From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 0/6] Allow setting caching mode in arch_add_memory()
 for P2PDMA
Date: Mon, 9 Dec 2019 21:43:45 +0100
Message-ID: <20191209204345.GA29265@lst.de>
References: <20191209191346.5197-1-logang@deltatee.com>
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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>
List-Id: platform-driver-x86.vger.kernel.org

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.