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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [RFC PATCH v1 36/57] xen: Remove PAGE_SIZE compile-time constant assumption
To prepare for supporting boot-time page size selection, refactor code to remove assumptions about PAGE_SIZE being compile-time constant. Code intended to be equivalent when compile-time page size is active. Allocate enough "frame_list" static storage in the balloon driver for the maximum supported page size. Although continue to use only the first PAGE_SIZE of the buffer at run-time to maintain existing behaviour. Refactor xen_biovec_phys_mergeable() to convert ifdeffery to c if/else. For compile-time page size, the compiler will choose one branch and strip the dead one. For boot-time, it can be evaluated at run time. Refactor a BUILD_BUG_ON to evaluate the limit (when the minimum supported page size is selected at boot-time). Reserve enough storage for max page size in "struct remap_data" and "struct xenbus_map_node". Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx> --- ***NOTE*** Any confused maintainers may want to read the cover note here for context: https://lore.kernel.org/all/20241014105514.3206191-1-ryan.roberts@xxxxxxx/ drivers/xen/balloon.c | 11 ++++++----- drivers/xen/biomerge.c | 12 ++++++------ drivers/xen/privcmd.c | 2 +- drivers/xen/xenbus/xenbus_client.c | 5 +++-- drivers/xen/xlate_mmu.c | 6 +++--- include/xen/page.h | 2 ++ 6 files changed, 21 insertions(+), 17 deletions(-) diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index 528395133b4f8..0ed5f6453af0e 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -131,7 +131,8 @@ struct balloon_stats balloon_stats; EXPORT_SYMBOL_GPL(balloon_stats); /* We increase/decrease in batches which fit in a page */ -static xen_pfn_t frame_list[PAGE_SIZE / sizeof(xen_pfn_t)]; +static xen_pfn_t frame_list[PAGE_SIZE_MAX / sizeof(xen_pfn_t)]; +#define FRAME_LIST_NR_ENTRIES (PAGE_SIZE / sizeof(xen_pfn_t)) /* List of ballooned pages, threaded through the mem_map array. */ @@ -389,8 +390,8 @@ static enum bp_state increase_reservation(unsigned long nr_pages) unsigned long i; struct page *page; - if (nr_pages > ARRAY_SIZE(frame_list)) - nr_pages = ARRAY_SIZE(frame_list); + if (nr_pages > FRAME_LIST_NR_ENTRIES) + nr_pages = FRAME_LIST_NR_ENTRIES; page = list_first_entry_or_null(&ballooned_pages, struct page, lru); for (i = 0; i < nr_pages; i++) { @@ -434,8 +435,8 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) int ret; LIST_HEAD(pages); - if (nr_pages > ARRAY_SIZE(frame_list)) - nr_pages = ARRAY_SIZE(frame_list); + if (nr_pages > FRAME_LIST_NR_ENTRIES) + nr_pages = FRAME_LIST_NR_ENTRIES; for (i = 0; i < nr_pages; i++) { page = alloc_page(gfp); diff --git a/drivers/xen/biomerge.c b/drivers/xen/biomerge.c index 05a286d24f148..28f0887e40026 100644 --- a/drivers/xen/biomerge.c +++ b/drivers/xen/biomerge.c @@ -8,16 +8,16 @@ bool