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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0551EC433F5 for ; Thu, 28 Oct 2021 01:28:35 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id B776760F92 for ; Thu, 28 Oct 2021 01:28:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org B776760F92 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.217585.377690 (Exim 4.92) (envelope-from ) id 1mfuDG-0007FG-2b; Thu, 28 Oct 2021 01:28:14 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 217585.377690; 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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1635384490; bh=/SSWR3C7/EFbNOMT4a7VbNksXhwttXyDyCOgW8/+9o4=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=uTLG0uLy2rMhIXZATdlVQ02SNddE8n59TcHIess2YsKlSp957d4y/uv0vqufOTM4k rErWJE2paJcCoPn9jTtHjgxsEkwHDzRnFxQ1PvR9JDZX2Z4aKLX0V5Bzf97n6ydWTr 32y08ShXCj/uVPtH1ffJ4lTZo5mW/IzYl6NqVsuWa2ntNDtOh7pC+lpizsDlXAlfnZ GMc4z+7ffJV7xXy+QSDnabq90mk50KVk8qLDP2jPan47OBKqyhZECc2dZ4+qE+GorY 77njjyVKAC920D1pemGJPKzlLIrJ/h2G5VSyWeuXB3fkyKpM9SBN6y0YRvWr9qCu/G hIGYfbA9ger8Q== Date: Wed, 27 Oct 2021 18:28:08 -0700 (PDT) From: Stefano Stabellini X-X-Sender: sstabellini@sstabellini-ThinkPad-T480s To: Oleksandr Tyshchenko cc: xen-devel@lists.xenproject.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Oleksandr Tyshchenko , Stefano Stabellini , Russell King , Julien Grall Subject: Re: [PATCH V2 2/4] arm/xen: Switch to use gnttab_setup_auto_xlat_frames() for DT In-Reply-To: <1635264312-3796-3-git-send-email-olekstysh@gmail.com> Message-ID: References: <1635264312-3796-1-git-send-email-olekstysh@gmail.com> <1635264312-3796-3-git-send-email-olekstysh@gmail.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII On Tue, 26 Oct 2021, Oleksandr Tyshchenko wrote: > From: Oleksandr Tyshchenko > > Read the start address of the grant table space from DT > (region 0). > > This patch mostly restores behaviour before commit 3cf4095d7446 > ("arm/xen: Use xen_xlate_map_ballooned_pages to setup grant table") > but trying not to break the ACPI support added after that commit. > So the patch touches DT part only and leaves the ACPI part with > xen_xlate_map_ballooned_pages(). > > This is a preparation for using Xen extended region feature > where unused regions of guest physical address space (provided > by the hypervisor) will be used to create grant/foreign/whatever > mappings instead of wasting real RAM pages from the domain memory > for establishing these mappings. > > The immediate benefit of this change: > - Avoid superpage shattering in Xen P2M when establishing > stage-2 mapping (GFN <-> MFN) for the grant table space > - Avoid wasting real RAM pages (reducing the amount of memory > usuable) for mapping grant table space > - The grant table space is always mapped at the exact > same place (region 0 is reserved for the grant table) > > Signed-off-by: Oleksandr Tyshchenko > --- > Changes RFC -> V2: > - new patch > --- > arch/arm/xen/enlighten.c | 32 +++++++++++++++++++++++++------- > 1 file changed, 25 insertions(+), 7 deletions(-) > > diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c > index 7f1c106b..dea46ec 100644 > --- a/arch/arm/xen/enlighten.c > +++ b/arch/arm/xen/enlighten.c > @@ -59,6 +59,9 @@ unsigned long xen_released_pages; > struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS] __initdata; > > static __read_mostly unsigned int xen_events_irq; > +static phys_addr_t xen_grant_frames; __read_mostly > +#define GRANT_TABLE_INDEX 0 > > uint32_t xen_start_flags; > EXPORT_SYMBOL(xen_start_flags); > @@ -303,6 +306,7 @@ static void __init xen_acpi_guest_init(void) > static void __init xen_dt_guest_init(void) > { > struct device_node *xen_node; > + struct resource res; > > xen_node = of_find_compatible_node(NULL, NULL, "xen,xen"); > if (!xen_node) { > @@ -310,6 +314,12 @@ static void __init xen_dt_guest_init(void) > return; > } > > + if (of_address_to_resource(xen_node, GRANT_TABLE_INDEX, &res)) { > + pr_err("Xen grant table region is not found\n"); > + return; > + } > + xen_grant_frames = res.start; > + > xen_events_irq = irq_of_parse_and_map(xen_node, 0); > } > > @@ -317,16 +327,20 @@ static int __init xen_guest_init(void) > { > struct xen_add_to_physmap xatp; > struct shared_info *shared_info_page = NULL; > - int cpu; > + int rc, cpu; > > if (!xen_domain()) > return 0; > > if (!acpi_disabled) > xen_acpi_guest_init(); > - else > + else { > xen_dt_guest_init(); > > + if (!xen_grant_frames) > + return -ENODEV; maybe we can avoid this, see below > + } > + > if (!xen_events_irq) { > pr_err("Xen event channel interrupt not found\n"); > return -ENODEV; > @@ -370,12 +384,16 @@ static int __init xen_guest_init(void) > for_each_possible_cpu(cpu) > per_cpu(xen_vcpu_id, cpu) = cpu; > > - xen_auto_xlat_grant_frames.count = gnttab_max_grant_frames(); > - if (xen_xlate_map_ballooned_pages(&xen_auto_xlat_grant_frames.pfn, > - &xen_auto_xlat_grant_frames.vaddr, > - xen_auto_xlat_grant_frames.count)) { > + if (!acpi_disabled) { To make the code more resilient couldn't we do: if (!acpi_disabled || !xen_grant_frames) { > + xen_auto_xlat_grant_frames.count = gnttab_max_grant_frames(); > + rc = xen_xlate_map_ballooned_pages(&xen_auto_xlat_grant_frames.pfn, > + &xen_auto_xlat_grant_frames.vaddr, > + xen_auto_xlat_grant_frames.count); > + } else > + rc = gnttab_setup_auto_xlat_frames(xen_grant_frames); > + if (rc) { > free_percpu(xen_vcpu_info); > - return -ENOMEM; > + return rc; > } > gnttab_init();