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Date:   Mon, 9 Dec 2019 21:43:45 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Logan Gunthorpe <logang@deltatee.com>
Cc:     linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
        platform-driver-x86@vger.kernel.org, linux-mm@kvack.org,
        Christoph Hellwig <hch@lst.de>,
        Dan Williams <dan.j.williams@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 0/6] Allow setting caching mode in arch_add_memory()
 for P2PDMA
Message-ID: <20191209204345.GA29265@lst.de>
References: <20191209191346.5197-1-logang@deltatee.com>
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On Mon, Dec 09, 2019 at 12:13:40PM -0700, Logan Gunthorpe wrote:
> This changes is pretty routine for most of the arches: x86_64, s390, arm64
> and powerpc simply need to thread the pgprot through to where the page tables
> are setup. x86_32 unfortunately sets up the page tables at boot so
> must use _set_memory_prot() to change their caching mode. ia64 and sh
> don't appear to have an easy way to change the page tables so, for now
> at least, we just return -EINVAL on such mappings and thus they will
> not support P2PDMA memory until the work for this is done.

ia64 and sh don't support ZONE_DEVICE mappings anyway as far as I know.

This generally looks fine to me.