Bug 202443

Summary:	_PXM below host bridge is ignored
Product:	Drivers	Reporter:	Bjorn Helgaas (bjorn)
Component:	PCI	Assignee:	drivers_pci (drivers_pci)
Status:	NEW ---
Severity:	normal
Priority:	P1
Hardware:	All
OS:	Linux
URL:	https://lore.kernel.org/linux-pci/20180912152140.3676-2-Jonathan.Cameron@huawei.com
Kernel Version:	v4.19	Subsystem:
Regression:	No	Bisected commit-id:
Attachments:	dmesg DSDT.dsl

Description Bjorn Helgaas 2019-01-28 21:12:47 UTC

Created attachment 280833 [details]
dmesg

Jonathan Cameron <Jonathan.Cameron@huawei.com> noticed that we use the NUMA proximity domain of PCI host bridges, but we assume all devices below the host bridge are in the same proximity domain, ignoring any _PXM methods they may have.

He posted a patch (https://lore.kernel.org/linux-pci/20180912152140.3676-2-Jonathan.Cameron@huawei.com) to fix this, but Martin Hundebøll <martin@geanix.com> reported that it caused a regression.  Martin's report had several attachments, so it was rejected by the mailing list.  I'll attach them here (from Message-ID e4bd3423-ae2a-262c-1391-f9741ac4fdd0@geanix.com).

Comment 1 Bjorn Helgaas 2019-01-28 21:15:47 UTC

Created attachment 280835 [details]
DSDT.dsl

Martin's disassembly of DSDT from Message-ID 8a0fd569-fa52-b884-ef0d-18aab1ef8c3f@geanix.com using

  iasl -e SSDT1.asl SSDT2.asl SSDT3.asl SSDT4.asl SSDT5.asl SSDT6.asl 
SSDT7.asl  -d DSDT.asl

Comment 2 Bjorn Helgaas 2019-01-28 21:34:21 UTC

Ingo Molnar <mingo@kernel.org> also reported the regression at https://lore.kernel.org/linux-pci/20181113071712.GA2353@gmail.com on an AMD ThreadRipper system (MSI X399 SLI PLUS (MS-7B09)).

Thomas Lendacky <Thomas.Lendacky@amd.com> reproduced a similar problem by instrumenting a kernel to skip the SRAT, which resulted in a General Protection Fault (https://lore.kernel.org/linux-pci/f27cb1b2-d468-8a07-49f8-475cf0842592@amd.com).