[PATCH] PCI: Relax ACS requirement for Intel RCiEP devices.

[PATCH] PCI: Relax ACS requirement for Intel RCiEP devices.

[Ashok Raj]

All Intel platforms guarantee that all root complex implementations
must send transactions up to IOMMU for address translations. Hence for
RCiEP devices that are Vendor ID Intel, can claim exception for lack of
ACS support.


3.16 Root-Complex Peer to Peer Considerations
When DMA remapping is enabled, peer-to-peer requests through the
Root-Complex must be handled
as follows:
• The input address in the request is translated (through first-level,
  second-level or nested translation) to a host physical address (HPA).
  The address decoding for peer addresses must be done only on the
  translated HPA. Hardware implementations are free to further limit
  peer-to-peer accesses to specific host physical address regions
  (or to completely disallow peer-forwarding of translated requests).
• Since address translation changes the contents (address field) of
  the PCI Express Transaction Layer Packet (TLP), for PCI Express
  peer-to-peer requests with ECRC, the Root-Complex hardware must use
  the new ECRC (re-computed with the translated address) if it
  decides to forward the TLP as a peer request.
• Root-ports, and multi-function root-complex integrated endpoints, may
  support additional peerto-peer control features by supporting PCI Express
  Access Control Services (ACS) capability. Refer to ACS capability in
  PCI Express specifications for details.

Since Linux didn't give special treatment to allow this exception, certain
RCiEP MFD devices are getting grouped in a single iommu group. This
doesn't permit a single device to be assigned to a guest for instance.

In one vendor system: Device 14.x were grouped in a single IOMMU group.

/sys/kernel/iommu_groups/5/devices/0000:00:14.0
/sys/kernel/iommu_groups/5/devices/0000:00:14.2
/sys/kernel/iommu_groups/5/devices/0000:00:14.3

After the patch:
/sys/kernel/iommu_groups/5/devices/0000:00:14.0
/sys/kernel/iommu_groups/5/devices/0000:00:14.2
/sys/kernel/iommu_groups/6/devices/0000:00:14.3 <<< new group

14.0 and 14.2 are integrated devices, but legacy end points.
Whereas 14.3 was a PCIe compliant RCiEP.

00:14.3 Network controller: Intel Corporation Device 9df0 (rev 30)
Capabilities: [40] Express (v2) Root Complex Integrated Endpoint, MSI 00

This permits assigning this device to a guest VM.

Fixes: f096c061f552 ("iommu: Rework iommu_group_get_for_pci_dev()")
Signed-off-by: Ashok Raj <ashok.raj@intel.com>
To: Joerg Roedel <joro@8bytes.org>
To: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-kernel@vger.kernel.org
Cc: iommu@lists.linux-foundation.org
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Darrel Goeddel <DGoeddel@forcepoint.com>
Cc: Mark Scott <mscott@forcepoint.com>,
Cc: Romil Sharma <rsharma@forcepoint.com>
Cc: Ashok Raj <ashok.raj@intel.com>
---
v2: Moved functionality from iommu to pci quirks - Alex Williamson

 drivers/pci/quirks.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 28c9a2409c50..63373ca0a3fe 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -4682,6 +4682,20 @@ static int pci_quirk_mf_endpoint_acs(struct pci_dev *dev, u16 acs_flags)
 		PCI_ACS_CR | PCI_ACS_UF | PCI_ACS_DT);
 }
 
+static int pci_quirk_rciep_acs(struct pci_dev *dev, u16 acs_flags)
+{
+	/*
+	 * RCiEP's are required to allow p2p only on translated addresses.
+	 * Refer to Intel VT-d specification Section 3.16 Root-Complex Peer
+	 * to Peer Considerations
+	 */
+	if (pci_pcie_type(dev) != PCI_EXP_TYPE_RC_END)
+		return -ENOTTY;
+
+	return pci_acs_ctrl_enabled(acs_flags,
+		PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF);
+}
+
 static int pci_quirk_brcm_acs(struct pci_dev *dev, u16 acs_flags)
 {
 	/*
@@ -4764,6 +4778,7 @@ static const struct pci_dev_acs_enabled {
 	/* I219 */
 	{ PCI_VENDOR_ID_INTEL, 0x15b7, pci_quirk_mf_endpoint_acs },
 	{ PCI_VENDOR_ID_INTEL, 0x15b8, pci_quirk_mf_endpoint_acs },
+	{ PCI_VENDOR_ID_INTEL, PCI_ANY_ID, pci_quirk_rciep_acs },
 	/* QCOM QDF2xxx root ports */
 	{ PCI_VENDOR_ID_QCOM, 0x0400, pci_quirk_qcom_rp_acs },
 	{ PCI_VENDOR_ID_QCOM, 0x0401, pci_quirk_qcom_rp_acs },
-- 
2.7.4

Re: [PATCH] PCI: Relax ACS requirement for Intel RCiEP devices.

