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Date: Thu, 4 May 2017 13:32:07 +0000
From: Bharat Bhushan <bharat.bhushan@....com>
To: "shankerd@...eaurora.org" <shankerd@...eaurora.org>,
Robin Murphy <robin.murphy@....com>,
Nate Watterson <nwatters@...eaurora.org>,
"Joerg Roedel" <joro@...tes.org>,
"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] iommu/dma: Setup iova_domain granule for IOMMU_DMA_MSI
cookies
Hi Robin,
I faced same issue on our platform and debugged to get the root cause of the issue. Also fixed in somewhat similar way, cleared iova_off and not change size for if cookie->type is IOMMU_DMA_MSI_COOKIE. Anyways that was not as good as below changes.
While just now I saw this was already discussed and solved. Should have looked earlier to save time, but the debugging was some learning experience 😊
I have tested your below change and it works fine on NXP platform.
Thanks
-Bharat
> -----Original Message-----
> From: iommu-bounces@...ts.linux-foundation.org [mailto:iommu-
> bounces@...ts.linux-foundation.org] On Behalf Of Shanker Donthineni
> Sent: Thursday, April 13, 2017 8:00 PM
> To: Robin Murphy <robin.murphy@....com>; Nate Watterson
> <nwatters@...eaurora.org>; Joerg Roedel <joro@...tes.org>;
> iommu@...ts.linux-foundation.org; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH] iommu/dma: Setup iova_domain granule for
> IOMMU_DMA_MSI cookies
>
> Hi Robin,
>
> I tested your changes and the device pass-through feature works fine on
> QDF2400 server platform. Maybe Nate comments on the patch contents but
> it fixes the problem.
>
>
> @@ -317,13 +317,13 @@ static void iommu_dma_free_iova(struct
> iommu_dma_cookie *cookie,
> dma_addr_t iova, size_t size) {
> struct iova_domain *iovad = &cookie->iovad;
> - unsigned long shift = iova_shift(iovad);
>
> /* The MSI case is only ever cleaning up its most recent allocation */
> if (cookie->type == IOMMU_DMA_MSI_COOKIE)
> cookie->msi_iova -= size;
> else
> - free_iova_fast(iovad, iova >> shift, size >> shift);
> + free_iova_fast(iovad, iova_pfn(iovad, iova),
> + size >> iova_shift(iovad));
> }
>
> static void __iommu_dma_unmap(struct iommu_domain *domain,
> dma_addr_t dma_addr, @@ -538,11 +538,14 @@ static dma_addr_t
> __iommu_dma_map(struct device *dev, phys_addr_t phys, {
> struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
> struct iommu_dma_cookie *cookie = domain->iova_cookie;
> - struct iova_domain *iovad = &cookie->iovad;
> - size_t iova_off = iova_offset(iovad, phys);
> + size_t iova_off = 0;
> dma_addr_t iova;
>
> - size = iova_align(iovad, size + iova_off);
> + if (cookie->type == IOMMU_DMA_IOVA_COOKIE) {
> + iova_off = iova_offset(&cookie->iovad, phys);
> + size = iova_align(&cookie->iovad, size + iova_off);
> + }
>
>
> On 04/13/2017 06:21 AM, Robin Murphy wrote:
> > Hi Nate,
> >
> > On 13/04/17 09:55, Nate Watterson wrote:
> >> Currently, the __iommu_dma_{map/free} functions call
> >> iova_{offset/align} making them unsuitable for use with iommu_domains
> >> having an IOMMU_DMA_MSI cookie since the cookie's iova_domain
> member, iovad, is uninitialized.
> >>
> >> Now that iommu_dma_get_msi_page() calls __iommu_dma_map()
> regardless
> >> of cookie type, failures are being seen when mapping MSI target
> >> addresses for devices attached to UNMANAGED domains. To work
> around
> >> this issue, the iova_domain granule for IOMMU_DMA_MSI cookies is
> >> initialized to the value returned by cookie_msi_granule().
