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From: Ingo Molnar <mingo@kernel.org>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: linux-efi <linux-efi@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Andy Lutomirski <luto@kernel.org>,
	Arend Van Spriel <arend.vanspriel@broadcom.com>,
	Bhupesh Sharma <bhsharma@redhat.com>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@intel.com>,
	Eric Snowberg <eric.snowberg@oracle.com>,
	Hans de Goede <hdegoede@redhat.com>,
	Joe Perches <joe@perches.com>, Jon Hunter <jonathanh@nvidia.com>,
	Julien Thierry <julien.thierry@arm.com>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Nathan Chancellor <natechancellor@gmail.com>,
	Peter Zijlstra <peterz@infradead.org>,
	"Prakhya, Sai Praneeth" <sai.praneeth.prakhya@intel.com>,
	Sedat Dilek <sedat.dilek@gmail.com>,
	YiFei Zhu <zhuyifei1999@gmail.com>
Subject: Re: [PATCH 01/11] x86/efi: Allocate e820 buffer before calling efi_exit_boot_service
Date: Fri, 30 Nov 2018 09:36:01 +0100
Message-ID: <20181130083601.GA97998@gmail.com> (raw)
In-Reply-To: <CAKv+Gu8OMvnxb-n+ubYETRNhm79_H1RkGp+-7N1KF6Hgg3cbCQ@mail.gmail.com>


* Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:

> On Fri, 30 Nov 2018 at 08:29, Ingo Molnar <mingo@kernel.org> wrote:
> >
> >
> > * Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
> >
> > > From: Eric Snowberg <eric.snowberg@oracle.com>
> > >
> > > Commit d64934019f6c ("x86/efi: Use efi_exit_boot_services()")
> > > introduced a regression on systems with large memory maps
> > > causing them to hang on boot. The first "goto get_map" that was removed
> > > from exit_boot insured there was enough room for the memory map when
> > > efi_call_early(exit_boot_services) was called. This happens when
> > > (nr_desc > ARRAY_SIZE(params->e820_table).
> > >
> > > Chain of events:
> > >   exit_boot()
> > >     efi_exit_boot_services()
> > >       efi_get_memory_map <- at this point the mm can't grow over 8 desc
> > >       priv_func()
> > >         exit_boot_func()
> > >           allocate_e820ext() <- new mm grows over 8 desc from e820 alloc
> > >       efi_call_early(exit_boot_services) <- mm key doesn't match so retry
> > >       efi_call_early(get_memory_map) <- not enough room for new mm
> > >       system hangs
> > >
> > > This patch allocates the e820 buffer before calling efi_exit_boot_services
> > > and fixes the regression.
> > >
> > > Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
> > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> > > ---
> > >  arch/x86/boot/compressed/eboot.c | 65 ++++++++++++++++++++------------
> > >  1 file changed, 41 insertions(+), 24 deletions(-)
> >
> > Any objections against marking this for -stable and filing it in
> > efi/urgent? Boot hangs are show-stopper bugs, so distributions would want
> > to backport this fix anyway.
> >
> 
> No objections per se, but this is the kind of patch that might go the
> other way as well, so I would prefer to give it some wider coverage at
> first, given how quickly patches are taken into -stable.
> 
> I can make a note of it and send it to Greg halfway into the next -rc cycle.

So there should be at least one week of testing because I just sent the 
EFI fixes to Linus, plus -stable gets at least a week of testing as well.

Also, in practice, -next and early -rc cycles get only the fraction of 
testing that later -rc's or -stable gets. So if we want this in -stable 
we might as well do it now - or the real testing gets delayed by ~3 
months in practice. That's also the pattern encouraged by Linus: if it's 
a fix that matters then it should be upstreamed with the usual regression 
fixes.

Anyway, your call!

