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Mon, 8 Mar 2021 23:44:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 955F3C433CA Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=fail smtp.mailfrom=pdaly@codeaurora.org Date: Mon, 8 Mar 2021 15:44:28 -0800 From: Patrick Daly To: Catalin Marinas Cc: David Hildenbrand , linux-arm-kernel@lists.infradead.org, Will Deacon , Vincenzo Frascino , Anshuman Khandual , linux-mm@kvack.org Subject: Re: [PATCH] arm64: mte: Use PAGE_KERNEL_TAGGED in arch_add_memory Message-ID: <20210308234428.GA14896@pdaly-linux.qualcomm.com> References: <1614745263-27827-1-git-send-email-pdaly@codeaurora.org> <20210305111908.GA23855@arm.com> <20210305154340.GC23855@arm.com> <3dae4529-6c73-d4c0-3fa6-6c2bda6518c9@redhat.com> <20210305174413.GF23855@arm.com> <23d7530f-20cf-f7bb-b4e3-0a75606f0b19@redhat.com> <20210308111846.GC15644@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210308111846.GC15644@arm.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 77C422000381 X-Stat-Signature: 4pqa4rzyjkiw44pq6pqjof44xmhz34qb Received-SPF: none (mg.codeaurora.org>: No applicable sender policy available) receiver=imf11; identity=mailfrom; envelope-from=""; helo=z11.mailgun.us; client-ip=104.130.96.11 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1615247096-330222 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Mar 08, 2021 at 11:18:46AM +0000, Catalin Marinas wrote: > On Mon, Mar 08, 2021 at 12:00:17PM +0100, David Hildenbrand wrote: > > On 05.03.21 18:44, Catalin Marinas wrote: > > > On Fri, Mar 05, 2021 at 04:55:28PM +0100, David Hildenbrand wrote: > > > > On 05.03.21 16:43, Catalin Marinas wrote: > > > > > On Fri, Mar 05, 2021 at 11:19:08AM +0000, Catalin Marinas wrote: > > > > > > On Tue, Mar 02, 2021 at 08:21:03PM -0800, Patrick Daly wrote: > > > > > > > In a system which supports MTE, the linear kernel region must allow > > > > > > > reading/writing allocation tags. For memory present at boot this > > > > > > > is already being done in map_mem(). Add the same in arch_add_memory(). > > > > > > > > > > > > > > Signed-off-by: Patrick Daly > > > > > > > --- > > > > > > > arch/arm64/mm/mmu.c | 12 +++++++++++- > > > > > > > 1 file changed, 11 insertions(+), 1 deletion(-) > > > > > > > > > > > > > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > > > > > > > index 9b25d60b..0fcfe90 100644 > > > > > > > --- a/arch/arm64/mm/mmu.c > > > > > > > +++ b/arch/arm64/mm/mmu.c > > > > > > > @@ -1463,6 +1463,7 @@ int arch_add_memory(int nid, u64 start, u64 size, > > > > > > > struct mhp_params *params) > > > > > > > { > > > > > > > int ret, flags = 0; > > > > > > > + pgprot_t pgprot; > > > > > > > if (!inside_linear_region(start, size)) { > > > > > > > pr_err("[%llx %llx] is outside linear mapping region\n", start, start + size); > > > > > > > @@ -1477,8 +1478,17 @@ int arch_add_memory(int nid, u64 start, u64 size, > > > > > > > IS_ENABLED(CONFIG_KFENCE)) > > > > > > > flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; > > > > > > > + /* > > > > > > > + * The linear map must allow allocation tags reading/writing > > > > > > > + * if MTE is present. Otherwise, it has the same attributes as > > > > > > > + * PAGE_KERNEL. > > > > > > > + */ > > > > > > > + pgprot = params->pgprot; > > > > > > > + if (pgprot_val(pgprot) == pgprot_val(PAGE_KERNEL)) > > > > > > > + pgprot = PAGE_KERNEL_TAGGED; > > > > > > > + > > > > > > > __create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start), > > > > > > > - size, params->pgprot, __pgd_pgtable_alloc, > > > > > > > + size, pgprot, __pgd_pgtable_alloc, > > > > > > > flags); > > > [...] > > > > > ---------------8<------------------------------- > > > > > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h > > > > > index e17b96d0e4b5..5c78b92d9ec5 100644 > > > > > --- a/arch/arm64/include/asm/pgtable.h > > > > > +++ b/arch/arm64/include/asm/pgtable.h > > > > > @@ -486,6 +486,8 @@ static inline pmd_t pmd_mkdevmap(pmd_t pmd) > > > > > __pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_NORMAL_NC) | PTE_PXN | PTE_UXN) > > > > > #define pgprot_device(prot) \ > > > > > __pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_DEVICE_nGnRE) | PTE_PXN | PTE_UXN) > > > > > +#define pgprot_tagged(prot) \ > > > > > + __pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_NORMAL_TAGGED)) > > > > > /* > > > > > * DMA allocations for non-coherent devices use what the Arm architecture calls > > > > > * "Normal non-cacheable" memory, which permits speculation, unaligned accesses > > > > > diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h > > > > > index cdfc4e9f253e..f5f5044db2ce 100644 > > > > > --- a/include/linux/pgtable.h > > > > > +++ b/include/linux/pgtable.h > > > > > @@ -904,6 +904,10 @@ static inline void ptep_modify_prot_commit(struct vm_area_struct *vma, > > > > > #define pgprot_device pgprot_noncached > > > > > #endif > > > > > > > > > > +#ifndef pgprot_tagged > > > > > +#define pgprot_tagged(prot) (prot) > > > > > +#endif > > > > > + > > > > > #ifdef CONFIG_MMU > > > > > #ifndef pgprot_modify > > > > > #define pgprot_modify pgprot_modify > > > > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > > > > > index 5ba51a8bdaeb..4253d80a59ba 100644 > > > > > --- a/mm/memory_hotplug.c > > > > > +++ b/mm/memory_hotplug.c > > > > > @@ -1072,7 +1072,7 @@ static int online_memory_block(struct memory_block *mem, void *arg) > > > > > */ > > > > > int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags) > > > > > { > > > > > - struct mhp_params params = { .pgprot = PAGE_KERNEL }; > > > > > + struct mhp_params params = { .pgprot = pgprot_tagged(PAGE_KERNEL) }; > > > > > > > > This looks like we're pushing arch specific stuff ("tagged") in here. Can't > > > > we generalize this to something like > > > > > > > > pgprot_mhp_default > > > > > > > > (or a better name) > > > > > > > > that defaults to PAGE_KERNEL on all architectures except arm64 which > > > > overwrites this somehow? > > > > > > It works for me but I prefer the prot modification style similar to > > > pgprot_writecombine() etc. (i.e. takes a parameter like PAGE_KERNEL and > > > just changes bits of it). > > > > Sure, I'm wondering if we can abstract the "tagged" part here. > > > > pgprot_mhp(PAGE_KERNEL) whatsoever. > > > > But maybe we do consider the "tagged" part okay in common code already (it > > felt quite arm64 specific to me at first). I can spot untagged_addr() all > > over the place. So maybe pgprot_tagged() is just fine. > > That was my reasoning initially though 'tagged' in untagged_addr() > refers to some bits in the top part of the address and that will become > more common. 'Tagged' as a mapping attribute is specific to arm64 and > sparc for now. > > That said, pgprot_mhp() is probably better as the core code cannot tell > whether the arch implementation wants the hotplugged memory tagged or > not. Similarly, we'll add a pgprot_vmalloc() at some point. > > -- > Catalin Thanks for finding a cleaner solution than my original proposal. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project