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Message-ID: <YMM8Ua0HMmErLIQg@0xbeefdead.lan>
Date: Fri, 11 Jun 2021 06:34:57 -0400
From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To: Christoph Hellwig <hch@....de>,
Dominique MARTINET <dominique.martinet@...ark-techno.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
jianxiong Gao <jxgao@...gle.com>
Cc: Horia Geantă <horia.geanta@....com>,
Dominique MARTINET <dominique.martinet@...ark-techno.com>,
Jianxiong Gao <jxgao@...gle.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Lukas Hartmann <lukas@...mn.com>,
Aymen Sghaier <aymen.sghaier@....com>,
Herbert Xu <herbert@...dor.apana.org.au>,
"David S. Miller" <davem@...emloft.net>,
"linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>
Subject: Re: swiotlb/caamjr regression (Was: [GIT PULL] (swiotlb)
stable/for-linus-5.12)
On Fri, Jun 11, 2021 at 08:21:53AM +0200, Christoph Hellwig wrote:
> On Thu, Jun 10, 2021 at 05:52:07PM +0300, Horia Geantă wrote:
> > I've noticed the failure also in v5.10 and v5.11 stable kernels,
> > since the patch set has been backported.
>
> FYI, there has been a patch on the list that should have fixed this
> for about a month:
>
> https://lore.kernel.org/linux-iommu/20210510091816.GA2084@lst.de/T/#m0d0df6490350a08dcc24c9086c8edc165b402d6f
>
> but it seems like it never got picked up.
Yikes!
Dominique,
Would you be up to testing the attached (and inline) patch please?
Linus,
Would you be terribly offended if I took your code (s/unsigned
long/unsigned int), and used Chanho's description of the problem (see below)?
Christoph,
I took the liberty of putting your Reviewed-by on the patch, you OK with
that?
Jianxiong,
Would you be up for testing this patch on your NVMe rig please? I don't
forsee a problem.. but just in case
>From f06da55596675383fbf2563fe2919b2a8f68901b Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@...ux-foundation.org>
Date: Thu, 10 Jun 2021 12:41:26 -0700
Subject: [PATCH] swiotlb: manipulate orig_addr when tlb_addr has offset
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
in case of driver wants to sync part of ranges with offset,
swiotlb_tbl_sync_single() copies from orig_addr base to tlb_addr with
offset and ends up with data mismatch.
It was removed from
"swiotlb: don't modify orig_addr in swiotlb_tbl_sync_single",
but said logic has to be added back in.
[From Linus's email:
That commit which the removed the offset calculation entirely, because the old
(unsigned long)tlb_addr & (IO_TLB_SIZE - 1)
was wrong, but instead of removing it, I think it should have just
fixed it to be
(tlb_addr - mem->start) & (IO_TLB_SIZE - 1);
instead. That way the slot offset always matches the slot index calculation.]
The use-case that drivers are hitting is as follow:
1. Get dma_addr_t from dma_map_single()
dma_addr_t tlb_addr = dma_map_single(dev, vaddr, vsize, DMA_TO_DEVICE);
|<---------------vsize------------->|
+-----------------------------------+
| | original buffer
+-----------------------------------+
vaddr
swiotlb_align_offset
|<----->|<---------------vsize------------->|
+-------+-----------------------------------+
| | | swiotlb buffer
+-------+-----------------------------------+
tlb_addr
2. Do something
3. Sync dma_addr_t through dma_sync_single_for_device(..)
dma_sync_single_for_device(dev, tlb_addr + offset, size, DMA_TO_DEVICE);
Error case.
Copy data to original buffer but it is from base addr (instead of
base addr + offset) in original buffer:
swiotlb_align_offset
|<----->|<- offset ->|<- size ->|
+-------+-----------------------------------+
| | |##########| | swiotlb buffer
+-------+-----------------------------------+
tlb_addr
|<- size ->|
+-----------------------------------+
|##########| | original buffer
+-----------------------------------+
vaddr
The fix is to copy the data to the original buffer and take into
account the offset, like so:
swiotlb_align_offset
|<----->|<- offset ->|<- size ->|
+-------+-----------------------------------+
| | |##########| | swiotlb buffer
+-------+-----------------------------------+
tlb_addr
|<- offset ->|<- size ->|
+-----------------------------------+
| |##########| | original buffer
+-----------------------------------+
vaddr
[This patch text is from Bumyong's email; and his solution was very close
to Linus's, so incorporating his text]
Fixes: 16fc3cef33a0 ("swiotlb: don't modify orig_addr in swiotlb_tbl_sync_single")
Signed-off-by: Bumyong Lee <bumyong.lee@...sung.com>
Signed-off-by: Chanho Park <chanho61.park@...sung.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Reported-by: Dominique MARTINET <dominique.martinet@...ark-techno.com>
Reported-by: Horia Geantă <horia.geanta@....com>
Tested-by: Horia Geantă <horia.geanta@....com>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
CC: stable@...r.kernel.org
Signed-off-by: Konrad Rzeszutek Wilk <konrad@...nok.org>
---
kernel/dma/swiotlb.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 8ca7d50..dc438b5 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -342,6 +342,7 @@ static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size
{
struct io_tlb_mem *mem = io_tlb_default_mem;
int index = (tlb_addr - mem->start) >> IO_TLB_SHIFT;
+ unsigned int offset = (tlb_addr - mem->start) & (IO_TLB_SIZE - 1);
phys_addr_t orig_addr = mem->slots[index].orig_addr;
size_t alloc_size = mem->slots[index].alloc_size;
unsigned long pfn = PFN_DOWN(orig_addr);
@@ -350,6 +351,14 @@ static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size
if (orig_addr == INVALID_PHYS_ADDR)
return;
+ if (offset > alloc_size) {
+ dev_WARN_ONCE(dev, 1,
+ "Buffer overflow detected. Offset: %lu. Mapping size: %zu.\n",
+ offset, size);
+ return;
+ }
+ alloc_size -= offset;
+ orig_addr += offset;
if (size > alloc_size) {
dev_WARN_ONCE(dev, 1,
"Buffer overflow detected. Allocation size: %zu. Mapping size: %zu.\n",
--
1.8.3.1
View attachment "0001-swiotlb-manipulate-orig_addr-when-tlb_addr-has-offse.patch" of type "text/plain" (4629 bytes)
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