Re: [PATCH v10 13/15] PCI/AER: Forward RCH downstream port-detected errors to the CXL.mem dev handler

2023-09-26 Thread Dan Williams
Terry Bowman wrote:
> Hi Dan,
> 
> On 8/31/23 15:35, Dan Williams wrote:
> > Terry Bowman wrote:
> >> From: Robert Richter 
> >>
> >> In Restricted CXL Device (RCD) mode a CXL device is exposed as an
> >> RCiEP, but CXL downstream and upstream ports are not enumerated and
> >> not visible in the PCIe hierarchy. [1] Protocol and link errors from
> >> these non-enumerated ports are signaled as internal AER errors, either
> >> Uncorrectable Internal Error (UIE) or Corrected Internal Errors (CIE)
> >> via an RCEC.
> >>
> >> Restricted CXL host (RCH) downstream port-detected errors have the
> >> Requester ID of the RCEC set in the RCEC's AER Error Source ID
> >> register. A CXL handler must then inspect the error status in various
> >> CXL registers residing in the dport's component register space (CXL
> >> RAS capability) or the dport's RCRB (PCIe AER extended
> >> capability). [2]
> >>
> >> Errors showing up in the RCEC's error handler must be handled and
> >> connected to the CXL subsystem. Implement this by forwarding the error
> >> to all CXL devices below the RCEC. Since the entire CXL device is
> >> controlled only using PCIe Configuration Space of device 0, function
> >> 0, only pass it there [3]. The error handling is limited to currently
> >> supported devices with the Memory Device class code set (CXL Type 3
> >> Device, PCI_CLASS_MEMORY_CXL, 502h), handle downstream port errors in
> >> the device's cxl_pci driver. Support for other CXL Device Types
> >> (e.g. a CXL.cache Device) can be added later.
> >>
> >> To handle downstream port errors in addition to errors directed to the
> >> CXL endpoint device, a handler must also inspect the CXL RAS and PCIe
> >> AER capabilities of the CXL downstream port the device is connected
> >> to.
> >>
> >> Since CXL downstream port errors are signaled using internal errors,
> >> the handler requires those errors to be unmasked. This is subject of a
> >> follow-on patch.
> >>
> >> The reason for choosing this implementation is that the AER service
> >> driver claims the RCEC device, but does not allow it to register a
> >> custom specific handler to support CXL. Connecting the RCEC hard-wired
> >> with a CXL handler does not work, as the CXL subsystem might not be
> >> present all the time. The alternative to add an implementation to the
> >> portdrv to allow the registration of a custom RCEC error handler isn't
> >> worth doing it as CXL would be its only user. Instead, just check for
> >> an CXL RCEC and pass it down to the connected CXL device's error
> >> handler. With this approach the code can entirely be implemented in
> >> the PCIe AER driver and is independent of the CXL subsystem. The CXL
> >> driver only provides the handler.
> >>
> >> [1] CXL 3.0 spec: 9.11.8 CXL Devices Attached to an RCH
> >> [2] CXL 3.0 spec, 12.2.1.1 RCH Downstream Port-detected Errors
> >> [3] CXL 3.0 spec, 8.1.3 PCIe DVSEC for CXL Devices
> >>
> >> Co-developed-by: Terry Bowman 
> >> Signed-off-by: Terry Bowman 
> >> Signed-off-by: Robert Richter 
> >> Cc: "Oliver O'Halloran" 
> >> Cc: Bjorn Helgaas 
> >> Cc: linuxppc-dev@lists.ozlabs.org
> >> Cc: linux-...@vger.kernel.org
> >> Acked-by: Bjorn Helgaas 
> >> Reviewed-by: Jonathan Cameron 
> >> Reviewed-by: Dave Jiang 
> >> ---
> >>  drivers/pci/pcie/Kconfig | 12 +
> >>  drivers/pci/pcie/aer.c   | 96 +++-
> >>  2 files changed, 106 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/pci/pcie/Kconfig b/drivers/pci/pcie/Kconfig
> >> index 228652a59f27..4f0e70fafe2d 100644
> >> --- a/drivers/pci/pcie/Kconfig
> >> +++ b/drivers/pci/pcie/Kconfig
> >> @@ -49,6 +49,18 @@ config PCIEAER_INJECT
> >>  gotten from:
> >> 
> >> https://git.kernel.org/cgit/linux/kernel/git/gong.chen/aer-inject.git/
> >>  
> >> +config PCIEAER_CXL
> >> +  bool "PCI Express CXL RAS support for Restricted Hosts (RCH)"
> > 
> > Why the "for Restricted Hosts (RCH)" clarification? I am seeing nothing
> > that prevents this from working with RCECs on VH topologies.
> > 
> 
> The same option can be used in VH mode. Will remove the RCH reference.
> 
> > 
> >> +  default y
> > 
> > Minor, but I think "default PCIEAER" makes it slightly clearer that CXL
> > error handling comes along for the ride with PCIE AER.
> >
> 
> We found Kconfig entries do not typically list a dependancy and the default 
> to be the same. We prefer to leave as 'default y'. If you want we can make 
> your requested change. 

