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

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

[Wei Chen]

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(-)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 94b6821..30ea899 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -2686,6 +2686,8 @@ static int __init arm_smmu_init(void)
        if (ret)
                return ret;

+       pci_request_acs();
+
        return bus_set_iommu(&pci_bus_type, &arm_smmu_ops);
 }

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 9345a3f..ab365ec 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -2096,8 +2096,10 @@ static int __init arm_smmu_init(void)
 #endif

 #ifdef CONFIG_PCI
-       if (!iommu_present(&pci_bus_type))
+       if (!iommu_present(&pci_bus_type)) {
+               pci_request_acs();
                bus_set_iommu(&pci_bus_type, &arm_smmu_ops);
+       }
 #endif

        return 0;

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

[Robin Murphy]

On 13/06/16 10:20, 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-5wv7dgnIgG8@public.gmane.org>

Makes sense to me:

Reviewed-by: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>

p.s. The confidential disclaimer is a good way to get patches ignored 
here on the lists - please check with Steve about getting set up on the 
appropriate SMTP server.

Robin.

> ---
>   drivers/iommu/arm-smmu-v3.c | 2 ++
>   drivers/iommu/arm-smmu.c    | 4 +++-
>   2 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
> index 94b6821..30ea899 100644
> --- a/drivers/iommu/arm-smmu-v3.c
> +++ b/drivers/iommu/arm-smmu-v3.c
> @@ -2686,6 +2686,8 @@ static int __init arm_smmu_init(void)
>          if (ret)
>                  return ret;
>
> +       pci_request_acs();
> +
>          return bus_set_iommu(&pci_bus_type, &arm_smmu_ops);
>   }
>
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index 9345a3f..ab365ec 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -2096,8 +2096,10 @@ static int __init arm_smmu_init(void)
>   #endif
>
>   #ifdef CONFIG_PCI
> -       if (!iommu_present(&pci_bus_type))
> +       if (!iommu_present(&pci_bus_type)) {
> +               pci_request_acs();
>                  bus_set_iommu(&pci_bus_type, &arm_smmu_ops);
> +       }
>   #endif
>
>          return 0;
> --
> 2.7.4
>
> IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.
>
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>

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

[Auger Eric]

Wei,
Le 13/06/2016 à 13:18, Robin Murphy a écrit :
> On 13/06/16 10:20, 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.
nit: I would add ", when they get probed."

Besides Reviewed-by: Eric Auger <eric.auger-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

Best Regards

Eric
>>
>> Signed-off-by: Wei Chen <Wei.Chen-5wv7dgnIgG8@public.gmane.org>
> 
> Makes sense to me:
> 
> Reviewed-by: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>
> 
> p.s. The confidential disclaimer is a good way to get patches ignored
> here on the lists - please check with Steve about getting set up on the
> appropriate SMTP server.
> 
> Robin.
> 
>> ---
>>   drivers/iommu/arm-smmu-v3.c | 2 ++
>>   drivers/iommu/arm-smmu.c    | 4 +++-
>>   2 files changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
>> index 94b6821..30ea899 100644
>> --- a/drivers/iommu/arm-smmu-v3.c
>> +++ b/drivers/iommu/arm-smmu-v3.c
>> @@ -2686,6 +2686,8 @@ static int __init arm_smmu_init(void)
>>          if (ret)
>>                  return ret;
>>
>> +       pci_request_acs();
>> +
>>          return bus_set_iommu(&pci_bus_type, &arm_smmu_ops);
>>   }
>>
>> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
>> index 9345a3f..ab365ec 100644
>> --- a/drivers/iommu/arm-smmu.c
>> +++ b/drivers/iommu/arm-smmu.c
>> @@ -2096,8 +2096,10 @@ static int __init arm_smmu_init(void)
>>   #endif
>>
>>   #ifdef CONFIG_PCI
>> -       if (!iommu_present(&pci_bus_type))
>> +       if (!iommu_present(&pci_bus_type)) {
>> +               pci_request_acs();
>>                  bus_set_iommu(&pci_bus_type, &arm_smmu_ops);
>> +       }
>>   #endif
>>
>>          return 0;
>> -- 
>> 2.7.4
>>
>> IMPORTANT NOTICE: The contents of this email and any attachments are
>> confidential and may also be privileged. If you are not the intended
>> recipient, please notify the sender immediately and do not disclose
>> the contents to any other person, use it for any purpose, or store or
>> copy the information in any medium. Thank you.
>>
>> _______________________________________________
>> iommu mailing list
>> iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
>> https://lists.linuxfoundation.org/mailman/listinfo/iommu
>>
> 
> _______________________________________________
> iommu mailing list
> iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu

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

[Will Deacon]

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-5wv7dgnIgG8@public.gmane.org>
> ---
>  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

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

[Wei Chen]

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

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

[Will Deacon]

On Tue, Jun 14, 2016 at 11:11:36AM +0800, Wei Chen wrote:
> On 13 June 2016 at 20:45, Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org> 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-5wv7dgnIgG8@public.gmane.org>
> >> ---
> >>  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

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

[Wei Chen]

> -----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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