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 X-Spam-Level: X-Spam-Status: No, score=-18.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B2B15C4338F for ; Tue, 27 Jul 2021 18:12:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9B55F60F8F for ; Tue, 27 Jul 2021 18:12:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231997AbhG0SMJ (ORCPT ); Tue, 27 Jul 2021 14:12:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:54902 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230139AbhG0SMJ (ORCPT ); Tue, 27 Jul 2021 14:12:09 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id DD3946056B; Tue, 27 Jul 2021 18:12:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1627409529; bh=fUgkuFB9VQtgL1VRh8fF7edi9U2ibRcCUZV2oZL57h8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=cpxx1nirtagKB64kip87dBNB4SjfC/kG0WM5+aseu385nTOwDTylRCPPxcHHEKwf4 S/qfl0CnSLCp9sK+uhtUVArERHSiTR7kkyPKN3sq91+Zg5hJSy5mlTys4lOcf64vbg Uzt9HkAx8h1hcXSUxH2ZVPiwZInxVvvWK6Yd2+f2RvEJSo7d4I04xtqexTPdTbtzSq 6pPq1ijZab66hHRoS6BHWS/xdQG0UfWek6Cq3yLNt+lx7b1GmqOeo3uT4+9QhCTbuj obYyb3hXWK+0f4QnJlejAIT2PVix0kDbobIpTmsJqi74OX4pei/3hFhpxQmVgnTisi P/T7JGHLrHYog== Date: Tue, 27 Jul 2021 19:12:04 +0100 From: Will Deacon To: Marc Zyngier Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, qperret@google.com, dbrazdil@google.com, Srivatsa Vaddagiri , Shanker R Donthineni , James Morse , Suzuki K Poulose , Alexandru Elisei , kernel-team@android.com Subject: Re: [PATCH 12/16] mm/ioremap: Add arch-specific callbacks on ioremap/iounmap calls Message-ID: <20210727181203.GG19173@willie-the-truck> References: <20210715163159.1480168-1-maz@kernel.org> <20210715163159.1480168-13-maz@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210715163159.1480168-13-maz@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, Jul 15, 2021 at 05:31:55PM +0100, Marc Zyngier wrote: > Add a pair of hooks (ioremap_page_range_hook/iounmap_page_range_hook) > that can be implemented by an architecture. > > Signed-off-by: Marc Zyngier > --- > include/linux/io.h | 3 +++ > mm/ioremap.c | 13 ++++++++++++- > mm/vmalloc.c | 8 ++++++++ > 3 files changed, 23 insertions(+), 1 deletion(-) > > diff --git a/include/linux/io.h b/include/linux/io.h > index 9595151d800d..0ffc265f114c 100644 > --- a/include/linux/io.h > +++ b/include/linux/io.h > @@ -21,6 +21,9 @@ void __ioread32_copy(void *to, const void __iomem *from, size_t count); > void __iowrite64_copy(void __iomem *to, const void *from, size_t count); > > #ifdef CONFIG_MMU > +void ioremap_page_range_hook(unsigned long addr, unsigned long end, > + phys_addr_t phys_addr, pgprot_t prot); > +void iounmap_page_range_hook(phys_addr_t phys_addr, size_t size); > int ioremap_page_range(unsigned long addr, unsigned long end, > phys_addr_t phys_addr, pgprot_t prot); > #else Can we avoid these hooks by instead not registering the regions proactively in the guest and moving that logic to a fault handler which runs off the back of the injected data abort? From there, we could check if the faulting IPA is a memory address and register it as MMIO if not. Dunno, you've spent more time than me thinking about this, but just wondering if you'd had a crack at doing it that way, as it _seems_ simpler to my naive brain. Will