kvmarm.lists.cs.columbia.edu archive mirror
 help / color / mirror / Atom feed
From: Will Deacon <will@kernel.org>
To: Guo Ren <guoren@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Palmer Dabbelt <palmer@sifive.com>,
	Will Deacon <will.deacon@arm.com>,
	Atish Patra <Atish.Patra@wdc.com>,
	Julien Grall <julien.grall@arm.com>,
	gary@garyguo.net, linux-riscv@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, Mike Rapoport <rppt@linux.ibm.com>,
	Christoph Hellwig <hch@infradead.org>,
	aou@eecs.berkeley.edu, Arnd Bergmann <arnd@arndb.de>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	linux-arm-kernel@lists.infradead.org,
	Anup Patel <anup.Patel@wdc.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	iommu@lists.linux-foundation.org
Subject: Re: [PATCH RFC 11/14] arm64: Move the ASID allocator code in a separate file
Date: Thu, 12 Sep 2019 15:02:56 +0100	[thread overview]
Message-ID: <20190912140256.fwbutgmadpjbjnab@willie-the-truck> (raw)
In-Reply-To: <CAJF2gTSC1sGgmiTCgzKUTdPyUZ3LG4H7N8YbMyWr-E+eifGuYg@mail.gmail.com>

On Sun, Sep 08, 2019 at 07:52:55AM +0800, Guo Ren wrote:
> On Mon, Jun 24, 2019 at 6:40 PM Will Deacon <will@kernel.org> wrote:
> > > I'll keep my system use the same ASID for SMP + IOMMU :P
> >
> > You will want a separate allocator for that:
> >
> > https://lkml.kernel.org/r/20190610184714.6786-2-jean-philippe.brucker@arm.com
> 
> Yes, it is hard to maintain ASID between IOMMU and CPUMMU or different
> system, because it's difficult to synchronize the IO_ASID when the CPU
> ASID is rollover.
> But we could still use hardware broadcast TLB invalidation instruction
> to uniformly manage the ASID and IO_ASID, or OTHER_ASID in our IOMMU.

That's probably a bad idea, because you'll likely stall execution on the
CPU until the IOTLB has completed invalidation. In the case of ATS, I think
an endpoint ATC is permitted to take over a minute to respond. In reality, I
suspect the worst you'll ever see would be in the msec range, but that's
still an unacceptable period of time to hold a CPU.

> Welcome to join our disscusion:
> "Introduce an implementation of IOMMU in linux-riscv"
> 9 Sep 2019, 10:45 Jade-room-I&II (Corinthia Hotel Lisbon) RISC-V MC

I attended this session, but it unfortunately raised many more questions
than it answered.

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

  reply	other threads:[~2019-09-12 14:03 UTC|newest]

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 [this message]
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
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 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=20190912140256.fwbutgmadpjbjnab@willie-the-truck \
    --to=will@kernel.org \
    --cc=Atish.Patra@wdc.com \
    --cc=anup.Patel@wdc.com \
    --cc=aou@eecs.berkeley.edu \
    --cc=arnd@arndb.de \
    --cc=catalin.marinas@arm.com \
    --cc=gary@garyguo.net \
    --cc=guoren@kernel.org \
    --cc=hch@infradead.org \
    --cc=iommu@lists.linux-foundation.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=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
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).