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From: Qian Cai <cai@lca.pw>
To: Joerg Roedel <jroedel@suse.de>
Cc: iommu@lists.linux-foundation.org,
	Robin Murphy <robin.murphy@arm.com>,
	Christoph Hellwig <hch@lst.de>, Tom Murphy <murphyt7@tcd.ie>,
	linux-kernel@vger.kernel.org
Subject: Re: "Convert the AMD iommu driver to the dma-iommu api" is buggy
Date: Wed, 16 Oct 2019 12:11:27 -0400	[thread overview]
Message-ID: <1571242287.5937.66.camel@lca.pw> (raw)
In-Reply-To: <20191016160314.GH4695@suse.de>

On Wed, 2019-10-16 at 18:03 +0200, Joerg Roedel wrote:
> On Wed, Oct 16, 2019 at 11:53:33AM -0400, Qian Cai wrote:
> > On Wed, 2019-10-16 at 17:31 +0200, Joerg Roedel wrote:
> > The x86 one might just be a mistake.
> > 
> > diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
> > index ad05484d0c80..63c4b894751d 100644
> > --- a/drivers/iommu/amd_iommu.c
> > +++ b/drivers/iommu/amd_iommu.c
> > @@ -2542,7 +2542,7 @@ static int amd_iommu_map(struct iommu_domain *dom,
> > unsigned long iova,
> >         if (iommu_prot & IOMMU_WRITE)
> >                 prot |= IOMMU_PROT_IW;
> >  
> > -       ret = iommu_map_page(domain, iova, paddr, page_size, prot, GFP_KERNEL);
> > +       ret = iommu_map_page(domain, iova, paddr, page_size, prot, gfp);
> 
> Yeah, that is a bug, I spotted that too.
> 
> > @@ -1185,7 +1185,7 @@ static struct iommu_dma_msi_page
> > *iommu_dma_get_msi_page(struct device *dev,
> >         if (!iova)
> >                 goto out_free_page;
> >  
> > -       if (iommu_map(domain, iova, msi_addr, size, prot))
> > +       if (iommu_map_atomic(domain, iova, msi_addr, size, prot))
> >                 goto out_free_iova;
> 
> Not so sure this is a bug, this code is only about setting up MSIs on
> ARM. It probably doesn't need to be atomic.

The patch "iommu: Add gfp parameter to iommu_ops::map" does this. It could be
called from an atomic context as showed in the arm64 call traces,

+int iommu_map(struct iommu_domain *domain, unsigned long iova,
+             phys_addr_t paddr, size_t size, int prot)
+{
+       might_sleep();
+       return __iommu_map(domain, iova, paddr, size, prot, GFP_KERNEL);
+}
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

WARNING: multiple messages have this Message-ID (diff)
From: Qian Cai <cai@lca.pw>
To: Joerg Roedel <jroedel@suse.de>
Cc: Tom Murphy <murphyt7@tcd.ie>, Robin Murphy <robin.murphy@arm.com>,
	Christoph Hellwig <hch@lst.de>,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: "Convert the AMD iommu driver to the dma-iommu api" is buggy
Date: Wed, 16 Oct 2019 12:11:27 -0400	[thread overview]
Message-ID: <1571242287.5937.66.camel@lca.pw> (raw)
In-Reply-To: <20191016160314.GH4695@suse.de>

On Wed, 2019-10-16 at 18:03 +0200, Joerg Roedel wrote:
> On Wed, Oct 16, 2019 at 11:53:33AM -0400, Qian Cai wrote:
> > On Wed, 2019-10-16 at 17:31 +0200, Joerg Roedel wrote:
> > The x86 one might just be a mistake.
> > 
> > diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
> > index ad05484d0c80..63c4b894751d 100644
> > --- a/drivers/iommu/amd_iommu.c
> > +++ b/drivers/iommu/amd_iommu.c
> > @@ -2542,7 +2542,7 @@ static int amd_iommu_map(struct iommu_domain *dom,
> > unsigned long iova,
> >         if (iommu_prot & IOMMU_WRITE)
> >                 prot |= IOMMU_PROT_IW;
> >  
> > -       ret = iommu_map_page(domain, iova, paddr, page_size, prot, GFP_KERNEL);
> > +       ret = iommu_map_page(domain, iova, paddr, page_size, prot, gfp);
> 
> Yeah, that is a bug, I spotted that too.
> 
> > @@ -1185,7 +1185,7 @@ static struct iommu_dma_msi_page
> > *iommu_dma_get_msi_page(struct device *dev,
> >         if (!iova)
> >                 goto out_free_page;
> >  
> > -       if (iommu_map(domain, iova, msi_addr, size, prot))
> > +       if (iommu_map_atomic(domain, iova, msi_addr, size, prot))
> >                 goto out_free_iova;
> 
> Not so sure this is a bug, this code is only about setting up MSIs on
> ARM. It probably doesn't need to be atomic.

The patch "iommu: Add gfp parameter to iommu_ops::map" does this. It could be
called from an atomic context as showed in the arm64 call traces,

+int iommu_map(struct iommu_domain *domain, unsigned long iova,
+             phys_addr_t paddr, size_t size, int prot)
+{
+       might_sleep();
+       return __iommu_map(domain, iova, paddr, size, prot, GFP_KERNEL);
+}

  parent reply	other threads:[~2019-10-16 16:11 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-16 14:55 "Convert the AMD iommu driver to the dma-iommu api" is buggy Qian Cai
2019-10-16 14:55 ` Qian Cai
2019-10-16 14:59 ` Qian Cai
2019-10-16 14:59   ` Qian Cai
2019-10-16 15:31   ` Joerg Roedel
2019-10-16 15:31     ` Joerg Roedel
2019-10-16 15:53     ` Qian Cai
2019-10-16 15:53       ` Qian Cai
2019-10-16 16:03       ` Joerg Roedel
2019-10-16 16:03         ` Joerg Roedel
2019-10-16 16:09         ` Robin Murphy
2019-10-16 16:09           ` Robin Murphy
2019-10-16 16:36           ` Julien Grall
2019-10-16 16:36             ` Julien Grall
2019-10-16 16:11         ` Qian Cai [this message]
2019-10-16 16:11           ` Qian Cai
2019-10-16 16:26           ` Robin Murphy
2019-10-16 16:26             ` Robin Murphy
2019-10-16 15:44   ` Joerg Roedel
2019-10-16 15:44     ` Joerg Roedel
2019-10-17 14:39     ` Qian Cai
2019-10-17 14:39       ` Qian Cai
2019-10-18  9:39       ` Joerg Roedel
2019-10-18  9:39         ` Joerg Roedel

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