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[85.23.51.1]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-59e5f568737sm188515e87.21.2026.02.11.00.13.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Feb 2026 00:13:32 -0800 (PST) From: mpenttil@redhat.com To: linux-mm@kvack.org Cc: 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 Subject: [PATCH v5 2/6] mm: Add helper to convert HMM pfn to migrate pfn Date: Wed, 11 Feb 2026 10:12:57 +0200 Message-ID: <20260211081301.2940672-3-mpenttil@redhat.com> X-Mailer: git-send-email 2.50.0 In-Reply-To: <20260211081301.2940672-1-mpenttil@redhat.com> References: <20260211081301.2940672-1-mpenttil@redhat.com> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: FEu5JhqqfjxmdbbQ4_RsZfSjacUPb4ThZjH0JBgjYuI_1770797613 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Stat-Signature: xut5a585oqocq1m51dd4hruuxzmosq6c X-Rspamd-Queue-Id: E0D9718000C X-Rspam-User: X-HE-Tag: 1770797618-74940 X-HE-Meta: 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 PY66/O8T CjFni34GqERY/Qumog8+1O+zgNYGvYwVQMZTksXkLA7dKa5/6aS5kCmgxte18oHyTlvVYq4OtUjgWnx9Euv1dZvCZNr34bVtQCCKpQPOfrOOH4J+Tu6qF+Dxhha0t0NRGKKCiv49kgY+eQxNbWY99KS2H4UazownRpH1MUMP/htaXmhmSLyQIFQ1iWpMqFO9yf6qrXf4YMfFY0wSFYcRiUBXrCKcVQ5Rj9H/o1uJ9IRMSneUCJtcr18CENx7KanNaolKq3f+bwBXJcMnRW8P59uc+9PZtl3z4ozEpy8+VZ7x1OATgnLfQlhpq4qhZUesUMdqigMkIBMpn69V7R4NCRXR6nLSqz+/kImKJCbwgfkzrfAZEj8lti0wCFb7fg1MFRW6ZV8v5fQEGWpIvLyit5F9pfYvcFqA9UOZG 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: List-Subscribe: List-Unsubscribe: From: Mika Penttilä The unified HMM/migrate_device pagewalk does the "collecting" in HMM side, so need a helper to transfer pfns to 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 | 18 +++++++++-- include/linux/migrate.h | 3 +- mm/hmm.c | 6 ---- mm/migrate_device.c | 69 +++++++++++++++++++++++++++++++++++++++++ 4 files changed, 87 insertions(+), 9 deletions(-) diff --git a/include/linux/hmm.h b/include/linux/hmm.h index db75ffc949a7..b5418e318782 100644 --- a/include/linux/hmm.h +++ b/include/linux/hmm.h @@ -12,7 +12,7 @@ #include struct mmu_interval_notifier; - +struct migrate_vma; /* * On output: * 0 - The page is faultable and a future call with @@ -27,6 +27,7 @@ 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 - Migrate PTE installed * * On input: * 0 - Return the current state of the page, do not fault it. @@ -34,6 +35,7 @@ struct mmu_interval_notifier; * 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, request to migrate to device */ enum hmm_pfn_flags { /* Output fields and flags */ @@ -48,15 +50,25 @@ 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), }; +enum { + /* These flags are carried from input-to-output */ + HMM_PFN_INOUT_FLAGS = HMM_PFN_DMA_MAPPED | HMM_PFN_P2PDMA | + HMM_PFN_P2PDMA_BUS, +}; + /* * hmm_pfn_to_page() - return struct page pointed to by a device entry * @@ -107,6 +119,7 @@ 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 the associated vma */ struct hmm_range { struct mmu_interval_notifier *notifier; @@ -117,6 +130,7 @@ 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 26ca00c325d9..8e6c28efd4f8 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -3,6 +3,7 @@ #define _LINUX_MIGRATE_H #include +#include #include #include #include @@ -192,7 +193,7 @@ 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/hmm.c b/mm/hmm.c index 4ec74c18bef6..21ff99379836 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -41,12 +41,6 @@ enum { HMM_NEED_ALL_BITS = HMM_NEED_FAULT | HMM_NEED_WRITE_FAULT, }; -enum { - /* These flags are carried from input-to-output */ - HMM_PFN_INOUT_FLAGS = HMM_PFN_DMA_MAPPED | HMM_PFN_P2PDMA | - HMM_PFN_P2PDMA_BUS, -}; - static int hmm_pfns_fill(unsigned long addr, unsigned long end, struct hmm_range *range, unsigned long cpu_flags) { diff --git a/mm/migrate_device.c b/mm/migrate_device.c index 23379663b1e1..c773a82ea1ed 100644 --- a/mm/migrate_device.c +++ b/mm/migrate_device.c @@ -1489,3 +1489,72 @@ 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 migrate_vma to be populated + * + * When collecting happens by hmm_range_fault(), this populates + * the migrate->src[] and migrate->dst[] using range->hmm_pfns[]. + * Also, migrate->cpages and migrate->npages get initialized. + */ +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]; + + pfn &= ~HMM_PFN_INOUT_FLAGS; + + /* + * + * Don't do migration if valid and migrate flags are not both set. + * + */ + if ((pfn & (HMM_PFN_VALID | HMM_PFN_MIGRATE)) != + (HMM_PFN_VALID | HMM_PFN_MIGRATE)) { + migrate->src[i] = 0; + migrate->dst[i] = 0; + continue; + } + + migrate->cpages++; + + /* + * + * The zero page is encoded in a special way, valid and migrate is + * set, and pfn part is zero. Encode specially for migrate also. + * + */ + if (pfn == (HMM_PFN_VALID|HMM_PFN_MIGRATE)) { + migrate->src[i] = MIGRATE_PFN_MIGRATE; + migrate->dst[i] = 0; + continue; + } + if (pfn == (HMM_PFN_VALID|HMM_PFN_MIGRATE|HMM_PFN_COMPOUND)) { + migrate->src[i] = MIGRATE_PFN_MIGRATE|MIGRATE_PFN_COMPOUND; + migrate->dst[i] = 0; + continue; + } + + migrate->src[i] = migrate_pfn(page_to_pfn(hmm_pfn_to_page(pfn))) + | 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); -- 2.50.0