| Message ID | 20140419025339.2408.17866.stgit@amt.stowe |
|---|---|
| State | Changes Requested |
| Headers | show |
On Fri, Apr 18, 2014 at 08:53:39PM -0600, Myron Stowe wrote: > The vast majority of platforms are not supplying ACPI _PXM (proximity) > information corresponding to host bridge (PNP0A03/PNP0A08) devices > resulting in sysfs "numa_node" values of -1 (NUMA_NO_NODE) [1]: > # for i in /sys/devices/pci0000\:00/*/numa_node; do cat $i; done | uniq > -1 > > # find /sys/ -name "numa_node" | while read fname; do cat $fname; \ > done | uniq > -1 > > AMD based platforms provide a fall-back for this situation via amd_bus.c. > These platforms snoop out the information by directly reading specific > registers from the Northbridge and caching them via 'alloc_pci_root_info'. > > Later during boot processing when host bridges are discovered - > 'pci_acpi_scan_root' - the kernel looks for their corresponding ACPI _PXM > method - drivers/acpi/numa.c::acpi_get_node(). If the BIOS supplied a > _PXM method then that node (proximity) value is associated. If the BIOS > did not supply a _PXM method *and* the platform is AMD based, the > fall-back cached values obtained directly from the Northbridge are used; > otherwise, "NUMA_NO_NODE" is associated. > > There are a number of issues with this fall-back mechanism the most > notable being that amd_bus.c extracts a 3-bit number from a CPU register > and uses it as the node number. The node numbers used by Linux are > logical and there's no reason they need to be identical to settings in the > CPU registers. So if we have some node information obtained in the normal > way (from _PXM, SLIT, SRAT, etc.) and some from amd_bus.c, there's no > reason to believe they will be compatible. > > This patch warns when this situation occurs: > pci_root PNP0A08:00: [Firmware Bug]: No _PXM; guessing node number 0 > > [1] https://bugzilla.kernel.org/show_bug.cgi?id=72051 > > Signed-off-by: Myron Stowe <myron.stowe@redhat.com> > --- > > arch/x86/pci/acpi.c | 6 +++++- > 1 files changed, 5 insertions(+), 1 deletions(-) > > diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c > index 01edac6..80c09ba 100644 > --- a/arch/x86/pci/acpi.c > +++ b/arch/x86/pci/acpi.c > @@ -489,8 +489,12 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root) > } > > node = acpi_get_node(device->handle); > - if (node == NUMA_NO_NODE) > + if (node == NUMA_NO_NODE) { > node = x86_pci_root_bus_node(busnum); > + if (node != NUMA_NO_NODE) > + dev_info(&device->dev, FW_BUG "No _PXM; guessing node number %x\n", Hmm, I'm not really convinced this message is user-friendly enough. Can we be more descriptive here please?
On Sun, Apr 20, 2014 at 4:21 AM, Borislav Petkov <bp@suse.de> wrote: > On Fri, Apr 18, 2014 at 08:53:39PM -0600, Myron Stowe wrote: >> The vast majority of platforms are not supplying ACPI _PXM (proximity) >> information corresponding to host bridge (PNP0A03/PNP0A08) devices >> resulting in sysfs "numa_node" values of -1 (NUMA_NO_NODE) [1]: >> # for i in /sys/devices/pci0000\:00/*/numa_node; do cat $i; done | uniq >> -1 >> >> # find /sys/ -name "numa_node" | while read fname; do cat $fname; \ >> done | uniq >> -1 >> >> AMD based platforms provide a fall-back for this situation via amd_bus.c. >> These platforms snoop out the information by directly reading specific >> registers from the Northbridge and caching them via 'alloc_pci_root_info'. >> >> Later during boot processing when host bridges are discovered - >> 'pci_acpi_scan_root' - the kernel looks for their corresponding ACPI _PXM >> method - drivers/acpi/numa.c::acpi_get_node(). If the BIOS supplied a >> _PXM method then that node (proximity) value is associated. If the BIOS >> did not supply a _PXM method *and* the platform is AMD based, the >> fall-back cached values obtained directly from the Northbridge are used; >> otherwise, "NUMA_NO_NODE" is associated. >> >> There are a number of issues with this fall-back mechanism the most >> notable being that amd_bus.c extracts a 3-bit number from a CPU register >> and uses it as the node number. The node numbers used by Linux are >> logical and there's no reason they need to be identical to settings in the >> CPU registers. So if we have some node information obtained in the normal >> way (from _PXM, SLIT, SRAT, etc.) and some from amd_bus.c, there's no >> reason to believe they will be compatible. >> >> This