The tie breaker would be to follow whatever the local precedent is.
Indeed, it looks like "depends with default y" is consistent with other
drivers/pci/pcie/Kconfig entries. So I retract my comment.

> 
> >> +  depends on PCIEAER && CXL_PCI
> >> +  help
> >> +Enables error handling of downstream ports of a CXL host
> >> +that is operating in RCD mode (Restricted CXL Host, RCH).
> >> +The downstream port reports AER errors to a given RCEC.
> >> +Errors are handled by the CXL memory device driver.
> >> +

Re: [PATCH v10 13/15] PCI/AER: Forward RCH downstream port-detected errors to the CXL.mem dev handler

2023-09-20 Thread Terry Bowman
Hi Dan,

I adde danothe comment below.

On 9/19/23 15:58, Terry Bowman wrote:
> Hi Dan,
> 
> On 8/31/23 15:35, Dan Williams wrote:
>> Terry Bowman wrote:
>>> From: Robert Richter 
>>>
>>> In Restricted CXL Device (RCD) mode a CXL device is exposed as an
>>> RCiEP, but CXL downstream and upstream ports are not enumerated and
>>> not visible in the PCIe hierarchy. [1] Protocol and link errors from
>>> these non-enumerated ports are signaled as internal AER errors, either
>>> Uncorrectable Internal Error (UIE) or Corrected Internal Errors (CIE)
>>> via an RCEC.
>>>
>>> Restricted CXL host (RCH) downstream port-detected errors have the
>>> Requester ID of the RCEC set in the RCEC's AER Error Source ID
>>> register. A CXL handler must then inspect the error status in various
>>> CXL registers residing in the dport's component register space (CXL
>>> RAS capability) or the dport's RCRB (PCIe AER extended
>>> capability). [2]
>>>
>>> Errors showing up in the RCEC's error handler must be handled and
>>> connected to the CXL subsystem. Implement this by forwarding the error
>>> to all CXL devices below the RCEC. Since the entire CXL device is
>>> controlled only using PCIe Configuration Space of device 0, function
>>> 0, only pass it there [3]. The error handling is limited to currently
>>> supported devices with the Memory Device class code set (CXL Type 3
>>> Device, PCI_CLASS_MEMORY_CXL, 502h), handle downstream port errors in
>>> the device's cxl_pci driver. Support for other CXL Device Types
>>> (e.g. a CXL.cache Device) can be added later.
>>>
>>> To handle downstream port errors in addition to errors directed to the
>>> CXL endpoint device, a handler must also inspect the CXL RAS and PCIe
>>> AER capabilities of the CXL downstream port the device is connected
>>> to.
>>>
>>> Since CXL downstream port errors are signaled using internal errors,
>>> the handler requires those errors to be unmasked. This is subject of a
>>> follow-on patch.
>>>
>>> The reason for choosing this implementation is that the AER service
>>> driver claims the RCEC device, but does not allow it to register a
>>> custom specific handler to support CXL. Connecting the RCEC hard-wired
