From 8b8bae901ce23addbdcdb54fa1696fb2d049feb5 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Sat, 5 Mar 2011 13:21:51 +0100 Subject: PCI/ACPI: Report ASPM support to BIOS if not disabled from command line MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit We need to distinguish the situation in which ASPM support is disabled from the command line or through .config from the situation in which it is disabled, because the hardware or BIOS can't handle it. In the former case we should not report ASPM support to the BIOS through ACPI _OSC, but in the latter case we should do that. Introduce pcie_aspm_support_enabled() that can be used by acpi_pci_root_add() to determine whether or not it should report ASPM support to the BIOS through _OSC. Cc: stable@kernel.org References: https://bugzilla.kernel.org/show_bug.cgi?id=29722 References: https://bugzilla.kernel.org/show_bug.cgi?id=20232 Reported-and-tested-by: Ortwin Glück Reviewed-by: Kenji Kaneshige Tested-by: Kenji Kaneshige Signed-off-by: Rafael J. Wysocki Signed-off-by: Jesse Barnes diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c index 8524939..c7358dd 100644 --- a/drivers/acpi/pci_root.c +++ b/drivers/acpi/pci_root.c @@ -564,7 +564,7 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device) /* Indicate support for various _OSC capabilities. */ if (pci_ext_cfg_avail(root->bus->self)) flags |= OSC_EXT_PCI_CONFIG_SUPPORT; - if (pcie_aspm_enabled()) + if (pcie_aspm_support_enabled()) flags |= OSC_ACTIVE_STATE_PWR_SUPPORT | OSC_CLOCK_PWR_CAPABILITY_SUPPORT; if (pci_msi_enabled()) diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index 3188cd9..bbdb4fd 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -69,6 +69,7 @@ struct pcie_link_state { }; static int aspm_disabled, aspm_force, aspm_clear_state; +static bool aspm_support_enabled = true; static DEFINE_MUTEX(aspm_lock); static LIST_HEAD(link_list); @@ -896,6 +897,7 @@ static int __init pcie_aspm_disable(char *str) { if (!strcmp(str, "off")) { aspm_disabled = 1; + aspm_support_enabled = false; printk(KERN_INFO "PCIe ASPM is disabled\n"); } else if (!strcmp(str, "force")) { aspm_force = 1; @@ -930,3 +932,8 @@ int pcie_aspm_enabled(void) } EXPORT_SYMBOL(pcie_aspm_enabled); +bool pcie_aspm_support_enabled(void) +{ + return aspm_support_enabled; +} +EXPORT_SYMBOL(pcie_aspm_support_enabled); diff --git a/include/linux/pci.h b/include/linux/pci.h index 16c9f2e..96f70d7 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1002,12 +1002,11 @@ extern bool pcie_ports_auto; #endif #ifndef CONFIG_PCIEASPM -static inline int pcie_aspm_enabled(void) -{ - return 0; -} +static inline int pcie_aspm_enabled(void) { return 0; } +static inline bool pcie_aspm_support_enabled(void) { return false; } #else extern int pcie_aspm_enabled(void); +extern bool pcie_aspm_support_enabled(void); #endif #ifdef CONFIG_PCIEAER -- cgit v0.10.2 From 1a680b7c325882188865f05b9a88d32f75f26495 Mon Sep 17 00:00:00 2001 From: Naga Chumbalkar Date: Mon, 21 Mar 2011 03:29:08 +0000 Subject: PCI: PCIe links may not get configured for ASPM under POWERSAVE mode v3 -> v2: Moved ASPM enabling logic to pci_set_power_state() v2 -> v1: Preserved the logic in pci_raw_set_power_state() : Added ASPM enabling logic after scanning Root Bridge : http://marc.info/?l=linux-pci&m=130046996216391&w=2 v1 : http://marc.info/?l=linux-pci&m=130013164703283&w=2 The assumption made in commit 41cd766b065970ff6f6c89dd1cf55fa706c84a3d (PCI: Don't enable aspm before drivers have had a chance to veto it) that pci_enable_device() will result in re-configuring ASPM when aspm_policy is POWERSAVE is no longer valid. This is due to commit 97c145f7c87453cec90e91238fba5fe2c1561b32 (PCI: read current power state at enable time) which resets dev->current_state to D0. Due to this the call to pcie_aspm_pm_state_change() is never made. Note the equality check (below) that returns early: ./drivers/pci/pci.c: pci_raw_set_pci_power_state() 546 /* Check if we're already there */ 547 if (dev->current_state == state) 548 return 0; Therefore OSPM never configures the PCIe links for ASPM to turn them "on". Fix it by configuring ASPM from the pci_enable_device() code path. This also allows a driver such as the e1000e networking driver a chance to disable ASPM (L0s, L1), if need be, prior to enabling the device. A driver may perform this action if the device is known to mis-behave wrt ASPM. Signed-off-by: Naga Chumbalkar Acked-by: Rafael J. Wysocki Cc: Matthew Garrett Signed-off-by: Jesse Barnes diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index b714d78..2472e71 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -740,6 +740,12 @@ int pci_set_power_state(struct pci_dev *dev, pci_power_t state) if (!