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

Yazen Ghannam
2024-07-26T14:00:44Z

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;