From patchwork Thu Jul 18 11:57:14 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Julien Grall X-Patchwork-Id: 11048863 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 54A5E13AC for ; Thu, 18 Jul 2019 11:58:59 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4334F285A6 for ; Thu, 18 Jul 2019 11:58:59 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 373D9287CD; Thu, 18 Jul 2019 11:58:59 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id C6732285A6 for ; Thu, 18 Jul 2019 11:58:58 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1ho52K-0000sw-Ir; Thu, 18 Jul 2019 11:57:24 +0000 Received: from us1-rack-dfw2.inumbo.com ([104.130.134.6]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1ho52I-0000sr-U9 for xen-devel@lists.xenproject.org; Thu, 18 Jul 2019 11:57:22 +0000 X-Inumbo-ID: 32af65e9-a953-11e9-8980-bc764e045a96 Received: from foss.arm.com (unknown [217.140.110.172]) by us1-rack-dfw2.inumbo.com (Halon) with ESMTP id 32af65e9-a953-11e9-8980-bc764e045a96; Thu, 18 Jul 2019 11:57:20 +0000 (UTC) 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 B133C2B; Thu, 18 Jul 2019 04:57:20 -0700 (PDT) Received: from e108454-lin.cambridge.arm.com (e108454-lin.cambridge.arm.com [10.1.196.50]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 09A6B3F71A; Thu, 18 Jul 2019 04:57:19 -0700 (PDT) From: Julien Grall To: xen-devel@lists.xenproject.org Date: Thu, 18 Jul 2019 12:57:14 +0100 Message-Id: <20190718115714.634-1-julien.grall@arm.com> X-Mailer: git-send-email 2.11.0 Subject: [Xen-devel] [PATCH] xen/arm64: Correctly compute the virtual address in maddr_to_virt() X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Julien Grall , Stefano Stabellini , Volodymyr Babchuk MIME-Version: 1.0 Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" X-Virus-Scanned: ClamAV using ClamSMTP The helper maddr_to_virt() is used to translate a machine address to a virtual address. To save some valuable address space, some part of the machine address may be compressed. In theory the PDX code is free to compress any bits so there are no guarantee the machine index computed will be always greater than xenheap_mfn_start. This would result to return a virtual address that is not part of the direct map and trigger a crash at least on debug-build later on because of the check in virt_to_page(). A recently reverted patch (see 1191156361 "xen/arm: fix mask calculation in pdx_init_mask") allows the PDX to compress more bits and triggered a crash on AMD Seattle Platform. Avoid the crash by keeping track of the base PDX for the xenheap and use it for computing the virtual address. Note that virt_to_maddr() does not need to have similar modification as it is using the hardware to translate the virtual address to a machine address. Take the opportunity to fix the ASSERT() as the direct map base address correspond to the start of the RAM (this is not always 0). Signed-off-by: Julien Grall Reviewed-by: Stefano Stabellini --- With that, the patch 1191156361 "xen/arm: fix mask calculation in pdx_init_mask" could be re-instated. --- xen/arch/arm/mm.c | 2 ++ xen/include/asm-arm/mm.h | 6 ++++-- 2 files changed, 6 insertions(+), 2 deletions(-) diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c index 44258ad89c..e1cdeaaf2f 100644 --- a/xen/arch/arm/mm.c +++ b/xen/arch/arm/mm.c @@ -165,6 +165,7 @@ mfn_t xenheap_mfn_end __read_mostly; vaddr_t xenheap_virt_end __read_mostly; #ifdef CONFIG_ARM_64 vaddr_t xenheap_virt_start __read_mostly; +unsigned long xenheap_base_pdx __read_mostly; #endif unsigned long frametable_base_pdx __read_mostly; @@ -796,6 +797,7 @@ void __init setup_xenheap_mappings(unsigned long base_mfn, if ( mfn_eq(xenheap_mfn_start, INVALID_MFN) ) { xenheap_mfn_start = _mfn(base_mfn); + xenheap_base_pdx = mfn_to_pdx(_mfn(base_mfn)); xenheap_virt_start = DIRECTMAP_VIRT_START + (base_mfn - mfn) * PAGE_SIZE; } diff --git a/xen/include/asm-arm/mm.h b/xen/include/asm-arm/mm.h index 3dbc8a6469..d6b5544015 100644 --- a/xen/include/asm-arm/mm.h +++ b/xen/include/asm-arm/mm.h @@ -135,6 +135,7 @@ extern mfn_t xenheap_mfn_start, xenheap_mfn_end; extern vaddr_t xenheap_virt_end; #ifdef CONFIG_ARM_64 extern vaddr_t xenheap_virt_start; +extern unsigned long xenheap_base_pdx; #endif #ifdef CONFIG_ARM_32 @@ -253,9 +254,10 @@ static inline void *maddr_to_virt(paddr_t ma) #else static inline void *maddr_to_virt(paddr_t ma) { - ASSERT(mfn_to_pdx(maddr_to_mfn(ma)) < (DIRECTMAP_SIZE >> PAGE_SHIFT)); + ASSERT((mfn_to_pdx(maddr_to_mfn(ma)) - xenheap_base_pdx) < + (DIRECTMAP_SIZE >> PAGE_SHIFT)); return (void *)(XENHEAP_VIRT_START - - mfn_to_maddr(xenheap_mfn_start) + + (xenheap_base_pdx << PAGE_SHIFT) + ((ma & ma_va_bottom_mask) | ((ma & ma_top_mask) >> pfn_pdx_hole_shift))); }