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Re: [PATCH] iommu/arm-smmu: request pcie devices to enable ACS

Started byWill Deacon <will.deacon@arm.com>
First post2016-06-13 14:50 +0200
Last post2016-06-14 12:10 +0200
Articles 4 — 3 participants

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  Re: [PATCH] iommu/arm-smmu: request pcie devices to enable ACS Will Deacon <will.deacon@arm.com> - 2016-06-13 14:50 +0200
    Re: [PATCH] iommu/arm-smmu: request pcie devices to enable ACS Wei Chen <wei.chen@linaro.org> - 2016-06-14 05:20 +0200
      Re: [PATCH] iommu/arm-smmu: request pcie devices to enable ACS Will Deacon <will.deacon@arm.com> - 2016-06-14 11:00 +0200
        RE: [PATCH] iommu/arm-smmu: request pcie devices to enable ACS Wei Chen <Wei.Chen@arm.com> - 2016-06-14 12:10 +0200

#1420792 — Re: [PATCH] iommu/arm-smmu: request pcie devices to enable ACS

FromWill Deacon <will.deacon@arm.com>
Date2016-06-13 14:50 +0200
SubjectRe: [PATCH] iommu/arm-smmu: request pcie devices to enable ACS
Message-ID<rJztw-6l4-35@gated-at.bofh.it>
On Mon, Jun 13, 2016 at 05:20:17PM +0800, Wei Chen wrote:
> The PCIe ACS capability will affect the layout of iommu groups.
> Generally speaking, if the path from root port to the PCIe device
> is ACS enabled, the iommu will create a single iommu group for this
> PCIe device. If all PCIe devices on the path are ACS enabled then
> Linux can determine this path is ACS enabled.
> 
> Linux use two PCIe configuration registers to determine the ACS
> status of PCIe devices:
> ACS Capability Register and ACS Control Register.
> 
> The first register is used to check the implementation of ACS function
> of a PCIe device, the second register is used to check the enable status
> of ACS function. If one PCIe device has implemented and enabled the ACS
> function then Linux will determine this PCIe device enabled ACS.
> 
> From the Chapter:6.12 of PCI Express Base Specification Revision 3.1a,
> we can find that when a PCIe device implements ACS function, the enable
> status is set to disabled by default and can be enabled by ACS-aware
> software.
> 
> ACS will affect the iommu groups topology, so, the iommu driver is
> ACS-aware software. This patch adds a call to pci_request_acs() to the
> arm-smmu driver to enable the ACS function in PCIe devices that support
> it.
> 
> Signed-off-by: Wei Chen <Wei.Chen@arm.com>
> ---
>  drivers/iommu/arm-smmu-v3.c | 2 ++
>  drivers/iommu/arm-smmu.c    | 4 +++-
>  2 files changed, 5 insertions(+), 1 deletion(-)

Thanks, queued for 4.8 w/ Robin and Eric's reviewed-by tags and the minor
commit wording change.

Will

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#1421556

FromWei Chen <wei.chen@linaro.org>
Date2016-06-14 05:20 +0200
Message-ID<rJN3s-7p0-9@gated-at.bofh.it>
In reply to#1420792
On 13 June 2016 at 20:45, Will Deacon <will.deacon@arm.com> wrote:
> On Mon, Jun 13, 2016 at 05:20:17PM +0800, Wei Chen wrote:
>> The PCIe ACS capability will affect the layout of iommu groups.
>> Generally speaking, if the path from root port to the PCIe device
>> is ACS enabled, the iommu will create a single iommu group for this
>> PCIe device. If all PCIe devices on the path are ACS enabled then
>> Linux can determine this path is ACS enabled.
>>
>> Linux use two PCIe configuration registers to determine the ACS
>> status of PCIe devices:
>> ACS Capability Register and ACS Control Register.
>>
>> The first register is used to check the implementation of ACS function
>> of a PCIe device, the second register is used to check the enable status
>> of ACS function. If one PCIe device has implemented and enabled the ACS
>> function then Linux will determine this PCIe device enabled ACS.
>>
>> From the Chapter:6.12 of PCI Express Base Specification Revision 3.1a,
>> we can find that when a PCIe device implements ACS function, the enable
>> status is set to disabled by default and can be enabled by ACS-aware
>> software.
>>
>> ACS will affect the iommu groups topology, so, the iommu driver is
>> ACS-aware software. This patch adds a call to pci_request_acs() to the
>> arm-smmu driver to enable the ACS function in PCIe devices that support
>> it.
>>
>> Signed-off-by: Wei Chen <Wei.Chen@arm.com>
>> ---
>>  drivers/iommu/arm-smmu-v3.c | 2 ++
>>  drivers/iommu/arm-smmu.c    | 4 +++-
>>  2 files changed, 5 insertions(+), 1 deletion(-)
>
> Thanks, queued for 4.8 w/ Robin and Eric's reviewed-by tags and the minor
> commit wording change.
>

Thanks, I will post a v2 patch to include above changes.