>>> with a CXL handler does not work, as the CXL subsystem might not be
>>> present all the time. The alternative to add an implementation to the
>>> portdrv to allow the registration of a custom RCEC error handler isn't
>>> worth doing it as CXL would be its only user. Instead, just check for
>>> an CXL RCEC and pass it down to the connected CXL device's error
>>> handler. With this approach the code can entirely be implemented in
>>> the PCIe AER driver and is independent of the CXL subsystem. The CXL
>>> driver only provides the handler.
>>>
>>> [1] CXL 3.0 spec: 9.11.8 CXL Devices Attached to an RCH
>>> [2] CXL 3.0 spec, 12.2.1.1 RCH Downstream Port-detected Errors
>>> [3] CXL 3.0 spec, 8.1.3 PCIe DVSEC for CXL Devices
>>>
>>> Co-developed-by: Terry Bowman 
>>> Signed-off-by: Terry Bowman 
>>> Signed-off-by: Robert Richter 
>>> Cc: "Oliver O'Halloran" 
>>> Cc: Bjorn Helgaas 
>>> Cc: linuxppc-dev@lists.ozlabs.org
>>> Cc: linux-...@vger.kernel.org
>>> Acked-by: Bjorn Helgaas 
>>> Reviewed-by: Jonathan Cameron 
>>> Reviewed-by: Dave Jiang 
>>> ---
>>>  drivers/pci/pcie/Kconfig | 12 +
>>>  drivers/pci/pcie/aer.c   | 96 +++-
>>>  2 files changed, 106 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/pci/pcie/Kconfig b/drivers/pci/pcie/Kconfig
>>> index 228652a59f27..4f0e70fafe2d 100644
>>> --- a/drivers/pci/pcie/Kconfig
>>> +++ b/drivers/pci/pcie/Kconfig
>>> @@ -49,6 +49,18 @@ config PCIEAER_INJECT
>>>   gotten from:
>>>  
>>> https://git.kernel.org/cgit/linux/kernel/git/gong.chen/aer-inject.git/
>>>  
>>> +config PCIEAER_CXL
>>> +   bool "PCI Express CXL RAS support for Restricted Hosts (RCH)"
>>
>> Why the "for Restricted Hosts (RCH)" clarification? I am seeing nothing
>> that prevents this from working with RCECs on VH topologies.
>>
> 
> The same option can be used in VH mode. Will remove the RCH reference.
> 
>>
>>> +   default y
>>
>> Minor, but I think "default PCIEAER" makes it slightly clearer that CXL
>> error handling comes along for the ride with PCIE AER.
>>
> 
> We found Kconfig entries do not typically list a dependancy and the default 
> to be the same. We prefer to leave as 'default y'. If you want we can make 
> your requested change. 
> 
>>> +   depends on PCIEAER && CXL_PCI
>>> +   help
>>> + Enables error handling of downstream ports of a CXL host
>>> + that is operating in RCD mode (Restricted CXL Host, RCH).
>>> + The downstream port reports AER errors to a given RCEC.
>>> + Errors are handled by the CXL memory device driver.
>>> +
>>> + If unsure, say Y.
>>> +
>>>  #
>>>  # PCI Express ECRC
>>>  #
>>> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
>>> index d3344fcf1f79..c354ca5e8f2b 100644
>>> --- a/drivers/pci/pcie/aer.c
>>> +++ 

Re: [PATCH v10 13/15] PCI/AER: Forward RCH downstream port-detected errors to the CXL.mem dev handler