__pci_complete_power_transition(dev, state)) error = 0; + /* + * When aspm_policy is "powersave" this call ensures + * that ASPM is configured. + */ + if (!error && dev->bus->self) + pcie_aspm_powersave_config_link(dev->bus->self); return error; } diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index bbdb4fd..e61b82e 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -708,6 +708,28 @@ void pcie_aspm_pm_state_change(struct pci_dev *pdev) up_read(&pci_bus_sem); } +void pcie_aspm_powersave_config_link(struct pci_dev *pdev) +{ + struct pcie_link_state *link = pdev->link_state; + + if (aspm_disabled || !pci_is_pcie(pdev) || !link) + return; + + if (aspm_policy != POLICY_POWERSAVE) + return; + + if ((pdev->pcie_type != PCI_EXP_TYPE_ROOT_PORT) && + (pdev->pcie_type != PCI_EXP_TYPE_DOWNSTREAM)) + return; + + down_read(&pci_bus_sem); + mutex_lock(&aspm_lock); + pcie_config_aspm_path(link); + pcie_set_clkpm(link, policy_to_clkpm_state(link)); + mutex_unlock(&aspm_lock); + up_read(&pci_bus_sem); +} + /* * pci_disable_link_state - disable pci device's link state, so the link will * never enter specific states diff --git a/include/linux/pci-aspm.h b/include/linux/pci-aspm.h index ce681051..67cb3ae3 100644 --- a/include/linux/pci-aspm.h +++ b/include/linux/pci-aspm.h @@ -26,6 +26,7 @@ extern void pcie_aspm_init_link_state(struct pci_dev *pdev); extern void pcie_aspm_exit_link_state(struct pci_dev *pdev); extern void pcie_aspm_pm_state_change(struct pci_dev *pdev); +extern void pcie_aspm_powersave_config_link(struct pci_dev *pdev); extern void pci_disable_link_state(struct pci_dev *pdev, int state); extern void pcie_clear_aspm(void); extern void pcie_no_aspm(void); @@ -39,6 +40,9 @@ static inline void pcie_aspm_exit_link_state(struct pci_dev *pdev) static inline void pcie_aspm_pm_state_change(struct pci_dev *pdev) { } +static inline void pcie_aspm_powersave_config_link(struct pci_dev *pdev) +{ +} static inline void pci_disable_link_state(struct pci_dev *pdev, int state) { } -- cgit v0.10.2 From bbfa306a1e5d9618231aa0de3d52a8eb1219d0c3 Mon Sep 17 00:00:00 2001 From: Naga Chumbalkar Date: Mon, 21 Mar 2011 03:29:14 +0000 Subject: PCI: Changing ASPM policy, via /sys, to POWERSAVE could cause NMIs v3 -> v2: Modified the text that describes the problem v2 -> v1: Returned -EPERM v1 : http://marc.info/?l=linux-pci&m=130013194803727&w=2 For servers whose hardware cannot handle ASPM the BIOS ought to set the FADT bit shown below: In Sec 5.2.9.3 (IA-PC Boot Arch. Flags) of ACPI4.0a Specification, please see Table 5-11: PCIe ASPM Controls: If set, indicates to OSPM that it must not enable OPSM ASPM control on this platform. However there are shipping servers whose BIOS did not set this bit. (An example is the HP ProLiant DL385 G6. A Maintenance BIOS will fix that). For such servers even if a call is made via pci_no_aspm(), based on _OSC support in the BIOS, it may be too late because the ASPM code may have already allocated and filled its "link_list". So if a user sets the ASPM "policy" to "powersave" via /sys then pcie_aspm_set_policy() will run through the "link_list" and re-configure ASPM policy on devices that advertise ASPM L0s/L1 capability: # echo powersave > /sys/module/pcie_aspm/parameters/policy # cat /sys/module/pcie_aspm/parameters/policy default performance [powersave] That can cause NMIs since the hardware doesn't play well with ASPM: [ 1651.906015] NMI: PCI system error (SERR) for reason b1 on CPU 0. [ 1651.906015] Dazed and confused, but trying to continue Ideally, the BIOS should have set that FADT bit in the first place but we could be more robust - especially given the fact that Windows doesn't cause NMIs in the above scenario. There should be a sanity check to not allow a user to modify ASPM policy when aspm_disabled is set. Signed-off-by: