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[89.27.86.246]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-5bfe073e0f9sm1964634e87.54.2026.11.02.22.16.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Nov 2026 22:16:49 -0800 (PST) From: mpenttil@redhat.com To: linux-mm@kvack.org Cc: dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-kernel@vger.kernel.org, =?UTF-8?q?Mika=20Penttil=C3=A4?= , David Hildenbrand , Jason Gunthorpe , Leon Romanovsky , Alistair Popple , Balbir Singh , Zi Yan , Matthew Brost , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Lyude Paul , Danilo Krummrich Subject: [PATCH v17 02/12] mm: add helper to convert HMM pfn to migrate pfn Date: Tue, 3 Nov 2026 08:16:19 +0200 Message-ID: <20261103061629.972669-3-mpenttil@redhat.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20261103061629.972669-1-mpenttil@redhat.com> References: <20261103061629.972669-1-mpenttil@redhat.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Mika Penttilä The unified HMM/migrate_device pagewalk does the "collecting" on the HMM side, so we need a helper to transfer pfns to the migrate_vma world. Cc: David Hildenbrand Cc: Jason Gunthorpe Cc: Leon Romanovsky Cc: Alistair Popple Cc: Balbir Singh Cc: Zi Yan Cc: Matthew Brost Suggested-by: Alistair Popple Signed-off-by: Mika Penttilä --- include/linux/hmm.h | 29 +++++++++++++++++----- include/linux/migrate.h | 3 ++- mm/migrate_device.c | 55 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 80 insertions(+), 7 deletions(-) diff --git a/include/linux/hmm.h b/include/linux/hmm.h index 6f04e3932f5b..4f56f3419cb4 100644 --- a/include/linux/hmm.h +++ b/include/linux/hmm.h @@ -13,6 +13,8 @@ struct mmu_interval_notifier; +struct migrate_vma; + /* * On output: * 0 - The page is faultable and a future call with @@ -27,13 +29,22 @@ struct mmu_interval_notifier; * HMM_PFN_P2PDMA_BUS - Bus mapped P2P transfer * HMM_PFN_DMA_MAPPED - Flag preserved on input-to-output transformation * to mark that page is already DMA mapped + * HMM_PFN_MIGRATE - The entry is to be migrated. Note, HMM_PFN_MIGRATE + * alone without HMM_PFN_VALID denotes the + * empty page. + * This flag optionally together with HMM_PFN_COMPOUND + * are indicators for migrate_hmm_range_setup() to + * setup the migrate pfns. + * HMM_PFN_COMPOUND - The entry represents a > 0 order page * * On input: - * 0 - Return the current state of the page, do not fault it. - * HMM_PFN_REQ_FAULT - The output must have HMM_PFN_VALID or hmm_range_fault() - * will fail - * HMM_PFN_REQ_WRITE - The output must have HMM_PFN_WRITE or hmm_range_fault() - * will fail. Must be combined with HMM_PFN_REQ_FAULT. + * 0 - Return the current state of the page, do not fault it. + * HMM_PFN_REQ_FAULT - The output must have HMM_PFN_VALID or hmm_range_fault() + * will fail + * HMM_PFN_REQ_WRITE - The output must have HMM_PFN_WRITE or hmm_range_fault() + * will fail. Must be combined with HMM_PFN_REQ_FAULT. + * HMM_PFN_REQ_MIGRATE - For default_flags only, request to migrate the range, + * according to hmm_range.migrate.flags */ enum hmm_pfn_flags { /* Output fields and flags */ @@ -48,11 +59,15 @@ enum hmm_pfn_flags { HMM_PFN_P2PDMA = 1UL << (BITS_PER_LONG - 5), HMM_PFN_P2PDMA_BUS = 1UL << (BITS_PER_LONG - 6), - HMM_PFN_ORDER_SHIFT = (BITS_PER_LONG - 