* [PATCH] dma-direct: Fix return value of dma_direct_supported
@ 2018-10-03 23:48 Alexander Duyck
2018-10-04 11:25 ` Robin Murphy
0 siblings, 1 reply; 6+ messages in thread
From: Alexander Duyck @ 2018-10-03 23:48 UTC (permalink / raw)
To: iommu; +Cc: robin.murphy, linux-kernel, gregkh, linuxppc-dev, linux
It appears that in commit 9d7a224b463e ("dma-direct: always allow dma mask
<= physiscal memory size") the logic of the test was changed from a "<" to
a ">=" however I don't see any reason for that change. I am assuming that
there was some additional change planned, specifically I suspect the logic
was intended to be reversed and possibly used for a return. Since that is
the case I have gone ahead and done that.
This addresses issues I had on my system that prevented me from booting
with the above mentioned commit applied on an x86_64 system w/ Intel IOMMU.
Fixes: 9d7a224b463e ("dma-direct: always allow dma mask <= physiscal memory size")
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
---
kernel/dma/direct.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 5a0806b5351b..65872f6c2e93 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -301,9 +301,7 @@ int dma_direct_supported(struct device *dev, u64 mask)
min_mask = min_t(u64, min_mask, (max_pfn - 1) << PAGE_SHIFT);
- if (mask >= phys_to_dma(dev, min_mask))
- return 0;
- return 1;
+ return mask >= phys_to_dma(dev, min_mask);
}
int dma_direct_mapping_error(struct device *dev, dma_addr_t dma_addr)
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] dma-direct: Fix return value of dma_direct_supported 2018-10-03 23:48 [PATCH] dma-direct: Fix return value of dma_direct_supported Alexander Duyck @ 2018-10-04 11:25 ` Robin Murphy 2018-10-04 15:13 ` Alexander Duyck 0 siblings, 1 reply; 6+ messages in thread From: Robin Murphy @ 2018-10-04 11:25 UTC (permalink / raw) To: Alexander Duyck, iommu; +Cc: linuxppc-dev, linux-kernel, linux, gregkh On 04/10/18 00:48, Alexander Duyck wrote: > It appears that in commit 9d7a224b463e ("dma-direct: always allow dma mask > <= physiscal memory size") the logic of the test was changed from a "<" to > a ">=" however I don't see any reason for that change. I am assuming that > there was some additional change planned, specifically I suspect the logic > was intended to be reversed and possibly used for a return. Since that is > the case I have gone ahead and done that. Bah, seems I got hung up on the min_mask code above it and totally overlooked that the condition itself got flipped. It probably also can't help that it's an int return type, but treated as a bool by callers rather than "0 for success" as int tends to imply in isolation. Anyway, paying a bit more attention this time, I think this looks like the right fix - cheers Alex. Robin. > This addresses issues I had on my system that prevented me from booting > with the above mentioned commit applied on an x86_64 system w/ Intel IOMMU. > > Fixes: 9d7a224b463e ("dma-direct: always allow dma mask <= physiscal memory size") > Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> > --- > kernel/dma/direct.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c > index 5a0806b5351b..65872f6c2e93 100644 > --- a/kernel/dma/direct.c > +++ b/kernel/dma/direct.c > @@ -301,9 +301,7 @@ int dma_direct_supported(struct device *dev, u64 mask) > > min_mask = min_t(u64, min_mask, (max_pfn - 1) << PAGE_SHIFT); > > - if (mask >= phys_to_dma(dev, min_mask)) > - return 0; > - return 1; > + return mask >= phys_to_dma(dev, min_mask); > } > > int dma_direct_mapping_error(struct device *dev, dma_addr_t dma_addr) > > _______________________________________________ > iommu mailing list > iommu@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/iommu > ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] dma-direct: Fix return value of dma_direct_supported 2018-10-04 11:25 ` Robin Murphy @ 2018-10-04 15:13 ` Alexander Duyck 2018-10-05 7:17 ` Christoph Hellwig 2018-12-13 19:45 ` Lendacky, Thomas 0 siblings, 2 replies; 6+ messages in thread From: Alexander Duyck @ 2018-10-04 15:13 UTC (permalink / raw) To: Robin Murphy Cc: LKML, open list:INTEL IOMMU (VT-d), Greg KH, alexander.h.duyck, open list:LINUX FOR POWERPC (32-BIT AND 64-BIT), Christoph Hellwig, Guenter Roeck On Thu, Oct 4, 2018 at 4:25 AM Robin Murphy <robin.murphy@arm.com> wrote: > > On 04/10/18 00:48, Alexander Duyck wrote: > > It appears that in commit 9d7a224b463e ("dma-direct: always allow dma mask > > <= physiscal