Linux-EDAC Archive on lore.kernel.org
 help / color / Atom feed
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Yazen Ghannam <yazen.ghannam@amd.com>,
	Borislav Petkov <bp@suse.de>, "H. Peter Anvin" <hpa@zytor.com>,
	Ingo Molnar <mingo@kernel.org>,
	linux-edac <linux-edac@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Tony Luck <tony.luck@intel.com>, x86-ml <x86@kernel.org>
Subject: [PATCH 4.14 156/161] x86/MCE/AMD: Allow Reserved types to be overwritten in smca_banks[]
Date: Sun, 29 Dec 2019 18:20:04 +0100
Message-ID: <20191229162449.201703020@linuxfoundation.org> (raw)
In-Reply-To: <20191229162355.500086350@linuxfoundation.org>

From: Yazen Ghannam <yazen.ghannam@amd.com>

commit 966af20929ac24360ba3fac5533eb2ab003747da upstream.

Each logical CPU in Scalable MCA systems controls a unique set of MCA
banks in the system. These banks are not shared between CPUs. The bank
types and ordering will be the same across CPUs on currently available
systems.

However, some CPUs may see a bank as Reserved/Read-as-Zero (RAZ) while
other CPUs do not. In this case, the bank seen as Reserved on one CPU is
assumed to be the same type as the bank seen as a known type on another
CPU.

In general, this occurs when the hardware represented by the MCA bank
is disabled, e.g. disabled memory controllers on certain models, etc.
The MCA bank is disabled in the hardware, so there is no possibility of
getting an MCA/MCE from it even if it is assumed to have a known type.

For example:

Full system:
	Bank  |  Type seen on CPU0  |  Type seen on CPU1
	------------------------------------------------
	 0    |         LS          |          LS
	 1    |         UMC         |          UMC
	 2    |         CS          |          CS

System with hardware disabled:
	Bank  |  Type seen on CPU0  |  Type seen on CPU1
	------------------------------------------------
	 0    |         LS          |          LS
	 1    |         UMC         |          RAZ
	 2    |         CS          |          CS

For this reason, there is a single, global struct smca_banks[] that is
initialized at boot time. This array is initialized on each CPU as it
comes online. However, the array will not be updated if an entry already
exists.

This works as expected when the first CPU (usually CPU0) has all
possible MCA banks enabled. But if the first CPU has a subset, then it
will save a "Reserved" type in smca_banks[]. Successive CPUs will then
not be able to update smca_banks[] even if they encounter a known bank
type.

This may result in unexpected behavior. Depending on the system
configuration, a user may observe issues enumerating the MCA
thresholding sysfs interface. The issues may be as trivial as sysfs
entries not being available, or as severe as system hangs.

For example:

	Bank  |  Type seen on CPU0  |  Type seen on CPU1
	------------------------------------------------
	 0    |         LS          |          LS
	 1    |         RAZ         |          UMC
	 2    |         CS          |          CS

Extend the smca_banks[] entry check to return if the entry is a
non-reserved type. Otherwise, continue so that CPUs that encounter a
known bank type can update smca_banks[].

Fixes: 68627a697c19 ("x86/mce/AMD, EDAC/mce_amd: Enumerate Reserved SMCA bank type")
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: linux-edac <linux-edac@vger.kernel.org>
Cc: <stable@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20191121141508.141273-1-Yazen.Ghannam@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/kernel/cpu/mcheck/mce_amd.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kernel/cpu/mcheck/mce_amd.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c
@@ -228,7 +228,7 @@ static void smca_configure(unsigned int
 	}
 
 	/* Return early if this bank was already initialized. */
-	if (smca_banks[bank].hwid)
+	if (smca_banks[bank].hwid && smca_banks[bank].hwid->hwid_mcatype != 0)
 		return;
 
 	if (rdmsr_safe(MSR_AMD64_SMCA_MCx_IPID(bank), &low, &high)) {



      parent reply index

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20191229162355.500086350@linuxfoundation.org>
2019-12-29 17:18 ` [PATCH 4.14 066/161] x86/mce: Lower throttling MCE messages priority to warning Greg Kroah-Hartman
2019-12-29 17:19 ` [PATCH 4.14 111/161] EDAC/ghes: Fix grain calculation Greg Kroah-Hartman
2019-12-29 17:20 ` [PATCH 4.14 155/161] x86/MCE/AMD: Do not use rdmsr_safe_on_cpu() in smca_configure() Greg Kroah-Hartman
2019-12-29 17:20 ` Greg Kroah-Hartman [this message]

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191229162449.201703020@linuxfoundation.org \
    --to=gregkh@linuxfoundation.org \
    --cc=bp@suse.de \
    --cc=hpa@zytor.com \
    --cc=linux-edac@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@kernel.org \
    --cc=stable@vger.kernel.org \
    --cc=tglx@linutronix.de \
    --cc=tony.luck@intel.com \
    --cc=x86@kernel.org \
    --cc=yazen.ghannam@amd.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-EDAC Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-edac/0 linux-edac/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-edac linux-edac/ https://lore.kernel.org/linux-edac \
		linux-edac@vger.kernel.org
	public-inbox-index linux-edac

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-edac


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git