| Message ID | 1436474552-31789-13-git-send-email-julien.grall@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, 9 Jul 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 granuliarty, a single page will be spread over multiple > Xen frame. > > When a driver request/free a balloon page, the balloon driver will have > to split the Linux page in 4K chunk before asking Xen to add/remove the > frame from the guest. > > Note that this can work on any page granularity assuming it's a multiple > of 4K. > > 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> > --- > 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 | 147 +++++++++++++++++++++++++++++++++++--------------- > 1 file changed, 105 insertions(+), 42 deletions(-) > > diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c > index fd93369..19a72b1 100644 > --- a/drivers/xen/balloon.c > +++ b/drivers/xen/balloon.c > @@ -230,6 +230,7 @@ static enum bp_state reserve_additional_memory(long credit) > nid = memory_add_physaddr_to_nid(hotplug_start_paddr); > > #ifdef CONFIG_XEN_HAVE_PVMMU > + /* TODO */ I think you need to be more verbose than that: TODO what? > /* > * add_memory() will build page tables for the new memory so > * the p2m must contain invalid entries so the correct > @@ -242,8 +243,8 @@ static enum bp_state reserve_additional_memory(long credit) > if (!xen_feature(XENFEAT_auto_translated_physmap)) { > unsigned long pfn, i; > > - pfn = PFN_DOWN(hotplug_start_paddr); > - for (i = 0; i < balloon_hotplug; i++) { > + pfn = XEN_PFN_DOWN(hotplug_start_paddr); > + for (i = 0; i < (balloon_hotplug * XEN_PFN_PER_PAGE); i++) { > if (!set_phys_to_machine(pfn + i, INVALID_P2M_ENTRY)) { > pr_warn("set_phys_to_machine() failed, no memory added\n"); > return BP_ECANCELED; > @@ -323,10 +324,72 @@ static enum bp_state reserve_additional_memory(long credit) > } > #endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */ > > +static int set_frame(struct page *page, unsigned long pfn, void *data) > +{ > + unsigned long *index = data; > + > + frame_list[(*index)++] = pfn; > + > + return 0; > +} > + > +#ifdef CONFIG_XEN_HAVE_PVMMU > +static int pvmmu_update_mapping(struct page *page, unsigned long pfn, > + void *data) > +{ > + unsigned long *index = data; > + xen_pfn_t frame = frame_list[*index]; > + > + set_phys_to_machine(pfn, frame); > + /* Link back into the page tables if not highmem. */ > + if (!PageHighMem(page)) { > + int ret; > + ret = HYPERVISOR_update_va_mapping( > + (unsigned long)__va(pfn << XEN_PAGE_SHIFT), > + mfn_pte(frame, PAGE_KERNEL), > + 0); > + BUG_ON(ret); > + } > + > + (*index)++; > + > + return 0; > +} > +#endif > + > +static int balloon_remove_mapping(struct page *page, unsigned long pfn, > + void *data) > +{ > + unsigned long *index = data; > + > + /* We expect the frame_list to contain the same pfn */ > + BUG_ON(pfn != frame_list[*index]); > + > + frame_list[*index] = pfn_to_mfn(pfn); > + > +#ifdef CONFIG_XEN_HAVE_PVMMU > + if (!xen_feature(XENFEAT_auto_translated_physmap)) { > + if (!PageHighMem(page)) { > + int ret; > + > + ret = HYPERVISOR_update_va_mapping( > + (unsigned long)__va(pfn << XEN_PAGE_SHIFT), > + __pte_ma(0), 0); > + BUG_ON(ret); > + } > + __set_phys_to_machine(pfn, INVALID_P2M_ENTRY); > + } > +#endif > + > + (*index)++; > + > + return 0; > +} > + > static enum bp_state increase_reservation(unsigned long nr_pages) > { > int rc; > - unsigned long pfn, i; > + unsigned long i, frame_idx; > struct page *page; > struct