memory size") the logic of the test was changed from a "<" to > > a ">=" however I don't see any reason for that change. I am assuming that > > there was some additional change planned, specifically I suspect the logic > > was intended to be reversed and possibly used for a return. Since that is > > the case I have gone ahead and done that. > > Bah, seems I got hung up on the min_mask code above it and totally > overlooked that the condition itself got flipped. It probably also can't > help that it's an int return type, but treated as a bool by callers > rather than "0 for success" as int tends to imply in isolation. > > Anyway, paying a bit more attention this time, I think this looks like > the right fix - cheers Alex. > > Robin. Thanks for the review. - Alex P.S. It looks like I forgot to add Christoph to the original mail since I had just copied the To and Cc from the original submission, so I added him to the Cc for this. > > This addresses issues I had on my system that prevented me from booting > > with the above mentioned commit applied on an x86_64 system w/ Intel IOMMU. > > > > Fixes: 9d7a224b463e ("dma-direct: always allow dma mask <= physiscal memory size") > > Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> > > --- > > kernel/dma/direct.c | 4 +--- > > 1 file changed, 1 insertion(+), 3 deletions(-) > > > > diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c > > index 5a0806b5351b..65872f6c2e93 100644 > > --- a/kernel/dma/direct.c > > +++ b/kernel/dma/direct.c > > @@ -301,9 +301,7 @@ int dma_direct_supported(struct device *dev, u64 mask) > > > > min_mask = min_t(u64, min_mask, (max_pfn - 1) << PAGE_SHIFT); > > > > - if (mask >= phys_to_dma(dev, min_mask)) > > - return 0; > > - return 1; > > + return mask >= phys_to_dma(dev, min_mask); > > } > > > > int dma_direct_mapping_error(struct device *dev, dma_addr_t dma_addr) > > > > _______________________________________________ > > iommu mailing list > > iommu@lists.linux-foundation.org > > https://lists.linuxfoundation.org/mailman/listinfo/iommu > > > _______________________________________________ > iommu mailing list > iommu@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/iommu ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] dma-direct: Fix return value of dma_direct_supported 2018-10-04 15:13 ` Alexander Duyck @ 2018-10-05 7:17 ` Christoph Hellwig 2018-12-13 19:45 ` Lendacky, Thomas 1 sibling, 0 replies; 6+ messages in thread From: Christoph Hellwig @ 2018-10-05 7:17 UTC (permalink / raw) To: Alexander Duyck Cc: Robin Murphy, LKML, open list:INTEL IOMMU (VT-d), Greg KH, alexander.h.duyck, open list:LINUX FOR POWERPC (32-BIT AND 64-BIT), Christoph Hellwig, Guenter Roeck On Thu, Oct 04, 2018 at 08:13:26AM -0700, Alexander Duyck wrote: > Thanks for the review. > > - Alex > > P.S. It looks like I forgot to add Christoph to the original mail > since I had just copied the To and Cc from the original submission, so > I added him to the Cc for this. Yes, there was some oddness with replies appearing out of nowhere that I couldn't understand in my jetlagged state yesterday. Now thay I've caught up on iommu list traffic it all makes sense now. I've applied this with an Acked-by for Robin added based on his reply. ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] dma-direct: Fix return value of dma_direct_supported 2018-10-04 15:13 ` Alexander Duyck 2018-10-05 7:17 ` Christoph Hellwig @ 2018-12-13 19:45 ` Lendacky, Thomas 2018-12-13 19:58 ` Christoph Hellwig 1 sibling, 1 reply; 6+ messages in thread From: Lendacky, Thomas @ 2018-12-13 19:45 UTC (permalink / raw) To: Alexander Duyck, Robin Murphy, Christoph Hellwig Cc: LKML, open list:INTEL IOMMU (VT-d), Greg KH, alexander.h.duyck@linux.intel.com, open list:LINUX FOR POWERPC (32-BIT AND 64-BIT), Guenter Roeck On 10/04/2018 10:13 AM, Alexander Duyck wrote: > On Thu, Oct 4, 2018 at 4:25 AM Robin Murphy <robin.murphy@arm.com> wrote: >> >> On 04/10/18 00:48, Alexander Duyck wrote: >>> It appears that in commit 9d7a224b463e ("dma-direct: always allow dma mask >>> <= physiscal memory size") the logic of the test was changed from a "<" to >>> a ">=" however I don't see any reason for that change. I am assuming that >>> there was some additional change planned, specifically I suspect the logic >>> was intended to be reversed and possibly used for a return. Since that is >>> the case I have gone ahead and done that. >> >> Bah, seems I got hung up on the min_mask code above it and