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From:   Guo Ren <guoren@kernel.org>
Date:   Sun, 8 Sep 2019 07:52:55 +0800
Message-ID: <CAJF2gTSC1sGgmiTCgzKUTdPyUZ3LG4H7N8YbMyWr-E+eifGuYg@mail.gmail.com>
Subject: Re: [PATCH RFC 11/14] arm64: Move the ASID allocator code in a
 separate file
To:     Will Deacon <will@kernel.org>
Cc:     Will Deacon <will.deacon@arm.com>, julien.thierry@arm.com,
        aou@eecs.berkeley.edu, james.morse@arm.com,
        Arnd Bergmann <arnd@arndb.de>, suzuki.poulose@arm.com,
        Marc Zyngier <marc.zyngier@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Anup Patel <anup.Patel@wdc.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Mike Rapoport <rppt@linux.ibm.com>,
        Christoph Hellwig <hch@infradead.org>,
        Atish Patra <Atish.Patra@wdc.com>,
        Julien Grall <julien.grall@arm.com>,
        Palmer Dabbelt <palmer@sifive.com>, gary@garyguo.net,
        Paul Walmsley <paul.walmsley@sifive.com>,
        christoffer.dall@arm.com, linux-riscv@lists.infradead.org,
        kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org,
        iommu@lists.linux-foundation.org
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Thx Will,

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.

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

--
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/