xen_memory_reservation reservation = { > .address_bits = 0, > @@ -343,44 +406,43 @@ static enum bp_state increase_reservation(unsigned long nr_pages) > } > #endif > > - if (nr_pages > ARRAY_SIZE(frame_list)) > - nr_pages = ARRAY_SIZE(frame_list); > + if (nr_pages > (ARRAY_SIZE(frame_list) / XEN_PFN_PER_PAGE)) > + nr_pages = ARRAY_SIZE(frame_list) / XEN_PFN_PER_PAGE; > > + frame_idx = 0; > page = list_first_entry_or_null(&ballooned_pages, struct page, lru); > for (i = 0; i < nr_pages; i++) { > if (!page) { > nr_pages = i; > break; > } > - frame_list[i] = page_to_pfn(page); > + > + rc = xen_apply_to_page(page, set_frame, &frame_idx); > + > page = balloon_next_page(page); > } > > set_xen_guest_handle(reservation.extent_start, frame_list); > - reservation.nr_extents = nr_pages; > + reservation.nr_extents = nr_pages * XEN_PFN_PER_PAGE; > rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation); > if (rc <= 0) > return BP_EAGAIN; > > - for (i = 0; i < rc; i++) { > + /* rc is equal to the number of Xen page populated */ > + nr_pages = rc / XEN_PFN_PER_PAGE; Here we are purposedly ignoring any spares (rc % XEN_PFN_PER_PAGE). Instead of leaking them, maybe we should givem them back to Xen since we cannot use them? > + for (i = 0; i < nr_pages; i++) { > page = balloon_retrieve(false); > BUG_ON(page == NULL); > > - pfn = page_to_pfn(page); > - > #ifdef CONFIG_XEN_HAVE_PVMMU > + frame_idx = 0; Shouldn't this be before the beginning of the loop above? > if (!xen_feature(XENFEAT_auto_translated_physmap)) { > - set_phys_to_machine(pfn, frame_list[i]); > - > - /* Link back into the page tables if not highmem. */ > - if (!PageHighMem(page)) { > - int ret; > - ret = HYPERVISOR_update_va_mapping( > - (unsigned long)__va(pfn << PAGE_SHIFT), > - mfn_pte(frame_list[i], PAGE_KERNEL), > - 0); > - BUG_ON(ret); > - } > + int ret; > + > + ret = xen_apply_to_page(page, pvmmu_update_mapping, > + &frame_idx); > + BUG_ON(ret); > } > #endif > > @@ -388,7 +450,7 @@ static enum bp_state increase_reservation(unsigned long nr_pages) > __free_reserved_page(page); > } > > - balloon_stats.current_pages += rc; > + balloon_stats.current_pages += nr_pages; > > return BP_DONE; > } > @@ -396,7 +458,7 @@ 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; > + unsigned long pfn, i, frame_idx, nr_frames; > struct page *page; > int ret; > struct xen_memory_reservation reservation = { > @@ -414,9 +476,10 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) > } > #endif > > - if (nr_pages > ARRAY_SIZE(frame_list)) > - nr_pages = ARRAY_SIZE(frame_list); > + if (nr_pages > (ARRAY_SIZE(frame_list) / XEN_PFN_PER_PAGE)) > + nr_pages = ARRAY_SIZE(frame_list) / XEN_PFN_PER_PAGE; > > + frame_idx = 0; > for (i = 0; i < nr_pages; i++) { > page = alloc_page(gfp); > if (page == NULL) { > @@ -426,9 +489,12 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) > } > scrub_page(page); > > - frame_list[i] = page_to_pfn(page); > + ret = xen_apply_to_page(page, set_frame, &frame_idx); > + BUG_ON(ret); > } > > + nr_frames = nr_pages * XEN_PFN_PER_PAGE; > + > /* > * Ensure that ballooned highmem pages don't have kmaps. > * > @@ -439,22 +505,19 @@ 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. */ > + frame_idx = 0; > for (i = 0; i < nr_pages; i++) { > - pfn = frame_list[i]; > - frame_list[i] = pfn_to_mfn(pfn); > - page = pfn_to_page(pfn); > + /* > + * The Xen PFN for a given Linux Page are contiguous in > + * frame_list > + */ > + pfn = frame_list[frame_idx]; > + page = xen_pfn_to_page(pfn); > > -#ifdef CONFIG_XEN_HAVE_PVMMU > - if (!xen_feature(XENFEAT_auto_translated_physmap)) { > - if (!PageHighMem(page)) { > - ret = HYPERVISOR_update_va_mapping( > - (unsigned long)__va(pfn << PAGE_SHIFT), > - __pte_ma(0), 0); > - BUG_ON(ret); > - } > - __set_phys_to_machine(pfn, INVALID_P2M_ENTRY); > - } > -#endif > + > + ret = xen_apply_to_page(page, balloon_remove_mapping, > + &frame_idx); > + BUG_ON(ret); > > balloon_append(page); > } > @@ -462,9 +525,9 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) > flush_tlb_all(); > > set_xen_guest_handle(reservation.extent_start, frame_list); > - reservation.nr_extents = nr_pages; > + reservation.nr_extents = nr_frames; > ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation); > - BUG_ON(ret != nr_pages); > + BUG_ON(ret != nr_frames); > > balloon_stats.current_pages -= nr_pages; > > -- > 2.1.4 >
Hi Stefano, On 17/07/15 15:03, Stefano Stabellini wrote: >> --- >> drivers/xen/balloon.c | 147 +++++++++++++++++++++++++++++++++++--------------- >> 1 file changed, 105 insertions(+), 42 deletions(-) >> >> diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c >> index fd93369..19a72b1 100644 >> --- a/drivers/xen/balloon.c >> +++ b/drivers/xen/balloon.c >> @@ -230,6 +230,7 @@ static enum bp_state reserve_additional_memory(long credit) >> nid = memory_add_physaddr_to_nid(hotplug_start_paddr); >> >> #ifdef CONFIG_XEN_HAVE_PVMMU >> + /* TODO */ > > I think you need to be more verbose than that: TODO what? It was for me to remember fixing reserve_additional_memory. I did it and forgot to remove the TODO when I clean up. I will drop it in the next version. [...] >> static enum bp_state increase_reservation(unsigned long nr_pages) >> { >> int rc; >> - unsigned long pfn, i; >> + unsigned long i, frame_idx; >> struct page *page; >> struct xen_memory_reservation reservation = { >> .address_bits = 0, >> @@ -343,44 +406,43 @@ static enum bp_state increase_reservation(unsigned long nr_pages) >> } >> #endif >> >> - if (nr_pages > ARRAY_SIZE(frame_list)) >> - nr_pages = ARRAY_SIZE(frame_list); >> + if (nr_pages > (ARRAY_SIZE(frame_list) / XEN_PFN_PER_PAGE)) >> + nr_pages = ARRAY_SIZE(frame_list) / XEN_PFN_PER_PAGE; >> >> + frame_idx = 0; >> page = list_first_entry_or_null(&ballooned_pages, struct page, lru); >> for (i = 0; i < nr_pages; i++) { >> if (!page) { >> nr_pages = i; >> break; >> } >> - frame_list[i] = page_to_pfn(page); >> + >> + rc = xen_apply_to_page(page, set_frame, &frame_idx); >> + >> page = balloon_next_page(page); >> } >> >> set_xen_guest_handle(reservation.extent_start, frame_list); >> - reservation.nr_extents = nr_pages; >> + reservation.nr_extents = nr_pages * XEN_PFN_PER_PAGE; >> rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation); >> if (rc <= 0) >> return BP_EAGAIN; >> >> - for (i = 0; i < rc; i++) { >> + /* rc is equal to the number of Xen page populated */ >> + nr_pages = rc / XEN_PFN_PER_PAGE; > > Here we are purposedly ignoring any spares (rc % XEN_PFN_PER_PAGE). > Instead of leaking them, maybe we should givem them back to Xen since we > cannot use them? I will give a look to do it. >> + for (i = 0; i < nr_pages; i++) { >> page = balloon_retrieve(false); >> BUG_ON(page == NULL); >> >> - pfn = page_to_pfn(page); >> - >> #ifdef CONFIG_XEN_HAVE_PVMMU >> + frame_idx = 0; > > Shouldn't this be before the beginning of the loop above? Hmmmm... Yes. Note that I only compiled tested on x86, it would be good if someone test on real hardware at some point (I don't have any x86 Xen setup). Regards,
