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Date:      Fri, 22 Apr 2016 15:12:05 +0000 (UTC)
From:      Ruslan Bukin <br@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r298476 - head/sys/riscv/htif
Message-ID:  <201604221512.u3MFC5vH067947@repo.freebsd.org>
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Author: br
Date: Fri Apr 22 15:12:05 2016
New Revision: 298476
URL: https://svnweb.freebsd.org/changeset/base/298476

Log:
  Add memory barriers (fence instructions) so the data wrotten by hardware
  to physical address now can be read by VA.
  
  This fixes operation on Rocket Core (FPGA).
  
  Sponsored by:	DARPA, AFRL
  Sponsored by:	HEIF5

Modified:
  head/sys/riscv/htif/htif_block.c

Modified: head/sys/riscv/htif/htif_block.c
==============================================================================
--- head/sys/riscv/htif/htif_block.c	Fri Apr 22 15:08:50 2016	(r298475)
+++ head/sys/riscv/htif/htif_block.c	Fri Apr 22 15:12:05 2016	(r298476)
@@ -115,6 +115,7 @@ htif_blk_intr(void *arg, uint64_t entry)
 	data = HTIF_DEV_DATA(entry);
 
 	if (sc->curtag == data) {
+		wmb();
 		sc->cmd_done = 1;
 		wakeup(&sc->intr_chan);
 	} else {
@@ -198,6 +199,7 @@ htif_blk_task(void *arg)
 {
 	struct htif_blk_request req __aligned(HTIF_ALIGN);
 	struct htif_blk_softc *sc;
+	uint64_t req_paddr;
 	struct bio *bp;
 	uint64_t paddr;
 	uint64_t cmd;
@@ -217,11 +219,13 @@ htif_blk_task(void *arg)
 		if (bp->bio_cmd == BIO_READ || bp->bio_cmd == BIO_WRITE) {
 			HTIF_BLK_LOCK(sc);
 
+			rmb();
 			req.offset = (bp->bio_pblkno * sc->disk->d_sectorsize);
 			req.size = bp->bio_bcount;
 			paddr = vtophys(bp->bio_data);
 			KASSERT(paddr != 0, ("paddr is 0"));
 			req.addr = paddr;
+			sc->curtag++;
 			req.tag = sc->curtag;
 
 			cmd = sc->index;
@@ -230,9 +234,9 @@ htif_blk_task(void *arg)
 				cmd |= (HTIF_CMD_READ << HTIF_CMD_SHIFT);
 			else
 				cmd |= (HTIF_CMD_WRITE << HTIF_CMD_SHIFT);
-			paddr = vtophys(&req);
-			KASSERT(paddr != 0, ("paddr is 0"));
-			cmd |= paddr;
+			req_paddr = vtophys(&req);
+			KASSERT(req_paddr != 0, ("req_paddr is 0"));
+			cmd |= req_paddr;
 
 			sc->cmd_done = 0;
 			htif_command(cmd);

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