From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ard Biesheuvel Subject: Re: [PATCH] efi: arm: Don't mark ACPI reclaim memory as MEMBLOCK_NOMAP Date: Fri, 9 Jun 2017 09:01:52 +0000 Message-ID: References: <20170605080435.2498-1-ard.biesheuvel@linaro.org> <20170605090847.GC4650@leverpostej> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: <20170605090847.GC4650@leverpostej> Sender: linux-efi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Mark Rutland Cc: "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Matt Fleming , Leif Lindholm , James Morse List-Id: linux-efi@vger.kernel.org On 5 June 2017 at 09:08, Mark Rutland wrote: > On Mon, Jun 05, 2017 at 08:04:35AM +0000, Ard Biesheuvel wrote: >> On ARM, regions of memory that are described by UEFI as having special >> significance to the firmware itself are omitted from the linear mapping. >> This is necessary since we cannot guarantee that alternate mappings of >> the same physical region will use attributes that are compatible with >> the ones we use for the linear mapping, and aliases with mismatched >> attributes are prohibited by the architecture. >> >> The above does not apply to ACPI reclaim regions: such regions have no >> special significance to the firmware, and it is up to the OS to decide >> whether or not to preserve them after it has consumed their contents, >> and for how long, after which time the OS can use the memory in any way >> it likes. In the Linux case, such regions are preserved indefinitely, >> and are simply treated the same way as other 'reserved' memory types. >> >> Punching holes into the linear mapping causes page table fragmentation, >> which increases TLB pressure, and so we should avoid doing so if we can. >> So add a special case for regions of type EFI_ACPI_RECLAIM_MEMORY, and >> memblock_reserve() them instead of marking them MEMBLOCK_NOMAP. >> >> Signed-off-by: Ard Biesheuvel > > Sounds sane to me. FWIW: > > Acked-by: Mark Rutland > Thanks. I have queued this in efi/next From mboxrd@z Thu Jan 1 00:00:00 1970 From: ard.biesheuvel@linaro.org (Ard Biesheuvel) Date: Fri, 9 Jun 2017 09:01:52 +0000 Subject: [PATCH] efi: arm: Don't mark ACPI reclaim memory as MEMBLOCK_NOMAP In-Reply-To: <20170605090847.GC4650@leverpostej> References: <20170605080435.2498-1-ard.biesheuvel@linaro.org> <20170605090847.GC4650@leverpostej> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 5 June 2017 at 09:08, Mark Rutland wrote: > On Mon, Jun 05, 2017 at 08:04:35AM +0000, Ard Biesheuvel wrote: >> On ARM, regions of memory that are described by UEFI as having special >> significance to the firmware itself are omitted from the linear mapping. >> This is necessary since we cannot guarantee that alternate mappings of >> the same physical region will use attributes that are compatible with >> the ones we use for the linear mapping, and aliases with mismatched >> attributes are prohibited by the architecture. >> >> The above does not apply to ACPI reclaim regions: such regions have no >> special significance to the firmware, and it is up to the OS to decide >> whether or not to preserve them after it has consumed their contents, >> and for how long, after which time the OS can use the memory in any way >> it likes. In the Linux case, such regions are preserved indefinitely, >> and are simply treated the same way as other 'reserved' memory types. >> >> Punching holes into the linear mapping causes page table fragmentation, >> which increases TLB pressure, and so we should avoid doing so if we can. >> So add a special case for regions of type EFI_ACPI_RECLAIM_MEMORY, and >> memblock_reserve() them instead of marking them MEMBLOCK_NOMAP. >> >> Signed-off-by: Ard Biesheuvel > > Sounds sane to me. FWIW: > > Acked-by: Mark Rutland > Thanks. I have queued this in efi/next