[Alex Williamson]

On Thu, 28 May 2020 13:57:42 -0700
Ashok Raj <ashok.raj@intel.com> wrote:

> All Intel platforms guarantee that all root complex implementations
> must send transactions up to IOMMU for address translations. Hence for
> RCiEP devices that are Vendor ID Intel, can claim exception for lack of
> ACS support.
> 
> 
> 3.16 Root-Complex Peer to Peer Considerations
> When DMA remapping is enabled, peer-to-peer requests through the
> Root-Complex must be handled
> as follows:
> • The input address in the request is translated (through first-level,
>   second-level or nested translation) to a host physical address (HPA).
>   The address decoding for peer addresses must be done only on the
>   translated HPA. Hardware implementations are free to further limit
>   peer-to-peer accesses to specific host physical address regions
>   (or to completely disallow peer-forwarding of translated requests).
> • Since address translation changes the contents (address field) of
>   the PCI Express Transaction Layer Packet (TLP), for PCI Express
>   peer-to-peer requests with ECRC, the Root-Complex hardware must use
>   the new ECRC (re-computed with the translated address) if it
>   decides to forward the TLP as a peer request.
> • Root-ports, and multi-function root-complex integrated endpoints, may
>   support additional peerto-peer control features by supporting PCI Express
>   Access Control Services (ACS) capability. Refer to ACS capability in
>   PCI Express specifications for details.
> 
> Since Linux didn't give special treatment to allow this exception, certain
> RCiEP MFD devices are getting grouped in a single iommu group. This
> doesn't permit a single device to be assigned to a guest for instance.
> 
> In one vendor system: Device 14.x were grouped in a single IOMMU group.
> 
> /sys/kernel/iommu_groups/5/devices/0000:00:14.0
> /sys/kernel/iommu_groups/5/devices/0000:00:14.2
> /sys/kernel/iommu_groups/5/devices/0000:00:14.3
> 
> After the patch:
> /sys/kernel/iommu_groups/5/devices/0000:00:14.0
> /sys/kernel/iommu_groups/5/devices/0000:00:14.2
> /sys/kernel/iommu_groups/6/devices/0000:00:14.3 <<< new group
> 
> 14.0 and 14.2 are integrated devices, but legacy end points.
> Whereas 14.3 was a PCIe compliant RCiEP.
> 
> 00:14.3 Network controller: Intel Corporation Device 9df0 (rev 30)
> Capabilities: [40] Express (v2) Root Complex Integrated Endpoint, MSI 00
> 
> This permits assigning this device to a guest VM.
> 
> Fixes: f096c061f552 ("iommu: Rework iommu_group_get_for_pci_dev()")

I don't really understand this Fixes tag.  This seems like a feature,
not a fix.  If you want it in stable releases as a feature, request it
via Cc: stable@vger.kernel.org.  I'd drop that tag, that's my nit.
Otherwise:

Reviewed-by: Alex Williamson <alex.williamson@redhat.com>

> Signed-off-by: Ashok Raj <ashok.raj@intel.com>
> To: Joerg Roedel <joro@8bytes.org>
> To: Bjorn Helgaas <bhelgaas@google.com>
> Cc: linux-kernel@vger.kernel.org
> Cc: iommu@lists.linux-foundation.org
> Cc: Lu Baolu <baolu.lu@linux.intel.com>
> Cc: Alex Williamson <alex.williamson@redhat.com>
> Cc: Darrel Goeddel <DGoeddel@forcepoint.com>
> Cc: Mark Scott <mscott@forcepoint.com>,
> Cc: Romil Sharma <rsharma@forcepoint.com>
> Cc: Ashok Raj <ashok.raj@intel.com>
> ---
> v2: Moved functionality from iommu to pci quirks - Alex Williamson
> 
>  drivers/pci/quirks.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 28c9a2409c50..63373ca0a3fe 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -4682,6 +4682,20 @@ static int pci_quirk_mf_endpoint_acs(struct pci_dev *dev, u16 acs_flags)
>  		PCI_ACS_CR | PCI_ACS_UF | PCI_ACS_DT);
>  }
>  
> +static int pci_quirk_rciep_acs(struct pci_dev *dev, u16 acs_flags)
> +{
> +	/*
> +	 * RCiEP's are required to allow p2p only on translated addresses.
> +	 * Refer to Intel VT-d specification Section 3.16 Root-Complex Peer
> +	 * to Peer Considerations
> +	 */
> +	if (pci_pcie_type(dev) != PCI_EXP_TYPE_RC_END)
> +		return -ENOTTY;
> +
> +	return pci_acs_ctrl_enabled(acs_flags,
> +		PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF);
> +}
> +
>  static int pci_quirk_brcm_acs(struct pci_dev *dev, u16 acs_flags)
>  {
>  	/*
> @@ -4764,6 +4778,7 @@ static const struct pci_dev_acs_enabled {
>  	/* I219 */
>  	{ PCI_VENDOR_ID_INTEL, 0x15b7, pci_quirk_mf_endpoint_acs },
>  	{ PCI_VENDOR_ID_INTEL, 0x15b8, pci_quirk_mf_endpoint_acs },
> +	{ PCI_VENDOR_ID_INTEL, PCI_ANY_ID, pci_quirk_rciep_acs },
>  	/* QCOM QDF2xxx root ports */
>  	{ PCI_VENDOR_ID_QCOM, 0x0400, pci_quirk_qcom_rp_acs },
>  	{ PCI_VENDOR_ID_QCOM, 0x0401, pci_quirk_qcom_rp_acs },

Re: [PATCH] PCI: Relax ACS requirement for Intel RCiEP devices.

