| Message ID | 1441640038-23615-13-git-send-email-julien.grall@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, 7 Sep 2015, Julien Grall wrote: > For ARM64 guests, Linux is able to support either 64K or 4K page > granularity. Although, the hypercall interface is always based on 4K > page granularity. > > With 64K page granularity, a single page will be spread over multiple > Xen frame. > > To avoid splitting the page into 4K frame, take advantage of the > extent_order field to directly allocate/free chunk of the Linux page > size. > > Note that PVMMU is only used for PV guest (which is x86) and the page > granularity is always 4KB. Some BUILD_BUG_ON has been added to ensure > that because the code has not been modified. > > Signed-off-by: Julien Grall <julien.grall@citrix.com> Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > --- > Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> > Cc: David Vrabel <david.vrabel@citrix.com> > Cc: Wei Liu <wei.liu2@citrix.com> > > Note that two BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE) in code built > for the PV MMU code is kept in order to have at least one even if we > ever decide to drop of code section. > > Changes in v4: > - s/xen_page_to_pfn/page_to_xen_pfn/ based on the new naming > - Use the field lru in the page to get a list of pages when > decreasing the memory reservation. It avoids to use a static > array to store the pages (see v3). > - Update comment for EXTENT_ORDER. > > Changes in v3: > - Fix errors reported by checkpatch.pl > - s/mfn/gfn/ based on the new naming > - Rather than splitting the page into 4KB chunk, use the > extent_order field to allocate directly a Linux page size. This > is avoid lots of code for no benefits. > > Changes in v2: > - Use xen_apply_to_page to split a page in 4K chunk > - It's not necessary to have a smaller frame list. Re-use > PAGE_SIZE > - Convert reserve_additional_memory to use XEN_... macro > --- > drivers/xen/balloon.c | 59 ++++++++++++++++++++++++++++++++++++++------------- > 1 file changed, 44 insertions(+), 15 deletions(-) > > diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c > index c79329f..3babf13 100644 > --- a/drivers/xen/balloon.c > +++ b/drivers/xen/balloon.c > @@ -70,6 +70,11 @@ > #include <xen/features.h> > #include <xen/page.h> > > +/* Use one extent per PAGE_SIZE to avoid to break down the page into > + * multiple frame. > + */ > +#define EXTENT_ORDER (fls(XEN_PFN_PER_PAGE) - 1) > + > /* > * balloon_process() state: > * > @@ -230,6 +235,11 @@ static enum bp_state reserve_additional_memory(long credit) > nid = memory_add_physaddr_to_nid(hotplug_start_paddr); > > #ifdef CONFIG_XEN_HAVE_PVMMU > + /* We don't support PV MMU when Linux and Xen is using > + * different page granularity. > + */ > + BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE); > + > /* > * add_memory() will build page tables for the new memory so > * the p2m must contain invalid entries so the correct > @@ -326,11 +336,11 @@ static enum bp_state reserve_additional_memory(long credit) > static enum bp_state increase_reservation(unsigned long nr_pages) > { > int rc; > - unsigned long pfn, i; > + unsigned long i; > struct page *page; > struct xen_memory_reservation reservation = { > .address_bits = 0, > - .extent_order = 0, > + .extent_order = EXTENT_ORDER, > .domid = DOMID_SELF > }; > > @@ -352,7 +362,11 @@ static enum bp_state increase_reservation(unsigned long nr_pages) > nr_pages = i; > break; > } > - frame_list[i] = page_to_pfn(page); > + > + /* XENMEM_populate_physmap requires a PFN based on Xen > + * granularity. > + */ > + frame_list[i] = page_to_xen_pfn(page); > page = balloon_next_page(page); > } > > @@ -366,10 +380,15 @@ static enum bp_state increase_reservation(unsigned long nr_pages) > page = balloon_retrieve(false); > BUG_ON(page == NULL); > > - pfn = page_to_pfn(page); > - > #ifdef CONFIG_XEN_HAVE_PVMMU > + /* We