From patchwork Mon Oct 14 10:58:43 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ryan Roberts X-Patchwork-Id: 13834749 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A2F60D1A443 for ; Mon, 14 Oct 2024 11:02:41 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.818629.1231954 (Exim 4.92) (envelope-from ) id 1t0IqK-0008Fg-OA; Mon, 14 Oct 2024 11:02:28 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 818629.1231954; Mon, 14 Oct 2024 11:02:28 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1t0IqK-0008FZ-LI; Mon, 14 Oct 2024 11:02:28 +0000 Received: by outflank-mailman (input) for mailman id 818629; Mon, 14 Oct 2024 11:01:24 +0000 Received: from se1-gles-flk1-in.inumbo.com ([94.247.172.50] helo=se1-gles-flk1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1t0IpI-0007mu-7C for xen-devel@lists.xenproject.org; Mon, 14 Oct 2024 11:01:24 +0000 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by se1-gles-flk1.inumbo.com (Halon) with ESMTP id a5226c60-8a1b-11ef-99a2-01e77a169b0f; Mon, 14 Oct 2024 13:01:21 +0200 (CEST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6816B1713; Mon, 14 Oct 2024 04:01:50 -0700 (PDT) Received: from e125769.cambridge.arm.com (e125769.cambridge.arm.com [10.1.196.27]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4980A3F51B; Mon, 14 Oct 2024 04:01:18 -0700 (PDT) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: a5226c60-8a1b-11ef-99a2-01e77a169b0f From: Ryan Roberts To: Andrew Morton , Anshuman Khandual , Ard Biesheuvel , Catalin Marinas , David Hildenbrand , Greg Marsden , Ivan Ivanov , Kalesh Singh , Marc Zyngier , Mark Rutland , Matthias Brugger , Miroslav Benes , Will Deacon Cc: Ryan Roberts , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, xen-devel@lists.xenproject.org Subject: [RFC PATCH v1 36/57] xen: Remove PAGE_SIZE compile-time constant assumption Date: Mon, 14 Oct 2024 11:58:43 +0100 Message-ID: <20241014105912.3207374-36-ryan.roberts@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241014105912.3207374-1-ryan.roberts@arm.com> References: <20241014105514.3206191-1-ryan.roberts@arm.com> <20241014105912.3207374-1-ryan.roberts@arm.com> MIME-Version: 1.0 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 --- ***NOTE*** Any confused maintainers may want to read the cover note here for context: https://lore.kernel.org/all/20241014105514.3206191-1-ryan.roberts@arm.com/ 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)