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[85.23.51.1]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-395dca7bcddsm20698161fa.16.2026.05.24.22.08.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 24 May 2026 22:08:58 -0700 (PDT) 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 , Marco Pagani Subject: [PATCH v11 5/5] lib/test_hmm: add a new testcase for the migrate on fault Date: Mon, 25 May 2026 08:08:30 +0300 Message-ID: <20260525050830.100254-6-mpenttil@redhat.com> X-Mailer: git-send-email 2.50.0 In-Reply-To: <20260525050830.100254-1-mpenttil@redhat.com> References: <20260525050830.100254-1-mpenttil@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Mika Penttilä Enhance the hmm test driver (lib/test_hmm) with migrate on fault case. Cc: David Hildenbrand Cc: Jason Gunthorpe Cc: Leon Romanovsky Cc: Alistair Popple Cc: Balbir Singh Cc: Zi Yan Cc: Matthew Brost Signed-off-by: Marco Pagani Signed-off-by: Mika Penttilä --- lib/test_hmm.c | 116 ++++++++++++++++++++++++- lib/test_hmm_uapi.h | 19 ++-- tools/testing/selftests/mm/hmm-tests.c | 54 ++++++++++++ 3 files changed, 176 insertions(+), 13 deletions(-) diff --git a/lib/test_hmm.c b/lib/test_hmm.c index 1a3e21325cf2..d45666b51f33 100644 --- a/lib/test_hmm.c +++ b/lib/test_hmm.c @@ -36,6 +36,7 @@ #define DMIRROR_RANGE_FAULT_TIMEOUT 1000 #define DEVMEM_CHUNK_SIZE (256 * 1024 * 1024U) #define DEVMEM_CHUNKS_RESERVE 16 +#define PFNS_ARRAY_SIZE 64 /* * For device_private pages, dpage is just a dummy struct page @@ -355,6 +356,7 @@ static int dmirror_range_fault(struct dmirror *dmirror, struct mm_struct *mm = dmirror->notifier.mm; unsigned long timeout = jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT); + bool migrate = range->default_flags & HMM_PFN_REQ_MIGRATE; int ret; while (true) { @@ -364,9 +366,15 @@ static int dmirror_range_fault(struct dmirror *dmirror, } range->notifier_seq = mmu_interval_read_begin(range->notifier); - mmap_read_lock(mm); - ret = hmm_range_fault(range); - mmap_read_unlock(mm); + + /* mmap lock held for whole migrate on fault operation */ + if (!migrate) { + mmap_read_lock(mm); + ret = hmm_range_fault(range); + mmap_read_unlock(mm); + } else { + ret = hmm_range_fault(range); + } if (ret) { if (ret == -EBUSY) continue; @@ -382,7 +390,9 @@ static int dmirror_range_fault(struct dmirror *dmirror, break; } - ret = dmirror_do_fault(dmirror, range); + /* update device page table after migration */ + if (!migrate) + ret = dmirror_do_fault(dmirror, range); mutex_unlock(&dmirror->mutex); out: @@ -1258,6 +1268,100 @@ static int dmirror_migrate_to_device(struct dmirror *dmirror, return ret; } +static int do_fault_and_migrate(struct dmirror *dmirror, struct hmm_range *range) +{ + struct migrate_vma *migrate = range->migrate; + int ret; + + mmap_read_lock(dmirror->notifier.mm); + + /* Fault-in pages for migration */ + ret = dmirror_range_fault(dmirror, range); + + pr_debug("Migrating from sys mem to device