[Raj, Ashok]

On Thu, May 28, 2020 at 03:38:26PM -0600, Alex Williamson wrote:
> On Thu, 28 May 2020 13:57:42 -0700
> Ashok Raj <ashok.raj@intel.com> wrote:
> 
> > All Intel platforms guarantee that all root complex implementations
> > must send transactions up to IOMMU for address translations. Hence for
> > RCiEP devices that are Vendor ID Intel, can claim exception for lack of
> > ACS support.
> > 
> > 
> > 3.16 Root-Complex Peer to Peer Considerations
> > When DMA remapping is enabled, peer-to-peer requests through the
> > Root-Complex must be handled
> > as follows:
> > • The input address in the request is translated (through first-level,
> >   second-level or nested translation) to a host physical address (HPA).
> >   The address decoding for peer addresses must be done only on the
> >   translated HPA. Hardware implementations are free to further limit
> >   peer-to-peer accesses to specific host physical address regions
> >   (or to completely disallow peer-forwarding of translated requests).
> > • Since address translation changes the contents (address field) of
> >   the PCI Express Transaction Layer Packet (TLP), for PCI Express
> >   peer-to-peer requests with ECRC, the Root-Complex hardware must use
> >   the new ECRC (re-computed with the translated address) if it
> >   decides to forward the TLP as a peer request.
> > • Root-ports, and multi-function root-complex integrated endpoints, may
> >   support additional peerto-peer control features by supporting PCI Express
> >   Access Control Services (ACS) capability. Refer to ACS capability in
> >   PCI Express specifications for details.
> > 
> > Since Linux didn't give special treatment to allow this exception, certain
> > RCiEP MFD devices are getting grouped in a single iommu group. This
> > doesn't permit a single device to be assigned to a guest for instance.
> > 
> > In one vendor system: Device 14.x were grouped in a single IOMMU group.
> > 
> > /sys/kernel/iommu_groups/5/devices/0000:00:14.0
> > /sys/kernel/iommu_groups/5/devices/0000:00:14.2
> > /sys/kernel/iommu_groups/5/devices/0000:00:14.3
> > 
> > After the patch:
> > /sys/kernel/iommu_groups/5/devices/0000:00:14.0
> > /sys/kernel/iommu_groups/5/devices/0000:00:14.2
> > /sys/kernel/iommu_groups/6/devices/0000:00:14.3 <<< new group
> > 
> > 14.0 and 14.2 are integrated devices, but legacy end points.
> > Whereas 14.3 was a PCIe compliant RCiEP.
> > 
> > 00:14.3 Network controller: Intel Corporation Device 9df0 (rev 30)
> > Capabilities: [40] Express (v2) Root Complex Integrated Endpoint, MSI 00
> > 
> > This permits assigning this device to a guest VM.
> > 
> > Fixes: f096c061f552 ("iommu: Rework iommu_group_get_for_pci_dev()")
> 
> I don't really understand this Fixes tag.  This seems like a feature,
> not a fix.  If you want it in stable releases as a feature, request it
> via Cc: stable@vger.kernel.org.  I'd drop that tag, that's my nit.
> Otherwise:

Yes, i should have Cced Stable instead. 

Bjorn: Can you massage this in? or i can resend with Alex's Reviewed-by +
adding stable in cc list.

> 
> Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
> 
> > Signed-off-by: Ashok Raj <ashok.raj@intel.com>
> > To: Joerg Roedel <joro@8bytes.org>
> > To: Bjorn Helgaas <bhelgaas@google.com>
> > Cc: linux-kernel@vger.kernel.org
> > Cc: iommu@lists.linux-foundation.org
> > Cc: Lu Baolu <baolu.lu@linux.intel.com>
> > Cc: Alex Williamson <alex.williamson@redhat.com>
> > Cc: Darrel Goeddel <DGoeddel@forcepoint.com>
> > Cc: Mark Scott <mscott@forcepoint.com>,
> > Cc: Romil Sharma <rsharma@forcepoint.com>
> > Cc: Ashok Raj <ashok.raj@intel.com>
> > ---
> > v2: Moved functionality from iommu to pci quirks - Alex Williamson
> > 
> >  drivers/pci/quirks.c | 15 +++++++++++++++
> >  1 file changed, 15 insertions(+)
> > 
> > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> > index 28c9a2409c50..63373ca0a3fe 100644
> > --- a/drivers/pci/quirks.c
> > +++ b/drivers/pci/quirks.c
> > @@ -4682,6 +4682,20 @@ static int pci_quirk_mf_endpoint_acs(struct pci_dev *dev, u16 acs_flags)
> >  		PCI_ACS_CR | PCI_ACS_UF | PCI_ACS_DT);
> >  }
> >  
> > +static int pci_quirk_rciep_acs(struct pci_dev *dev, u16 acs_flags)
> > +{
> > +	/*
> > +	 * RCiEP's are required to allow p2p only on translated addresses.
> > +	 * Refer to Intel VT-d specification Section 3.16 Root-Complex Peer
> > +	 * to Peer Considerations
> > +	 */
> > +	if (pci_pcie_type(dev) != PCI_EXP_TYPE_RC_END)
> > +		return -ENOTTY;
> > +
> > +	return pci_acs_ctrl_enabled(acs_flags,
> > +		PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF);
> > +}
> > +
> >  static int pci_quirk_brcm_acs(struct pci_dev *dev, u16 acs_flags)
> >  {
> >  	/*
> > @@ -4764,6 +4778,7 @@ static const struct pci_dev_acs_enabled {
> >  	/* I219 */
> >  	{ PCI_VENDOR_ID_INTEL, 0x15b7, pci_quirk_mf_endpoint_acs },
> >  	{ PCI_VENDOR_ID_INTEL, 0x15b8, pci_quirk_mf_endpoint_acs },
> > +	{ PCI_VENDOR_ID_INTEL, PCI_ANY_ID, pci_quirk_rciep_acs },
> >  	/* QCOM QDF2xxx root ports */
> >  	{ PCI_VENDOR_ID_QCOM, 0x0400, pci_quirk_qcom_rp_acs },
> >  	{ PCI_VENDOR_ID_QCOM, 0x0401, pci_quirk_qcom_rp_acs },
> 

Re: Re: [PATCH] PCI: Relax ACS requirement for Intel RCiEP devices.

