| Message ID | 20180612134200.17456-5-andr2000@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 06/12/2018 09:41 AM, Oleksandr Andrushchenko wrote: > From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com> > > Extend grant table module API to allow allocating buffers that can > be used for DMA operations and mapping foreign grant references > on top of those. > The resulting buffer is similar to the one allocated by the balloon > driver in terms that proper memory reservation is made > ({increase|decrease}_reservation and VA mappings updated if needed). > This is useful for sharing foreign buffers with HW drivers which > cannot work with scattered buffers provided by the balloon driver, > but require DMAable memory instead. > > Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> with a small nit below > --- > drivers/xen/Kconfig | 13 ++++++ > drivers/xen/grant-table.c | 97 +++++++++++++++++++++++++++++++++++++++ > include/xen/grant_table.h | 18 ++++++++ > 3 files changed, 128 insertions(+) > > diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig > index e5d0c28372ea..39536ddfbce4 100644 > --- a/drivers/xen/Kconfig > +++ b/drivers/xen/Kconfig > @@ -161,6 +161,19 @@ config XEN_GRANT_DEV_ALLOC > to other domains. This can be used to implement frontend drivers > or as part of an inter-domain shared memory channel. > > +config XEN_GRANT_DMA_ALLOC > + bool "Allow allocating DMA capable buffers with grant reference module" > + depends on XEN && HAS_DMA > + help > + Extends grant table module API to allow allocating DMA capable > + buffers and mapping foreign grant references on top of it. > + The resulting buffer is similar to one allocated by the balloon > + driver in terms that proper memory reservation is made > + ({increase|decrease}_reservation and VA mappings updated if needed). I think you should drop the word "terms" and say "is made *by*" and "VA mappings *are* updated" And similar change in the commit message. -boris
On 06/13/2018 04:12 AM, Boris Ostrovsky wrote: > > > On 06/12/2018 09:41 AM, Oleksandr Andrushchenko wrote: >> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com> >> >> Extend grant table module API to allow allocating buffers that can >> be used for DMA operations and mapping foreign grant references >> on top of those. >> The resulting buffer is similar to the one allocated by the balloon >> driver in terms that proper memory reservation is made >> ({increase|decrease}_reservation and VA mappings updated if needed). >> This is useful for sharing foreign buffers with HW drivers which >> cannot work with scattered buffers provided by the balloon driver, >> but require DMAable memory instead. >> >> Signed-off-by: Oleksandr Andrushchenko >> <oleksandr_andrushchenko@epam.com> > > Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> > > with a small nit below > > >> --- >> drivers/xen/Kconfig | 13 ++++++ >> drivers/xen/grant-table.c | 97 +++++++++++++++++++++++++++++++++++++++ >> include/xen/grant_table.h | 18 ++++++++ >> 3 files changed, 128 insertions(+) >> >> diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig >> index e5d0c28372ea..39536ddfbce4 100644 >> --- a/drivers/xen/Kconfig >> +++ b/drivers/xen/Kconfig >> @@ -161,6 +161,19 @@ config XEN_GRANT_DEV_ALLOC >> to other domains. This can be used to implement frontend drivers >> or as part of an inter-domain shared memory channel. >> +config XEN_GRANT_DMA_ALLOC >> + bool "Allow allocating DMA capable buffers with grant reference >> module" >> + depends on XEN && HAS_DMA >> + help >> + Extends grant table module API to allow allocating DMA capable >> + buffers and mapping foreign grant references on top of it. >> + The resulting buffer is similar to one allocated by the balloon >> + driver in terms that proper memory reservation is made >> + ({increase|decrease}_reservation and VA mappings updated if >> needed). > > I think you should drop the word "terms" and say "is made *by*" and > "VA mappings *are* updated" > > And similar change in the commit message. > Will, change, thank you > -boris >
