PCI/DPC: Add "pcie_ports=dpc-native" to allow DPC without AER control

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@lixom.net>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index c7ac2f3ac99fd29bef9db55d03f01c20c9912ad9..806c89f79be8ec9cd34e6bf0e222eeeb7698888f 100644 (file)
--- 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 a32ec3487a8d0009cb699bbf4efe60e0f6953371..e06f42f58d3d4d87e71d2310e04beaeb3e4a68f3 100644 (file)
--- 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 944827a8c7d363f0066f8002e891a988b11ca565..1e673619b101d0bb576aa501c6b2964462c09afe 100644 (file)
--- 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 1b330129089fea765919e7ae477298473edb843c..5075cb9e850c56b6bbf9b2832af644aa484be652 100644 (file)
--- 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 0a87091a0800e8316a9d05a9bea7268528ff687c..160d67c593105a420740b5ffb818acc23f475898 100644 (file)
--- 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;
 }