[Darrel Goeddel]

On 5/28/20 4:38 PM, Alex Williamson wrote:
> On Thu, 28 May 2020 13:57:42 -0700
> Ashok Raj <ashok.raj@intel.com> wrote:
> 
>> All Intel platforms guarantee that all root complex implementations
>> must send transactions up to IOMMU for address translations. Hence for
>> RCiEP devices that are Vendor ID Intel, can claim exception for lack of
>> ACS support.
>>
>>
>> 3.16 Root-Complex Peer to Peer Considerations
>> When DMA remapping is enabled, peer-to-peer requests through the
>> Root-Complex must be handled
>> as follows:
>> • The input address in the request is translated (through first-level,
>>    second-level or nested translation) to a host physical address (HPA).
>>    The address decoding for peer addresses must be done only on the
>>    translated HPA. Hardware implementations are free to further limit
>>    peer-to-peer accesses to specific host physical address regions
>>    (or to completely disallow peer-forwarding of translated requests).
>> • Since address translation changes the contents (address field) of
>>    the PCI Express Transaction Layer Packet (TLP), for PCI Express
>>    peer-to-peer requests with ECRC, the Root-Complex hardware must use
>>    the new ECRC (re-computed with the translated address) if it
>>    decides to forward the TLP as a peer request.
>> • Root-ports, and multi-function root-complex integrated endpoints, may
>>    support additional peerto-peer control features by supporting PCI Express
>>    Access Control Services (ACS) capability. Refer to ACS capability in
>>    PCI Express specifications for details.
>>
>> Since Linux didn't give special treatment to allow this exception, certain
>> RCiEP MFD devices are getting grouped in a single iommu group. This
>> doesn't permit a single device to be assigned to a guest for instance.
>>
>> In one vendor system: Device 14.x were grouped in a single IOMMU group.
>>
>> /sys/kernel/iommu_groups/5/devices/0000:00:14.0
>> /sys/kernel/iommu_groups/5/devices/0000:00:14.2
>> /sys/kernel/iommu_groups/5/devices/0000:00:14.3
>>
>> After the patch:
>> /sys/kernel/iommu_groups/5/devices/0000:00:14.0
>> /sys/kernel/iommu_groups/5/devices/0000:00:14.2
>> /sys/kernel/iommu_groups/6/devices/0000:00:14.3 <<< new group
>>
>> 14.0 and 14.2 are integrated devices, but legacy end points.
>> Whereas 14.3 was a PCIe compliant RCiEP.
>>
>> 00:14.3 Network controller: Intel Corporation Device 9df0 (rev 30)
>> Capabilities: [40] Express (v2) Root Complex Integrated Endpoint, MSI 00
>>
>> This permits assigning this device to a guest VM.
>>
>> Fixes: f096c061f552 ("iommu: Rework iommu_group_get_for_pci_dev()")
> 
> I don't really understand this Fixes tag.  This seems like a feature,
> not a fix.  If you want it in stable releases as a feature, request it
> via Cc: stable@vger.kernel.org.  I'd drop that tag, that's my nit.
> Otherwise:
> 
> Reviewed-by: Alex Williamson <alex.williamson@redhat.com>

I have tested this patch with 5.6.14 as well as a slightly modified
version (without pci_acs_ctrl_enabled()) in a 3.10 enterprise linux
kernel.