xen_biovec_phys_mergeable(const struct bio_vec *vec1, const struct page *page) { -#if XEN_PAGE_SIZE == PAGE_SIZE - unsigned long bfn1 = pfn_to_bfn(page_to_pfn(vec1->bv_page)); - unsigned long bfn2 = pfn_to_bfn(page_to_pfn(page)); + if (XEN_PAGE_SIZE == PAGE_SIZE) { + unsigned long bfn1 = pfn_to_bfn(page_to_pfn(vec1->bv_page)); + unsigned long bfn2 = pfn_to_bfn(page_to_pfn(page)); + + return bfn1 + PFN_DOWN(vec1->bv_offset + vec1->bv_len) == bfn2; + } - return bfn1 + PFN_DOWN(vec1->bv_offset + vec1->bv_len) == bfn2; -#else /* * XXX: Add support for merging bio_vec when using different page * size in Xen and Linux. */ return false; -#endif } diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c index 9563650dfbafc..847f7b806caf7 100644 --- a/drivers/xen/privcmd.c +++ b/drivers/xen/privcmd.c @@ -557,7 +557,7 @@ static long privcmd_ioctl_mmap_batch( state.global_error = 0; state.version = version; - BUILD_BUG_ON(((PAGE_SIZE / sizeof(xen_pfn_t)) % XEN_PFN_PER_PAGE) != 0); + BUILD_BUG_ON(((PAGE_SIZE_MIN / sizeof(xen_pfn_t)) % XEN_PFN_PER_PAGE_MAX) != 0); /* mmap_batch_fn guarantees ret == 0 */ BUG_ON(traverse_pages_block(m.num, sizeof(xen_pfn_t), &pagelist, mmap_batch_fn, &state)); diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c index 51b3124b0d56c..99bde836c10c4 100644 --- a/drivers/xen/xenbus/xenbus_client.c +++ b/drivers/xen/xenbus/xenbus_client.c @@ -49,9 +49,10 @@ #include "xenbus.h" -#define XENBUS_PAGES(_grants) (DIV_ROUND_UP(_grants, XEN_PFN_PER_PAGE)) +#define XENBUS_PAGES(_grants) (DIV_ROUND_UP(_grants, XEN_PFN_PER_PAGE)) +#define XENBUS_PAGES_MAX(_grants) (DIV_ROUND_UP(_grants, XEN_PFN_PER_PAGE_MIN)) -#define XENBUS_MAX_RING_PAGES (XENBUS_PAGES(XENBUS_MAX_RING_GRANTS)) +#define XENBUS_MAX_RING_PAGES (XENBUS_PAGES_MAX(XENBUS_MAX_RING_GRANTS)) struct xenbus_map_node { struct list_head next; diff --git a/drivers/xen/xlate_mmu.c b/drivers/xen/xlate_mmu.c index f17c4c03db30c..a757c801a7542 100644 --- a/drivers/xen/xlate_mmu.c +++ b/drivers/xen/xlate_mmu.c @@ -74,9 +74,9 @@ struct remap_data { int mapped; /* Hypercall parameters */ - int h_errs[XEN_PFN_PER_PAGE]; - xen_ulong_t h_idxs[XEN_PFN_PER_PAGE]; - xen_pfn_t h_gpfns[XEN_PFN_PER_PAGE]; + int h_errs[XEN_PFN_PER_PAGE_MAX]; + xen_ulong_t h_idxs[XEN_PFN_PER_PAGE_MAX]; + xen_pfn_t h_gpfns[XEN_PFN_PER_PAGE_MAX]; int h_iter; /* Iterator */ }; diff --git a/include/xen/page.h b/include/xen/page.h index 285677b42943a..86683a30038a3 100644 --- a/include/xen/page.h +++ b/include/xen/page.h @@ -21,6 +21,8 @@ ((page_to_pfn(page)) << (PAGE_SHIFT - XEN_PAGE_SHIFT)) #define XEN_PFN_PER_PAGE (PAGE_SIZE / XEN_PAGE_SIZE) +#define XEN_PFN_PER_PAGE_MIN (PAGE_SIZE_MIN / XEN_PAGE_SIZE) +#define XEN_PFN_PER_PAGE_MAX (PAGE_SIZE_MAX / XEN_PAGE_SIZE) #define XEN_PFN_DOWN(x) ((x) >> XEN_PAGE_SHIFT) #define XEN_PFN_UP(x) (((x) + XEN_PAGE_SIZE-1) >> XEN_PAGE_SHIFT) -- 2.43.0
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