From: Alex Thorlton <athorlton@sgi.com>
To: Borislav Petkov <bp@suse.de>
Cc: Alex Thorlton <athorlton@sgi.com>,
linux-kernel@vger.kernel.org,
Matt Fleming <matt@codeblueprint.co.uk>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-efi@vger.kernel.org,
Russ Anderson <rja@sgi.com>, Dimitri Sivanich <sivanich@sgi.com>,
mike travis <travis@sgi.com>, Nathan Zimmer <nzimmer@sgi.com>
Subject: Re: [BUG] x86/efi: MMRs no longer properly mapped after switch to isolated page table
Date: Wed, 4 May 2016 11:32:53 -0500 [thread overview]
Message-ID: <20160504163253.GG113599@stormcage.americas.sgi.com> (raw)
In-Reply-To: <20160504103636.GA21554@pd.tnic>
On Wed, May 04, 2016 at 12:36:36PM +0200, Borislav Petkov wrote:
> On Tue, May 03, 2016 at 01:47:51PM -0500, Alex Thorlton wrote:
> > I think this will work for us, for the most part. Only issue is that
> > the efi_call_virt macro is only accessible from inside
> > runtime-wrappers.c. If we could pull that macro (and whatever else it
> > needs) up to the header file, I think that might work for us. Not sure
> > if that's the appropriate solution, but it's a start.
>
> Should be doable. You could give it a try and see how ugly it can get.
I can do that. I don't think it should be too bad - I just wanted to
make sure that was an appropriate move before starting to work on it.
> > Yes, I do have CONFIG_EFI_PGT_DUMP=y. I don't *think* I see anything
> > strange in there, but I could be missing something. I will send you a
> > full dump of my log buffer wit MLs et. al. off of Cc.
>
> Sure.
I am sending this shortly. Yesterday evening got away from me :)
> > Take note that the Oops bits here indicate that it was a *write* from
> > kernel space that triggered this most recent Oops, whereas the ones we
> > were hitting before were all just missing pages in the mappings.
> >
> > This means my suggestiong about the "if(efi_scratch..." bit was wrong.
> > This issue is still rolling around in my head. I'll address it below.
>
> One thing I don't see in your uv_call_virt() is you're not grabbing
> efi_runtime_lock like the rest of the EFI callers do. And there's
> __wake_up_common() somewhere there in the callstack, not on the current
> frame but there's also another uv_bios_call() in there and this all
> looks like some locking issue...
>
> So please convert it to the generic one first, do the calls as runtime
> services in drivers/firmware/efi/runtime-wrappers.c do and we can
> continue debugging.
Got it.
> > This is probably the answer for the future, when we can expect the
> > changes to these macros be merged with the mainline kernel, but I don't
> > know exactly how long it will be before that happens.
>
> What's the hurry exactly here? You want stuff fixed in 4.6 when it
> releases in less than two weeks?
Well, in a perfect world, yes. I realize that might be a bit of a
stretch, but we'd *really* prefer to have 4.6 not be outright broken. I
think we might be able to get at least a few small fixes through to at
least get our machines booting. If worse comes to worse, we can get the
fixes into -tip and then wrap back around and try to fix up 4.6 in a
later stable kernel release. I guess the best we can do is try to work
quickly and see where things end up.
> Lemme try to understand the fallout range: that's only UV1 or UV3 too?
> Because the latest oops comes from UV3...
>
> If it is UV1 only, I'd say we don't care since you guys wanted to even
> kill that support :-)
Sorry, I may not have made this clear. Currently *all* UVs *except* for
UV1s are broken. All of the testing I've done since we started
discussing this issue has been done on a UV3000, but everything >= UV2
is currently broken.
> Btw, does "efi=old_memmap" fix things and could it be used as an interim
> workaround until we've fixed everything properly and stuff has trickled
> into -stable.?
Unfortunately, without the call for map_low_mmrs, even that doesn't
work. I think that's an easy fix that we might be able to get in for
4.6 though. It's literally a one-liner. I'm going to try to get that
out today, so at least our old workaround still works. I think it might
still have some trouble with modules doing EFI calls, but I'd be at
least halfway happy if the machine boots :)
- Alex
next prev parent reply other threads:[~2016-05-04 16:32 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-27 15:41 [BUG] x86/efi: MMRs no longer properly mapped after switch to isolated page table Alex Thorlton
2016-04-27 18:23 ` Alex Thorlton
2016-04-27 22:51 ` Borislav Petkov
2016-04-28 1:41 ` Alex Thorlton
2016-04-28 12:57 ` Borislav Petkov
2016-04-29 15:41 ` Alex Thorlton
2016-04-30 22:12 ` Matt Fleming
2016-05-02 21:39 ` Alex Thorlton
2016-05-02 22:17 ` Mike Travis
2016-05-09 21:55 ` Matt Fleming
2016-05-10 17:35 ` Alex Thorlton
2016-05-02 10:02 ` Borislav Petkov
2016-05-02 22:27 ` Alex Thorlton
2016-05-03 0:10 ` Alex Thorlton
2016-05-03 9:48 ` Borislav Petkov
2016-05-03 18:47 ` Alex Thorlton
2016-05-04 10:36 ` Borislav Petkov
2016-05-04 16:32 ` Alex Thorlton [this message]
2016-04-29 9:01 ` Matt Fleming
2016-04-29 15:45 ` Alex Thorlton
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