Tested-by: Darrel Goeddel <dgoeddel@forcepoint.com>

>> Signed-off-by: Ashok Raj <ashok.raj@intel.com>
>> To: Joerg Roedel <joro@8bytes.org>
>> To: Bjorn Helgaas <bhelgaas@google.com>
>> Cc: linux-kernel@vger.kernel.org
>> Cc: iommu@lists.linux-foundation.org
>> Cc: Lu Baolu <baolu.lu@linux.intel.com>
>> Cc: Alex Williamson <alex.williamson@redhat.com>
>> Cc: Darrel Goeddel <DGoeddel@forcepoint.com>
>> Cc: Mark Scott <mscott@forcepoint.com>,
>> Cc: Romil Sharma <rsharma@forcepoint.com>
>> Cc: Ashok Raj <ashok.raj@intel.com>
>> ---
>> v2: Moved functionality from iommu to pci quirks - Alex Williamson
>>
>>   drivers/pci/quirks.c | 15 +++++++++++++++
>>   1 file changed, 15 insertions(+)
>>
>> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
>> index 28c9a2409c50..63373ca0a3fe 100644
>> --- a/drivers/pci/quirks.c
>> +++ b/drivers/pci/quirks.c
>> @@ -4682,6 +4682,20 @@ static int pci_quirk_mf_endpoint_acs(struct pci_dev *dev, u16 acs_flags)
>>   		PCI_ACS_CR | PCI_ACS_UF | PCI_ACS_DT);
>>   }
>>   
>> +static int pci_quirk_rciep_acs(struct pci_dev *dev, u16 acs_flags)
>> +{
>> +	/*
>> +	 * RCiEP's are required to allow p2p only on translated addresses.
>> +	 * Refer to Intel VT-d specification Section 3.16 Root-Complex Peer
>> +	 * to Peer Considerations
>> +	 */
>> +	if (pci_pcie_type(dev) != PCI_EXP_TYPE_RC_END)
>> +		return -ENOTTY;
>> +
>> +	return pci_acs_ctrl_enabled(acs_flags,
>> +		PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF);
>> +}
>> +
>>   static int pci_quirk_brcm_acs(struct pci_dev *dev, u16 acs_flags)
>>   {
>>   	/*
>> @@ -4764,6 +4778,7 @@ static const struct pci_dev_acs_enabled {
>>   	/* I219 */
>>   	{ PCI_VENDOR_ID_INTEL, 0x15b7, pci_quirk_mf_endpoint_acs },
>>   	{ PCI_VENDOR_ID_INTEL, 0x15b8, pci_quirk_mf_endpoint_acs },
>> +	{ PCI_VENDOR_ID_INTEL, PCI_ANY_ID, pci_quirk_rciep_acs },
>>   	/* QCOM QDF2xxx root ports */
>>   	{ PCI_VENDOR_ID_QCOM, 0x0400, pci_quirk_qcom_rp_acs },
>>   	{ PCI_VENDOR_ID_QCOM, 0x0401, pci_quirk_qcom_rp_acs },
> 

Re: [PATCH] PCI: Relax ACS requirement for Intel RCiEP devices.

[Bjorn Helgaas]

On Thu, May 28, 2020 at 01:57:42PM -0700, Ashok Raj wrote:
> All Intel platforms guarantee that all root complex implementations
> must send transactions up to IOMMU for address translations. Hence for
> RCiEP devices that are Vendor ID Intel, can claim exception for lack of
> ACS support.
> 
> 
> 3.16 Root-Complex Peer to Peer Considerations
> When DMA remapping is enabled, peer-to-peer requests through the
> Root-Complex must be handled
> as follows:
> • The input address in the request is translated (through first-level,
>   second-level or nested translation) to a host physical address (HPA).
>   The address decoding for peer addresses must be done only on the
>   translated HPA. Hardware implementations are free to further limit
>   peer-to-peer accesses to specific host physical address regions
>   (or to completely disallow peer-forwarding of translated requests).
> • Since address translation changes the contents (address field) of
>   the PCI Express Transaction Layer Packet (TLP), for PCI Express
>   peer-to-peer requests with ECRC, the Root-Complex hardware must use
>   the new ECRC (re-computed with the translated address) if it
>   decides to forward the TLP as a peer request.
> • Root-ports, and multi-function root-complex integrated endpoints, may
>   support additional peerto-peer control features by supporting PCI Express
>   Access Control Services (ACS) capability. Refer to ACS capability in
>   PCI Express specifications for details.
> 
> Since Linux didn't give special treatment to allow this exception, certain
> RCiEP MFD devices are getting grouped in a single iommu group. This
> doesn't permit a single device to be assigned to a guest for instance.
> 
> In one vendor system: Device 14.x were grouped in a single IOMMU group.
> 
> /sys/kernel/iommu_groups/5/devices/0000:00:14.0
> /sys/kernel/iommu_groups/5/devices/0000:00:14.2
> /sys/kernel/iommu_groups/5/devices/0000:00:14.3
> 
> After the patch:
> /sys/kernel/iommu_groups/5/devices/0000:00:14.0
> /sys/kernel/iommu_groups/5/devices/0000:00:14.2
> /sys/kernel/iommu_groups/6/devices/0000:00:14.3 <<< new group
> 
> 14.0 and 14.2 are integrated devices, but legacy end points.
> Whereas 14.3 was a PCIe compliant RCiEP.
> 
> 00:14.3 Network controller: Intel Corporation Device 9df0 (rev 30)
> Capabilities: [40] Express (v2) Root Complex Integrated Endpoint, MSI 00
> 
> This permits assigning this device to a guest VM.
> 
> Fixes: f096c061f552 ("iommu: Rework iommu_group_get_for_pci_dev()")
> Signed-off-by: Ashok Raj <ashok.raj@intel.com>
> To: Joerg Roedel <joro@8bytes.org>
> To: Bjorn Helgaas <bhelgaas@google.com>
> Cc: linux-kernel@vger.kernel.org
> Cc: iommu@lists.linux-foundation.org
> Cc: Lu Baolu <baolu.lu@linux.intel.com>
> Cc: Alex Williamson <alex.williamson@redhat.com>
> Cc: Darrel Goeddel <DGoeddel@forcepoint.com>
> Cc: Mark Scott <mscott@forcepoint.com>,
> Cc: Romil Sharma <rsharma@forcepoint.com>
> Cc: Ashok Raj <ashok.raj@intel.com>

Tentatively applied to pci/virtualization for v5.8, thanks!

The spec says this handling must apply "when DMA remapping is
enabled".  The patch does not check whether DMA remapping is enabled.

Is there any case where DMA remapping is *not* enabled, and we rely on
this patch to tell us whether the device is isolated?  It sounds like
it may give the wrong answer in such a case?

Can you confirm that I don't need to worry about this?  