patch warns when this situation occurs: >> pci_root PNP0A08:00: [Firmware Bug]: No _PXM; guessing node number 0 >> >> [1] https://bugzilla.kernel.org/show_bug.cgi?id=72051 >> >> Signed-off-by: Myron Stowe <myron.stowe@redhat.com> >> --- >> >> arch/x86/pci/acpi.c | 6 +++++- >> 1 files changed, 5 insertions(+), 1 deletions(-) >> >> diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c >> index 01edac6..80c09ba 100644 >> --- a/arch/x86/pci/acpi.c >> +++ b/arch/x86/pci/acpi.c >> @@ -489,8 +489,12 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root) >> } >> >> node = acpi_get_node(device->handle); >> - if (node == NUMA_NO_NODE) >> + if (node == NUMA_NO_NODE) { >> node = x86_pci_root_bus_node(busnum); >> + if (node != NUMA_NO_NODE) >> + dev_info(&device->dev, FW_BUG "No _PXM; guessing node number %x\n", > > Hmm, I'm not really convinced this message is user-friendly enough. Can > we be more descriptive here please? > How about - dev_info(&device->dev, FW_BUG "no _PXM; falling back to node %d from hardware (may be inconsistent with ACPI node numbers)\n", node); > -- > Regards/Gruss, > Boris. > > Sent from a fat crate under my desk. Formatting is fine. > -- > -- > To unsubscribe from this list: send the line "unsubscribe linux-acpi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Apr 28, 2014 at 03:24:39PM -0600, Myron Stowe wrote: > >> @@ -489,8 +489,12 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root) > >> } > >> > >> node = acpi_get_node(device->handle); > >> - if (node == NUMA_NO_NODE) > >> + if (node == NUMA_NO_NODE) { > >> node = x86_pci_root_bus_node(busnum); > >> + if (node != NUMA_NO_NODE) > >> + dev_info(&device->dev, FW_BUG "No _PXM; guessing node number %x\n", > > > > Hmm, I'm not really convinced this message is user-friendly enough. Can > > we be more descriptive here please? > > > > How about - > dev_info(&device->dev, FW_BUG "no _PXM; falling back to node %d from > hardware (may be inconsistent with ACPI node numbers)\n", node); Yep, better.
diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c index 01edac6..80c09ba 100644 --- a/arch/x86/pci/acpi.c +++ b/arch/x86/pci/acpi.c @@ -489,8 +489,12 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root) } node = acpi_get_node(device->handle); - if (node == NUMA_NO_NODE) + if (node == NUMA_NO_NODE) { node = x86_pci_root_bus_node(busnum); + if (node != NUMA_NO_NODE) + dev_info(&device->dev, FW_BUG "No _PXM; guessing node number %x\n", + node); + } if (node != NUMA_NO_NODE && !node_online(node)) node = NUMA_NO_NODE;
The vast majority of platforms are not supplying ACPI _PXM (proximity) information corresponding to host bridge (PNP0A03/PNP0A08) devices resulting in sysfs "numa_node" values of -1 (NUMA_NO_NODE) [1]: # for i in /sys/devices/pci0000\:00/*/numa_node; do cat $i; done | uniq -1 # find /sys/ -name "numa_node" | while read fname; do cat $fname; \ done | uniq -1 AMD based platforms provide a fall-back for this situation via amd_bus.c. These platforms snoop out the information by directly reading specific registers from the Northbridge and caching them via 'alloc_pci_root_info'. Later during boot processing when host bridges are discovered - 'pci_acpi_scan_root' - the kernel looks for their corresponding ACPI _PXM method - drivers/acpi/numa.c::acpi_get_node(). If the BIOS supplied a _PXM method then that node (proximity) value is associated. If the BIOS did not supply a _PXM method *and* the platform is AMD based, the fall-back cached values obtained directly from the Northbridge are used; otherwise, "NUMA_NO_NODE" is associated. There are a number of issues with this fall-back mechanism the most notable being that amd_bus.c extracts a 3-bit number from a CPU register and uses it as the node number. The node numbers used by Linux are logical and there's no reason they need to be identical to settings in the CPU registers. So if we have some node information obtained in the normal way (from _PXM, SLIT, SRAT, etc.) and some from amd_bus.c, there's no reason to believe they will be compatible. This patch warns when this situation occurs: pci_root PNP0A08:00: [Firmware Bug]: No _PXM; guessing node number 0 [1] https://bugzilla.kernel.org/show_bug.cgi?id=72051 Signed-off-by: Myron Stowe <myron.stowe@redhat.com> --- arch/x86/pci/acpi.c | 6 +++++- 1 files changed, 5 insertions(+), 1 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html