* [linux-safety] [PATCH v2 1/5] x86/mce: do not overwrite no_way_out if mce_end() fails
2020-11-27 16:18 [linux-safety] [PATCH v2 0/5] x86/MCE: some minor fixes Paoloni, Gabriele
@ 2020-11-27 16:18 ` Paoloni, Gabriele
2020-11-27 16:18 ` [linux-safety] [PATCH v2 2/5] x86/mce: move the mce_panic() call and 'kill_it' assignments to the right places Paoloni, Gabriele
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Paoloni, Gabriele @ 2020-11-27 16:18 UTC (permalink / raw)
To: tony.luck, bp, tglx, mingo, x86, hpa, linux-edac, linux-kernel
Cc: gabriele.paoloni, linux-safety
Currently if mce_end() fails 'no_way_out' is set equal to 'worst'.
'worst' is the worst severity that was found across the MCA banks
associated with the current CPU; however at this point 'no_way_out'
could have been already set by mca_start() by looking at all
severities of all CPUs that entered the MCE handler.
If mce_end() fails, check first if no_way_out is already set and,
if so, stick to it, otherwise use the local worst value.
Cc: <stable@vger.kernel.org>
Signed-off-by: Gabriele Paoloni <gabriele.paoloni@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
arch/x86/kernel/cpu/mce/core.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 4102b866e7c0..32b7099e3511 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1384,8 +1384,10 @@ noinstr void do_machine_check(struct pt_regs *regs)
* When there's any problem use only local no_way_out state.
*/
if (!lmce) {
- if (mce_end(order) < 0)
- no_way_out = worst >= MCE_PANIC_SEVERITY;
+ if (mce_end(order) < 0) {
+ if (!no_way_out)
+ no_way_out = worst >= MCE_PANIC_SEVERITY;
+ }
} else {
/*
* If there was a fatal machine check we should have
--
2.20.1
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^ permalink raw reply related [flat|nested] 6+ messages in thread* [linux-safety] [PATCH v2 2/5] x86/mce: move the mce_panic() call and 'kill_it' assignments to the right places
2020-11-27 16:18 [linux-safety] [PATCH v2 0/5] x86/MCE: some minor fixes Paoloni, Gabriele
2020-11-27 16:18 ` [linux-safety] [PATCH v2 1/5] x86/mce: do not overwrite no_way_out if mce_end() fails Paoloni, Gabriele
@ 2020-11-27 16:18 ` Paoloni, Gabriele
2020-11-27 16:18 ` [linux-safety] [PATCH v2 3/5] x86/mce: for LMCE panic only if mca_cfg.tolerant < 3 Paoloni, Gabriele
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Paoloni, Gabriele @ 2020-11-27 16:18 UTC (permalink / raw)
To: tony.luck, bp, tglx, mingo, x86, hpa, linux-edac, linux-kernel
Cc: gabriele.paoloni, linux-safety
Right now for local MCEs we panic(),if needed, right after lmce is
set. For global MCEs mce_reign() takes care of calling mce_panic().
Hence:
- improve readibility by moving the conditional evaluation of
tolerant up to when kill_it is set first;
- move the mce_panic() call up into the statement where mce_end()
fails.
Signed-off-by: Gabriele Paoloni <gabriele.paoloni@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
arch/x86/kernel/cpu/mce/core.c | 18 +++++++-----------
1 file changed, 7 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 32b7099e3511..50e9b0893a92 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1350,8 +1350,7 @@ noinstr void do_machine_check(struct pt_regs *regs)
* severity is MCE_AR_SEVERITY we have other options.
*/
if (!(m.mcgstatus & MCG_STATUS_RIPV))
- kill_it = 1;
-
+ kill_it = (cfg->tolerant == 3) ? 0 : 1;
/*
* Check if this MCE is signaled to only this logical processor,
* on Intel, Zhaoxin only.
