87 lines
3.5 KiB
Diff
87 lines
3.5 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Yazen Ghannam <yazen.ghannam@amd.com>
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Date: Thu, 21 Nov 2019 08:15:08 -0600
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Subject: [PATCH] x86/MCE/AMD: Allow Reserved types to be overwritten in
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smca_banks[]
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Each logical CPU in Scalable MCA systems controls a unique set of MCA
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banks in the system. These banks are not shared between CPUs. The bank
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types and ordering will be the same across CPUs on currently available
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systems.
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However, some CPUs may see a bank as Reserved/Read-as-Zero (RAZ) while
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other CPUs do not. In this case, the bank seen as Reserved on one CPU is
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assumed to be the same type as the bank seen as a known type on another
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CPU.
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In general, this occurs when the hardware represented by the MCA bank
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is disabled, e.g. disabled memory controllers on certain models, etc.
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The MCA bank is disabled in the hardware, so there is no possibility of
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getting an MCA/MCE from it even if it is assumed to have a known type.
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For example:
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Full system:
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Bank | Type seen on CPU0 | Type seen on CPU1
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------------------------------------------------
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0 | LS | LS
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1 | UMC | UMC
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2 | CS | CS
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System with hardware disabled:
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Bank | Type seen on CPU0 | Type seen on CPU1
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------------------------------------------------
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0 | LS | LS
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1 | UMC | RAZ
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2 | CS | CS
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For this reason, there is a single, global struct smca_banks[] that is
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initialized at boot time. This array is initialized on each CPU as it
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comes online. However, the array will not be updated if an entry already
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exists.
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This works as expected when the first CPU (usually CPU0) has all
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possible MCA banks enabled. But if the first CPU has a subset, then it
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will save a "Reserved" type in smca_banks[]. Successive CPUs will then
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not be able to update smca_banks[] even if they encounter a known bank
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type.
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This may result in unexpected behavior. Depending on the system
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configuration, a user may observe issues enumerating the MCA
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thresholding sysfs interface. The issues may be as trivial as sysfs
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entries not being available, or as severe as system hangs.
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For example:
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Bank | Type seen on CPU0 | Type seen on CPU1
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------------------------------------------------
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0 | LS | LS
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1 | RAZ | UMC
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2 | CS | CS
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Extend the smca_banks[] entry check to return if the entry is a
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non-reserved type. Otherwise, continue so that CPUs that encounter a
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known bank type can update smca_banks[].
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Fixes: 68627a697c19 ("x86/mce/AMD, EDAC/mce_amd: Enumerate Reserved SMCA bank type")
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Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
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Signed-off-by: Borislav Petkov <bp@suse.de>
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Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
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---
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arch/x86/kernel/cpu/mce/amd.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/arch/x86/kernel/cpu/mce/amd.c b/arch/x86/kernel/cpu/mce/amd.c
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index 6ea7fdc82f3c..08e09c8c269f 100644
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--- a/arch/x86/kernel/cpu/mce/amd.c
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+++ b/arch/x86/kernel/cpu/mce/amd.c
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@@ -266,7 +266,7 @@ static void smca_configure(unsigned int bank, unsigned int cpu)
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smca_set_misc_banks_map(bank, cpu);
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/* Return early if this bank was already initialized. */
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- if (smca_banks[bank].hwid)
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+ if (smca_banks[bank].hwid && smca_banks[bank].hwid->hwid_mcatype != 0)
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return;
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if (rdmsr_safe_on_cpu(cpu, MSR_AMD64_SMCA_MCx_IPID(bank), &low, &high)) {
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