2023-09-19 Thread Terry Bowman
Hi Dan,

On 8/31/23 15:35, Dan Williams wrote:
> Terry Bowman wrote:
>> From: Robert Richter 
>>
>> In Restricted CXL Device (RCD) mode a CXL device is exposed as an
>> RCiEP, but CXL downstream and upstream ports are not enumerated and
>> not visible in the PCIe hierarchy. [1] Protocol and link errors from
>> these non-enumerated ports are signaled as internal AER errors, either
>> Uncorrectable Internal Error (UIE) or Corrected Internal Errors (CIE)
>> via an RCEC.
>>
>> Restricted CXL host (RCH) downstream port-detected errors have the
>> Requester ID of the RCEC set in the RCEC's AER Error Source ID
>> register. A CXL handler must then inspect the error status in various
>> CXL registers residing in the dport's component register space (CXL
>> RAS capability) or the dport's RCRB (PCIe AER extended
>> capability). [2]
>>
>> Errors showing up in the RCEC's error handler must be handled and
>> connected to the CXL subsystem. Implement this by forwarding the error
>> to all CXL devices below the RCEC. Since the entire CXL device is
>> controlled only using PCIe Configuration Space of device 0, function
>> 0, only pass it there [3]. The error handling is limited to currently
>> supported devices with the Memory Device class code set (CXL Type 3
>> Device, PCI_CLASS_MEMORY_CXL, 502h), handle downstream port errors in
>> the device's cxl_pci driver. Support for other CXL Device Types
>> (e.g. a CXL.cache Device) can be added later.
>>
>> To handle downstream port errors in addition to errors directed to the
>> CXL endpoint device, a handler must also inspect the CXL RAS and PCIe
>> AER capabilities of the CXL downstream port the device is connected
>> to.
>>
>> Since CXL downstream port errors are signaled using internal errors,
>> the handler requires those errors to be unmasked. This is subject of a
>> follow-on patch.
>>
>> The reason for choosing this implementation is that the AER service
>> driver claims the RCEC device, but does not allow it to register a
>> custom specific handler to support CXL. Connecting the RCEC hard-wired
>> with a CXL handler does not work, as the CXL subsystem might not be
>> present all the time. The alternative to add an implementation to the
>> portdrv to allow the registration of a custom RCEC error handler isn't
>> worth doing it as CXL would be its only user. Instead, just check for
>> an CXL RCEC and pass it down to the connected CXL device's error
>> handler. With this approach the code can entirely be implemented in
>> the PCIe AER driver and is independent of the CXL subsystem. The CXL
>> driver only provides the handler.
>>
>> [1] CXL 3.0 spec: 9.11.8 CXL Devices Attached to an RCH
>> [2] CXL 3.0 spec, 12.2.1.1 RCH Downstream Port-detected Errors
>> [3] CXL 3.0 spec, 8.1.3 PCIe DVSEC for CXL Devices
>>
>> Co-developed-by: Terry Bowman 
>> Signed-off-by: Terry Bowman 
>> Signed-off-by: Robert Richter 
>> Cc: "Oliver O'Halloran" 
>> Cc: Bjorn Helgaas 
>> Cc: linuxppc-dev@lists.ozlabs.org
>> Cc: linux-...@vger.kernel.org
>> Acked-by: Bjorn Helgaas 
>> Reviewed-by: Jonathan Cameron 
>> Reviewed-by: Dave Jiang 
>> ---
>>  drivers/pci/pcie/Kconfig | 12 +
>>  drivers/pci/pcie/aer.c   | 96 +++-
>>  2 files changed, 106 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/pci/pcie/Kconfig b/drivers/pci/pcie/Kconfig
>> index 228652a59f27..4f0e70fafe2d 100644
>> --- a/drivers/pci/pcie/Kconfig
>> +++ b/drivers/pci/pcie/Kconfig
>> @@ -49,6 +49,18 @@ config PCIEAER_INJECT
>>gotten from:
>>   
>> https://git.kernel.org/cgit/linux/kernel/git/gong.chen/aer-inject.git/
>>  
>> +config PCIEAER_CXL
>> +bool "PCI Express CXL RAS support for Restricted Hosts (RCH)"
> 
> Why the "for Restricted Hosts (RCH)" clarification? I am seeing nothing
> that prevents this from working with RCECs on VH topologies.
> 

The same option can be used in VH mode. Will remove the RCH reference.