@@ -1387,6 +1386,12 @@ noinstr void do_machine_check(struct pt_regs *regs)
if (mce_end(order) < 0) {
if (!no_way_out)
no_way_out = worst >= MCE_PANIC_SEVERITY;
+ /*
+ * mce_reign() has probably failed hence evaluate if we need
+ * to panic
+ */
+ if (no_way_out && mca_cfg.tolerant < 3)
+ mce_panic("Fatal machine check on current CPU", &m, msg);
}
} else {
/*
@@ -1403,15 +1408,6 @@ noinstr void do_machine_check(struct pt_regs *regs)
}
}
- /*
- * If tolerant is at an insane level we drop requests to kill
- * processes and continue even when there is no way out.
- */
- if (cfg->tolerant == 3)
- kill_it = 0;
- else if (no_way_out)
- mce_panic("Fatal machine check on current CPU", &m, msg);
-
if (worst > 0)
irq_work_queue(&mce_irq_work);
--
2.20.1
---------------------------------------------------------------------
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^ permalink raw reply related [flat|nested] 6+ messages in thread* [linux-safety] [PATCH v2 3/5] x86/mce: for LMCE panic only if mca_cfg.tolerant < 3
2020-11-27 16:18 [linux-safety] [PATCH v2 0/5] x86/MCE: some minor fixes Paoloni, Gabriele
2020-11-27 16:18 ` [linux-safety] [PATCH v2 1/5] x86/mce: do not overwrite no_way_out if mce_end() fails Paoloni, Gabriele
2020-11-27 16:18 ` [linux-safety] [PATCH v2 2/5] x86/mce: move the mce_panic() call and 'kill_it' assignments to the right places Paoloni, Gabriele
@ 2020-11-27 16:18 ` Paoloni, Gabriele
2020-11-27 16:18 ` [linux-safety] [PATCH v2 4/5] x86/mce: remove redundant call to irq_work_queue() Paoloni, Gabriele
2020-11-27 16:18 ` [linux-safety] [PATCH v2 5/5] x86/mce: rename kill_it as kill_current_task Paoloni, Gabriele
4 siblings, 0 replies; 6+ messages in thread
From: Paoloni, Gabriele @ 2020-11-27 16:18 UTC (permalink / raw)
To: tony.luck, bp, tglx, mingo, x86, hpa, linux-edac, linux-kernel
Cc: gabriele.paoloni, linux-safety
Right now for LMCE if no_way_out is set mce_panic() is called
regardless of mca_cfg.tolerant. This is not correct as, if
mca_cfg.tolerant = 3, the code should never panic.
Signed-off-by: Gabriele Paoloni <gabriele.paoloni@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
arch/x86/kernel/cpu/mce/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 50e9b0893a92..d766a3f6a343 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1367,7 +1367,7 @@ noinstr void do_machine_check(struct pt_regs *regs)
* to see it will clear it.
*/
if (lmce) {
- if (no_way_out)
+ if (no_way_out && mca_cfg.tolerant < 3)
mce_panic("Fatal local machine check", &m, msg);
} else {
order = mce_start(&no_way_out);
--
2.20.1
---------------------------------------------------------------------
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^ permalink raw reply related [flat|nested] 6+ messages in thread* [linux-safety] [PATCH v2 4/5] x86/mce: remove redundant call to irq_work_queue()
2020-11-27 16:18 [linux-safety] [PATCH v2 0/5] x86/MCE: some minor fixes Paoloni, Gabriele
` (2 preceding siblings ...)
2020-11-27 16:18 ` [linux-safety] [PATCH v2 3/5] x86/mce: for LMCE panic only if mca_cfg.tolerant < 3 Paoloni, Gabriele
@ 2020-11-27 16:18 ` Paoloni, Gabriele
2020-11-27 16:18 ` [linux-safety] [PATCH v2 5/5] x86/mce: rename kill_it as kill_current_task Paoloni, Gabriele
4 siblings, 0 replies; 6+ messages in thread
From: Paoloni, Gabriele @ 2020-11-27 16:18 UTC (permalink / raw)
To: tony.luck, bp, tglx, mingo, x86, hpa, linux-edac, linux-kernel
Cc: gabriele.paoloni, linux-safety
Right now in do_machine_check() __mc_scan_banks() triggers
the following call tree:
__mc_scan_banks()->mce_log()->irq_work_queue(&mce_irq_work).
Hence the call of irq_work_queue() below after __mc_scan_banks()
seems redundant. Just remove it.
