From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D327422DFF3; Mon, 10 Mar 2025 17:59:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741629594; cv=none; b=FTgxNWb7ICTN3+/67STbwsdsX/xaJ/sQZRPDW5Ww9bjkU6bUpPls98OgNTQw4itXK+NjxA9moI0tfxDf0R62bWRds7Tr3I0Cq0EMHBXlyDJrpyz9GRdN8FjEL6dWCfC6JLKA44oPqQKzitbAXq20BCYMBvl7CezEaovkaK/1620= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741629594; c=relaxed/simple; bh=HBqOC1HtsDajxMGzPWBPLoJj3yICzZMUPA4YfK8mgD4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=YbwKC9LMRnycEVwjcEjM1ZkUMWswJukHyORO9qCzE/gfgY2NIIQsmANzfRv12MS51vq7lmxHCH+Ee6qtWLnCFE+dO4YiZSZ5DtGC4/pPvNXi1/BRUcJ6DdgC7xMOTmKeIcLlWAaozyab/cEd2ZpYH6oQRzhMyYrGsyRN25gHOV4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=WjL44dcM; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="WjL44dcM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5B958C4CEE5; Mon, 10 Mar 2025 17:59:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1741629594; bh=HBqOC1HtsDajxMGzPWBPLoJj3yICzZMUPA4YfK8mgD4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WjL44dcMnmA5J1tf6k/Zg/FBbh9DkQm4wGXYKmMr7tog2A8Aug2uop4lqQSrJ0Fpe yhI1ouqyFIifJP7g+O6AUFfO/swmNMCSyQqmZXM4pd7XyCgJd1JFCgxY/yMmGKAP93 BMMPsuvglPm2EmrXE1f3VuVU5fY6V6zis/sOVHkc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Juergen Gross , Alan Robinson , Jan Beulich , Sasha Levin Subject: [PATCH 5.15 347/620] x86/xen: allow larger contiguous memory regions in PV guests Date: Mon, 10 Mar 2025 18:03:13 +0100 Message-ID: <20250310170559.309317250@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250310170545.553361750@linuxfoundation.org> References: <20250310170545.553361750@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Juergen Gross [ Upstream commit e93ec87286bd1fd30b7389e7a387cfb259f297e3 ] Today a PV guest (including dom0) can create 2MB contiguous memory regions for DMA buffers at max. This has led to problems at least with the megaraid_sas driver, which wants to allocate a 2.3MB DMA buffer. The limiting factor is the frame array used to do the hypercall for making the memory contiguous, which has 512 entries and is just a static array in mmu_pv.c. In order to not waste memory for non-PV guests, put the initial frame array into .init.data section and dynamically allocate an array from the .init_after_bootmem hook of PV guests. In case a contiguous memory area larger than the initially supported 2MB is requested, allocate a larger buffer for the frame list. Note that such an allocation is tried only after memory management has been initialized properly, which is tested via a flag being set in the .init_after_bootmem hook. Fixes: 9f40ec84a797 ("xen/swiotlb: add alignment check for dma buffers") Signed-off-by: Juergen Gross Tested-by: Alan Robinson Reviewed-by: Jan Beulich Signed-off-by: Juergen Gross Signed-off-by: Sasha Levin --- arch/x86/xen/mmu_pv.c | 71 +++++++++++++++++++++++++++++++++++++------ 1 file changed, 62 insertions(+), 9 deletions(-) diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c index 03c9ec0212c9e..f88071566cac5 100644 --- a/arch/x86/xen/mmu_pv.c +++ b/arch/x86/xen/mmu_pv.c @@ -95,6 +95,51 @@ static pud_t level3_user_vsyscall[PTRS_PER_PUD] __page_aligned_bss; */ static DEFINE_SPINLOCK(xen_reservation_lock); +/* Protected by xen_reservation_lock. */ +#define MIN_CONTIG_ORDER 9 /* 2MB */ +static unsigned int discontig_frames_order = MIN_CONTIG_ORDER; +static unsigned long discontig_frames_early[1UL << MIN_CONTIG_ORDER] __initdata; +static unsigned long *discontig_frames __refdata = discontig_frames_early; +static bool discontig_frames_dyn; + +static int alloc_discontig_frames(unsigned int order) +{ + unsigned long *new_array, *old_array; + unsigned int old_order; + unsigned long flags; + + BUG_ON(order < MIN_CONTIG_ORDER); + BUILD_BUG_ON(sizeof(discontig_frames_early) != PAGE_SIZE); + + new_array = (unsigned long *)__get_free_pages(GFP_KERNEL, + order - MIN_CONTIG_ORDER); + if (!new_array) + return -ENOMEM; + + spin_lock_irqsave(&xen_reservation_lock, flags); + + old_order = discontig_frames_order; + + if (order > discontig_frames_order || !discontig_frames_dyn) { + if (!discontig_frames_dyn) + old_array = NULL; + else + old_array = discontig_frames; + + discontig_frames = new_array; + discontig_frames_order = order; + discontig_frames_dyn = true; + } else { + old_array = new_array; + } + + spin_unlock_irqrestore(&xen_reservation_lock, flags); + + free_pages((unsigned long)old_array, old_order - MIN_CONTIG_ORDER); + + return 0; +} + /* * Note about cr3 (pagetable base) values: * @@ -791,6 +836,9 @@ static void __init xen_after_bootmem(void) static_branch_enable(&xen_struct_pages_ready); SetPagePinned(virt_to_page(level3_user_vsyscall)); xen_pgd_walk(&init_mm, xen_mark_pinned, FIXADDR_TOP); + + if (alloc_discontig_frames(MIN_CONTIG_ORDER)) + BUG(); } static void xen_unpin_page(struct mm_struct *mm, struct page *page, @@ -2151,10 +2199,6 @@ void __init xen_init_mmu_ops(void) memset(dummy_mapping, 0xff, PAGE_SIZE); } -/* Protected by xen_reservation_lock. */ -#define MAX_CONTIG_ORDER 9 /* 2MB */ -static unsigned long discontig_frames[1< MAX_CONTIG_ORDER)) - return -ENOMEM; + if (unlikely(order > discontig_frames_order)) { + if (!discontig_frames_dyn) + return -ENOMEM; + + if (alloc_discontig_frames(order)) + return -ENOMEM; + } memset((void *) vstart, 0, PAGE_SIZE << order); spin_lock_irqsave(&xen_reservation_lock, flags); + in_frames = discontig_frames; + /* 1. Zap current PTEs, remembering MFNs. */ xen_zap_pfn_range(vstart, order, in_frames, NULL); @@ -2306,12 +2357,12 @@ int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order, void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order) { - unsigned long *out_frames = discontig_frames, in_frame; + unsigned long *out_frames, in_frame; unsigned long flags; int success; unsigned long vstart; - if (unlikely(order > MAX_CONTIG_ORDER)) + if (unlikely(order > discontig_frames_order)) return; vstart = (unsigned long)phys_to_virt(pstart); @@ -2319,6 +2370,8 @@ void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order) spin_lock_irqsave(&xen_reservation_lock, flags); + out_frames = discontig_frames; + /* 1. Find start MFN of contiguous extent. */ in_frame = virt_to_mfn(vstart); -- 2.39.5