totally >> overlooked that the condition itself got flipped. It probably also can't >> help that it's an int return type, but treated as a bool by callers >> rather than "0 for success" as int tends to imply in isolation. >> >> Anyway, paying a bit more attention this time, I think this looks like >> the right fix - cheers Alex. >> >> Robin. > > Thanks for the review. > > - Alex > > P.S. It looks like I forgot to add Christoph to the original mail > since I had just copied the To and Cc from the original submission, so > I added him to the Cc for this. > >>> This addresses issues I had on my system that prevented me from booting >>> with the above mentioned commit applied on an x86_64 system w/ Intel IOMMU. >>> >>> Fixes: 9d7a224b463e ("dma-direct: always allow dma mask <= physiscal memory size") >>> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> >>> --- >>> kernel/dma/direct.c | 4 +--- >>> 1 file changed, 1 insertion(+), 3 deletions(-) >>> >>> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c >>> index 5a0806b5351b..65872f6c2e93 100644 >>> --- a/kernel/dma/direct.c >>> +++ b/kernel/dma/direct.c >>> @@ -301,9 +301,7 @@ int dma_direct_supported(struct device *dev, u64 mask) >>> >>> min_mask = min_t(u64, min_mask, (max_pfn - 1) << PAGE_SHIFT); >>> >>> - if (mask >= phys_to_dma(dev, min_mask)) >>> - return 0; >>> - return 1; >>> + return mask >= phys_to_dma(dev, min_mask); So I think this needs to be __phys_to_dma() here. I only recently got a system that had a device where the driver only supported 32-bit DMA and found that when SME is active this returns 0 and causes the driver to fail to initialize. This is because the SME encryption bit (bit 47) is part of the check when using phys_to_dma(). During actual DMA when SME is active, bounce buffers will be used for anything that can't meet the 48-bit requirement. But for this test, using __phys_to_dma() should give the desired results, right? If you agree with this, I'll submit a patch to make the change. I missed this in 4.19, so I'll need to submit something to stable, too. The only issue there is the 4.20 fix won't apply cleanly to 4.19. Thanks, Tom >>> } >>> >>> int dma_direct_mapping_error(struct device *dev, dma_addr_t dma_addr) >>> >>> _______________________________________________ >>> iommu mailing list >>> iommu@lists.linux-foundation.org >>> https://lists.linuxfoundation.org/mailman/listinfo/iommu >>> >> _______________________________________________ >> iommu mailing list >> iommu@lists.linux-foundation.org >> https://lists.linuxfoundation.org/mailman/listinfo/iommu ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] dma-direct: Fix return value of dma_direct_supported 2018-12-13 19:45 ` Lendacky, Thomas @ 2018-12-13 19:58 ` Christoph Hellwig 0 siblings, 0 replies; 6+ messages in thread From: Christoph Hellwig @ 2018-12-13 19:58 UTC (permalink / raw) To: Lendacky, Thomas Cc: open list:LINUX FOR POWERPC (32-BIT AND 64-BIT), Alexander Duyck, LKML, open list:INTEL IOMMU (VT-d), Greg KH, alexander.h.duyck@linux.intel.com, Robin Murphy, Christoph Hellwig, Guenter Roeck On Thu, Dec 13, 2018 at 07:45:57PM +0000, Lendacky, Thomas wrote: > So I think this needs to be __phys_to_dma() here. I only recently got a > system that had a device where the driver only supported 32-bit DMA and > found that when SME is active this returns 0 and causes the driver to fail > to initialize. This is because the SME encryption bit (bit 47) is part of > the check when using phys_to_dma(). During actual DMA when SME is active, > bounce buffers will be used for anything that can't meet the 48-bit > requirement. But for this test, using __phys_to_dma() should give the > desired results, right? > > If you agree with this, I'll submit a patch to make the change. I missed > this in 4.19, so I'll need to submit something to stable, too. The only > issue there is the 4.20 fix won't apply cleanly to 4.19. Yes, please send a patch. Please make sure it includes a code comment that explains why the __-prefixed version is used. ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2018-12-13 20:01 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2018-10-03 23:48 [PATCH] dma-direct: Fix return value of dma_direct_supported Alexander Duyck 2018-10-04 11:25 ` Robin Murphy 2018-10-04 15:13 ` Alexander Duyck 2018-10-05 7:17 ` Christoph Hellwig 2018-12-13 19:45 ` Lendacky, Thomas 2018-12-13 19:58 ` Christoph Hellwig
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