> Will
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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#1421679

FromWill Deacon <will.deacon@arm.com>
Date2016-06-14 11:00 +0200
Message-ID<rJSmt-2tW-3@gated-at.bofh.it>
In reply to#1421556
On Tue, Jun 14, 2016 at 11:11:36AM +0800, Wei Chen wrote:
> On 13 June 2016 at 20:45, Will Deacon <will.deacon@arm.com> wrote:
> > On Mon, Jun 13, 2016 at 05:20:17PM +0800, Wei Chen wrote:
> >> The PCIe ACS capability will affect the layout of iommu groups.
> >> Generally speaking, if the path from root port to the PCIe device
> >> is ACS enabled, the iommu will create a single iommu group for this
> >> PCIe device. If all PCIe devices on the path are ACS enabled then
> >> Linux can determine this path is ACS enabled.
> >>
> >> Linux use two PCIe configuration registers to determine the ACS
> >> status of PCIe devices:
> >> ACS Capability Register and ACS Control Register.
> >>
> >> The first register is used to check the implementation of ACS function
> >> of a PCIe device, the second register is used to check the enable status
> >> of ACS function. If one PCIe device has implemented and enabled the ACS
> >> function then Linux will determine this PCIe device enabled ACS.
> >>
> >> From the Chapter:6.12 of PCI Express Base Specification Revision 3.1a,
> >> we can find that when a PCIe device implements ACS function, the enable
> >> status is set to disabled by default and can be enabled by ACS-aware
> >> software.
> >>
> >> ACS will affect the iommu groups topology, so, the iommu driver is
> >> ACS-aware software. This patch adds a call to pci_request_acs() to the
> >> arm-smmu driver to enable the ACS function in PCIe devices that support
> >> it.
> >>
> >> Signed-off-by: Wei Chen <Wei.Chen@arm.com>
> >> ---
> >>  drivers/iommu/arm-smmu-v3.c | 2 ++
> >>  drivers/iommu/arm-smmu.c    | 4 +++-
> >>  2 files changed, 5 insertions(+), 1 deletion(-)
> >
> > Thanks, queued for 4.8 w/ Robin and Eric's reviewed-by tags and the minor
> > commit wording change.
> >
> 
> Thanks, I will post a v2 patch to include above changes.

:/ As above, I've already queued this.

Will

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#1421737

FromWei Chen <Wei.Chen@arm.com>
Date2016-06-14 12:10 +0200
Message-ID<rJTse-3r2-27@gated-at.bofh.it>
In reply to#1421679

> -----Original Message-----
> From: Will Deacon [mailto:will.deacon@arm.com]
> Sent: 2016年6月14日 16:56
> To: Wei Chen
> Cc: Wei Chen; Steve Capper; joro@8bytes.org; linux-kernel@vger.kernel.org;
> iommu@lists.linux-foundation.org; Robin Murphy; linux-arm-
> kernel@lists.infradead.org
> Subject: Re: [PATCH] iommu/arm-smmu: request pcie devices to enable ACS
>
> On Tue, Jun 14, 2016 at 11:11:36AM +0800, Wei Chen wrote:
> > On 13 June 2016 at 20:45, Will Deacon <will.deacon@arm.com> wrote:
> > > On Mon, Jun 13, 2016 at 05:20:17PM +0800, Wei Chen wrote:
> > >> The PCIe ACS capability will affect the layout of iommu groups.
> > >> Generally speaking, if the path from root port to the PCIe device
> > >> is ACS enabled, the iommu will create a single iommu group for this
> > >> PCIe device. If all PCIe devices on the path are ACS enabled then
> > >> Linux can determine this path is ACS enabled.
> > >>
> > >> Linux use two PCIe configuration registers to determine the ACS
> > >> status of PCIe devices:
> > >> ACS Capability Register and ACS Control Register.
> > >>
> > >> The first register is used to check the implementation of ACS
> > >> function of a PCIe device, the second register is used to check the
> > >> enable status of ACS function. If one PCIe device has implemented
> > >> and enabled the ACS function then Linux will determine this PCIe
> device enabled ACS.
> > >>
> > >> From the Chapter:6.12 of PCI Express Base Specification Revision
> > >> 3.1a, we can find that when a PCIe device implements ACS function,
> > >> the enable status is set to disabled by default and can be enabled
> > >> by ACS-aware software.
> > >>
> > >> ACS will affect the iommu groups topology, so, the iommu driver is
> > >> ACS-aware software. This patch adds a call to pci_request_acs() to
> > >> the arm-smmu driver to enable the ACS function in PCIe devices that
> > >> support it.
> > >>
> > >> Signed-off-by: Wei Chen <Wei.Chen@arm.com>
> > >> ---
> > >>  drivers/iommu/arm-smmu-v3.c | 2 ++
> > >>  drivers/iommu/arm-smmu.c    | 4 +++-
> > >>  2 files changed, 5 insertions(+), 1 deletion(-)
> > >
> > > Thanks, queued for 4.8 w/ Robin and Eric's reviewed-by tags and the
> > > minor commit wording change.
> > >
> >
> > Thanks, I will post a v2 patch to include above changes.
>
> :/ As above, I've already queued this.
Oh, thank you :)
>
> Will

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