KVM ARM Archive on lore.kernel.org
 help / color / Atom feed
From: Will Deacon <will@kernel.org>
To: "qi.fuli@fujitsu.com" <qi.fuli@fujitsu.com>
Cc: "aou@eecs.berkeley.edu" <aou@eecs.berkeley.edu>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"rppt@linux.ibm.com" <rppt@linux.ibm.com>,
	"hch@infradead.org" <hch@infradead.org>,
	Atish Patra <Atish.Patra@wdc.com>,
	Julien Grall <julien.grall@arm.com>,
	Anup Patel <anup.Patel@wdc.com>, Guo Ren <guoren@kernel.org>,
	"gary@garyguo.net" <gary@garyguo.net>,
	Palmer Dabbelt <palmer@sifive.com>,
	"linux-riscv@lists.infradead.org"
	<linux-riscv@lists.infradead.org>,
	"paul.walmsley@sifive.com" <paul.walmsley@sifive.com>,
	"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH RFC 11/14] arm64: Move the ASID allocator code in a separate file
Date: Thu, 27 Jun 2019 11:26:57 +0100
Message-ID: <20190627102656.elizqwby4sw4vi5j@willie-the-truck> (raw)
In-Reply-To: <c5be6baa-91aa-c178-6698-c83d4d82a217@jp.fujitsu.com>

On Thu, Jun 27, 2019 at 09:41:42AM +0000, qi.fuli@fujitsu.com wrote:
> 
> On 6/24/19 7:22 PM, Will Deacon wrote:
> > On Mon, Jun 24, 2019 at 12:35:35AM +0800, Guo Ren wrote:
> >> On Fri, Jun 21, 2019 at 10:16 PM Catalin Marinas
> >> <catalin.marinas@arm.com> wrote:
> >>> On Wed, Jun 19, 2019 at 07:51:03PM +0800, Guo Ren wrote:
> >>>> On Wed, Jun 19, 2019 at 4:54 PM Julien Grall <julien.grall@arm.com> wrote:
> >>>>> On 6/19/19 9:07 AM, Guo Ren wrote:
> >>>>>> Move arm asid allocator code in a generic one is a agood idea, I've
> >>>>>> made a patchset for C-SKY and test is on processing, See:
> >>>>>> https://lore.kernel.org/linux-csky/1560930553-26502-1-git-send-email-guoren@kernel.org/
> >>>>>>
> >>>>>> If you plan to seperate it into generic one, I could co-work with you.
> >>>>> Was the ASID allocator work out of box on C-Sky?
> >>>> Almost done, but one question:
> >>>> arm64 remove the code in switch_mm:
> >>>>    cpumask_clear_cpu(cpu, mm_cpumask(prev));
> >>>>    cpumask_set_cpu(cpu, mm_cpumask(next));
> >>>>
> >>>> Why? Although arm64 cache operations could affect all harts with CTC
> >>>> method of interconnect, I think we should keep these code for
> >>>> primitive integrity in linux. Because cpu_bitmap is in mm_struct
> >>>> instead of mm->context.
> >>> We didn't have a use for this in the arm64 code, so no point in
> >>> maintaining the mm_cpumask. On some arm32 systems (ARMv6) with no
> >>> hardware broadcast of some TLB/cache operations, we use it to track
> >>> where the task has run to issue IPI for TLB invalidation or some
> >>> deferred I-cache invalidation.
> >> The operation of set/clear mm_cpumask was removed in arm64 compared to
> >> arm32. It seems no side effect on current arm64 system, but from
> >> software meaning it's wrong.
> >> I think we should keep mm_cpumask just like arm32.
> > It was a while ago now, but I remember the atomic update of the mm_cpumask
> > being quite expensive when I was profiling this stuff, so I removed it
> > because we don't need it for arm64 (at least, it doesn't allow us to
> > optimise our shootdowns in practice).
> 
> I think mm_cpumask can be used for filtering the cpus that there are TBL 
> entries on.

I'm aware that you want to use IPIs for broadcasting TLB invalidation
but that is only tangentially related to this thread, which is about the
current ASID algorithm and the need to update mm_cpumask today.

Please don't conflate the two threads; I already made my position reasonably
clear:

https://lore.kernel.org/linux-arm-kernel/20190617170328.GJ30800@fuggles.cambridge.arm.com/

I will follow-up with another reply there.

