From: Matt Fleming <matt@codeblueprint.co.uk>
To: Sylvain Chouleur <sylvain.chouleur@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Andy Lutomirski <luto@amacapital.net>,
Borislav Petkov <bp@alien8.de>,
Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
Toshi Kani <toshi.kani@hp.com>, Brian Gerst <brgerst@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Luis Rodriguez <mcgrof@suse.com>,
Andrew Morton <akpm@linux-foundation.org>,
Denys Vlasenko <dvlasenk@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
ricardo.neri@intel.com, Hugh Dickins <hughd@google.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>
Subject: Re: [tip:efi/core] x86/mm/pat: Use _PAGE_GLOBAL bit for EFI page table mappings
Date: Wed, 2 Mar 2016 11:20:36 +0000 [thread overview]
Message-ID: <20160302112036.GB2649@codeblueprint.co.uk> (raw)
In-Reply-To: <CAD_mUW1WQs64RYA6tD0SMTaCdETqVfNaYDcnfmVCoVLdUa53cQ@mail.gmail.com>
On Mon, 29 Feb, at 11:56:56AM, Sylvain Chouleur wrote:
> 2016-02-24 20:45 GMT+01:00 Matt Fleming <matt@codeblueprint.co.uk>:
> > On Wed, 24 Feb, at 10:56:13AM, Linus Torvalds wrote:
> >> On Wed, Feb 24, 2016 at 8:36 AM, Andy Lutomirski <luto@amacapital.net> wrote:
> >> >>
> >> >> So the EFI runtime crap should not change once it is mapped. And those
> >> >> should be global. It is only natural.
> >> >
> >> > Why is it natural?
> >> >
> >> > Long-term, I'd rather see EFI runtime services use an actual mm_struct
> >> > and use_mm.
> >>
> >> Definitely.
> >>
> >> The EFI runtime page mapping may be unchanging, but that doesn't mean
> >> we should be mapping it all the time - the mapping may not change, but
> >> we will change away from it.
> >
> > There is movement towards hanging the EFI memory map off of mm_struct
> > for x86. ARM and arm64 already do this and there were some patches
> > from Sylvain (Cc'd) to do this for the purposes of having a task
> > context that could be preempted while in the middle of an EFI runtime
> > call for some Intel platforms,
> >
> > https://lkml.kernel.org/r/1452702762-27216-4-git-send-email-sylvain.chouleur@gmail.com
>
> I was thinking we could use the efi kthread to handle the efi services
> generically, not only for the interruptible case, and have a way to decide if we
> allow interruptions inside the efi call itself or not.
>
> Then all runtime services would use an mm_struct. The drawback is that you will
> need two context switchs to be able to execute the runtime service.
I would be surprised if the asynchronous nature of having a special
EFI kthread would buy you any benefit in general. And in fact, in the
efi-pstore code you can be invoked in IRQ context and you really don't
want to start talking to a kthread.
next prev parent reply other threads:[~2016-03-02 11:20 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-17 12:35 [GIT PULL 00/13] EFI changes for v4.6 part 2 Matt Fleming
2016-02-17 12:35 ` [PATCH 01/13] efi: Reformat GUID tables to follow the format in UEFI spec Matt Fleming
2016-02-22 12:12 ` [tip:efi/core] " =?UTF-8?B?dGlwLWJvdCBmb3IgUGV0ZXIgSm9uZXMgPHRpcGJvdEB6eXRvci5jb20+?=
2016-02-17 12:35 ` [PATCH 02/13] efi/runtime-wrappers: Run UEFI Runtime Services with interrupts enabled Matt Fleming
2016-02-22 12:13 ` [tip:efi/core] " =?UTF-8?B?dGlwLWJvdCBmb3IgQXJkIEJpZXNoZXV2ZWwgPHRpcGJvdEB6eXRvci5jb20+?=
2016-02-17 12:35 ` [PATCH 03/13] x86/mm/pageattr: Use _PAGE_GLOBAL bit for EFI page table mappings Matt Fleming