Signed-off-by: Gabriele Paoloni <gabriele.paoloni@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
arch/x86/kernel/cpu/mce/core.c | 3 ---
1 file changed, 3 deletions(-)
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index d766a3f6a343..802302c54762 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1408,9 +1408,6 @@ noinstr void do_machine_check(struct pt_regs *regs)
}
}
- if (worst > 0)
- irq_work_queue(&mce_irq_work);
-
if (worst != MCE_AR_SEVERITY && !kill_it)
goto out;
--
2.20.1
---------------------------------------------------------------------
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^ permalink raw reply related [flat|nested] 6+ messages in thread* [linux-safety] [PATCH v2 5/5] x86/mce: rename kill_it as kill_current_task
2020-11-27 16:18 [linux-safety] [PATCH v2 0/5] x86/MCE: some minor fixes Paoloni, Gabriele
` (3 preceding siblings ...)
2020-11-27 16:18 ` [linux-safety] [PATCH v2 4/5] x86/mce: remove redundant call to irq_work_queue() Paoloni, Gabriele
@ 2020-11-27 16:18 ` Paoloni, Gabriele
4 siblings, 0 replies; 6+ messages in thread
From: Paoloni, Gabriele @ 2020-11-27 16:18 UTC (permalink / raw)
To: tony.luck, bp, tglx, mingo, x86, hpa, linux-edac, linux-kernel
Cc: gabriele.paoloni, linux-safety
Currently if an MCE happens in user-mode or while the kernel
is copying data from user space, 'kill_it' is used to check
if we can recover the execution of the interrupted task or
not; the flag name however is not much meaningful, hence
rename it to match its goal.
Signed-off-by: Gabriele Paoloni <gabriele.paoloni@intel.com>
---
arch/x86/kernel/cpu/mce/core.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 802302c54762..740a4fcc1e90 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1320,10 +1320,10 @@ noinstr void do_machine_check(struct pt_regs *regs)
int no_way_out = 0;
/*
- * If kill_it gets set, there might be a way to recover from this
+ * If kill_current_task is not set, there might be a way to recover from this
* error.
*/
- int kill_it = 0;
+ int kill_current_task = 0;
/*
* MCEs are always local on AMD. Same is determined by MCG_STATUS_LMCES
@@ -1350,7 +1350,7 @@ noinstr void do_machine_check(struct pt_regs *regs)
* severity is MCE_AR_SEVERITY we have other options.
*/
if (!(m.mcgstatus & MCG_STATUS_RIPV))
- kill_it = (cfg->tolerant == 3) ? 0 : 1;
+ kill_current_task = (cfg->tolerant == 3) ? 0 : 1;
/*
* Check if this MCE is signaled to only this logical processor,
* on Intel, Zhaoxin only.
@@ -1408,7 +1408,7 @@ noinstr void do_machine_check(struct pt_regs *regs)
}
}
- if (worst != MCE_AR_SEVERITY && !kill_it)
+ if (worst != MCE_AR_SEVERITY && !kill_current_task)
goto out;
/* Fault was in user mode and we need to take some action */
@@ -1416,7 +1416,7 @@ noinstr void do_machine_check(struct pt_regs *regs)
/* If this triggers there is no way to recover. Die hard. */
BUG_ON(!on_thread_stack() || !user_mode(regs));
- queue_task_work(&m, kill_it);
+ queue_task_work(&m, kill_current_task);
} else {
/*
@@ -1434,7 +1434,7 @@ noinstr void do_machine_check(struct pt_regs *regs)
}
if (m.kflags & MCE_IN_KERNEL_COPYIN)
- queue_task_work(&m, kill_it);
+ queue_task_work(&m, kill_current_task);
}
out:
mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);
--
2.20.1
---------------------------------------------------------------------
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^ permalink raw reply related [flat|nested] 6+ messages in thread