PCI: disable SERR for kdump kernel
PATCH v2 1/1 PCI: disable SERR for kdump kernel
Found one system with infiniband with SRIOV enabled, kdump kernel SRIOV BAR probing trigger one pci fatal error.
That assert error pin, and host get reset by BMC.
We can just ignore that error to let kernel go on
and kdump to create vmcore.
-v2: add debug print out
--- drivers/pci/probe.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+)
drivers/pci/probe.c +23 -0
@@ -17,6 +17,8 @@#include <linux/acpi.h> #include <linux/irqdomain.h> #include <linux/pm_runtime.h> +#include <linux/crash_dump.h> +#include "pci.h" #define CARDBUS_LATENCY_TIMER 176/* secondary latency timer */
@@ -1515,6 +1517,24 @@ static void pci_msi_setup_pci_dev(structpci_msix_clear_and_set_ctrl (dev,PCI_MSIX_FLAGS_ENABLE ,0 ); } +static void pci_disable_serr (struct pci_dev *dev) +{ +u16 pci_cmd, pci_bctl; + +pci_read_config_word (dev,PCI_COMMAND , &pci_cmd); + pci_cmd &= ~PCI_COMMAND_SERR ; +pci_write_config_word (dev,PCI_COMMAND , pci_cmd); +dev_printk (KERN_DEBUG , &dev->dev,"SERR cleared\n" ); + +/* Program bridge control value */ +if ((dev->class >>8 ) ==PCI_CLASS_BRIDGE_PCI ) { +pci_read_config_word (dev,PCI_BRIDGE_CONTROL , &pci_bctl); + pci_bctl &= ~PCI_BRIDGE_CTL_SERR ; +pci_write_config_word (dev,PCI_BRIDGE_CONTROL , pci_bctl); +dev_printk (KERN_DEBUG , &dev->dev,"BRIDGE SERR cleared\n" ); + } +} +/** * pci_setup_device - fill in class and map information of a device * @dev: the device structure to fill
@@ -1572,6 +1592,9 @@ int pci_setup_device(struct pci_dev *dev/* device class may be changed after fixup */ class = dev->class >>8 ; +if (is_kdump_kernel ()) +pci_disable_serr (dev); +if (dev->non_compliant_bars) {pci_read_config_word (dev,PCI_COMMAND , &cmd);if (cmd & (PCI_COMMAND_IO |PCI_COMMAND_MEMORY )) {
drivers/pci/probe.c int pci_setup_device(struct pci_dev *dev · line 1597
Quoted 9 lines · Yinghai Lu
*
pci_setup_device- fill in class and map information of a device
* @dev: the device structure to filldrivers/pci/probe.c +3
-0@@ -1572,6 +1592,9 @@ int pci_setup_device(struct pci_dev *dev/* device class may be changed after fixup */ class = dev->class >>8 ; +if (is_kdump_kernel ()) +pci_disable_serr (dev); +
This sounds like something that needs to be done while shutting down the first kernel as part of the kdump procedure rather than boot of the kdump kernel in pci setup.
Signature · 3 lines
Sinan Kaya Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
Bjorn Helgaas
maintainerQuoted 7 lines · Sinan Kaya
Quoted 6 lines · Yinghai Lu
*
pci_setup_device- fill in class and map information of a device
* @dev: the device structure to filldrivers/pci/probe.c +0
-0@@ -1572,6 +1592,9 @@ int pci_setup_device(struct pci_dev *dev/* device class may be changed after fixup */ class = dev->class >>8 ;
Quoted 7 lines
drivers/pci/probe.c int pci_setup_device(struct pci_dev *dev · line 1597
Quoted 3 lines
drivers/pci/probe.c +3
-0+if (is_kdump_kernel ()) +pci_disable_serr (dev); +This sounds like something that needs to be done while shutting down the first kernel as part of the kdump procedure rather than boot of the kdump kernel in pci setup.
In general, I would rather make the new kernel more tolerant than make assumptions about how the old kernel shut down. I don't know if there's an explicit statement of kexec philosophy on this (it'd be nice if there were), but it seems like a more robust strategy, e.g., less prone to revlock issues between the old/new kernels.