don't support PV MMU when Linux and Xen is using > + * different page granularity. > + */ > + BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE); > + > if (!xen_feature(XENFEAT_auto_translated_physmap)) { > + unsigned long pfn = page_to_pfn(page); > + > set_phys_to_machine(pfn, frame_list[i]); > > /* Link back into the page tables if not highmem. */ > @@ -396,14 +415,15 @@ static enum bp_state increase_reservation(unsigned long nr_pages) > static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) > { > enum bp_state state = BP_DONE; > - unsigned long pfn, i; > - struct page *page; > + unsigned long i; > + struct page *page, *tmp; > int ret; > struct xen_memory_reservation reservation = { > .address_bits = 0, > - .extent_order = 0, > + .extent_order = EXTENT_ORDER, > .domid = DOMID_SELF > }; > + LIST_HEAD(pages); > > #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG > if (balloon_stats.hotplug_pages) { > @@ -425,8 +445,7 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) > break; > } > scrub_page(page); > - > - frame_list[i] = page_to_pfn(page); > + list_add(&page->lru, &pages); > } > > /* > @@ -438,14 +457,23 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) > */ > kmap_flush_unused(); > > - /* Update direct mapping, invalidate P2M, and add to balloon. */ > - for (i = 0; i < nr_pages; i++) { > - pfn = frame_list[i]; > - frame_list[i] = pfn_to_gfn(pfn); > - page = pfn_to_page(pfn); > + /* > + * Setup the frame, update direct mapping, invalidate P2M, > + * and add to balloon. > + */ > + list_for_each_entry_safe(page, tmp, &pages, lru) { > + /* XENMEM_decrease_reservation requires a GFN */ > + frame_list[i] = xen_page_to_gfn(page); > > #ifdef CONFIG_XEN_HAVE_PVMMU > + /* We don't support PV MMU when Linux and Xen is using > + * different page granularity. > + */ > + BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE); > + > if (!xen_feature(XENFEAT_auto_translated_physmap)) { > + unsigned long pfn = page_to_pfn(page); > + > if (!PageHighMem(page)) { > ret = HYPERVISOR_update_va_mapping( > (unsigned long)__va(pfn << PAGE_SHIFT), > @@ -455,6 +483,7 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) > __set_phys_to_machine(pfn, INVALID_P2M_ENTRY); > } > #endif > + list_del(&page->lru); > > balloon_append(page); > } > -- > 2.1.4 >
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index c79329f..3babf13 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -70,6 +70,11 @@ #include <xen/features.h> #include <xen/page.h> +/* Use one extent per PAGE_SIZE to avoid to break down the page into + * multiple frame. + */ +#define EXTENT_ORDER (fls(XEN_PFN_PER_PAGE) - 1) + /* * balloon_process() state: * @@ -230,6 +235,11 @@ static enum bp_state reserve_additional_memory(long credit) nid = memory_add_physaddr_to_nid(hotplug_start_paddr); #ifdef CONFIG_XEN_HAVE_PVMMU + /* We don't support PV MMU when Linux and Xen is using + * different page granularity. + */ + BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE); + /* * add_memory() will build page tables for the new memory so * the p2m must contain invalid entries so the correct @@ -326,11 +336,11 @@ static enum bp_state reserve_additional_memory(long credit) static enum bp_state increase_reservation(unsigned long nr_pages) { int rc; - unsigned long pfn, i; + unsigned long i; struct page *page; struct xen_memory_reservation reservation = { .address_bits = 0, - .extent_order = 0, + .extent_order = EXTENT_ORDER, .domid = DOMID_SELF }; @@ -352,7 +362,11 @@ static enum bp_state increase_reservation(unsigned long nr_pages) nr_pages = i; break; } - frame_list[i] = page_to_pfn(page); + + /* XENMEM_populate_physmap requires a PFN based on Xen + * granularity. + */ + frame_list[i] = page_to_xen_pfn(page); page = balloon_next_page(page); } @@ -366,10 +380,15 @@ static enum bp_state increase_reservation(unsigned long nr_pages) page = balloon_retrieve(false); BUG_ON(page == NULL); - pfn = page_to_pfn(page); - #ifdef CONFIG_XEN_HAVE_PVMMU + /* We don't support PV MMU when Linux and Xen is using + * different page granularity. + */ + BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE); + if (!xen_feature(XENFEAT_auto_translated_physmap)) { + unsigned long pfn = page_to_pfn(page); + set_phys_to_machine(pfn, frame_list[i]); /* Link back into the page tables if not highmem. */ @@ -396,14 +415,15 @@ static enum bp_state increase_reservation(unsigned long nr_pages) static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) { enum bp_state state = BP_DONE; - unsigned long pfn, i; - struct page *page; + unsigned long i; + struct page *page, *tmp; int ret; struct xen_memory_reservation reservation = { .address_bits = 0, - .extent_order = 0, + .extent_order = EXTENT_ORDER, .domid = DOMID_SELF }; + LIST_HEAD(pages); #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG if (balloon_stats.hotplug_pages) { @@ -425,8 +445,7 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) break; } scrub_page(page); - - frame_list[i] = page_to_pfn(page); + list_add(&page->lru, &pages); } /* @@ -438,14 +457,23 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) */ kmap_flush_unused(); - /* Update direct mapping, invalidate P2M, and add to balloon. */ - for (i = 0; i < nr_pages; i++) { - pfn = frame_list[i]; - frame_list[i] = pfn_to_gfn(pfn); - page = pfn_to_page(pfn); + /* + * Setup the frame, update direct mapping, invalidate P2M, + * and add to balloon. + */ + list_for_each_entry_safe(page, tmp, &pages, lru) { + /* XENMEM_decrease_reservation requires a GFN */ + frame_list[i] = xen_page_to_gfn(page); #ifdef CONFIG_XEN_HAVE_PVMMU + /* We don't support PV MMU when Linux and Xen is using + * different page granularity. + */ + BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE); + if (!xen_feature(XENFEAT_auto_translated_physmap)) { + unsigned long pfn = page_to_pfn(page); + if (!PageHighMem(page)) { ret = HYPERVISOR_update_va_mapping( (unsigned long)__va(pfn << PAGE_SHIFT), @@ -455,6 +483,7 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) __set_phys_to_machine(pfn, INVALID_P2M_ENTRY); } #endif + list_del(&page->lru); balloon_append(page); }
For ARM64 guests, Linux is able to support either 64K or 4K page granularity. Although, the hypercall interface is always based on 4K page granularity. With 64K page granularity, a single page will be spread over multiple Xen frame. To avoid splitting the page into 4K frame, take advantage of the extent_order field to directly allocate/free chunk of the Linux page size. Note that PVMMU is only used for PV guest (which is x86) and the page granularity is always 4KB. Some BUILD_BUG_ON has been added to ensure that because the code has not been modified. Signed-off-by: Julien Grall <julien.grall@citrix.com> --- Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Wei Liu <wei.liu2@citrix.com> Note that two BUILD_BUG_ON(XEN_PAGE_SIZE != PAGE_SIZE) in code built for the PV MMU code is kept in order to have at least one even if we ever decide to drop of code section. Changes in v4: - s/xen_page_to_pfn/page_to_xen_pfn/ based on the new naming - Use the field lru in the page to get a list of pages when decreasing the memory reservation. It avoids to use a static array to store the pages (see v3). - Update comment for EXTENT_ORDER. Changes in v3: - Fix errors reported by checkpatch.pl - s/mfn/gfn/ based on the new naming - Rather than splitting the page into 4KB chunk, use the extent_order field to allocate directly a Linux page size. This is avoid lots of code for no benefits. Changes in v2: - Use xen_apply_to_page to split a page in 4K chunk - It's not necessary to have a smaller frame list. Re-use PAGE_SIZE - Convert reserve_additional_memory to use XEN_... macro --- drivers/xen/balloon.c | 59 ++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 44 insertions(+), 15 deletions(-)