From mboxrd@z Thu Jan 1 00:00:00 1970 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 E31C2D2A526 for ; Wed, 16 Oct 2024 14:58:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=QNtz0ohpUJK/9Ux1ygODWQvOgRkwbRUr7jS22pxa4fk=; b=3zg/YJXJ8QRVRLUuvOSIByXTZu kfHkBk8+BXwuug0pB5sONYg7nY89lNzr94tGTRyjqbiP8JKGMLl5t4VL+7Fcxc4AcH/izStsv3dPA 0Ay/JjnkNiS7GoJ/GZRiHB/VnFMjeodNNb5JjaNtGhYq1cUOni0GDIijHTX6ADxI4IwpP4N0YR2Zq 4OQt59IcxSmgXmGl2tj/zvclFnniDjpVsnz9jpNRf9W+8z7Q8hBMCcgo/1qAFDOD8oF9Sk5trw2mT HxCk3X55jgw40T2JnmUbHY4a28Z/rt799yxj/XbCeMTcv5KdzLLUWTqTUMZALzbBRWGGiecvhEOxA a97TeHpQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1t15U8-0000000CAcz-2icK; Wed, 16 Oct 2024 14:58:48 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1t15Ig-0000000C8Hn-1Wah for linux-arm-kernel@lists.infradead.org; Wed, 16 Oct 2024 14:47:00 +0000 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 8CE951007; Wed, 16 Oct 2024 07:47:27 -0700 (PDT) Received: from [10.1.28.177] (XHFQ2J9959.cambridge.arm.com [10.1.28.177]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 47B933F71E; Wed, 16 Oct 2024 07:46:55 -0700 (PDT) Message-ID: <829b5662-13c0-4728-894c-b2d578681b11@arm.com> Date: Wed, 16 Oct 2024 15:46:53 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v1 36/57] xen: Remove PAGE_SIZE compile-time constant assumption Content-Language: en-GB 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 , Juergen Gross , Stefano Stabellini Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, xen-devel@lists.xenproject.org References: <20241014105514.3206191-1-ryan.roberts@arm.com> <20241014105912.3207374-1-ryan.roberts@arm.com> <20241014105912.3207374-36-ryan.roberts@arm.com> From: Ryan Roberts In-Reply-To: <20241014105912.3207374-36-ryan.roberts@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241016_074658_755891_6A347574 X-CRM114-Status: GOOD ( 29.62 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org + Juergen Gross, Stefano Stabellini This was a rather tricky series to get the recipients correct for and my script did not realize that "supporter" was a pseudonym for "maintainer" so you were missed off the original post. Appologies! More context in cover letter: https://lore.kernel.org/all/20241014105514.3206191-1-ryan.roberts@arm.com/ On 14/10/2024 11:58, Ryan Roberts wrote: > 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)