mem\n"); + migrate_hmm_range_setup(range); + + dmirror_migrate_alloc_and_copy(migrate, dmirror); + migrate_vma_pages(migrate); + dmirror_migrate_finalize_and_map(migrate, dmirror); + migrate_vma_finalize(migrate); + + mmap_read_unlock(dmirror->notifier.mm); + return ret; +} + +static int dmirror_fault_and_migrate_to_device(struct dmirror *dmirror, + struct hmm_dmirror_cmd *cmd) +{ + unsigned long start, size, end, next; + unsigned long src_pfns[PFNS_ARRAY_SIZE] = { 0 }; + unsigned long dst_pfns[PFNS_ARRAY_SIZE] = { 0 }; + struct migrate_vma migrate = { 0 }; + struct hmm_range range = { 0 }; + struct dmirror_bounce bounce; + int ret = 0; + + /* Whole range */ + start = cmd->addr; + size = cmd->npages << PAGE_SHIFT; + end = start + size; + + if (!mmget_not_zero(dmirror->notifier.mm)) { + ret = -EFAULT; + goto out; + } + + migrate.pgmap_owner = dmirror->mdevice; + migrate.src = src_pfns; + migrate.dst = dst_pfns; + migrate.flags = MIGRATE_VMA_SELECT_SYSTEM; + + range.migrate = &migrate; + range.hmm_pfns = src_pfns; + range.pfn_flags_mask = 0; + range.default_flags = HMM_PFN_REQ_FAULT | HMM_PFN_REQ_MIGRATE; + range.dev_private_owner = dmirror->mdevice; + range.notifier = &dmirror->notifier; + + for (next = start; next < end; next = range.end) { + range.start = next; + range.end = min(end, next + (PFNS_ARRAY_SIZE << PAGE_SHIFT)); + + pr_debug("Fault and migrate range start:%#lx end:%#lx\n", + range.start, range.end); + + ret = do_fault_and_migrate(dmirror, &range); + if (ret) + goto out_mmput; + } + + /* + * Return the migrated data for verification. + * Only for pages in device zone + */ + ret = dmirror_bounce_init(&bounce, start, size); + if (ret) + goto out_mmput; + + mutex_lock(&dmirror->mutex); + ret = dmirror_do_read(dmirror, start, end, &bounce); + mutex_unlock(&dmirror->mutex); + if (ret == 0) { + ret = copy_to_user(u64_to_user_ptr(cmd->ptr), bounce.ptr, bounce.size); + if (ret) + ret = -EFAULT; + } + + cmd->cpages = bounce.cpages; + dmirror_bounce_fini(&bounce); + + +out_mmput: + mmput(dmirror->notifier.mm); +out: + return ret; +} + static void dmirror_mkentry(struct dmirror *dmirror, struct hmm_range *range, unsigned char *perm, unsigned long entry) { @@ -1524,6 +1628,10 @@ static long dmirror_fops_unlocked_ioctl(struct file *filp, ret = dmirror_migrate_to_device(dmirror, &cmd); break; + case HMM_DMIRROR_MIGRATE_ON_FAULT_TO_DEV: + ret = dmirror_fault_and_migrate_to_device(dmirror, &cmd); + break; + case HMM_DMIRROR_MIGRATE_TO_SYS: ret = dmirror_migrate_to_system(dmirror, &cmd); break; diff --git a/lib/test_hmm_uapi.h b/lib/test_hmm_uapi.h index f94c6d457338..0b6e7a419e36 100644 --- a/lib/test_hmm_uapi.h +++ b/lib/test_hmm_uapi.h @@ -29,15 +29,16 @@ struct hmm_dmirror_cmd { }; /* Expose the address space of the calling process through hmm device file */ -#define HMM_DMIRROR_READ _IOWR('H', 0x00, struct hmm_dmirror_cmd) -#define HMM_DMIRROR_WRITE _IOWR('H', 0x01, struct hmm_dmirror_cmd) -#define HMM_DMIRROR_MIGRATE_TO_DEV _IOWR('H', 0x02, struct hmm_dmirror_cmd) -#define HMM_DMIRROR_MIGRATE_TO_SYS _IOWR('H', 0x03, struct hmm_dmirror_cmd) -#define HMM_DMIRROR_SNAPSHOT _IOWR('H', 0x04, struct hmm_dmirror_cmd) -#define HMM_DMIRROR_EXCLUSIVE _IOWR('H', 0x05, struct hmm_dmirror_cmd) -#define HMM_DMIRROR_CHECK_EXCLUSIVE _IOWR('H', 0x06, struct hmm_dmirror_cmd) -#define HMM_DMIRROR_RELEASE _IOWR('H', 0x07, struct hmm_dmirror_cmd) -#define HMM_DMIRROR_FLAGS _IOWR('H', 0x08, struct hmm_dmirror_cmd) +#define HMM_DMIRROR_READ _IOWR('H', 0x00, struct hmm_dmirror_cmd) +#define HMM_DMIRROR_WRITE _IOWR('H', 0x01, struct hmm_dmirror_cmd) +#define HMM_DMIRROR_MIGRATE_TO_DEV _IOWR('H', 0x02, struct hmm_dmirror_cmd) +#define HMM_DMIRROR_MIGRATE_ON_FAULT_TO_DEV _IOWR('H', 0x03, struct hmm_dmirror_cmd) +#define HMM_DMIRROR_MIGRATE_TO_SYS _IOWR('H', 0x04, struct hmm_dmirror_cmd) +#define HMM_DMIRROR_SNAPSHOT _IOWR('H', 0x05, struct hmm_dmirror_cmd) +#define HMM_DMIRROR_EXCLUSIVE _IOWR('H', 0x06, struct hmm_dmirror_cmd) +#define HMM_DMIRROR_CHECK_EXCLUSIVE _IOWR('H', 0x07, struct hmm_dmirror_cmd) +#define HMM_DMIRROR_RELEASE _IOWR('H', 0x08, struct hmm_dmirror_cmd) +#define HMM_DMIRROR_FLAGS _IOWR('H', 0x09, struct hmm_dmirror_cmd) #define HMM_DMIRROR_FLAG_FAIL_ALLOC (1ULL << 0) diff --git a/tools/testing/selftests/mm/hmm-tests.c b/tools/testing/selftests/mm/hmm-tests.c index 77fb4c5d871b..c8d6a3c33ef2 100644 --- a/tools/testing/selftests/mm/hmm-tests.c +++ b/tools/testing/selftests/mm/hmm-tests.c @@ -278,6 +278,13 @@ static int hmm_migrate_sys_to_dev(int fd, return hmm_dmirror_cmd(fd, HMM_DMIRROR_MIGRATE_TO_DEV, buffer, npages); } +static int hmm_migrate_on_fault_sys_to_dev(int fd, + struct hmm_buffer *buffer, + unsigned long npages) +{ + return hmm_dmirror_cmd(fd, HMM_DMIRROR_MIGRATE_ON_FAULT_TO_DEV, buffer, npages); +} + static int hmm_migrate_dev_to_sys(int fd, struct hmm_buffer *buffer, unsigned long npages) @@ -985,6 +992,53 @@ TEST_F(hmm, migrate) hmm_buffer_free(buffer); } + +/* + * Fault and migrate anonymous memory to device private memory. + */ +TEST_F(hmm, migrate_on_fault) +{ + struct hmm_buffer *buffer; + unsigned long npages; + unsigned long size; + unsigned long i; + int *ptr; + int ret; + + npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift; + ASSERT_NE(npages, 0); + size = npages << self->page_shift; + + buffer = malloc(sizeof(*buffer)); + ASSERT_NE(buffer, NULL); + + buffer->fd = -1; + buffer->size = size; + buffer->mirror = malloc(size); + ASSERT_NE(buffer->mirror, NULL); + + buffer->ptr = mmap(NULL, size, + PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, + buffer->fd, 0); + ASSERT_NE(buffer->ptr, MAP_FAILED); + + /* Initialize buffer in system memory. */ + for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i) + ptr[i] = i; + + /* Fault and migrate memory to device. */ + ret = hmm_migrate_on_fault_sys_to_dev(self->fd, buffer, npages); + ASSERT_EQ(ret, 0); + ASSERT_EQ(buffer->cpages, npages); + + /* Check what the device read. */ + for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i) + ASSERT_EQ(ptr[i], i); + + hmm_buffer_free(buffer); +} + /* * Migrate private file memory to device private memory. */ -- 2.50.0