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From: Yazen Ghannam <yazen.ghannam@amd.com>
To: "linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>
Cc: "Ghannam, Yazen" <Yazen.Ghannam@amd.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"bp@suse.de" <bp@suse.de>,
	"tony.luck@intel.com" <tony.luck@intel.com>,
	"x86@kernel.org" <x86@kernel.org>
Subject: [v3,6/6] x86/MCE: Treat MCE bank as initialized if control bits set in hardware
Date: Tue, 30 Apr 2019 20:32:21 +0000
Message-ID: <20190430203206.104163-7-Yazen.Ghannam@amd.com> (raw)

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

The OS is expected to write all bits to MCA_CTL for each bank. However,
some banks may be unused in which case the registers for such banks are
Read-as-Zero/Writes-Ignored. Also, the OS may not write any control bits
because of quirks, etc.

A bank can be considered uninitialized if the MCA_CTL register returns
zero. This is because either the OS did not write anything or because
the hardware is enforcing RAZ/WI for the bank.

Set a bank's init value based on if the control bits are set or not in
hardware.

Return an error code in the sysfs interface for uninitialized banks.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
---
Link:
https://lkml.kernel.org/r/20190411201743.43195-7-Yazen.Ghannam@amd.com

v2->v3:
* No change.

v1->v2:
* New in v2.
* Based on discussion from v1 patch 2.

 arch/x86/kernel/cpu/mce/core.c | 9 +++++++++
 1 file changed, 9 insertions(+)

-- 
2.17.1

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 551366c155ef..e59947e10ee0 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1574,6 +1574,9 @@ static void __mcheck_cpu_init_clear_banks(void)
 
 		/* Save bits set in hardware. */
 		rdmsrl(msr_ops.ctl(i), b->ctl);
+
+		/* Bank is initialized if bits are set in hardware. */
+		b->init = !!b->ctl;
 	}
 }
 
@@ -2098,6 +2101,9 @@ static ssize_t show_bank(struct device *s, struct device_attribute *attr,
 
 	b = &per_cpu(mce_banks_percpu, s->id)[bank];
 
+	if (!b->init)
+		return -ENODEV;
+
 	return sprintf(buf, "%llx\n", b->ctl);
 }
 
@@ -2116,6 +2122,9 @@ static ssize_t set_bank(struct device *s, struct device_attribute *attr,
 
 	b = &per_cpu(mce_banks_percpu, s->id)[bank];
 
+	if (!b->init)
+		return -ENODEV;
+
 	b->ctl = new;
 	mce_restart();
 

From: "Ghannam, Yazen" <Yazen.Ghannam@amd.com>
To: "linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>
Cc: "Ghannam, Yazen" <Yazen.Ghannam@amd.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"bp@suse.de" <bp@suse.de>,
	"tony.luck@intel.com" <tony.luck@intel.com>,
	"x86@kernel.org" <x86@kernel.org>
Subject: [PATCH v3 6/6] x86/MCE: Treat MCE bank as initialized if control bits set in hardware
Date: Tue, 30 Apr 2019 20:32:21 +0000
Message-ID: <20190430203206.104163-7-Yazen.Ghannam@amd.com> (raw)
Message-ID: <20190430203221.pUl2riiA5M7bDkyKvlbhgXre6SNpV0H4cBqMSBMvcLs@z> (raw)
In-Reply-To: <20190430203206.104163-1-Yazen.Ghannam@amd.com>

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

The OS is expected to write all bits to MCA_CTL for each bank. However,
some banks may be unused in which case the registers for such banks are
Read-as-Zero/Writes-Ignored. Also, the OS may not write any control bits
because of quirks, etc.

A bank can be considered uninitialized if the MCA_CTL register returns
zero. This is because either the OS did not write anything or because
the hardware is enforcing RAZ/WI for the bank.

Set a bank's init value based on if the control bits are set or not in
hardware.