Naga Chumbalkar Acked-by: Rafael J. Wysocki Cc: Matthew Garrett Signed-off-by: Jesse Barnes diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index e61b82e..eee09f7 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -770,6 +770,8 @@ static int pcie_aspm_set_policy(const char *val, struct kernel_param *kp) int i; struct pcie_link_state *link; + if (aspm_disabled) + return -EPERM; for (i = 0; i < ARRAY_SIZE(policy_str); i++) if (!strncmp(val, policy_str[i], strlen(policy_str[i]))) break; @@ -824,6 +826,8 @@ static ssize_t link_state_store(struct device *dev, struct pcie_link_state *link, *root = pdev->link_state->root; u32 val = buf[0] - '0', state = 0; + if (aspm_disabled) + return -EPERM; if (n < 1 || val > 3) return -EINVAL; -- cgit v0.10.2 From eca67315e0e0d5fd91264d79c88694006dbc7d31 Mon Sep 17 00:00:00 2001 From: Naga Chumbalkar Date: Mon, 21 Mar 2011 03:29:20 +0000 Subject: PCI: Disable ASPM when _OSC control is not granted for PCIe services v3 -> v2: Added text to describe the problem v2 -> v1: Split this patch from v1 v1 : Part of: http://marc.info/?l=linux-pci&m=130042212003242&w=2 Disable ASPM when no _OSC control for PCIe services is granted by the BIOS. This is to protect systems with a buggy BIOS that did not set the ACPI FADT "ASPM Controls" bit even though the underlying HW can't do ASPM. To turn "on" ASPM the minimum the BIOS needs to do: 1. Clear the ACPI FADT "ASPM Controls" bit. 2. Support _OSC appropriately There is no _OSC Control bit for ASPM. However, we expect the BIOS to support _OSC for a Root Bridge that originates a PCIe hierarchy. If this is not the case - we are better off not enabling ASPM on that server. Commit 852972acff8f10f3a15679be2059bb94916cba5d (ACPI: Disable ASPM if the Platform won't provide _OSC control for PCIe) describes the above scenario. To quote verbatim from there: [The PCI SIG documentation for the _OSC OS/firmware handshaking interface states: "If the _OSC control method is absent from the scope of a host bridge device, then the operating system must not enable or attempt to use any features defined in this section for the hierarchy originated by the host bridge." The obvious interpretation of this is that the OS should not attempt to use PCIe hotplug, PME or AER - however, the specification also notes that an _OSC method is *required* for PCIe hierarchies, and experimental validation with An Alternative OS indicates that it doesn't use any PCIe functionality if the _OSC method is missing. That arguably means we shouldn't be using MSI or extended config space, but right now our problems seem to be limited to vendors being surprised when ASPM gets enabled on machines when other OSs refuse to do so. So, for now, let's just disable ASPM if the _OSC method doesn't exist or refuses to hand over PCIe capability control.] Signed-off-by: Naga Chumbalkar Cc: Rafael J. Wysocki Cc: Matthew Garrett Signed-off-by: Jesse Barnes diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c index c7358dd..f911a2f 100644 --- a/drivers/acpi/pci_root.c +++ b/drivers/acpi/pci_root.c @@ -32,6 +32,7 @@ #include #include #include +#include #include #include #include @@ -591,12 +592,16 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device) status = acpi_pci_osc_control_set(device->handle, &flags, OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL); - if (ACPI_SUCCESS(status)) + if (ACPI_SUCCESS(status)) { dev_info(root->bus->bridge, "ACPI _OSC control (0x%02x) granted\n", flags); - else + } else { dev_dbg(root->bus->bridge, "ACPI _OSC request failed (code %d)\n", status); + printk(KERN_INFO "Unable to assume _OSC PCIe control. " + "Disabling ASPM\n"); + pcie_no_aspm(); + } } pci_acpi_add_bus_pm_notifier(device, root->bus); diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c index 5130d0d..595654a 100644 --- a/drivers/pci/pcie/portdrv_core.c +++ b/drivers/pci/pcie/portdrv_core.c @@ -15,7 +15,6 @@ #include #include #include -#include #include "../pci.h" #include "portdrv.h" @@ -356,10 +355,8 @@ int pcie_port_device_register(struct pci_dev *dev) /* Get and check PCI Express port services */ capabilities = get_port_device_capability(dev); - if (!capabilities) { - pcie_no_aspm(); + if (!capabilities) return 0; - } pci_set_master(dev); /* -- cgit v0.10.2