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Groups > linux.kernel > #1355984
| From | Toshi Kani <toshi.kani@hpe.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table |
| Date | 2016-03-11 16:40 +0100 |
| Message-ID | <rbxkt-8dl-7@gated-at.bofh.it> (permalink) |
| References | <rbmp4-f1-7@gated-at.bofh.it> <rbmp4-f1-5@gated-at.bofh.it> <rbroJ-3VO-11@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Fri, 2016-03-11 at 09:12 +0000, Borislav Petkov wrote:
> On Thu, Mar 10, 2016 at 09:45:45PM -0700, Toshi Kani wrote:
:
> >
> > -static inline void pat_disable(const char *reason)
> > +void pat_disable(const char *reason)
> > {
> > + if (boot_cpu_done) {
> > + pr_info("x86/PAT: PAT cannot be disabled after
> > initialized\n");
>
> pr_err()
Will do.
>
> > + return;
> > + }
> > +
> > __pat_enabled = 0;
> > pr_info("x86/PAT: %s\n", reason);
> > +
> > + pat_disable_init();
>
> Why can't you call pat_init() here simply? It checks pat_enabled(). You
> can call it pat_setup() or so if it looks confusing to call an init
> function in a disable function...
How about pat_disable_setup()? It's only used for the disabled case, so
I'd prefer to keep the word "disable".
Yes, calling pat_init() from pat_disable() works too. I changed it in this
way because:
- pat_bsp_init() calls pat_disabled() in an error case. It is simpler to
avoid a recursive call to pat_init().
- pat_bsp_init() has two different error paths, 1) call pat_disable() and
return, and 2) goto done and call pat_init_cache_modes(). We can remove
case 2) to keep the error handling consistent in this way.
> Then you don't have to add yet another static disable_init_done but rely
> on boot_cpu_done which gets set in pat_init().
Right, but it will do 'boot_cpu_done = true' twice, and this implicit
recursive call may cause an issue in future if someone makes change
carelessly.
> Also, I don't see the static_cpu_has() check I suggested yesterday - we
> need to check the feature bits if PAT gets disabled early on some old
> Intels.
Sorry, I should have mentioned it. I ended up not needing this change. The
table in patch 2/2 covers this case as:
MTRR PAT ACTION
====================================================================
E D MTRR calls pat_init() -> PAT disabled per cpu_has_pat
That is, the check with cpu_has_pat in pat_bsp_init() calls pat_disable()
in this case. I preferred this way because it will continue to log a
message "PAT not supported by CPU.", and keeps __pat_enabled as the single
variable to manage the PAT state.
Thanks,
-Toshi
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[PATCH 0/2] Refactor MTRR and PAT initializations Toshi Kani <toshi.kani@hpe.com> - 2016-03-11 05:00 +0100
[PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Toshi Kani <toshi.kani@hpe.com> - 2016-03-11 05:00 +0100
Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Borislav Petkov <bp@alien8.de> - 2016-03-11 10:20 +0100
Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Toshi Kani <toshi.kani@hpe.com> - 2016-03-11 16:40 +0100
Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Borislav Petkov <bp@alien8.de> - 2016-03-11 17:00 +0100
Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Toshi Kani <toshi.kani@hpe.com> - 2016-03-11 19:40 +0100
Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Borislav Petkov <bp@alien8.de> - 2016-03-12 13:00 +0100
Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Toshi Kani <toshi.kani@hpe.com> - 2016-03-14 21:50 +0100
Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Borislav Petkov <bp@alien8.de> - 2016-03-15 12:10 +0100
Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Toshi Kani <toshi.kani@hpe.com> - 2016-03-15 22:10 +0100
Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-03-15 01:30 +0100
Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Toshi Kani <toshi.kani@hpe.com> - 2016-03-15 03:20 +0100
Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Borislav Petkov <bp@alien8.de> - 2016-03-15 12:10 +0100
Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Toshi Kani <toshi.kani@hpe.com> - 2016-03-15 16:00 +0100
Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Borislav Petkov <bp@alien8.de> - 2016-03-15 16:50 +0100
Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Toshi Kani <toshi.kani@hpe.com> - 2016-03-15 17:20 +0100
Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table Borislav Petkov <bp@alien8.de> - 2016-03-15 17:40 +0100
Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-03-15 22:40 +0100
[PATCH 2/2] x86/mtrr: Refactor PAT initialization code Toshi Kani <toshi.kani@hpe.com> - 2016-03-11 05:00 +0100
Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Ingo Molnar <mingo@kernel.org> - 2016-03-11 10:10 +0100
Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Ingo Molnar <mingo@kernel.org> - 2016-03-11 10:20 +0100
Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Toshi Kani <toshi.kani@hpe.com> - 2016-03-11 18:50 +0100
Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Ingo Molnar <mingo@kernel.org> - 2016-03-12 17:20 +0100
Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Toshi Kani <toshi.kani@hpe.com> - 2016-03-14 20:00 +0100
Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code "Luis R. Rodriguez" <mcgrof@suse.com> - 2016-03-15 00:00 +0100
Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Toshi Kani <toshi.kani@hpe.com> - 2016-03-15 00:50 +0100
Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Borislav Petkov <bp@suse.de> - 2016-03-15 17:00 +0100
Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Borislav Petkov <bp@alien8.de> - 2016-03-11 10:30 +0100
Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Toshi Kani <toshi.kani@hpe.com> - 2016-03-11 19:10 +0100
Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-03-11 23:20 +0100
Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Toshi Kani <toshi.kani@hpe.com> - 2016-03-12 00:10 +0100
Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-03-12 00:40 +0100
Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Toshi Kani <toshi.kani@hpe.com> - 2016-03-12 01:30 +0100
Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-03-15 01:20 +0100
Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code Toshi Kani <toshi.kani@hpe.com> - 2016-03-16 00:00 +0100
Re: [PATCH 2/2] x86/mtrr: Refactor PAT initialization code "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-03-16 00:30 +0100
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