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig index e5d0c28372ea..39536ddfbce4 100644 --- a/drivers/xen/Kconfig +++ b/drivers/xen/Kconfig @@ -161,6 +161,19 @@ config XEN_GRANT_DEV_ALLOC to other domains. This can be used to implement frontend drivers or as part of an inter-domain shared memory channel. +config XEN_GRANT_DMA_ALLOC + bool "Allow allocating DMA capable buffers with grant reference module" + depends on XEN && HAS_DMA + help + Extends grant table module API to allow allocating DMA capable + buffers and mapping foreign grant references on top of it. + The resulting buffer is similar to one allocated by the balloon + driver in terms that proper memory reservation is made + ({increase|decrease}_reservation and VA mappings updated if needed). + This is useful for sharing foreign buffers with HW drivers which + cannot work with scattered buffers provided by the balloon driver, + but require DMAable memory instead. + config SWIOTLB_XEN def_bool y select SWIOTLB diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c index dbb48a89e987..26ed498b5e6d 100644 --- a/drivers/xen/grant-table.c +++ b/drivers/xen/grant-table.c @@ -45,6 +45,9 @@ #include <linux/workqueue.h> #include <linux/ratelimit.h> #include <linux/moduleparam.h> +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC +#include <linux/dma-mapping.h> +#endif #include <xen/xen.h> #include <xen/interface/xen.h> @@ -57,6 +60,7 @@ #ifdef CONFIG_X86 #include <asm/xen/cpuid.h> #endif +#include <xen/mem-reservation.h> #include <asm/xen/hypercall.h> #include <asm/xen/interface.h> @@ -838,6 +842,99 @@ void gnttab_free_pages(int nr_pages, struct page **pages) } EXPORT_SYMBOL_GPL(gnttab_free_pages); +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC +/** + * gnttab_dma_alloc_pages - alloc DMAable pages suitable for grant mapping into + * @args: arguments to the function + */ +int gnttab_dma_alloc_pages(struct gnttab_dma_alloc_args *args) +{ + unsigned long pfn, start_pfn; + size_t size; + int i, ret; + + size = args->nr_pages << PAGE_SHIFT; + if (args->coherent) + args->vaddr = dma_alloc_coherent(args->dev, size, + &args->dev_bus_addr, + GFP_KERNEL | __GFP_NOWARN); + else + args->vaddr = dma_alloc_wc(args->dev, size, + &args->dev_bus_addr, + GFP_KERNEL | __GFP_NOWARN); + if (!args->vaddr) { + pr_debug("Failed to allocate DMA buffer of size %zu\n", size); + return -ENOMEM; + } + + start_pfn = __phys_to_pfn(args->dev_bus_addr); + for (pfn = start_pfn, i = 0; pfn < start_pfn + args->nr_pages; + pfn++, i++) { + struct page *page = pfn_to_page(pfn); + + args->pages[i] = page; + args->frames[i] = xen_page_to_gfn(page); + xenmem_reservation_scrub_page(page); + } + + xenmem_reservation_va_mapping_reset(args->nr_pages, args->pages); + + ret = xenmem_reservation_decrease(args->nr_pages, args->frames); + if (ret != args->nr_pages) { + pr_debug("Failed to decrease reservation for DMA buffer\n"); + ret = -EFAULT; + goto fail; + } + + ret = gnttab_pages_set_private(args->nr_pages, args->pages); + if (ret < 0) + goto fail; + + return 0; + +fail: + gnttab_dma_free_pages(args); + return ret; +} +EXPORT_SYMBOL_GPL(gnttab_dma_alloc_pages); + +/** + * gnttab_dma_free_pages - free DMAable pages + * @args: arguments to the function + */ +int gnttab_dma_free_pages(struct gnttab_dma_alloc_args *args) +{ + size_t size; + int i, ret; + + gnttab_pages_clear_private(args->nr_pages, args->pages); + + for (i = 0; i < args->nr_pages; i++) + args->frames[i] = page_to_xen_pfn(args->pages[i]); + + ret = xenmem_reservation_increase(args->nr_pages, args->frames); + if (ret != args->nr_pages) { + pr_debug("Failed to decrease reservation for DMA buffer\n"); + ret = -EFAULT; + } else { + ret = 0; + } + + xenmem_reservation_va_mapping_update(args->nr_pages, args->pages, + args->frames); + + size = args->nr_pages << PAGE_SHIFT; + if (args->coherent) + dma_free_coherent(args->dev, size, + args->vaddr, args->dev_bus_addr); + else + dma_free_wc(args->dev, size, + args->vaddr, args->dev_bus_addr); + return ret; +} +EXPORT_SYMBOL_GPL(gnttab_dma_free_pages); +#endif + /* Handling of paged out grant targets (GNTST_eagain) */ #define MAX_DELAY 256 static inline void diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h index de03f2542bb7..9bc5bc07d4d3 100644 --- a/include/xen/grant_table.h +++ b/include/xen/grant_table.h @@ -198,6 +198,24 @@ void gnttab_free_auto_xlat_frames(void); int gnttab_alloc_pages(int nr_pages, struct page **pages); void gnttab_free_pages(int nr_pages, struct page **pages); +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC +struct gnttab_dma_alloc_args { + /* Device for which DMA memory will be/was allocated. */ + struct device *dev; + /* If set then DMA buffer is coherent and write-combine otherwise. */ + bool coherent; + + int nr_pages; + struct page **pages; + xen_pfn_t *frames; + void *vaddr; + dma_addr_t dev_bus_addr; +}; + +int gnttab_dma_alloc_pages(struct gnttab_dma_alloc_args *args); +int gnttab_dma_free_pages(struct gnttab_dma_alloc_args *args); +#endif + int gnttab_pages_set_private(int nr_pages, struct page **pages); void gnttab_pages_clear_private(int nr_pages, struct page **pages);