11), + /* Migrate request */ + HMM_PFN_MIGRATE = 1UL << (BITS_PER_LONG - 7), + HMM_PFN_COMPOUND = 1UL << (BITS_PER_LONG - 8), + HMM_PFN_ORDER_SHIFT = (BITS_PER_LONG - 13), /* Input flags */ HMM_PFN_REQ_FAULT = HMM_PFN_VALID, HMM_PFN_REQ_WRITE = HMM_PFN_WRITE, + HMM_PFN_REQ_MIGRATE = HMM_PFN_MIGRATE, HMM_PFN_FLAGS = ~((1UL << HMM_PFN_ORDER_SHIFT) - 1), }; @@ -107,6 +122,7 @@ static inline unsigned int hmm_pfn_to_map_order(unsigned long hmm_pfn) * @default_flags: default flags for the range (write, read, ... see hmm doc) * @pfn_flags_mask: allows to mask pfn flags so that only default_flags matter * @dev_private_owner: owner of device private pages + * @migrate: structure for migrating a range of a VMA */ struct hmm_range { struct mmu_interval_notifier *notifier; @@ -117,6 +133,7 @@ struct hmm_range { unsigned long default_flags; unsigned long pfn_flags_mask; void *dev_private_owner; + struct migrate_vma *migrate; }; /* diff --git a/include/linux/migrate.h b/include/linux/migrate.h index 78424b3824c2..280ec9a866c7 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -3,6 +3,7 @@ #define _LINUX_MIGRATE_H #include +#include #include #include #include @@ -202,7 +203,7 @@ void migrate_device_pages(unsigned long *src_pfns, unsigned long *dst_pfns, unsigned long npages); void migrate_device_finalize(unsigned long *src_pfns, unsigned long *dst_pfns, unsigned long npages); - +void migrate_hmm_range_setup(struct hmm_range *range); #endif /* CONFIG_MIGRATION */ #endif /* _LINUX_MIGRATE_H */ diff --git a/mm/migrate_device.c b/mm/migrate_device.c index 9e19fadfa65c..ba6775a0d37e 100644 --- a/mm/migrate_device.c +++ b/mm/migrate_device.c @@ -1530,3 +1530,58 @@ int migrate_device_coherent_folio(struct folio *folio) return 0; return -EBUSY; } + +/** + * migrate_hmm_range_setup() - prepare to migrate a range of memory + * @range: contains pointer to struct migrate_vma to be set up. + * + * When collecting has been done with hmm_range_fault(), this + * should be called next, and completes range->migrate by + * populating migrate->src[] and migrate->dst[] + * using range->hmm_pfns[]. + * Also, migrate->cpages and migrate->npages get initialized. + * After migrate_hmm_range_setup(), range->migrate is good + * for the rest of the migrate_vma_* flow. + */ +void migrate_hmm_range_setup(struct hmm_range *range) +{ + struct migrate_vma *migrate = range->migrate; + + if (!migrate) + return; + + migrate->npages = (migrate->end - migrate->start) >> PAGE_SHIFT; + migrate->cpages = 0; + + for (unsigned long i = 0; i < migrate->npages; i++) { + unsigned long pfn = range->hmm_pfns[i]; + + /* + * We are only interested in entries to be + * migrated. + */ + if (!(pfn & HMM_PFN_MIGRATE)) { + migrate->src[i] = 0; + migrate->dst[i] = 0; + continue; + } + + migrate->cpages++; + + /* HMM_PFN_MIGRATE without HMM_PFN_VALID denotes the special zero page */ + if (pfn & HMM_PFN_VALID) + migrate->src[i] = migrate_pfn(page_to_pfn(hmm_pfn_to_page(pfn))); + else + migrate->src[i] = 0; + + migrate->src[i] |= MIGRATE_PFN_MIGRATE; + migrate->src[i] |= (pfn & HMM_PFN_WRITE) ? MIGRATE_PFN_WRITE : 0; + migrate->src[i] |= (pfn & HMM_PFN_COMPOUND) ? MIGRATE_PFN_COMPOUND : 0; + migrate->dst[i] = 0; + } + + if (migrate->cpages) + migrate_vma_unmap(migrate); + +} +EXPORT_SYMBOL(migrate_hmm_range_setup); -- 2.55.0