep_ctx->ep_info) & EP_STATE_MASK,
-			   num_trbs, mem_flags);
+			   num_trbs, true, mem_flags);
 	if (ret)
 		return ret;
 
@@ -3474,7 +3479,7 @@ static int queue_command(struct xhci_hcd *xhci, u32 field1, u32 field2,
 		reserved_trbs++;
 
 	ret = prepare_ring(xhci, xhci->cmd_ring, EP_STATE_RUNNING,
-			reserved_trbs, GFP_ATOMIC);
+			reserved_trbs, false, GFP_ATOMIC);
 	if (ret < 0) {
 		xhci_err(xhci, "ERR: No room for command on command ring\n");
 		if (command_must_succeed)
@@ -3482,8 +3487,8 @@ static int queue_command(struct xhci_hcd *xhci, u32 field1, u32 field2,
 					"unfailable commands failed.\n");
 		return ret;
 	}
-	queue_trb(xhci, xhci->cmd_ring, false, false, field1, field2, field3,
-			field4 | xhci->cmd_ring->cycle_state);
+	queue_trb(xhci, xhci->cmd_ring, false, false, false, field1, field2,
+			field3,	field4 | xhci->cmd_ring->cycle_state);
 	return 0;
 }