From: Borislav Petkov <bp@alien8.de>
To: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Lutomirski <luto@kernel.org>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
lkml <linux-kernel@vger.kernel.org>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH] x86/PAT: have pat_enabled() properly reflect state when running on e.g. Xen
Date: Tue, 5 Jul 2022 17:04:32 +0200 [thread overview]
Message-ID: <YsRTAGI2PhfZ5V7M@zn.tnic> (raw)
In-Reply-To: <9385fa60-fa5d-f559-a137-6608408f88b0@suse.com>
On Thu, Apr 28, 2022 at 04:50:29PM +0200, Jan Beulich wrote:
> --- a/arch/x86/mm/pat/memtype.c
> +++ b/arch/x86/mm/pat/memtype.c
> @@ -62,6 +62,7 @@
>
> static bool __read_mostly pat_bp_initialized;
> static bool __read_mostly pat_disabled = !IS_ENABLED(CONFIG_X86_PAT);
> +static bool __initdata pat_force_disabled = !IS_ENABLED(CONFIG_X86_PAT);
> static bool __read_mostly pat_bp_enabled;
> static bool __read_mostly pat_cm_initialized;
Why yet another boolean var?
Why not extend pat_enabled() to reflect the Xen case and explain it
properly above it?
My comment is likely wrong because I don't know what the Xen HV hides or
doesn't but you get the idea...
diff --git a/arch/x86/mm/pat/memtype.c b/arch/x86/mm/pat/memtype.c
index d5ef64ddd35e..a8f1a02f9bc2 100644
--- a/arch/x86/mm/pat/memtype.c
+++ b/arch/x86/mm/pat/memtype.c
@@ -92,6 +92,13 @@ early_param("nopat", nopat);
bool pat_enabled(void)
{
+ /*
+ * Xen PV doesn't expose the PAT MSR to dom0 so the proper init path
+ * there cannot be exercised. Announce PAT is enabled in that case too.
+ */
+ if (cpu_feature_enabled(X86_FEATURE_XENPV) && !pat_disabled)
+ return true;
+
return pat_bp_enabled;
}
EXPORT_SYMBOL_GPL(pat_enabled);
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2022-07-05 15:08 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-28 14:50 [PATCH] x86/PAT: have pat_enabled() properly reflect state when running on e.g. Xen Jan Beulich
2022-05-03 12:54 ` Juergen Gross
2022-05-11 13:32 ` Juergen Gross
2022-05-21 13:56 ` Chuck Zmudzinski
2022-05-25 8:55 ` Ping: " Jan Beulich
2022-07-04 11:58 ` Thorsten Leemhuis
2022-07-04 12:26 ` Jan Beulich
2022-07-05 10:57 ` Thorsten Leemhuis
2022-07-05 11:02 ` Jan Beulich
2022-07-05 13:36 ` Borislav Petkov
2022-07-05 13:38 ` Juergen Gross
2022-07-14 17:17 ` Chuck Zmudzinski
2022-07-14 22:33 ` Chuck Zmudzinski
2022-07-14 22:45 ` Chuck Zmudzinski
2022-07-19 14:26 ` Chuck Zmudzinski
2022-07-05 15:04 ` Borislav Petkov [this message]
2022-07-05 15:56 ` Jan Beulich
2022-07-05 16:14 ` Borislav Petkov
2022-07-06 6:17 ` Jan Beulich
2022-07-06 17:01 ` Borislav Petkov
2022-07-07 6:38 ` Jan Beulich
2022-07-11 10:40 ` Borislav Petkov
2022-07-11 11:38 ` Chuck Zmudzinski
2022-07-11 12:28 ` [PATCH] x86/PAT: have pat_enabled() properly reflect state when running on e.g. Xen, with corrected patch Chuck Zmudzinski
2022-07-11 14:18 ` [PATCH] x86/PAT: have pat_enabled() properly reflect state when running on e.g. Xen Chuck Zmudzinski
2022-07-11 14:31 ` Juergen Gross
2022-07-11 17:41 ` Chuck Zmudzinski
2022-07-12 5:49 ` Juergen Gross
2022-07-12 6:04 ` Jan Beulich
2022-07-12 13:22 ` Chuck Zmudzinski
2022-07-12 13:32 ` Juergen Gross
2022-07-12 15:09 ` Chuck Zmudzinski
2022-07-12 15:30 ` Juergen Gross
2022-07-12 16:34 ` Chuck Zmudzinski
2022-08-15 10:20 ` [tip: x86/urgent] x86/PAT: Have pat_enabled() properly reflect state when running on Xen tip-bot2 for Jan Beulich
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=YsRTAGI2PhfZ5V7M@zn.tnic \
--to=bp@alien8.de \
--cc=dave.hansen@linux.intel.com \
--cc=jbeulich@suse.com \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=peterz@infradead.org \
--cc=xen-devel@lists.xenproject.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).