Bjorn
Quoted 16 lines · Bjorn Helgaas
Quoted 7 lines · Sinan Kaya
Quoted 6 lines · Yinghai Lu
*
pci_setup_device- fill in class and map information of a device
* @dev: the device structure to filldrivers/pci/probe.c +0
-0@@ -1572,6 +1592,9 @@ int pci_setup_device(struct pci_dev *dev/* device class may be changed after fixup */ class = dev->class >>8 ;Quoted 7 lines
drivers/pci/probe.c int pci_setup_device(struct pci_dev *dev · line 1597
Quoted 3 lines
drivers/pci/probe.c +3
-0+if (is_kdump_kernel ()) +pci_disable_serr (dev); +This sounds like something that needs to be done while shutting down the first kernel as part of the kdump procedure rather than boot of the kdump kernel in pci setup.
Quoted 6 lines
In general, I would rather make the new kernel more tolerant than make assumptions about how the old kernel shut down. I don't know if there's an explicit statement of kexec philosophy on this (it'd be nice if there were), but it seems like a more robust strategy, e.g., less prone to revlock issues between the old/new kernels.
What if the secondary kernel never gets a chance to boot due to excessive errors? Code might not even make to the point where PCI driver is executed.
If I remember this right, kexec is already doing PCI cleanup operation during shutdown and it is also calling the shutdown hook of device drivers.
(I recently added a shutdown hook to my own HIDMA driver for the very same reason)
The requirement for the second kernel boot is not to have any pending DMA and IRQs so that secondary kernel can boot safely.
Maybe, the right thing is to look for a way to put PCI into some safe mode. There should be some code there disabling the COMMAND enable bits if not already.
This code could be added to the same place.
http://lxr.free-electrons.com/ident?i=pci_device_shutdown
469 /*
470 * If this is a kexec reboot, turn off Bus Master bit on the 471 * device to tell it to not continue to do DMA. Don't touch 472 * devices in D3cold or unknown states. 473 * If it is not a kexec reboot, firmware will hit the PCI 474 * devices with big hammer and stop their DMA any way. 475 */
476 if (kexec_in_progress && (pci_dev->current_state <= PCI_D3hot))
477 pci_clear_master(pci_dev);
Quoted 2 lines
Bjorn
Signature · 3 lines
Sinan Kaya Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
Quoted 7 lines · Sinan Kaya
Quoted 6 lines · Yinghai Lu
*
pci_setup_device- fill in class and map information of a device
* @dev: the device structure to filldrivers/pci/probe.c +0
-0@@ -1572,6 +1592,9 @@ int pci_setup_device(struct pci_dev *dev/* device class may be changed after fixup */ class = dev->class >>8 ;
Quoted 7 lines
drivers/pci/probe.c int pci_setup_device(struct pci_dev *dev · line 1597
Quoted 3 lines
drivers/pci/probe.c +3
-0+if (is_kdump_kernel ()) +pci_disable_serr (dev); +This sounds like something that needs to be done while shutting down the first kernel as part of the kdump procedure rather than boot of the kdump kernel in pci setup.
For kdump path, first kernel shutdown path is not called.
We have to do sth in second kernel instead.
Thanks
Yinghai
Quoted 16 lines · Yinghai Lu
Quoted 7 lines · Sinan Kaya
Quoted 6 lines · Yinghai Lu
*
pci_setup_device- fill in class and map information of a device
* @dev: the device structure to filldrivers/pci/probe.c +0
-0@@ -1572,6 +1592,9 @@ int pci_setup_device(struct pci_dev *dev/* device class may be changed after fixup */ class = dev->class >>8 ;Quoted 7 lines
drivers/pci/probe.c int pci_setup_device(struct pci_dev *dev · line 1597
Quoted 3 lines
drivers/pci/probe.c +3
-0+if (is_kdump_kernel ()) +pci_disable_serr (dev); +This sounds like something that needs to be done while shutting down the first kernel as part of the kdump procedure rather than boot of the kdump kernel in pci setup.
Quoted 4 lines
For kdump path, first kernel shutdown path is not called.
We have to do sth in second kernel instead.
I didn't know that. Bjorn's compatibility point is also a concern. Ideally you want something in both places.
Quoted 4 lines
Thanks
Yinghai
Signature · 3 lines
Sinan Kaya Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.