x86/amd_nb: Simplify root device search

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The "root" device search was introduced to support SMN access for Zen
systems. This device represents a PCIe root complex. It is not the
same as the "CPU/node" devices found at slots 0x18-0x1F.

There may be multiple PCIe root complexes within an AMD node. Such is
the case with server or High-end Desktop (HEDT) systems, etc. Therefore
it is not enough to assume "root <-> AMD node" is a 1-to-1 association.

Currently, this is handled by skipping "extra" root complexes during the
search. However, the hardware provides the PCI bus number of an AMD
node's root device.

Use the hardware info to get the root device's bus and drop the extra
search code and PCI IDs.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20241206161210.163701-7-yazen.ghannam@amd.com

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This commit is contained in:

Yazen Ghannam 2024-12-06 16:11:59 +00:00 • committed by Borislav Petkov (AMD)

parent 962f1970a3

commit 40a5f6ffdf

3 changed files with 61 additions and 76 deletions

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arch/x86/include/asm/amd_node.h

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arch/x86/kernel/amd_nb.c

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arch/x86/kernel/amd_node.c

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