diff mbox series

[4/9] x86/mce: Move machine_check_poll() status checks to helper functions

Message ID 20240523155641.2805411-5-yazen.ghannam@amd.com (mailing list archive)
State New, archived
Headers show
Series AMD MCA interrupts rework | expand

Commit Message

Yazen Ghannam May 23, 2024, 3:56 p.m. UTC 
There are a number of generic and vendor-specific status checks in
machine_check_poll(). These are used to determine if an error should be
skipped.

Move these into helper functions. Future vendor-specific checks will be
added to the helpers.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
---
 arch/x86/kernel/cpu/mce/core.c | 79 +++++++++++++++++-----------------
 1 file changed, 39 insertions(+), 40 deletions(-)

Comments

Borislav Petkov June 3, 2024, 5:37 p.m. UTC | #1 
On Thu, May 23, 2024 at 10:56:36AM -0500, Yazen Ghannam wrote:
> @@ -709,48 +747,9 @@ void machine_check_poll(enum mcp_flags flags, mce_banks_t *b)
>  		if (!mca_cfg.cmci_disabled)
>  			mce_track_storm(&m);
>  
> -		/* If this entry is not valid, ignore it */
> -		if (!(m.status & MCI_STATUS_VAL))
> +		if (!log_poll_error(flags, &m))
>  			continue;
>  
> -		/*
> -		 * If we are logging everything (at CPU online) or this
> -		 * is a corrected error, then we must log it.
> -		 */
> -		if ((flags & MCP_UC) || !(m.status & MCI_STATUS_UC))
> -			goto log_it;
> -
> -		/*
> -		 * Newer Intel systems that support software error
> -		 * recovery need to make additional checks. Other
> -		 * CPUs should skip over uncorrected errors, but log
> -		 * everything else.
> -		 */

You lost that comment.

> -		if (!mca_cfg.ser) {
> -			if (m.status & MCI_STATUS_UC)
> -				continue;
> -			goto log_it;
> -		}
> -
> -		/* Log "not enabled" (speculative) errors */
> -		if (!(m.status & MCI_STATUS_EN))
> -			goto log_it;
> -
> -		/*
> -		 * Log UCNA (SDM: 15.6.3 "UCR Error Classification")
> -		 * UC == 1 && PCC == 0 && S == 0
> -		 */
> -		if (!(m.status & MCI_STATUS_PCC) && !(m.status & MCI_STATUS_S))
> -			goto log_it;
> -
> -		/*
> -		 * Skip anything else. Presumption is that our read of this
> -		 * bank is racing with a machine check. Leave the log alone
> -		 * for do_machine_check() to deal with it.
> -		 */
> -		continue;
> -
> -log_it:
>  		if (flags & MCP_DONTLOG)
>  			goto clear_it;

Btw, the code looks really weird now:

                if (!log_poll_error(flags, &m))
                        continue;

                if (flags & MCP_DONTLOG)
                        goto clear_it;

i.e.,

1. Should I log it?

2. Should I not log it?

Oh well, it was like that before logically so...
Yazen Ghannam July 26, 2024, 2 p.m. UTC | #2 
On Mon, Jun 03, 2024 at 07:37:27PM +0200, Borislav Petkov wrote:
> On Thu, May 23, 2024 at 10:56:36AM -0500, Yazen Ghannam wrote:
> > @@ -709,48 +747,9 @@ void machine_check_poll(enum mcp_flags flags, mce_banks_t *b)
> >  		if (!mca_cfg.cmci_disabled)
> >  			mce_track_storm(&m);
> >  
> > -		/* If this entry is not valid, ignore it */
> > -		if (!(m.status & MCI_STATUS_VAL))
> > +		if (!log_poll_error(flags, &m))
> >  			continue;
> >  
> > -		/*
> > -		 * If we are logging everything (at CPU online) or this
> > -		 * is a corrected error, then we must log it.
> > -		 */
> > -		if ((flags & MCP_UC) || !(m.status & MCI_STATUS_UC))
> > -			goto log_it;
> > -
> > -		/*
> > -		 * Newer Intel systems that support software error
> > -		 * recovery need to make additional checks. Other
> > -		 * CPUs should skip over uncorrected errors, but log
> > -		 * everything else.
> > -		 */
> 
> You lost that comment.
> 

Sorry, will keep it.

> > -		if (!mca_cfg.ser) {
> > -			if (m.status & MCI_STATUS_UC)
> > -				continue;
> > -			goto log_it;
> > -		}
> > -
> > -		/* Log "not enabled" (speculative) errors */
> > -		if (!(m.status & MCI_STATUS_EN))
> > -			goto log_it;
> > -
> > -		/*
> > -		 * Log UCNA (SDM: 15.6.3 "UCR Error Classification")
> > -		 * UC == 1 && PCC == 0 && S == 0
> > -		 */
> > -		if (!(m.status & MCI_STATUS_PCC) && !(m.status & MCI_STATUS_S))
> > -			goto log_it;
> > -
> > -		/*
> > -		 * Skip anything else. Presumption is that our read of this
> > -		 * bank is racing with a machine check. Leave the log alone
> > -		 * for do_machine_check() to deal with it.
> > -		 */
> > -		continue;
> > -
> > -log_it:
> >  		if (flags & MCP_DONTLOG)
> >  			goto clear_it;
> 
> Btw, the code looks really weird now:
> 
>                 if (!log_poll_error(flags, &m))
>                         continue;
> 
>                 if (flags & MCP_DONTLOG)
>                         goto clear_it;
> 
> i.e.,
> 
> 1. Should I log it?
> 
> 2. Should I not log it?
> 
> Oh well, it was like that before logically so...
>

We can rename the new function and add comments. What do you think of
the change below?