> ---
> v2: Moved functionality from iommu to pci quirks - Alex Williamson
> 
>  drivers/pci/quirks.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 28c9a2409c50..63373ca0a3fe 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -4682,6 +4682,20 @@ static int pci_quirk_mf_endpoint_acs(struct pci_dev *dev, u16 acs_flags)
>  		PCI_ACS_CR | PCI_ACS_UF | PCI_ACS_DT);
>  }
>  
> +static int pci_quirk_rciep_acs(struct pci_dev *dev, u16 acs_flags)
> +{
> +	/*
> +	 * RCiEP's are required to allow p2p only on translated addresses.
> +	 * Refer to Intel VT-d specification Section 3.16 Root-Complex Peer
> +	 * to Peer Considerations
> +	 */
> +	if (pci_pcie_type(dev) != PCI_EXP_TYPE_RC_END)
> +		return -ENOTTY;
> +
> +	return pci_acs_ctrl_enabled(acs_flags,
> +		PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF);
> +}
> +
>  static int pci_quirk_brcm_acs(struct pci_dev *dev, u16 acs_flags)
>  {
>  	/*
> @@ -4764,6 +4778,7 @@ static const struct pci_dev_acs_enabled {
>  	/* I219 */
>  	{ PCI_VENDOR_ID_INTEL, 0x15b7, pci_quirk_mf_endpoint_acs },
>  	{ PCI_VENDOR_ID_INTEL, 0x15b8, pci_quirk_mf_endpoint_acs },
> +	{ PCI_VENDOR_ID_INTEL, PCI_ANY_ID, pci_quirk_rciep_acs },
>  	/* QCOM QDF2xxx root ports */
>  	{ PCI_VENDOR_ID_QCOM, 0x0400, pci_quirk_qcom_rp_acs },
>  	{ PCI_VENDOR_ID_QCOM, 0x0401, pci_quirk_qcom_rp_acs },
> -- 
> 2.7.4
> 

Re: [PATCH] PCI: Relax ACS requirement for Intel RCiEP devices.

[Raj, Ashok]

On Mon, Jun 01, 2020 at 04:25:19PM -0500, Bjorn Helgaas wrote:
> On Thu, May 28, 2020 at 01:57:42PM -0700, Ashok Raj wrote:
> > All Intel platforms guarantee that all root complex implementations
> > must send transactions up to IOMMU for address translations. Hence for
> > RCiEP devices that are Vendor ID Intel, can claim exception for lack of
> > ACS support.
> > 
> > 
> > 3.16 Root-Complex Peer to Peer Considerations
> > When DMA remapping is enabled, peer-to-peer requests through the
> > Root-Complex must be handled
> > as follows:
> > • The input address in the request is translated (through first-level,
> >   second-level or nested translation) to a host physical address (HPA).
> >   The address decoding for peer addresses must be done only on the
> >   translated HPA. Hardware implementations are free to further limit
> >   peer-to-peer accesses to specific host physical address regions
> >   (or to completely disallow peer-forwarding of translated requests).
> > • Since address translation changes the contents (address field) of
> >   the PCI Express Transaction Layer Packet (TLP), for PCI Express
> >   peer-to-peer requests with ECRC, the Root-Complex hardware must use
> >   the new ECRC (re-computed with the translated address) if it
> >   decides to forward the TLP as a peer request.
> > • Root-ports, and multi-function root-complex integrated endpoints, may
> >   support additional peerto-peer control features by supporting PCI Express
> >   Access Control Services (ACS) capability. Refer to ACS capability in
> >   PCI Express specifications for details.
> > 
> > Since Linux didn't give special treatment to allow this exception, certain
> > RCiEP MFD devices are getting grouped in a single iommu group. This
> > doesn't permit a single device to be assigned to a guest for instance.
> > 
> > In one vendor system: Device 14.x were grouped in a single IOMMU group.
> > 
> > /sys/kernel/iommu_groups/5/devices/0000:00:14.0
> > /sys/kernel/iommu_groups/5/devices/0000:00:14.2
> > /sys/kernel/iommu_groups/5/devices/0000:00:14.3
> > 
> > After the patch:
> > /sys/kernel/iommu_groups/5/devices/0000:00:14.0
> > /sys/kernel/iommu_groups/5/devices/0000:00:14.2
> > /sys/kernel/iommu_groups/6/devices/0000:00:14.3 <<< new group
> > 
> > 14.0 and 14.2 are integrated devices, but legacy end points.
> > Whereas 14.3 was a PCIe compliant RCiEP.
> > 
> > 00:14.3 Network controller: Intel Corporation Device 9df0 (rev 30)
> > Capabilities: [40] Express (v2) Root Complex Integrated Endpoint, MSI 00
> > 
> > This permits assigning this device to a guest VM.
> > 
> > Fixes: f096c061f552 ("iommu: Rework iommu_group_get_for_pci_dev()")
> > Signed-off-by: Ashok Raj <ashok.raj@intel.com>
> > To: Joerg Roedel <joro@8bytes.org>
> > To: Bjorn Helgaas <bhelgaas@google.com>
> > Cc: linux-kernel@vger.kernel.org
> > Cc: iommu@lists.linux-foundation.org
> > Cc: Lu Baolu <baolu.lu@linux.intel.com>
> > Cc: Alex Williamson <alex.williamson@redhat.com>
> > Cc: Darrel Goeddel <DGoeddel@forcepoint.com>
> > Cc: Mark Scott <mscott@forcepoint.com>,
> > Cc: Romil Sharma <rsharma@forcepoint.com>
> > Cc: Ashok Raj <ashok.raj@intel.com>
> 
> Tentatively applied to pci/virtualization for v5.8, thanks!
> 
> The spec says this handling must apply "when DMA remapping is
> enabled".  The patch does not check whether DMA remapping is enabled.
> 
> Is there any case where DMA remapping is *not* enabled, and we rely on
> this patch to tell us whether the device is isolated?  It sounds like
> it may give the wrong answer in such a case?
> 
> Can you confirm that I don't need to worry about this?  