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index fd93369..19a72b1 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -230,6 +230,7 @@ static enum bp_state reserve_additional_memory(long credit) nid = memory_add_physaddr_to_nid(hotplug_start_paddr); #ifdef CONFIG_XEN_HAVE_PVMMU + /* TODO */ /* * add_memory() will build page tables for the new memory so * the p2m must contain invalid entries so the correct @@ -242,8 +243,8 @@ static enum bp_state reserve_additional_memory(long credit) if (!xen_feature(XENFEAT_auto_translated_physmap)) { unsigned long pfn, i; - pfn = PFN_DOWN(hotplug_start_paddr); - for (i = 0; i < balloon_hotplug; i++) { + pfn = XEN_PFN_DOWN(hotplug_start_paddr); + for (i = 0; i < (balloon_hotplug * XEN_PFN_PER_PAGE); i++) { if (!set_phys_to_machine(pfn + i, INVALID_P2M_ENTRY)) { pr_warn("set_phys_to_machine() failed, no memory added\n"); return BP_ECANCELED; @@ -323,10 +324,72 @@ static enum bp_state reserve_additional_memory(long credit) } #endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */ +static int set_frame(struct page *page, unsigned long pfn, void *data) +{ + unsigned long *index = data; + + frame_list[(*index)++] = pfn; + + return 0; +} + +#ifdef CONFIG_XEN_HAVE_PVMMU +static int pvmmu_update_mapping(struct page *page, unsigned long pfn, + void *data) +{ + unsigned long *index = data; + xen_pfn_t frame = frame_list[*index]; + + set_phys_to_machine(pfn, frame); + /* Link back into the page tables if not highmem. */ + if (!PageHighMem(page)) { + int ret; + ret = HYPERVISOR_update_va_mapping( + (unsigned long)__va(pfn << XEN_PAGE_SHIFT), + mfn_pte(frame, PAGE_KERNEL), + 0); + BUG_ON(ret); + } + + (*index)++; + + return 0; +} +#endif + +static int balloon_remove_mapping(struct page *page, unsigned long pfn, + void *data) +{ + unsigned long *index = data; + + /* We expect the frame_list to contain the same pfn */ + BUG_ON(pfn != frame_list[*index]); + + frame_list[*index] = pfn_to_mfn(pfn); + +#ifdef CONFIG_XEN_HAVE_PVMMU + if (!xen_feature(XENFEAT_auto_translated_physmap)) { + if (!PageHighMem(page)) { + int ret; + + ret = HYPERVISOR_update_va_mapping( + (unsigned long)__va(pfn << XEN_PAGE_SHIFT), + __pte_ma(0), 0); + BUG_ON(ret); + } + __set_phys_to_machine(pfn, INVALID_P2M_ENTRY); + } +#endif + + (*index)++; + + return 0; +} + static enum bp_state increase_reservation(unsigned long nr_pages) { int rc; - unsigned long pfn, i; + unsigned long i, frame_idx; struct page *page; struct xen_memory_reservation reservation = { .address_bits = 0, @@ -343,44 +406,43 @@ static enum bp_state increase_reservation(unsigned long nr_pages) } #endif - if (nr_pages > ARRAY_SIZE(frame_list)) - nr_pages = ARRAY_SIZE(frame_list); + if (nr_pages > (ARRAY_SIZE(frame_list) / XEN_PFN_PER_PAGE)) + nr_pages = ARRAY_SIZE(frame_list) / XEN_PFN_PER_PAGE; + frame_idx = 0; page = list_first_entry_or_null(&ballooned_pages, struct page, lru); for (i = 0; i < nr_pages; i++) { if (!page) { nr_pages = i; break; } - frame_list[i] = page_to_pfn(page); + + rc = xen_apply_to_page(page, set_frame, &frame_idx); + page = balloon_next_page(page); } set_xen_guest_handle(reservation.extent_start, frame_list); - reservation.nr_extents = nr_pages; + reservation.nr_extents = nr_pages * XEN_PFN_PER_PAGE; rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation); if (rc <= 0) return BP_EAGAIN; - for (i = 0; i < rc; i++) { + /* rc is equal to the number of Xen page