2016-02-22 12:13 ` [tip:efi/core] x86/mm/pat: " =?UTF-8?B?dGlwLWJvdCBmb3IgU2FpIFByYW5lZXRoIDx0aXBib3RAenl0b3IuY29tPg==?=
2016-02-23 17:47 ` Andy Lutomirski
2016-02-23 18:08 ` Linus Torvalds
2016-02-23 18:12 ` Borislav Petkov
2016-02-24 2:09 ` H. Peter Anvin
2016-02-24 2:13 ` H. Peter Anvin
2016-02-25 8:59 ` Ingo Molnar
2016-02-24 0:50 ` Sai Praneeth Prakhya
2016-02-24 2:43 ` Andy Lutomirski
2016-02-24 14:10 ` Matt Fleming
2016-02-24 16:20 ` Borislav Petkov
2016-02-24 16:36 ` Andy Lutomirski
2016-02-24 18:56 ` Linus Torvalds
2016-02-24 19:45 ` Matt Fleming
2016-02-24 19:50 ` Andy Lutomirski
2016-02-29 10:56 ` Sylvain Chouleur
2016-03-02 11:20 ` Matt Fleming [this message]
2016-02-24 19:33 ` Matt Fleming
2016-02-24 19:49 ` Andy Lutomirski
2016-02-25 9:06 ` Ingo Molnar
2016-02-25 15:27 ` Matt Fleming
2016-02-24 16:41 ` Borislav Petkov
2016-02-24 16:47 ` Andy Lutomirski
2016-02-24 16:39 ` Andy Lutomirski
2016-02-25 16:00 ` Matt Fleming
2016-02-17 12:35 ` [PATCH 04/13] efi/arm64: Drop __init annotation from handle_kernel_image() Matt Fleming
2016-02-22 12:14 ` [tip:efi/core] " =?UTF-8?B?dGlwLWJvdCBmb3IgQXJkIEJpZXNoZXV2ZWwgPHRpcGJvdEB6eXRvci5jb20+?=
2016-02-17 12:35 ` [PATCH 05/13] arm64: vmlinux.lds.S: Handle .init.rodata.xxx and .init.bss sections Matt Fleming
2016-02-22 12:14 ` [tip:efi/core] arm64/vmlinux.lds.S: " =?UTF-8?B?dGlwLWJvdCBmb3IgQXJkIEJpZXNoZXV2ZWwgPHRpcGJvdEB6eXRvci5jb20+?=
2016-02-17 12:35 ` [PATCH 06/13] efi/efistub: Prevent __init annotations from being used Matt Fleming
2016-02-22 12:14 ` [tip:efi/core] " =?UTF-8?B?dGlwLWJvdCBmb3IgQXJkIEJpZXNoZXV2ZWwgPHRpcGJvdEB6eXRvci5jb20+?=
2016-02-17 12:36 ` [PATCH 07/13] efi/arm-init: Use read-only early mappings Matt Fleming
2016-02-22 12:15 ` [tip:efi/core] " =?UTF-8?B?dGlwLWJvdCBmb3IgQXJkIEJpZXNoZXV2ZWwgPHRpcGJvdEB6eXRvci5jb20+?=
2016-02-17 12:36 ` [PATCH 08/13] efi/arm: Check for LPAE support before booting a LPAE kernel Matt Fleming
2016-02-22 12:15 ` [tip:efi/core] " =?UTF-8?B?dGlwLWJvdCBmb3IgQXJkIEJpZXNoZXV2ZWwgPHRpcGJvdEB6eXRvci5jb20+?=
2016-02-17 12:36 ` [PATCH 09/13] efi/arm64: Check for h/w support before booting a >4 KB granule kernel Matt Fleming
2016-02-22 12:16 ` [tip:efi/core] efi/arm64: Check for h/w support before booting a >4 KB granular kernel =?UTF-8?B?dGlwLWJvdCBmb3IgQXJkIEJpZXNoZXV2ZWwgPHRpcGJvdEB6eXRvci5jb20+?=
2016-03-06 3:35 ` [PATCH 09/13] efi/arm64: Check for h/w support before booting a >4 KB granule kernel Ard Biesheuvel
2016-03-07 11:02 ` Matt Fleming
2016-03-07 11:05 ` Ard Biesheuvel
2016-02-17 12:36 ` [PATCH 10/13] efi/arm*: Perform hardware compatibility check Matt Fleming
2016-02-22 12:16 ` [tip:efi/core] " =?UTF-8?B?dGlwLWJvdCBmb3IgQXJkIEJpZXNoZXV2ZWwgPHRpcGJvdEB6eXRvci5jb20+?=
2016-02-17 12:36 ` [PATCH 11/13] x86/mm/pageattr: Don't implicitly allow _PAGE_RW in kernel_map_pages_in_pgd() Matt Fleming
2016-02-22 12:16 ` [tip:efi/core] x86/mm/pat: " =?UTF-8?B?dGlwLWJvdCBmb3IgU2FpIFByYW5lZXRoIDx0aXBib3RAenl0b3IuY29tPg==?=
2016-02-17 12:36 ` [PATCH 12/13] x86/efi: Map EFI_MEMORY_{XP,RO} memory region bits to EFI page tables Matt Fleming
2016-02-22 12:17 ` [tip:efi/core] " =?UTF-8?B?dGlwLWJvdCBmb3IgU2FpIFByYW5lZXRoIDx0aXBib3RAenl0b3IuY29tPg==?=
2016-02-17 12:36 ` [PATCH 13/13] x86/efi: Only map kernel text for EFI mixed mode Matt Fleming
2016-02-22 12:17 ` [tip:efi/core] " =?UTF-8?B?dGlwLWJvdCBmb3IgU2FpIFByYW5lZXRoIDx0aXBib3RAenl0b3IuY29tPg==?=
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