Return an error code in the sysfs interface for uninitialized banks.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
---
Link:
https://lkml.kernel.org/r/20190411201743.43195-7-Yazen.Ghannam@amd.com

v2->v3:
* No change.

v1->v2:
* New in v2.
* Based on discussion from v1 patch 2.

 arch/x86/kernel/cpu/mce/core.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 551366c155ef..e59947e10ee0 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1574,6 +1574,9 @@ static void __mcheck_cpu_init_clear_banks(void)
 
 		/* Save bits set in hardware. */
 		rdmsrl(msr_ops.ctl(i), b->ctl);
+
+		/* Bank is initialized if bits are set in hardware. */
+		b->init = !!b->ctl;
 	}
 }
 
@@ -2098,6 +2101,9 @@ static ssize_t show_bank(struct device *s, struct device_attribute *attr,
 
 	b = &per_cpu(mce_banks_percpu, s->id)[bank];
 
+	if (!b->init)
+		return -ENODEV;
+
 	return sprintf(buf, "%llx\n", b->ctl);
 }
 
@@ -2116,6 +2122,9 @@ static ssize_t set_bank(struct device *s, struct device_attribute *attr,
 
 	b = &per_cpu(mce_banks_percpu, s->id)[bank];
 
+	if (!b->init)
+		return -ENODEV;
+
 	b->ctl = new;
 	mce_restart();
 
-- 
2.17.1


         reply index

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-30 20:32 [PATCH v3 0/6] Handle MCA banks in a per_cpu way Ghannam, Yazen
2019-04-30 20:32 ` [v3,1/6] x86/MCE: Make struct mce_banks[] static Yazen Ghannam
2019-04-30 20:32   ` [PATCH v3 1/6] " Ghannam, Yazen
2019-04-30 20:32 ` [v3,2/6] x86/MCE: Handle MCA controls in a per_cpu way Yazen Ghannam
2019-04-30 20:32   ` [PATCH v3 2/6] " Ghannam, Yazen
2019-04-30 20:32 ` [v3,3/6] x86/MCE/AMD: Don't cache block addresses on SMCA systems Yazen Ghannam
2019-04-30 20:32   ` [PATCH v3 3/6] " Ghannam, Yazen
2019-04-30 20:32 ` [v3,5/6] x86/MCE: Save MCA control bits that get set in hardware Yazen Ghannam
2019-04-30 20:32   ` [PATCH v3 5/6] " Ghannam, Yazen
2019-05-16 15:52   ` Luck, Tony
2019-05-16 16:14     ` Ghannam, Yazen
2019-05-16 16:56       ` Borislav Petkov
2019-05-16 17:09         ` Ghannam, Yazen
2019-05-16 17:21           ` Borislav Petkov
2019-05-16 20:20             ` Ghannam, Yazen
2019-05-16 20:34               ` Borislav Petkov
2019-05-16 20:59                 ` Luck, Tony
2019-05-17 10:10                   ` Borislav Petkov
2019-05-17 15:46                     ` Ghannam, Yazen
2019-05-17 16:37                       ` Borislav Petkov
2019-05-17 17:26                         ` Luck, Tony
2019-05-17 17:48                           ` Borislav Petkov
2019-05-17 18:06                             ` Luck, Tony
2019-05-17 19:34                               ` Borislav Petkov
2019-05-17 19:44                                 ` Luck, Tony
2019-05-17 19:50                                   ` Borislav Petkov
2019-05-17 19:49                                 ` Ghannam, Yazen
2019-05-17 20:02                                   ` Borislav Petkov
2019-05-23 20:00                                     ` Ghannam, Yazen
2019-05-27 23:28                                       ` Borislav Petkov
2019-06-07 14:49                                         ` Ghannam, Yazen
2019-06-07 16:37                                           ` Borislav Petkov
2019-06-07 16:44                                             ` Ghannam, Yazen
2019-06-07 16:59                                               ` Borislav Petkov
2019-06-07 17:08                                                 ` Ghannam, Yazen
2019-06-07 17:20                                                   ` Borislav Petkov
2019-06-11  5:13                                             ` Borislav Petkov
2019-04-30 20:32 ` [v3,4/6] x86/MCE: Make number of MCA banks per_cpu Yazen Ghannam
2019-04-30 20:32   ` [PATCH v3 4/6] " Ghannam, Yazen
2019-05-18 11:25   ` Borislav Petkov
2019-05-21 17:52     ` Ghannam, Yazen
2019-05-21 20:29       ` Borislav Petkov
2019-05-21 20:42         ` Luck, Tony
2019-05-21 23:09           ` Borislav Petkov
2019-05-22 14:01             ` Ghannam, Yazen
2019-04-30 20:32 ` Yazen Ghannam [this message]
2019-04-30 20:32   ` [PATCH v3 6/6] x86/MCE: Treat MCE bank as initialized if control bits set in hardware Ghannam, Yazen

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