Thanks,
Yazen

@@ -797,9 +797,11 @@ void machine_check_poll(enum mcp_flags flags, mce_banks_t *b)
		if (!mca_cfg.cmci_disabled)
			mce_track_storm(&m);

-               if (!log_poll_error(flags, &m, &status_reg))
+               /* Verify that the error should be logged based on hardware conditions. */
+               if (!loggable_poll_error(flags, &m, &status_reg))
			continue;

+               /* Clear a loggable error, e.g., one leftover from boot time. */
		if (flags & MCP_DONTLOG)
			goto clear_it;
Borislav Petkov Aug. 1, 2024, 1:04 p.m. UTC | #3 
On Fri, Jul 26, 2024 at 10:00:30AM -0400, Yazen Ghannam wrote:
> @@ -797,9 +797,11 @@ void machine_check_poll(enum mcp_flags flags, mce_banks_t *b)
> 		if (!mca_cfg.cmci_disabled)
> 			mce_track_storm(&m);
> 
> -               if (!log_poll_error(flags, &m, &status_reg))
> +               /* Verify that the error should be logged based on hardware conditions. */
> +               if (!loggable_poll_error(flags, &m, &status_reg))

Right, or do

		if (!should_log_poll_error(...)

as it becomes maximally readable then - like a plain English sentence.

> 			continue;
> 
> +               /* Clear a loggable error, e.g., one leftover from boot time. */
> 		if (flags & MCP_DONTLOG)
> 			goto clear_it;

So yeah, I guess.
diff mbox series

Patch

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 70c8df1a766a..704e651203b4 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -662,6 +662,44 @@  static noinstr void mce_read_aux(struct mce *m, int i)
 
 DEFINE_PER_CPU(unsigned, mce_poll_count);
 
+static bool ser_log_poll_error(struct mce *m)
+{
+	/* Log "not enabled" (speculative) errors */
+	if (!(m->status & MCI_STATUS_EN))
+		return true;
+
+	/*
+	 * Log UCNA (SDM: 15.6.3 "UCR Error Classification")
+	 * UC == 1 && PCC == 0 && S == 0
+	 */
+	if (!(m->status & MCI_STATUS_PCC) && !(m->status & MCI_STATUS_S))
+		return true;
+
+	return false;
+}
+
+static bool log_poll_error(enum mcp_flags flags, struct mce *m)
+{
+	/* If this entry is not valid, ignore it. */
+	if (!(m->status & MCI_STATUS_VAL))
+		return false;
+
+	/*
+	 * If we are logging everything (at CPU online) or this
+	 * is a corrected error, then we must log it.
+	 */
+	if ((flags & MCP_UC) || !(m->status & MCI_STATUS_UC))
+		return true;
+
+	if (mca_cfg.ser)
+		return ser_log_poll_error(m);
+
+	if (m->status & MCI_STATUS_UC)
+		return false;
+
+	return true;
+}
+
 /*
  * Poll for corrected events or events that happened before reset.
  * Those are just logged through /dev/mcelog.
@@ -709,48 +747,9 @@  void machine_check_poll(enum mcp_flags flags, mce_banks_t *b)
 		if (!mca_cfg.cmci_disabled)
 			mce_track_storm(&m);
 
-		/* If this entry is not valid, ignore it */
-		if (!(m.status & MCI_STATUS_VAL))
+		if (!log_poll_error(flags, &m))
 			continue;
 
-		/*
-		 * If we are logging everything (at CPU online) or this
-		 * is a corrected error, then we must log it.
-		 */
-		if ((flags & MCP_UC) || !(m.status & MCI_STATUS_UC))
-			goto log_it;
-
-		/*
-		 * Newer Intel systems that support software error
-		 * recovery need to make additional checks. Other
-		 * CPUs should skip over uncorrected errors, but log
-		 * everything else.
-		 */
-		if (!mca_cfg.ser) {
-			if (m.status & MCI_STATUS_UC)
-				continue;
-			goto log_it;
-		}
-
-		/* Log "not enabled" (speculative) errors */
-		if (!(m.status & MCI_STATUS_EN))
-			goto log_it;
-
-		/*
-		 * Log UCNA (SDM: 15.6.3 "UCR Error Classification")
-		 * UC == 1 && PCC == 0 && S == 0
-		 */
-		if (!(m.status & MCI_STATUS_PCC) && !(m.status & MCI_STATUS_S))
-			goto log_it;
-
-		/*
-		 * Skip anything else. Presumption is that our read of this
-		 * bank is racing with a machine check. Leave the log alone
-		 * for do_machine_check() to deal with it.
-		 */
-		continue;
-
-log_it:
 		if (flags & MCP_DONTLOG)
 			goto clear_it;