> 
>> +default y
> 
> Minor, but I think "default PCIEAER" makes it slightly clearer that CXL
> error handling comes along for the ride with PCIE AER.
>

We found Kconfig entries do not typically list a dependancy and the default 
to be the same. We prefer to leave as 'default y'. If you want we can make 
your requested change. 

>> +depends on PCIEAER && CXL_PCI
>> +help
>> +  Enables error handling of downstream ports of a CXL host
>> +  that is operating in RCD mode (Restricted CXL Host, RCH).
>> +  The downstream port reports AER errors to a given RCEC.
>> +  Errors are handled by the CXL memory device driver.
>> +
>> +  If unsure, say Y.
>> +
>>  #
>>  # PCI Express ECRC
>>  #
>> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
>> index d3344fcf1f79..c354ca5e8f2b 100644
>> --- a/drivers/pci/pcie/aer.c
>> +++ b/drivers/pci/pcie/aer.c
>> @@ -946,14 +946,100 @@ static bool find_source_device(struct pci_dev *parent,
>>  return true;
>>  }
>>  
>> +#ifdef CONFIG_PCIEAER_CXL
>> +
>> +static bool 

RE: [PATCH v10 13/15] PCI/AER: Forward RCH downstream port-detected errors to the CXL.mem dev handler

2023-08-31 Thread Dan Williams
Terry Bowman wrote:
> From: Robert Richter 
> 
> In Restricted CXL Device (RCD) mode a CXL device is exposed as an
> RCiEP, but CXL downstream and upstream ports are not enumerated and
> not visible in the PCIe hierarchy. [1] Protocol and link errors from
> these non-enumerated ports are signaled as internal AER errors, either
> Uncorrectable Internal Error (UIE) or Corrected Internal Errors (CIE)
> via an RCEC.
> 
> Restricted CXL host (RCH) downstream port-detected errors have the
> Requester ID of the RCEC set in the RCEC's AER Error Source ID
> register. A CXL handler must then inspect the error status in various
> CXL registers residing in the dport's component register space (CXL
> RAS capability) or the dport's RCRB (PCIe AER extended
> capability). [2]
> 
> Errors showing up in the RCEC's error handler must be handled and
> connected to the CXL subsystem. Implement this by forwarding the error
> to all CXL devices below the RCEC. Since the entire CXL device is
> controlled only using PCIe Configuration Space of device 0, function
> 0, only pass it there [3]. The error handling is limited to currently
> supported devices with the Memory Device class code set (CXL Type 3
> Device, PCI_CLASS_MEMORY_CXL, 502h), handle downstream port errors in
> the device's cxl_pci driver. Support for other CXL Device Types
> (e.g. a CXL.cache Device) can be added later.
> 
> To handle downstream port errors in addition to errors directed to the
> CXL endpoint device, a handler must also inspect the CXL RAS and PCIe
> AER capabilities of the CXL downstream port the device is connected
> to.
> 
> Since CXL downstream port errors are signaled using internal errors,
> the handler requires those errors to be unmasked. This is subject of a
> follow-on patch.
> 
> The reason for choosing this implementation is that the AER service
> driver claims the RCEC device, but does not allow it to register a
> custom specific handler to support CXL. Connecting the RCEC hard-wired
> with a CXL handler does not work, as the CXL subsystem might not be
> present all the time. The alternative to add an implementation to the
> portdrv to allow the registration of a custom RCEC error handler isn't
> worth doing it as CXL would be its only user. Instead, just check for
> an CXL RCEC and pass it down to the connected CXL device's error
> handler. With this approach the code can entirely be implemented in
> the PCIe AER driver and is independent of the CXL subsystem. The CXL
> driver only provides the handler.
> 
> [1] CXL 3.0 spec: 9.11.8 CXL Devices Attached to an RCH
> [2] CXL 3.0 spec, 12.2.1.1 RCH Downstream Port-detected Errors
> [3] CXL 3.0 spec, 8.1.3 PCIe DVSEC for CXL Devices
> 
> Co-developed-by: Terry Bowman 
> Signed-off-by: Terry Bowman 
> Signed-off-by: Robert Richter 
> Cc: "Oliver O'Halloran" 
> Cc: Bjorn Helgaas 
> Cc: linuxppc-dev@lists.ozlabs.org
> Cc: linux-...@vger.kernel.org
> Acked-by: Bjorn Helgaas 
> Reviewed-by: Jonathan Cameron 
> Reviewed-by: Dave Jiang 
> ---
>  drivers/pci/pcie/Kconfig | 12 +
>  drivers/pci/pcie/aer.c   | 96 +++-
>  2 files changed, 106 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/pcie/Kconfig b/drivers/pci/pcie/Kconfig
> index 228652a59f27..4f0e70fafe2d 100644
> --- a/drivers/pci/pcie/Kconfig
> +++ b/drivers/pci/pcie/Kconfig
> @@ -49,6 +49,18 @@ config PCIEAER_INJECT
> gotten from:
>
> https://git.kernel.org/cgit/linux/kernel/git/gong.chen/aer-inject.git/
>  
> +config PCIEAER_CXL
> + bool "PCI Express CXL RAS support for Restricted Hosts (RCH)"

