From: will.deacon@arm•com (Will Deacon)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 2/2] iommu/arm-smmu: add support for iova_to_phys through ATS1PR
Date: Fri, 26 Sep 2014 11:24:30 +0100 [thread overview]
Message-ID: <20140926102430.GF22293@arm.com> (raw)
In-Reply-To: <vnkw38bgkbal.fsf@mitchelh-linux.qualcomm.com>
On Wed, Sep 24, 2014 at 09:34:26PM +0100, Mitchel Humpherys wrote:
> On Wed, Sep 24 2014 at 09:37:12 AM, Will Deacon <will.deacon@arm•com> wrote:
> > On Wed, Sep 24, 2014 at 02:12:00AM +0100, Mitchel Humpherys wrote:
> >> On Mon, Sep 22 2014 at 08:26:14 AM, Will Deacon <will.deacon@arm•com> wrote:
> >> > On Thu, Sep 11, 2014 at 07:30:44PM +0100, Mitchel Humpherys wrote:
> >> >> + return arm_smmu_iova_to_phys_soft(domain, iova);
> >> >> + }
> >> >> +
> >> >> + phys = readl_relaxed(cb_base + ARM_SMMU_CB_PAR_LO);
> >> >> + phys |= ((u64) readl_relaxed(cb_base + ARM_SMMU_CB_PAR_HI)) << 32;
> >> >> +
> >> >> + if (phys & CB_PAR_F) {
> >> >> + dev_err(dev, "translation fault on %s!\n", dev_name(dev));
> >> >> + dev_err(dev, "PAR = 0x%llx\n", phys);
> >> >> + }
> >> >> + phys = (phys & 0xFFFFFFF000ULL) | (iova & 0x00000FFF);
> >> >
> >> > How does this work for 64k pages?
> >>
> >> So at the moment we're always assuming that we're using v7/v8 long
> >> descriptor format, right? All I see in the spec (14.5.15 SMMU_CBn_PAR)
> >> is that bits[47:12]=>PA[47:12]... Or am I missing something completely?
> >
> > I think you've got 64k pages confused with the short-descriptor format.
> >
> > When we use 64k pages with long descriptors, you're masked off bits 15-12 of
> > the iova above, so you'll have a hole in the physical address afaict.
>
> Even with long descriptors the spec says bits 15-12 should come from
> CB_PAR... It makes no mention of reinterpreting those bits depending on
> the programmed page granule. The only thing I can conclude from the
> spec is that hardware should be smart enough to do the right thing with
> bits 15-12 when the page granule is 64k. Although even if hardware is
> smart enough I guess CB_PAR[15:12] should be the same as iova[15:12] for
> the 64k case?
Yeah, fair enough, the code you have should work correctly then.
Unfortunately, I don't have any suitable hardware on which to test it.
Will
next prev parent reply other threads:[~2014-09-26 10:24 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-11 18:30 [PATCH 0/2] iommu/arm-smmu: hard iova_to_phys Mitchel Humpherys
2014-09-11 18:30 ` [PATCH 1/2] iopoll: Introduce memory-mapped IO polling macros Mitchel Humpherys
2014-09-22 15:23 ` Will Deacon
2014-09-11 18:30 ` [PATCH 2/2] iommu/arm-smmu: add support for iova_to_phys through ATS1PR Mitchel Humpherys
2014-09-22 15:26 ` Will Deacon
2014-09-24 1:12 ` Mitchel Humpherys
2014-09-24 16:37 ` Will Deacon
2014-09-24 20:34 ` Mitchel Humpherys
2014-09-26 10:24 ` Will Deacon [this message]
2014-09-26 17:20 ` Mitchel Humpherys
2014-09-11 18:53 ` [PATCH 0/2] iommu/arm-smmu: hard iova_to_phys Mitchel Humpherys
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