| Message ID | 20211115193026.27568-3-alex.sierra@amd.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add MEMORY_DEVICE_COHERENT for coherent device memory mapping | expand |
On Tuesday, 16 November 2021 6:30:19 AM AEDT Alex Sierra wrote: > This case is used to migrate pages from device memory, back to system > memory. Device coherent type memory is cache coherent from device and CPU > point of view. > > Signed-off-by: Alex Sierra <alex.sierra@amd.com> > --- > v2: > condition added when migrations from device coherent pages. > --- > include/linux/migrate.h | 1 + > mm/migrate.c | 9 +++++++-- > 2 files changed, 8 insertions(+), 2 deletions(-) > > diff --git a/include/linux/migrate.h b/include/linux/migrate.h > index c8077e936691..e74bb0978f6f 100644 > --- a/include/linux/migrate.h > +++ b/include/linux/migrate.h > @@ -138,6 +138,7 @@ static inline unsigned long migrate_pfn(unsigned long pfn) > enum migrate_vma_direction { > MIGRATE_VMA_SELECT_SYSTEM = 1 << 0, > MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1, > + MIGRATE_VMA_SELECT_DEVICE_COHERENT = 1 << 2, > }; > > struct migrate_vma { > diff --git a/mm/migrate.c b/mm/migrate.c > index f74422a42192..166bfec7d85e 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -2340,8 +2340,6 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, > if (is_writable_device_private_entry(entry)) > mpfn |= MIGRATE_PFN_WRITE; > } else { > - if (!(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM)) > - goto next; > pfn = pte_pfn(pte); > if (is_zero_pfn(pfn)) { > mpfn = MIGRATE_PFN_MIGRATE; > @@ -2349,6 +2347,13 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, > goto next; > } > page = vm_normal_page(migrate->vma, addr, pte); > + if (!is_zone_device_page(page) && > + !(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM)) > + goto next; > + if (is_zone_device_page(page) && > + (!(migrate->flags & MIGRATE_VMA_SELECT_DEVICE_COHERENT) || > + page->pgmap->owner != migrate->pgmap_owner)) > + goto next; Thanks Alex, couple of comments on this: 1. vm_normal_page() can return NULL so you need to add a check for page == NULL otherwise the call to is_zone_device_page(NULL) will crash. 2. The check for a coherent device page is too indirect. Being explicit and using is_zone_device_coherent_page() instead would make it more direct and obvious, particularly for developers who may not immediately realise that device-private pages should never have pte_present() entries. > mpfn = migrate_pfn(pfn) | MIGRATE_PFN_MIGRATE; > mpfn |= pte_write(pte) ? MIGRATE_PFN_WRITE : 0; > } >
diff --git a/include/linux/migrate.h b/include/linux/migrate.h index c8077e936691..e74bb0978f6f 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -138,6 +138,7 @@ static inline unsigned long migrate_pfn(unsigned long pfn) enum migrate_vma_direction { MIGRATE_VMA_SELECT_SYSTEM = 1 << 0, MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1, + MIGRATE_VMA_SELECT_DEVICE_COHERENT = 1 << 2, }; struct migrate_vma { diff --git a/mm/migrate.c b/mm/migrate.c index f74422a42192..166bfec7d85e 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -2340,8 +2340,6 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, if (is_writable_device_private_entry(entry)) mpfn |= MIGRATE_PFN_WRITE; } else { - if (!(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM)) - goto next; pfn = pte_pfn(pte); if (is_zero_pfn(pfn)) { mpfn = MIGRATE_PFN_MIGRATE; @@ -2349,6 +2347,13 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, goto next; } page = vm_normal_page(migrate->vma, addr, pte); + if (!is_zone_device_page(page) && + !(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM)) + goto next; + if (is_zone_device_page(page) && + (!(migrate->flags & MIGRATE_VMA_SELECT_DEVICE_COHERENT) || + page->pgmap->owner != migrate->pgmap_owner)) + goto next; mpfn = migrate_pfn(pfn) | MIGRATE_PFN_MIGRATE; mpfn |= pte_write(pte) ? MIGRATE_PFN_WRITE : 0; }
This case is used to migrate pages from device memory, back to system memory. Device coherent type memory is cache coherent from device and CPU point of view. Signed-off-by: Alex Sierra <alex.sierra@amd.com> --- v2: condition added when migrations from device coherent pages. --- include/linux/migrate.h | 1 + mm/migrate.c | 9 +++++++-- 2 files changed, 8 insertions(+), 2 deletions(-)