Why the "for Restricted Hosts (RCH)" clarification? I am seeing nothing
that prevents this from working with RCECs on VH topologies.


> + default y

Minor, but I think "default PCIEAER" makes it slightly clearer that CXL
error handling comes along for the ride with PCIE AER.

> + depends on PCIEAER && CXL_PCI
> + help
> +   Enables error handling of downstream ports of a CXL host
> +   that is operating in RCD mode (Restricted CXL Host, RCH).
> +   The downstream port reports AER errors to a given RCEC.
> +   Errors are handled by the CXL memory device driver.
> +
> +   If unsure, say Y.
> +
>  #
>  # PCI Express ECRC
>  #
> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> index d3344fcf1f79..c354ca5e8f2b 100644
> --- a/drivers/pci/pcie/aer.c
> +++ b/drivers/pci/pcie/aer.c
> @@ -946,14 +946,100 @@ static bool find_source_device(struct pci_dev *parent,
>   return true;
>  }
>  
> +#ifdef CONFIG_PCIEAER_CXL
> +
> +static bool is_cxl_mem_dev(struct pci_dev *dev)
> +{
> + /*
> +  * The capability, status, and control fields in Device 0,
> +  * Function 0 DVSEC control the CXL functionality of the
> +  * entire device (CXL 3.0, 8.1.3).
> +  */
> + if (dev->devfn != PCI_DEVFN(0, 0))
> + return false;
> +
> + /*
> +  * CXL Memory Devices must have the 502h class code set (CXL
> +  * 

[PATCH v10 13/15] PCI/AER: Forward RCH downstream port-detected errors to the CXL.mem dev handler

2023-08-31 Thread Terry Bowman
From: Robert Richter 

In Restricted CXL Device (RCD) mode a CXL device is exposed as an
RCiEP, but CXL downstream and upstream ports are not enumerated and
not visible in the PCIe hierarchy. [1] Protocol and link errors from
these non-enumerated ports are signaled as internal AER errors, either
Uncorrectable Internal Error (UIE) or Corrected Internal Errors (CIE)
via an RCEC.

Restricted CXL host (RCH) downstream port-detected errors have the
Requester ID of the RCEC set in the RCEC's AER Error Source ID
register. A CXL handler must then inspect the error status in various
CXL registers residing in the dport's component register space (CXL
RAS capability) or the dport's RCRB (PCIe AER extended
capability). [2]

Errors showing up in the RCEC's error handler must be handled and
connected to the CXL subsystem. Implement this by forwarding the error
to all CXL devices below the RCEC. Since the entire CXL device is
controlled only using PCIe Configuration Space of device 0, function
0, only pass it there [3]. The error handling is limited to currently
supported devices with the Memory Device class code set (CXL Type 3
Device, PCI_CLASS_MEMORY_CXL, 502h), handle downstream port errors in
the device's cxl_pci driver. Support for other CXL Device Types
(e.g. a CXL.cache Device) can be added later.