populated */ + nr_pages = rc / XEN_PFN_PER_PAGE; + + for (i = 0; i < nr_pages; i++) { page = balloon_retrieve(false); BUG_ON(page == NULL); - pfn = page_to_pfn(page); - #ifdef CONFIG_XEN_HAVE_PVMMU + frame_idx = 0; if (!xen_feature(XENFEAT_auto_translated_physmap)) { - set_phys_to_machine(pfn, frame_list[i]); - - /* Link back into the page tables if not highmem. */ - if (!PageHighMem(page)) { - int ret; - ret = HYPERVISOR_update_va_mapping( - (unsigned long)__va(pfn << PAGE_SHIFT), - mfn_pte(frame_list[i], PAGE_KERNEL), - 0); - BUG_ON(ret); - } + int ret; + + ret = xen_apply_to_page(page, pvmmu_update_mapping, + &frame_idx); + BUG_ON(ret); } #endif @@ -388,7 +450,7 @@ static enum bp_state increase_reservation(unsigned long nr_pages) __free_reserved_page(page); } - balloon_stats.current_pages += rc; + balloon_stats.current_pages += nr_pages; return BP_DONE; } @@ -396,7 +458,7 @@ 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; + unsigned long pfn, i, frame_idx, nr_frames; struct page *page; int ret; struct xen_memory_reservation reservation = { @@ -414,9 +476,10 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) } #endif - if (nr_pages > ARRAY_SIZE(frame_list)) - nr_pages = ARRAY_SIZE(frame_list); + if (nr_pages > (ARRAY_SIZE(frame_list) / XEN_PFN_PER_PAGE)) + nr_pages = ARRAY_SIZE(frame_list) / XEN_PFN_PER_PAGE; + frame_idx = 0; for (i = 0; i < nr_pages; i++) { page = alloc_page(gfp); if (page == NULL) { @@ -426,9 +489,12 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) } scrub_page(page); - frame_list[i] = page_to_pfn(page); + ret = xen_apply_to_page(page, set_frame, &frame_idx); + BUG_ON(ret); } + nr_frames = nr_pages * XEN_PFN_PER_PAGE; + /* * Ensure that ballooned highmem pages don't have kmaps. * @@ -439,22 +505,19 @@ 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. */ + frame_idx = 0; for (i = 0; i < nr_pages; i++) { - pfn = frame_list[i]; - frame_list[i] = pfn_to_mfn(pfn); - page = pfn_to_page(pfn); + /* + * The Xen PFN for a given Linux Page are contiguous in + * frame_list + */ + pfn = frame_list[frame_idx]; + page = xen_pfn_to_page(pfn); -#ifdef CONFIG_XEN_HAVE_PVMMU - if (!xen_feature(XENFEAT_auto_translated_physmap)) { - if (!PageHighMem(page)) { - ret = HYPERVISOR_update_va_mapping( - (unsigned long)__va(pfn << PAGE_SHIFT), - __pte_ma(0), 0); - BUG_ON(ret); - } - __set_phys_to_machine(pfn, INVALID_P2M_ENTRY); - } -#endif + + ret = xen_apply_to_page(page, balloon_remove_mapping, + &frame_idx); + BUG_ON(ret); balloon_append(page); } @@ -462,9 +525,9 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) flush_tlb_all(); set_xen_guest_handle(reservation.extent_start, frame_list); - reservation.nr_extents = nr_pages; + reservation.nr_extents = nr_frames; ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation); - BUG_ON(ret != nr_pages); + BUG_ON(ret != nr_frames); balloon_stats.current_pages -= nr_pages;
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 granuliarty, a single page will be spread over multiple Xen frame. When a driver request/free a balloon page, the balloon driver will have to split the Linux page in 4K chunk before asking Xen to add/remove the frame from the guest. Note that this can work on any page granularity assuming it's a multiple of 4K. 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> --- 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 | 147 +++++++++++++++++++++++++++++++++++--------------- 1 file changed, 105 insertions(+), 42 deletions(-)