IOMMU Archive on lore.kernel.org
 help / color / Atom feed
From: Guo Ren <guoren@kernel.org>
To: Will Deacon <will@kernel.org>
Cc: julien.thierry@arm.com, Catalin Marinas <catalin.marinas@arm.com>,
	Palmer Dabbelt <palmer@sifive.com>,
	Will Deacon <will.deacon@arm.com>,
	christoffer.dall@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>,
	aou@eecs.berkeley.edu, Arnd Bergmann <arnd@arndb.de>,
	suzuki.poulose@arm.com, 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, james.morse@arm.com
Subject: Re: [PATCH RFC 11/14] arm64: Move the ASID allocator code in a separate file
Date: Thu, 12 Sep 2019 15:59:43 +0100
Message-ID: <CAJF2gTT2c45HRfATF+=zs-HNToFAKgq1inKRmJMV3uPYBo4iVg@mail.gmail.com> (raw)
In-Reply-To: <20190912140256.fwbutgmadpjbjnab@willie-the-truck>

Thx Will for reply.

On Thu, Sep 12, 2019 at 3:03 PM Will Deacon <will@kernel.org> wrote:
>
> 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.
Just as I've said in the session that IOTLB invalidate delay is
another topic, My main proposal is to introduce stage1.pgd and
stage2.pgd as address space identifiers between different TLB systems
based on vmid, asid. My last part of sildes will show you how to
translate stage1/2.pgd to as/vmid in PCI ATS system and the method
could work with SMMU-v3 and intel Vt-d. (It's regret for me there is
no time to show you the whole slides.)

In our light IOMMU implementation, there's no IOTLB invalidate delay
problem. Becasue IOMMU is very close to CPU MMU and interconnect's
delay is the same with SMP CPUs MMU (no PCI, VM supported).

To solve the problem, we could define a async mode in sfence.vma.b to
slove the problem and finished with per_cpu_irq/exception.

-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

  reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20190321163623.20219-1-julien.grall@arm.com>
     [not found] ` <20190321163623.20219-12-julien.grall@arm.com>
     [not found]   ` <0dfe120b-066a-2ac8-13bc-3f5a29e2caa3@arm.com>
     [not found]     ` <CAJF2gTTXHHgDboaexdHA284y6kNZVSjLis5-Q2rDnXCxr4RSmA@mail.gmail.com>
     [not found]       ` <c871a5ae-914f-a8bb-9474-1dcfec5d45bf@arm.com>
     [not found]         ` <20190619091219.GB7767@fuggles.cambridge.arm.com>
     [not found]           ` <CAJF2gTTmFq3yYa9UrdZRAFwJgC=KmKTe2_NFy_UZBUQovqQJPg@mail.gmail.com>
     [not found]             ` <20190619123939.GF7767@fuggles.cambridge.arm.com>
     [not found]               ` <CAJF2gTSiiiewTLwVAXvPLO7rTSUw1rg8VtFLzANdP2S2EEbTjg@mail.gmail.com>
     [not found]                 ` <20190624104006.lvm32nahemaqklxc@willie-the-truck>
2019-09-07 23:52                   ` Guo Ren
2019-09-12 14:02                     ` Will Deacon
2019-09-12 14:59                       ` Guo Ren [this message]
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

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='CAJF2gTT2c45HRfATF+=zs-HNToFAKgq1inKRmJMV3uPYBo4iVg@mail.gmail.com' \
    --to=guoren@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=christoffer.dall@arm.com \
    --cc=gary@garyguo.net \
    --cc=iommu@lists.linux-foundation.org \
    --cc=james.morse@arm.com \
    --cc=julien.grall@arm.com \
    --cc=julien.thierry@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=suzuki.poulose@arm.com \
    --cc=will.deacon@arm.com \
    --cc=will@kernel.org \
    /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

IOMMU Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-iommu/0 linux-iommu/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 linux-iommu linux-iommu/ https://lore.kernel.org/linux-iommu \
		iommu@lists.linux-foundation.org iommu@archiver.kernel.org
	public-inbox-index linux-iommu


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.linux-foundation.lists.iommu


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