I think all of this makes sense only when DMA remapping is enabled.
Otherwise there is no enforcement for isolation. 

Cheers,
Ashok

Re: [PATCH] PCI: Relax ACS requirement for Intel RCiEP devices.

[Alex Williamson]

On Mon, 1 Jun 2020 14:40:23 -0700
"Raj, Ashok" <ashok.raj@intel.com> wrote:

> On Mon, Jun 01, 2020 at 04:25:19PM -0500, Bjorn Helgaas wrote:
> > On Thu, May 28, 2020 at 01:57:42PM -0700, Ashok Raj wrote:  
> > > All Intel platforms guarantee that all root complex implementations
> > > must send transactions up to IOMMU for address translations. Hence for
> > > RCiEP devices that are Vendor ID Intel, can claim exception for lack of
> > > ACS support.
> > > 
> > > 
> > > 3.16 Root-Complex Peer to Peer Considerations
> > > When DMA remapping is enabled, peer-to-peer requests through the
> > > Root-Complex must be handled
> > > as follows:
> > > • The input address in the request is translated (through first-level,
> > >   second-level or nested translation) to a host physical address (HPA).
> > >   The address decoding for peer addresses must be done only on the
> > >   translated HPA. Hardware implementations are free to further limit
> > >   peer-to-peer accesses to specific host physical address regions
> > >   (or to completely disallow peer-forwarding of translated requests).
> > > • Since address translation changes the contents (address field) of
> > >   the PCI Express Transaction Layer Packet (TLP), for PCI Express
> > >   peer-to-peer requests with ECRC, the Root-Complex hardware must use
> > >   the new ECRC (re-computed with the translated address) if it
> > >   decides to forward the TLP as a peer request.
> > > • Root-ports, and multi-function root-complex integrated endpoints, may
> > >   support additional peerto-peer control features by supporting PCI Express
> > >   Access Control Services (ACS) capability. Refer to ACS capability in
> > >   PCI Express specifications for details.
> > > 
> > > Since Linux didn't give special treatment to allow this exception, certain
> > > RCiEP MFD devices are getting grouped in a single iommu group. This
> > > doesn't permit a single device to be assigned to a guest for instance.
> > > 
> > > In one vendor system: Device 14.x were grouped in a single IOMMU group.
> > > 
> > > /sys/kernel/iommu_groups/5/devices/0000:00:14.0
> > > /sys/kernel/iommu_groups/5/devices/0000:00:14.2
> > > /sys/kernel/iommu_groups/5/devices/0000:00:14.3
> > > 
> > > After the patch:
> > > /sys/kernel/iommu_groups/5/devices/0000:00:14.0
> > > /sys/kernel/iommu_groups/5/devices/0000:00:14.2
> > > /sys/kernel/iommu_groups/6/devices/0000:00:14.3 <<< new group
> > > 
> > > 14.0 and 14.2 are integrated devices, but legacy end points.
> > > Whereas 14.3 was a PCIe compliant RCiEP.
> > > 
> > > 00:14.3 Network controller: Intel Corporation Device 9df0 (rev 30)
> > > Capabilities: [40] Express (v2) Root Complex Integrated Endpoint, MSI 00
> > > 
> > > This permits assigning this device to a guest VM.
> > > 
> > > Fixes: f096c061f552 ("iommu: Rework iommu_group_get_for_pci_dev()")
> > > Signed-off-by: Ashok Raj <ashok.raj@intel.com>
> > > To: Joerg Roedel <joro@8bytes.org>
> > > To: Bjorn Helgaas <bhelgaas@google.com>
> > > Cc: linux-kernel@vger.kernel.org
> > > Cc: iommu@lists.linux-foundation.org
> > > Cc: Lu Baolu <baolu.lu@linux.intel.com>
> > > Cc: Alex Williamson <alex.williamson@redhat.com>
> > > Cc: Darrel Goeddel <DGoeddel@forcepoint.com>
> > > Cc: Mark Scott <mscott@forcepoint.com>,
> > > Cc: Romil Sharma <rsharma@forcepoint.com>
> > > Cc: Ashok Raj <ashok.raj@intel.com>  
> > 
> > Tentatively applied to pci/virtualization for v5.8, thanks!
> > 
> > The spec says this handling must apply "when DMA remapping is
> > enabled".  The patch does not check whether DMA remapping is enabled.
> > 
> > Is there any case where DMA remapping is *not* enabled, and we rely on
> > this patch to tell us whether the device is isolated?  It sounds like
> > it may give the wrong answer in such a case?
> > 
> > Can you confirm that I don't need to worry about this?    
> 
> I think all of this makes sense only when DMA remapping is enabled.
> Otherwise there is no enforcement for isolation. 

