APPLIED: [PATCH][SRU][E][F] PCI/DPC: Add "pcie_ports=dpc-native" to allow DPC without AER control

[Khaled Elmously]

Applied to Eoan/master-next and Focal/master-next


On 2020-03-27 12:45:17 , Jay Vosburgh wrote:
> From: Olof Johansson <olof at lixom.net>
> 
> BugLink: https://bugs.launchpad.net/bugs/1869423
> 
> Prior to eed85ff4c0da7 ("PCI/DPC: Enable DPC only if AER is available"),
> Linux handled DPC events regardless of whether firmware had granted it
> ownership of AER or DPC, e.g., via _OSC.
> 
> PCIe r5.0, sec 6.2.10, recommends that the OS link control of DPC to
> control of AER, so after eed85ff4c0da7, Linux handles DPC events only if it
> has control of AER.
> 
> On platforms that do not grant OS control of AER via _OSC, Linux DPC
> handling worked before eed85ff4c0da7 but not after.
> 
> To make Linux DPC handling work on those platforms the same way they did
> before, add a "pcie_ports=dpc-native" kernel parameter that makes Linux
> handle DPC events regardless of whether it has control of AER.
> 
> [bhelgaas: commit log, move pcie_ports_dpc_native to drivers/pci/]
> Link: https://lore.kernel.org/r/20191023192205.97024-1-olof@lixom.net
> Signed-off-by: Olof Johansson <olof at lixom.net>
> Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
> (cherry picked from commit 35a0b2378c199d4f26e458b2ca38ea56aaf2d9b8)
> Signed-off-by: Jay Vosburgh <jay.vosburgh at canonical.com>
> 
> ---
>  Documentation/admin-guide/kernel-parameters.txt | 2 ++
>  drivers/pci/pcie/dpc.c                          | 2 +-
>  drivers/pci/pcie/portdrv.h                      | 2 ++
>  drivers/pci/pcie/portdrv_core.c                 | 7 ++++++-
>  drivers/pci/pcie/portdrv_pci.c                  | 8 ++++++++
>  5 files changed, 19 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index c7ac2f3ac99f..806c89f79be8 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -3540,6 +3540,8 @@
>  			even if the platform doesn't give the OS permission to
>  			use them.  This may cause conflicts if the platform
>  			also tries to use these services.
> +		dpc-native	Use native PCIe service for DPC only.  May
> +				cause conflicts if firmware uses AER or DPC.
>  		compat	Disable native PCIe services (PME, AER, DPC, PCIe
>  			hotplug).
>  
> diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
> index a32ec3487a8d..e06f42f58d3d 100644
> --- a/drivers/pci/pcie/dpc.c
> +++ b/drivers/pci/pcie/dpc.c
> @@ -291,7 +291,7 @@ static int dpc_probe(struct pcie_device *dev)
>  	int status;
>  	u16 ctl, cap;
>  
> -	if (pcie_aer_get_firmware_first(pdev))
> +	if (pcie_aer_get_firmware_first(pdev) && !pcie_ports_dpc_native)
>  		return -ENOTSUPP;
>  
>  	dpc = devm_kzalloc(device, sizeof(*dpc), GFP_KERNEL);
> diff --git a/drivers/pci/pcie/portdrv.h b/drivers/pci/pcie/portdrv.h
> index 944827a8c7d3..1e673619b101 100644
> --- a/drivers/pci/pcie/portdrv.h
> +++ b/drivers/pci/pcie/portdrv.h
> @@ -25,6 +25,8 @@
>  
>  #define PCIE_PORT_DEVICE_MAXSERVICES   5
>  
> +extern bool pcie_ports_dpc_native;
> +
>  #ifdef CONFIG_PCIEAER
>  int pcie_aer_init(void);
>  #else
> diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c
> index 1b330129089f..5075cb9e850c 100644
> --- a/drivers/pci/pcie/portdrv_core.c
> +++ b/drivers/pci/pcie/portdrv_core.c
> @@ -250,8 +250,13 @@ static int get_port_device_capability(struct pci_dev *dev)
>  		pcie_pme_interrupt_enable(dev, false);
>  	}
>  
> +	/*
> +	 * With dpc-native, allow Linux to use DPC even if it doesn't have
> +	 * permission to use AER.
> +	 */
>  	if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC) &&
> -	    pci_aer_available() && services & PCIE_PORT_SERVICE_AER)
> +	    pci_aer_available() &&
> +	    (pcie_ports_dpc_native || (services & PCIE_PORT_SERVICE_AER)))
>  		services |= PCIE_PORT_SERVICE_DPC;
>  
>  	if (pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM ||
> diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c
> index 0a87091a0800..160d67c59310 100644
> --- a/drivers/pci/pcie/portdrv_pci.c
> +++ b/drivers/pci/pcie/portdrv_pci.c
> @@ -29,12 +29,20 @@ bool pcie_ports_disabled;
>   */
>  bool pcie_ports_native;
>  
> +/*
> + * If the user specified "pcie_ports=dpc-native", use the Linux DPC PCIe
> + * service even if the platform hasn't given us permission.
> + */
> +bool pcie_ports_dpc_native;
> +
>  static int __init pcie_port_setup(char *str)
>  {
>  	if (!strncmp(str, "compat", 6))
>  		pcie_ports_disabled = true;
>  	else if (!strncmp(str, "native", 6))
>  		pcie_ports_native = true;
> +	else if (!strncmp(str, "dpc-native", 10))
> +		pcie_ports_dpc_native = true;
>  
>  	return 1;
>  }
> -- 
> 2.7.4
> 
> 
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