From: Will Deacon <will@kernel.org>
To: Guo Ren <guoren@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 15:02:56 +0100
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
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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 [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
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