Thanks,

	Ingo

  reply index

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-29 17:12 [GIT PULL 00/11] EFI updates Ard Biesheuvel
2018-11-29 17:12 ` [PATCH 01/11] x86/efi: Allocate e820 buffer before calling efi_exit_boot_service Ard Biesheuvel
2018-11-30  7:29   ` Ingo Molnar
2018-11-30  8:26     ` Ard Biesheuvel
2018-11-30  8:36       ` Ingo Molnar [this message]
2018-11-30  9:55   ` [tip:efi/core] " tip-bot for Eric Snowberg
2018-11-29 17:12 ` [PATCH 02/11] efi/fdt: Indentation fix Ard Biesheuvel
2018-11-30  7:56   ` [PATCH] efi/fdt: More cleanups Ingo Molnar
2018-11-30  8:31     ` Ard Biesheuvel
2018-11-30  9:48       ` Ingo Molnar
2018-11-30  9:56   ` [tip:efi/core] efi/fdt: Indentation fix tip-bot for Julien Thierry
2018-11-29 17:12 ` [PATCH 03/11] efi/fdt: Simplify get_fdt flow Ard Biesheuvel
2018-11-30  9:57   ` [tip:efi/core] efi/fdt: Simplify the get_fdt() flow tip-bot for Julien Thierry
2018-11-29 17:12 ` [PATCH 04/11] x86/mm/pageattr: Introduce helper function to unmap EFI boot services Ard Biesheuvel
2018-11-30  9:58   ` [tip:efi/core] " tip-bot for Sai Praneeth Prakhya
2018-11-29 17:12 ` [PATCH 05/11] x86/efi: Unmap EFI boot services code/data regions from efi_pgd Ard Biesheuvel
2018-11-30  9:58   ` [tip:efi/core] " tip-bot for Sai Praneeth Prakhya
2018-12-17 18:06     ` Prakhya, Sai Praneeth
2018-12-17 18:10       ` Ard Biesheuvel
2018-12-17 18:42         ` Prakhya, Sai Praneeth
2018-12-17 19:35           ` Ard Biesheuvel
2018-12-17 19:48             ` Prakhya, Sai Praneeth
2018-12-21 17:02               ` Ard Biesheuvel
2018-12-21 17:13                 ` Borislav Petkov
2018-12-21 17:26                   ` Ard Biesheuvel
2018-12-21 19:29                     ` Borislav Petkov
2018-12-22 11:07                       ` Ard Biesheuvel
2019-01-07 15:57                         ` Matt Fleming
2018-12-21 17:52                 ` Prakhya, Sai Praneeth
2018-11-29 17:12 ` [PATCH 06/11] x86/efi: Move efi_<reserve/free>_boot_services() to arch/x86 Ard Biesheuvel
2018-11-30  9:59   ` [tip:efi/core] " tip-bot for Sai Praneeth Prakhya
2018-11-29 17:12 ` [PATCH 07/11] efi/libstub: Disable some warnings for x86{,_64} Ard Biesheuvel
2018-11-30  9:59   ` [tip:efi/core] " tip-bot for Nathan Chancellor
2018-11-29 17:12 ` [PATCH 08/11] firmware: efi: add NULL pointer checks in efivars api functions Ard Biesheuvel
2018-11-30  8:11   ` Ingo Molnar
2018-11-30  8:37     ` Ard Biesheuvel
2018-11-30  9:56   ` [tip:efi/core] firmware/efi: Add NULL pointer checks in efivars API functions tip-bot for Arend van Spriel
2018-11-29 17:12 ` [PATCH 09/11] efi: permit multiple entries in persistent memreserve data structure Ard Biesheuvel
2018-11-30 10:00   ` [tip:efi/core] efi: Permit " tip-bot for Ard Biesheuvel
2018-11-29 17:12 ` [PATCH 10/11] efi: reduce the amount of memblock reservations for persistent allocations Ard Biesheuvel
2018-11-30  8:38   ` Ingo Molnar
2018-11-30  8:39     ` Ard Biesheuvel
2018-11-30 10:00   ` [tip:efi/core] efi: Reduce " tip-bot for Ard Biesheuvel
2018-11-29 17:12 ` [PATCH 11/11] efi/x86: earlyprintk - Fix infinite loop on some screen widths Ard Biesheuvel
2018-11-30  8:05   ` Ingo Molnar
2018-11-30  8:32     ` Ard Biesheuvel
2018-11-30  9:55   ` [tip:efi/core] x86/earlyprintk/efi: " tip-bot for YiFei Zhu
2018-11-29 18:27 ` [GIT PULL 00/11] EFI updates Prakhya, Sai Praneeth
2018-11-30 12:01   ` Ard Biesheuvel
2018-11-30 18:01     ` Prakhya, Sai Praneeth

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