> > Oh bum. Thanks for the report.
> >
> > However, I really don't like bodging around it with deliberate
> > undefined behaviour. Fixing things properly doesn't seem too hard:
> >
> > ----->8-----
> > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> > index 8348f366ddd1..62618e77bedc 100644
> > --- a/drivers/iommu/dma-iommu.c
> > +++ b/drivers/iommu/dma-iommu.c
> > @@ -396,13 +396,13 @@ static void iommu_dma_free_iova(struct
> > iommu_dma_cookie *cookie,
> > dma_addr_t iova, size_t size) {
> > struct iova_domain *iovad = &cookie->iovad;
> > - unsigned long shift = iova_shift(iovad);
> >
> > /* The MSI case is only ever cleaning up its most recent
> > allocation */
> > if (cookie->type == IOMMU_DMA_MSI_COOKIE)
> > cookie->msi_iova -= size;
> > else
> > - free_iova_fast(iovad, iova >> shift, size >> shift);
> > + free_iova_fast(iovad, iova_pfn(iovad, iova),
> > + size >> iova_shift(iovad));
> > }
> >
> > static void __iommu_dma_unmap(struct iommu_domain *domain,
> dma_addr_t
> > dma_addr, @@ -617,11 +617,14 @@ static dma_addr_t
> > __iommu_dma_map(struct device *dev, phys_addr_t phys, {
> > struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
> > struct iommu_dma_cookie *cookie = domain->iova_cookie;
> > - struct iova_domain *iovad = &cookie->iovad;
> > - size_t iova_off = iova_offset(iovad, phys);
> > + size_t iova_off = 0;
> > dma_addr_t iova;
> >
> > - size = iova_align(iovad, size + iova_off);
> > + if (cookie->type == IOMMU_DMA_IOVA_COOKIE) {
> > + iova_off = iova_offset(&cookie->iovad, phys);
> > + size = iova_align(&cookie->iovad, size + iova_off);
> > + }
> > +
> > iova = iommu_dma_alloc_iova(domain, size, dma_get_mask(dev),
> dev);
> > if (!iova)
> > return DMA_ERROR_CODE;
> > -----8<-----
> >
> > Untested, and you'll probably want to double-check it anyway given
> > that the original oversight was mine in the first place ;)
> >
> > Robin.
> >
> >> Fixes: a44e6657585b ("iommu/dma: Clean up MSI IOVA allocation")
> >> Signed-off-by: Nate Watterson <nwatters@...eaurora.org>
> >> ---
> >> drivers/iommu/dma-iommu.c | 10 ++++++++++
> >> 1 file changed, 10 insertions(+)
> >>
> >> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> >> index 8348f366..d7b0816 100644
> >> --- a/drivers/iommu/dma-iommu.c
> >> +++ b/drivers/iommu/dma-iommu.c
> >> @@ -127,6 +127,16 @@ int iommu_get_msi_cookie(struct
> iommu_domain
> >> *domain, dma_addr_t base)
> >>
> >> cookie->msi_iova = base;
> >> domain->iova_cookie = cookie;
> >> +
> >> + /*
> >> + * Setup granule for compatibility with __iommu_dma_{alloc/free}
> and
> >> + * add a compile time check to ensure that writing granule won't
> >> + * clobber msi_iova.
> >> + */
> >> + cookie->iovad.granule = cookie_msi_granule(cookie);
> >> + BUILD_BUG_ON(offsetof(struct iova_domain, granule) <
> >> + sizeof(cookie->msi_iova));
> >> +
> >> return 0;
> >> }
> >> EXPORT_SYMBOL(iommu_get_msi_cookie);
> >>
>
> --
> Shanker Donthineni
> Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm
> Technologies, Inc.
> Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux
> Foundation Collaborative Project.
>
> _______________________________________________
> iommu mailing list
> iommu@...ts.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu
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