Will
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

  reply index

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-21 16:36 [PATCH RFC 00/14] kvm/arm: Align the VMID allocation with the arm64 ASID one Julien Grall
2019-03-21 16:36 ` [PATCH RFC 01/14] arm64/mm: Introduce asid_info structure and move asid_generation/asid_map to it Julien Grall
2019-03-21 17:03   ` Suzuki K Poulose
2019-03-21 17:27     ` Julien Grall
2019-03-21 16:36 ` [PATCH RFC 02/14] arm64/mm: Move active_asids and reserved_asids to asid_info Julien Grall
2019-03-21 16:36 ` [PATCH RFC 03/14] arm64/mm: Move bits " Julien Grall
2019-03-21 16:36 ` [PATCH RFC 04/14] arm64/mm: Move the variable lock and tlb_flush_pending " Julien Grall
2019-03-21 16:36 ` [PATCH RFC 05/14] arm64/mm: Remove dependency on MM in new_context Julien Grall
2019-03-21 16:36 ` [PATCH RFC 06/14] arm64/mm: Store the number of asid allocated per context Julien Grall
2019-03-21 16:36 ` [PATCH RFC 07/14] arm64/mm: Introduce NUM_ASIDS Julien Grall
2019-03-21 16:36 ` [PATCH RFC 08/14] arm64/mm: Split asid_inits in 2 parts Julien Grall
2019-03-21 16:36 ` [PATCH RFC 09/14] arm64/mm: Split the function check_and_switch_context in 3 parts Julien Grall
2019-03-21 16:36 ` [PATCH RFC 10/14] arm64/mm: Introduce a callback to flush the local context Julien Grall
2019-03-21 16:36 ` [PATCH RFC 11/14] arm64: Move the ASID allocator code in a separate file Julien Grall
2019-06-05 16:56   ` Julien Grall
2019-06-05 20:41     ` Palmer Dabbelt
2019-06-11  1:56       ` Gary Guo
2019-06-19  8:07     ` Guo Ren
2019-06-19  8:54       ` Julien Grall
2019-06-19  9:12         ` Will Deacon
2019-06-19 12:18           ` Guo Ren
2019-06-19 12:39             ` Will Deacon
2019-06-20  9:33               ` Guo Ren
2019-06-24 10:40                 ` Will Deacon
2019-06-25  7:25                   ` Palmer Dabbelt
2019-09-07 23:52                   ` Guo Ren
2019-09-12 14:02                     ` Will Deacon
2019-09-12 14:59                       ` Guo Ren
2019-09-13  7:13                         ` Guo Ren
2019-09-14  8:49                           ` Guo Ren
2019-09-16 12:57                           ` Jean-Philippe Brucker
2019-09-19 13:07                             ` Guo Ren
2019-09-19 15:18                               ` Jean-Philippe Brucker
2019-09-20  0:07                                 ` Guo Ren
2019-09-20  7:18                                   ` Jean-Philippe Brucker
2019-09-14 14:01                       ` Palmer Dabbelt
2019-09-15  5:03                         ` Anup Patel
2019-09-16 18:18                           ` Will Deacon
2019-09-16 18:28                             ` Palmer Dabbelt
2019-09-17  3:42                             ` Anup Patel
2019-09-19 13:36                               ` Guo Ren
2019-06-19 11:51         ` Guo Ren
2019-06-19 12:52           ` Julien Grall
2019-06-21 14:16           ` Catalin Marinas
2019-06-23 16:35             ` Guo Ren
2019-06-24 10:22               ` Will Deacon
2019-06-27  9:41                 ` qi.fuli
2019-06-27 10:26                   ` Will Deacon [this message]
2019-06-24 15:38               ` Catalin Marinas
2019-06-30  4:29                 ` Guo Ren
2019-07-01  9:17                   ` Catalin Marinas
2019-07-16  3:31                     ` Guo Ren
2019-07-22 16:38                       ` Catalin Marinas
2019-03-21 16:36 ` [PATCH RFC 12/14] arm64/lib: asid: Allow user to update the context under the lock Julien Grall
2019-03-21 16:36 ` [PATCH RFC 13/14] arm/kvm: Introduce a new VMID allocator Julien Grall
2019-03-21 16:36 ` [PATCH RFC 14/14] kvm/arm: Align the VMID allocation with the arm64 ASID one Julien Grall

Reply instructions:

You may reply publically 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=20190627102656.elizqwby4sw4vi5j@willie-the-truck \
    --to=will@kernel.org \
    --cc=Atish.Patra@wdc.com \
    --cc=anup.Patel@wdc.com \
    --cc=aou@eecs.berkeley.edu \
    --cc=catalin.marinas@arm.com \
    --cc=gary@garyguo.net \
    --cc=guoren@kernel.org \
    --cc=hch@infradead.org \
    --cc=julien.grall@arm.com \
    --cc=kvmarm@lists.cs.columbia.edu \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-riscv@lists.infradead.org \
    --cc=marc.zyngier@arm.com \
    --cc=palmer@sifive.com \
    --cc=paul.walmsley@sifive.com \
    --cc=qi.fuli@fujitsu.com \
    --cc=rppt@linux.ibm.com \
    --cc=will.deacon@arm.com \
    /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

KVM ARM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/kvmarm/0 kvmarm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 kvmarm kvmarm/ https://lore.kernel.org/kvmarm \
		kvmarm@lists.cs.columbia.edu kvmarm@archiver.kernel.org
	public-inbox-index kvmarm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/edu.columbia.cs.lists.kvmarm


AGPL code for this site: git clone https://public-inbox.org/ public-inbox