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b=j3QZjKt2RDG++7vwN6aJe3RA7jXlLMR25KRKluo6b+e2fpyRs/pTz6vg3MeMVgz3Y H/uFrc3+3pyN38Avf0YeUAxm/S/O+UYkxoG1yg2hevAJ7xtnMPU4ruJWSG/bl4vDRu a2+E5u83/YxSpGaDgPepX4M+KVq5eQWV3LxaqaNvqgJ0xF/Xh37LMhSBpaanlugiGi a6+IqmVFl9eTuZSg2ZqPukR9Tb5u+HfSSew9/Q5ZdNFqsJuWTV56233K9JINsg6JB4 SaDj00V23Bhf5UDAvsQeyU1kxlfysMR0sLQ47c99jCokiOgVXxgydYh+6zjRxefc3x m/QmnRG8vSOaA== X-Mailer: emacs 31.1 (via feedmail 11-beta-1 I) From: Aneesh Kumar K.V To: Catalin Marinas Cc: linux-coco@lists.linux.dev, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, iommu@lists.linux.dev, Andrew Morton , christian.koenig@amd.com, Jason Gunthorpe , Joerg Roedel , Marc Zyngier , Marek Szyprowski , Robin Murphy , Steven Price , Sumit Semwal , Suzuki K Poulose , Thomas Gleixner , Will Deacon , dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-media@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH v7 06/13] dma-contiguous: Accept an explicit minimum alignment In-Reply-To: References: <20260921144847.501151-1-aneesh.kumar@kernel.org> <20260921144847.501151-7-aneesh.kumar@kernel.org> Date: Wed, 23 Sep 2026 17:19:52 +0530 Message-ID: MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Queue-Id: AD2644000D X-Rspam-User: X-Rspamd-Server: rspam07 X-Stat-Signature: e51f9b1w9ufjcqkusbnhtcja6cyxwd54 X-HE-Tag: 1790164202-797288 X-HE-Meta: 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 1Nm66pgK amc1GSCB5o8FA1IIQH1tLrgTGdWIsxYvSw/yyvwEdkMGPAckCD4cl6ekLRAKm7396xV1yg0EdNO1S793lwGYAisK3U/WQ9RqmWg0gtxGIOo/+yzFWvpWhzkdNKkRiiXX5fhf2MasfpX82TsK1aqi/VeoFW07USj20sywbOya1pjLccAhnOBjTQJUWvKe6FXHjNM6ZQE7Y+fWjLb9+I1IH+sV70g+SiLBaUnPylZy4ZxgiYP8jcbBImKlaWwKpNUQ2ci4Hx+UcTHONeeLpLb0RXbM84w== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Catalin Marinas writes: > On Mon, Sep 21, 2026 at 08:18:40PM +0530, Aneesh Kumar K.V (Arm) wrote: >> @@ -125,7 +126,8 @@ static inline int dma_contiguous_reserve_area(phys_addr_t size, >> return -ENOSYS; >> } >> static inline struct page *dma_alloc_from_contiguous(struct device *dev, >> - size_t count, unsigned int order, bool no_warn) >> + size_t count, unsigned int order, unsigned int required_order, >> + bool no_warn) >> { >> return NULL; >> } >> @@ -136,7 +138,7 @@ static inline bool dma_release_from_contiguous(struct device *dev, >> } >> /* Use fallback alloc() and free() when CONFIG_DMA_CMA=n */ >> static inline struct page *dma_alloc_contiguous(struct device *dev, size_t size, >> - gfp_t gfp) >> + gfp_t gfp, unsigned int align_order) > > Can we not just bake the alignment further down in these functions > rather than getting the callers to pass the {required,align}_order? > But, we need this to be conditional on CoCo shared allocations. We could derive that from attrs and pass attrs instead of align_order, i.e. something like: struct page *dma_alloc_from_contiguous(struct device *dev, size_t count, - unsigned int align, unsigned int required_align, bool no_warn) + unsigned int align, unsigned long attrs, bool no_warn) { - if (required_align > CONFIG_CMA_ALIGNMENT) + if (!dma_contiguous_resolve_alignment(attrs, &align)) return NULL; - align = min(max(align, required_align), CONFIG_CMA_ALIGNMENT); return cma_alloc(dev_get_cma_area(dev), count, align, no_warn); } with +static bool dma_contiguous_resolve_alignment(unsigned long attrs, + unsigned int *align) +{ + unsigned int required_align = 0; + + if (attrs & __DMA_ATTR_ALLOC_CC_SHARED) + required_align = get_order(cc_shared_granule_size()); + if (required_align > CONFIG_CMA_ALIGNMENT) + return false; + + *align = min(max(*align, required_align), CONFIG_CMA_ALIGNMENT); + return true; +} + -aneesh