Date:   Tue, 14 Dec 2021 17:20:35 +0100
In-Reply-To: <20211214162050.660953-1-glider@google.com>
Message-Id: <20211214162050.660953-29-glider@google.com>
Mime-Version: 1.0
References: <20211214162050.660953-1-glider@google.com>
Subject: [PATCH 28/43] kmsan: dma: unpoison DMA mappings
From:   Alexander Potapenko <glider@google.com>
To:     glider@google.com
Cc:     Alexander Viro <viro@zeniv.linux.org.uk>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andrey Konovalov <andreyknvl@google.com>,
        Andy Lutomirski <luto@kernel.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Arnd Bergmann <arnd@arndb.de>, Borislav Petkov <bp@alien8.de>,
        Christoph Hellwig <hch@lst.de>,
        Christoph Lameter <cl@linux.com>,
        David Rientjes <rientjes@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Eric Dumazet <edumazet@google.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Ilya Leoshkevich <iii@linux.ibm.com>,
        Ingo Molnar <mingo@redhat.com>, Jens Axboe <axboe@kernel.dk>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Kees Cook <keescook@chromium.org>,
        Marco Elver <elver@google.com>,
        Matthew Wilcox <willy@infradead.org>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Pekka Enberg <penberg@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Petr Mladek <pmladek@suse.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Vegard Nossum <vegard.nossum@oracle.com>,
        Vlastimil Babka <vbabka@suse.cz>, linux-mm@kvack.org,
        linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

KMSAN doesn't know about DMA memory writes performed by devices.
We unpoison such memory when it's mapped to avoid false positive
reports.

Signed-off-by: Alexander Potapenko <glider@google.com>
---
Link: https://linux-review.googlesource.com/id/Ia162dc4c5a92e74d4686c1be32a4dfeffc5c32cd
---
 kernel/dma/mapping.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index 9478eccd1c8e6..0560080813761 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -156,6 +156,7 @@ dma_addr_t dma_map_page_attrs(struct device *dev, struct page *page,
 		addr = dma_direct_map_page(dev, page, offset, size, dir, attrs);
 	else
 		addr = ops->map_page(dev, page, offset, size, dir, attrs);
+	kmsan_handle_dma(page, offset, size, dir);
 	debug_dma_map_page(dev, page, offset, size, dir, addr, attrs);
 
 	return addr;
@@ -194,11 +195,13 @@ static int __dma_map_sg_attrs(struct device *dev, struct scatterlist *sg,
 	else
 		ents = ops->map_sg(dev, sg, nents, dir, attrs);
 
-	if (ents > 0)
+	if (ents > 0) {
+		kmsan_handle_dma_sg(sg, nents, dir);
 		debug_dma_map_sg(dev, sg, nents, ents, dir, attrs);
-	else if (WARN_ON_ONCE(ents != -EINVAL && ents != -ENOMEM &&
-			      ents != -EIO))
+	} else if (WARN_ON_ONCE(ents != -EINVAL && ents != -ENOMEM &&
+				ents != -EIO)) {
 		return -EIO;
+	}
 
 	return ents;
 }
-- 
2.34.1.173.g76aa8bc2d0-goog