Re: [PATCH 0/6] Allow setting caching mode in arch_add_memory() for P2PDMA
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- To: Logan Gunthorpe <logang@xxxxxxxxxxxx>
- Subject: Re: [PATCH 0/6] Allow setting caching mode in arch_add_memory() for P2PDMA
- From: Christoph Hellwig <hch@xxxxxx>
- Date: Mon, 9 Dec 2019 21:43:45 +0100
- Cc: linux-kernel@xxxxxxxxxxxxxxx, linux-arm-kernel@xxxxxxxxxxxxxxxxxxx, linux-ia64@xxxxxxxxxxxxxxx, linuxppc-dev@xxxxxxxxxxxxxxxx, linux-s390@xxxxxxxxxxxxxxx, linux-sh@xxxxxxxxxxxxxxx, platform-driver-x86@xxxxxxxxxxxxxxx, linux-mm@xxxxxxxxx, Christoph Hellwig <hch@xxxxxx>, Dan Williams <dan.j.williams@xxxxxxxxx>, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Catalin Marinas <catalin.marinas@xxxxxxx>, Will Deacon <will@xxxxxxxxxx>, Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, Borislav Petkov <bp@xxxxxxxxx>, Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>, Andy Lutomirski <luto@xxxxxxxxxx>, Peter Zijlstra <peterz@xxxxxxxxxxxxx>
- In-reply-to: <20191209191346.5197-1-logang@deltatee.com>
- References: <20191209191346.5197-1-logang@deltatee.com>
- User-agent: Mutt/1.5.17 (2007-11-01)
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.
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