To handle downstream port errors in addition to errors directed to the
CXL endpoint device, a handler must also inspect the CXL RAS and PCIe
AER capabilities of the CXL downstream port the device is connected
to.

Since CXL downstream port errors are signaled using internal errors,
the handler requires those errors to be unmasked. This is subject of a
follow-on patch.

The reason for choosing this implementation is that the AER service
driver claims the RCEC device, but does not allow it to register a
custom specific handler to support CXL. Connecting the RCEC hard-wired
with a CXL handler does not work, as the CXL subsystem might not be
present all the time. The alternative to add an implementation to the
portdrv to allow the registration of a custom RCEC error handler isn't
worth doing it as CXL would be its only user. Instead, just check for
an CXL RCEC and pass it down to the connected CXL device's error
handler. With this approach the code can entirely be implemented in
the PCIe AER driver and is independent of the CXL subsystem. The CXL
driver only provides the handler.

[1] CXL 3.0 spec: 9.11.8 CXL Devices Attached to an RCH
[2] CXL 3.0 spec, 12.2.1.1 RCH Downstream Port-detected Errors
[3] CXL 3.0 spec, 8.1.3 PCIe DVSEC for CXL Devices

Co-developed-by: Terry Bowman 
Signed-off-by: Terry Bowman 
Signed-off-by: Robert Richter 
Cc: "Oliver O'Halloran" 
Cc: Bjorn Helgaas 
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-...@vger.kernel.org
Acked-by: Bjorn Helgaas 
Reviewed-by: Jonathan Cameron 
Reviewed-by: Dave Jiang 
---
 drivers/pci/pcie/Kconfig | 12 +
 drivers/pci/pcie/aer.c   | 96 +++-
 2 files changed, 106 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pcie/Kconfig b/drivers/pci/pcie/Kconfig
index 228652a59f27..4f0e70fafe2d 100644
--- a/drivers/pci/pcie/Kconfig
+++ b/drivers/pci/pcie/Kconfig
@@ -49,6 +49,18 @@ config PCIEAER_INJECT
  gotten from:
 
https://git.kernel.org/cgit/linux/kernel/git/gong.chen/aer-inject.git/
 
+config PCIEAER_CXL
+   bool "PCI Express CXL RAS support for Restricted Hosts (RCH)"
+   default y
+   depends on PCIEAER && CXL_PCI
+   help
+ Enables error handling of downstream ports of a CXL host
+ that is operating in RCD mode (Restricted CXL Host, RCH).
+ The downstream port reports AER errors to a given RCEC.
+ Errors are handled by the CXL memory device driver.
+
+ If unsure, say Y.
+
 #
 # PCI Express ECRC
 #
diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index d3344fcf1f79..c354ca5e8f2b 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -946,14 +946,100 @@ static bool find_source_device(struct pci_dev *parent,
return true;
 }
 
+#ifdef CONFIG_PCIEAER_CXL
+
+static bool is_cxl_mem_dev(struct pci_dev *dev)
+{
+   /*
+* The capability, status, and control fields in Device 0,
+* Function 0 DVSEC control the CXL functionality of the
+* entire device (CXL 3.0, 8.1.3).
+*/
+   if (dev->devfn != PCI_DEVFN(0, 0))
+   return false;
+
+   /*
+* CXL Memory Devices must have the 502h class code set (CXL
+* 3.0, 8.1.12.1).
+*/
+   if ((dev->class >> 8) != PCI_CLASS_MEMORY_CXL)
+   return false;
+
+   return true;
+}
+
+static bool cxl_error_is_native(struct pci_dev *dev)
+{
+   struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
+
+   if (pcie_ports_native)
+   return true;
+
+   return host->native_aer && host->native_cxl_error;
+}
+
+static bool is_internal_error(struct aer_err_info *info)
+{
+   if