| Message ID | 1655740136-3974-3-git-send-email-olekstysh@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Ability to allocate contiguous (was DMAable) pages using unpopulated-alloc | expand |
On Mon, 20 Jun 2022, Oleksandr Tyshchenko wrote: > From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> > > Depends on CONFIG_XEN_UNPOPULATED_ALLOC. If enabled then unpopulated > contiguous pages will be allocated for grant mapping into instead of > ballooning out real RAM pages. > > Also fallback to allocate DMAable pages (balloon out real RAM pages) > if we failed to allocate unpopulated contiguous pages. Use recently > introduced is_xen_unpopulated_page() in gnttab_dma_free_pages() to know > what API to use for freeing pages. > > Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> > --- > Please note, I haven't re-checked yet the use-case where the xen-swiotlb > is involved (proposed by Stefano): > https://lore.kernel.org/xen-devel/alpine.DEB.2.22.394.2206031348230.2783803@ubuntu-linux-20-04-desktop/ > I will re-check that for next version and add corresponding comment > in the code. Great. The patch looks good so far. > Changes RFC -> V1: > - update commit subject/description > - rework to avoid introducing alternative implementation > of gnttab_dma_alloc(free)_pages(), use IS_ENABLED() > - implement a fallback to real RAM pages if we failed to allocate > unpopulated contiguous pages (resolve initial TODO) > - update according to the API renaming (s/dma/contiguous) > --- > drivers/xen/grant-table.c | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c > index 738029d..15e426b 100644 > --- a/drivers/xen/grant-table.c > +++ b/drivers/xen/grant-table.c > @@ -1047,6 +1047,23 @@ int gnttab_dma_alloc_pages(struct gnttab_dma_alloc_args *args) > size_t size; > int i, ret; > > + if (IS_ENABLED(CONFIG_XEN_UNPOPULATED_ALLOC)) { > + ret = xen_alloc_unpopulated_contiguous_pages(args->dev, args->nr_pages, > + args->pages); > + if (ret < 0) > + goto fallback; > + > + ret = gnttab_pages_set_private(args->nr_pages, args->pages); > + if (ret < 0) > + goto fail; > + > + args->vaddr = page_to_virt(args->pages[0]); > + args->dev_bus_addr = page_to_phys(args->pages[0]); > + > + return ret; > + } > + > +fallback: > size = args->nr_pages << PAGE_SHIFT; > if (args->coherent) > args->vaddr = dma_alloc_coherent(args->dev, size, > @@ -1103,6 +1120,13 @@ int gnttab_dma_free_pages(struct gnttab_dma_alloc_args *args) > > gnttab_pages_clear_private(args->nr_pages, args->pages); > > + if (IS_ENABLED(CONFIG_XEN_UNPOPULATED_ALLOC) && > + is_xen_unpopulated_page(args->pages[0])) { > + xen_free_unpopulated_contiguous_pages(args->dev, args->nr_pages, > + args->pages); > + return 0; > + } > + > for (i = 0; i < args->nr_pages; i++) > args->frames[i] = page_to_xen_pfn(args->pages[i]); > > -- > 2.7.4 >
diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c index 738029d..15e426b 100644 --- a/drivers/xen/grant-table.c +++ b/drivers/xen/grant-table.c @@ -1047,6 +1047,23 @@ int gnttab_dma_alloc_pages(struct gnttab_dma_alloc_args *args) size_t size; int i, ret; + if (IS_ENABLED(CONFIG_XEN_UNPOPULATED_ALLOC)) { + ret = xen_alloc_unpopulated_contiguous_pages(args->dev, args->nr_pages, + args->pages); + if (ret < 0) + goto fallback; + + ret = gnttab_pages_set_private(args->nr_pages, args->pages); + if (ret < 0) + goto fail; + + args->vaddr = page_to_virt(args->pages[0]); + args->dev_bus_addr = page_to_phys(args->pages[0]); + + return ret; + } + +fallback: size = args->nr_pages << PAGE_SHIFT; if (args->coherent) args->vaddr = dma_alloc_coherent(args->dev, size, @@ -1103,6 +1120,13 @@ int gnttab_dma_free_pages(struct gnttab_dma_alloc_args *args) gnttab_pages_clear_private(args->nr_pages, args->pages); + if (IS_ENABLED(CONFIG_XEN_UNPOPULATED_ALLOC) && + is_xen_unpopulated_page(args->pages[0])) { + xen_free_unpopulated_contiguous_pages(args->dev, args->nr_pages, + args->pages); + return 0; + } + for (i = 0; i < args->nr_pages; i++) args->frames[i] = page_to_xen_pfn(args->pages[i]);