Yep, without an IOMMU all devices operate in the same IOVA space and we
have no isolation.  We only enable ACS when an IOMMU driver requests it
and it's only used by IOMMU code to determine IOMMU grouping of
devices.  Thanks,

Alex

Re: [PATCH] PCI: Relax ACS requirement for Intel RCiEP devices.

[Bjorn Helgaas]

On Mon, Jun 01, 2020 at 03:56:55PM -0600, Alex Williamson wrote:
> On Mon, 1 Jun 2020 14:40:23 -0700
> "Raj, Ashok" <ashok.raj@intel.com> wrote:
> 
> > On Mon, Jun 01, 2020 at 04:25:19PM -0500, Bjorn Helgaas wrote:
> > > On Thu, May 28, 2020 at 01:57:42PM -0700, Ashok Raj wrote:  
> > > > All Intel platforms guarantee that all root complex implementations
> > > > must send transactions up to IOMMU for address translations. Hence for
> > > > RCiEP devices that are Vendor ID Intel, can claim exception for lack of
> > > > ACS support.
> > > > 
> > > > 
> > > > 3.16 Root-Complex Peer to Peer Considerations
> > > > When DMA remapping is enabled, peer-to-peer requests through the
> > > > Root-Complex must be handled
> > > > as follows:
> > > > • The input address in the request is translated (through first-level,
> > > >   second-level or nested translation) to a host physical address (HPA).
> > > >   The address decoding for peer addresses must be done only on the
> > > >   translated HPA. Hardware implementations are free to further limit
> > > >   peer-to-peer accesses to specific host physical address regions
> > > >   (or to completely disallow peer-forwarding of translated requests).
> > > > • Since address translation changes the contents (address field) of
> > > >   the PCI Express Transaction Layer Packet (TLP), for PCI Express
> > > >   peer-to-peer requests with ECRC, the Root-Complex hardware must use
> > > >   the new ECRC (re-computed with the translated address) if it
> > > >   decides to forward the TLP as a peer request.
> > > > • Root-ports, and multi-function root-complex integrated endpoints, may
> > > >   support additional peerto-peer control features by supporting PCI Express
> > > >   Access Control Services (ACS) capability. Refer to ACS capability in
> > > >   PCI Express specifications for details.
> > > > 
> > > > Since Linux didn't give special treatment to allow this exception, certain
> > > > RCiEP MFD devices are getting grouped in a single iommu group. This
> > > > doesn't permit a single device to be assigned to a guest for instance.
> > > > 
> > > > In one vendor system: Device 14.x were grouped in a single IOMMU group.
> > > > 
> > > > /sys/kernel/iommu_groups/5/devices/0000:00:14.0
> > > > /sys/kernel/iommu_groups/5/devices/0000:00:14.2
> > > > /sys/kernel/iommu_groups/5/devices/0000:00:14.3
> > > > 
> > > > After the patch:
> > > > /sys/kernel/iommu_groups/5/devices/0000:00:14.0
> > > > /sys/kernel/iommu_groups/5/devices/0000:00:14.2
> > > > /sys/kernel/iommu_groups/6/devices/0000:00:14.3 <<< new group
> > > > 
> > > > 14.0 and 14.2 are integrated devices, but legacy end points.
> > > > Whereas 14.3 was a PCIe compliant RCiEP.
> > > > 
> > > > 00:14.3 Network controller: Intel Corporation Device 9df0 (rev 30)
> > > > Capabilities: [40] Express (v2) Root Complex Integrated Endpoint, MSI 00
> > > > 
> > > > This permits assigning this device to a guest VM.
> > > > 
> > > > Fixes: f096c061f552 ("iommu: Rework iommu_group_get_for_pci_dev()")
> > > > Signed-off-by: Ashok Raj <ashok.raj@intel.com>
> > > > To: Joerg Roedel <joro@8bytes.org>
> > > > To: Bjorn Helgaas <bhelgaas@google.com>
> > > > Cc: linux-kernel@vger.kernel.org
> > > > Cc: iommu@lists.linux-foundation.org
> > > > Cc: Lu Baolu <baolu.lu@linux.intel.com>
> > > > Cc: Alex Williamson <alex.williamson@redhat.com>
> > > > Cc: Darrel Goeddel <DGoeddel@forcepoint.com>
> > > > Cc: Mark Scott <mscott@forcepoint.com>,
> > > > Cc: Romil Sharma <rsharma@forcepoint.com>
> > > > Cc: Ashok Raj <ashok.raj@intel.com>  
> > > 
> > > Tentatively applied to pci/virtualization for v5.8, thanks!
> > > 
> > > The spec says this handling must apply "when DMA remapping is
> > > enabled".  The patch does not check whether DMA remapping is enabled.
> > > 
> > > Is there any case where DMA remapping is *not* enabled, and we rely on
> > > this patch to tell us whether the device is isolated?  It sounds like
> > > it may give the wrong answer in such a case?
> > > 
> > > Can you confirm that I don't need to worry about this?    
> > 
> > I think all of this makes sense only when DMA remapping is enabled.
> > Otherwise there is no enforcement for isolation. 
> 
> Yep, without an IOMMU all devices operate in the same IOVA space and we
> have no isolation.  We only enable ACS when an IOMMU driver requests it
> and it's only used by IOMMU code to determine IOMMU grouping of
> devices.  Thanks,

Thanks, Ashok and Alex.  I wish it were more obvious from the code,
but I am reassured.

I also added a stable tag to help get this backported.