From: Borislav Petkov <bp@alien8.de>
To: Juergen Gross <jgross@suse.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH v4 09/12] x86/mtrr: construct a memory map with cache modes
Date: Sat, 1 Apr 2023 16:24:19 +0200 [thread overview]
Message-ID: <20230401142419.GCZCg+k9fgFPdAO4c/@fat_crate.local> (raw)
In-Reply-To: <8860c326-3ba5-bd4c-1dab-17772e8fcda0@suse.com>
On Fri, Mar 31, 2023 at 03:23:13PM +0200, Juergen Gross wrote:
> In general the critical case is add_map_entry_at() returning 2 (in the
> case it is returning 1, the index can be set to -1, but there is always
> the "continue" statement right after that, which would execute the "i++"
> of the "for" statement).
>
> add_map_entry_at() can return 2 only, if it detects "merge_prev" and
> "merge_next". "merge_prev" can be set only if the current index was > 0,
> which makes it impossible to return 2 if the index was 0.
Yeah, in the meantime I did add some debug printks in order to find my
way around that code...
> How should it be named? AMD TOP_MEM2 MSR?
It is already called that way - see "git grep TOP_MEM2" output.
> The problem isn't an added MTRR register, but a possibly replaced or removed
> one. Handling that is much more complicated, so I've chosen to do it the simple
> way.
Pls put that blurb over the function: needs to be called when MTRRs get
modified so that the map is kept valid, yadda yadda...
> In the end I'd expect setting of MTRRs to be a rare event, so there shouldn't be
> a performance issue with that approach.
Ack.
> Okay, I'll add some more comments.
Thx.
> OTOH, what was hard to write should be hard to read (just kidding).
I'm not kidding - it is not super easy.
:-)
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2023-04-01 14:24 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-06 16:34 [PATCH v4 00/12] x86/mtrr: fix handling with PAT but without MTRR Juergen Gross
2023-03-06 16:34 ` [PATCH v4 01/12] x86/mtrr: split off physical address size calculation Juergen Gross
2023-03-06 16:34 ` [PATCH v4 02/12] x86/mtrr: optimize mtrr_calc_physbits() Juergen Gross
2023-03-20 12:50 ` Borislav Petkov
2023-03-06 16:34 ` [PATCH v4 03/12] x86/mtrr: support setting MTRR state for software defined MTRRs Juergen Gross
2023-03-20 12:59 ` Huang, Kai
2023-03-20 13:47 ` Juergen Gross
2023-03-20 21:34 ` Huang, Kai
2023-03-20 22:42 ` Borislav Petkov
2023-03-21 6:01 ` Juergen Gross
2023-03-20 19:05 ` Borislav Petkov
2023-03-21 6:00 ` Juergen Gross
2023-03-21 10:30 ` Borislav Petkov
2023-03-21 15:49 ` Juergen Gross
2023-03-06 16:34 ` [PATCH v4 04/12] x86/hyperv: set MTRR state when running as SEV-SNP Hyper-V guest Juergen Gross
2023-03-06 16:34 ` [PATCH v4 05/12] x86/xen: set MTRR state when running as Xen PV initial domain Juergen Gross
2023-03-07 21:47 ` Boris Ostrovsky
2023-03-23 12:43 ` Borislav Petkov
2023-03-06 16:34 ` [PATCH v4 06/12] x86/mtrr: replace vendor tests in MTRR code Juergen Gross
2023-03-24 16:56 ` Borislav Petkov
2023-03-27 5:43 ` Juergen Gross
2023-03-27 7:14 ` Borislav Petkov
2023-03-06 16:34 ` [PATCH v4 07/12] x86/mtrr: allocate mtrr_value array dynamically Juergen Gross
2023-03-20 12:25 ` Huang, Kai
2023-03-20 13:49 ` Juergen Gross
2023-03-20 15:31 ` Dave Hansen
2023-03-20 15:49 ` Juergen Gross
2023-03-26 22:05 ` Borislav Petkov
2023-03-27 5:44 ` Juergen Gross
2023-03-06 16:34 ` [PATCH v4 08/12] x86/mtrr: add get_effective_type() service function Juergen Gross
2023-03-06 16:34 ` [PATCH v4 09/12] x86/mtrr: construct a memory map with cache modes Juergen Gross
2023-03-29 12:51 ` Borislav Petkov
2023-03-29 13:39 ` Juergen Gross
2023-03-31 12:55 ` Borislav Petkov
2023-03-31 13:23 ` Juergen Gross
2023-04-01 14:24 ` Borislav Petkov [this message]
2023-04-03 6:57 ` Juergen Gross
2023-03-31 12:57 ` Borislav Petkov
2023-03-31 13:35 ` Juergen Gross
2023-04-01 14:26 ` Borislav Petkov
2023-04-03 7:02 ` Juergen Gross
2023-03-06 16:34 ` [PATCH v4 10/12] x86/mtrr: use new cache_map in mtrr_type_lookup() Juergen Gross
2023-03-06 16:34 ` [PATCH v4 11/12] x86/mtrr: don't let mtrr_type_lookup() return MTRR_TYPE_INVALID Juergen Gross
2023-03-06 16:34 ` [PATCH v4 12/12] x86/mm: only check uniform after calling mtrr_type_lookup() Juergen Gross
2023-03-07 21:09 ` [PATCH v4 00/12] x86/mtrr: fix handling with PAT but without MTRR Michael Kelley (LINUX)
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230401142419.GCZCg+k9fgFPdAO4c/@fat_crate.local \
--to=bp@alien8.de \
--cc=dave.hansen@linux.intel.com \
--cc=hpa@zytor.com \
--cc=jgross@suse.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.