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=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 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 CFE7CC4727C for ; Wed, 30 Sep 2020 17:33:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7DF5C2076A for ; Wed, 30 Sep 2020 17:33:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731396AbgI3RdC (ORCPT ); Wed, 30 Sep 2020 13:33:02 -0400 Received: from lhrrgout.huawei.com ([185.176.76.210]:2933 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725355AbgI3RdB (ORCPT ); Wed, 30 Sep 2020 13:33:01 -0400 Received: from lhreml710-chm.china.huawei.com (unknown [172.18.7.108]) by Forcepoint Email with ESMTP id 39BD6143B61A661FC7AA; Wed, 30 Sep 2020 18:33:00 +0100 (IST) Received: from localhost (10.227.96.57) by lhreml710-chm.china.huawei.com (10.201.108.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1913.5; Wed, 30 Sep 2020 18:33:00 +0100 Date: Wed, 30 Sep 2020 18:32:59 +0100 From: Jonathan Cameron To: Ard Biesheuvel CC: , , , , Sudeep Holla , Lorenzo Pieralisi Subject: Re: [PATCH] arm64: permit ACPI core to map kernel memory used for table overrides Message-ID: <20200930183259.00004582@huawei.com> In-Reply-To: <20200929132522.18067-1-ardb@kernel.org> References: <20200929132522.18067-1-ardb@kernel.org> Organization: Huawei tech. R&D (UK) Ltd. X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; i686-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.227.96.57] X-ClientProxiedBy: lhreml710-chm.china.huawei.com (10.201.108.61) To lhreml710-chm.china.huawei.com (10.201.108.61) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Tue, 29 Sep 2020 15:25:22 +0200 Ard Biesheuvel wrote: > Jonathan reports that the strict policy for memory mapped by the > ACPI core breaks the use case of passing ACPI table overrides via > initramfs. This is due to the fact that the memory type used for > loading the initramfs in memory is not recognized as a memory type > that is typically used by firmware to pass firmware tables. > > Since the purpose of the strict policy is to ensure that no AML or > other ACPI code can manipulate any memory that is used by the kernel > to keep its internal state or the state of user tasks, we can relax > the permission check, and allow mappings of memory that is reserved > and marked as NOMAP via memblock, and therefore not covered by the > linear mapping to begin with. > My over enthusiastic filters went and swept this one away so I missed it. Catalin, thanks for pointing it out! Anyhow, retested and still looks good. Slightly tighter check makes sense. > Cc: Sudeep Holla > Cc: Lorenzo Pieralisi > Fixes: 1583052d111f ("arm64/acpi: disallow AML memory opregions to access kernel memory") > Fixes: 325f5585ec36 ("arm64/acpi: disallow writeable AML opregion mapping for EFI code regions") > Reported-by: Jonathan Cameron > Signed-off-by: Ard Biesheuvel Tested-by: Jonathan Cameron > --- > arch/arm64/kernel/acpi.c | 22 ++++++++++++++++++-- > include/linux/acpi.h | 2 +- > 2 files changed, 21 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c > index a85174d05473..cada0b816c8a 100644 > --- a/arch/arm64/kernel/acpi.c > +++ b/arch/arm64/kernel/acpi.c > @@ -298,8 +298,21 @@ void __iomem *acpi_os_ioremap(acpi_physical_address phys, acpi_size size) > case EFI_BOOT_SERVICES_DATA: > case EFI_CONVENTIONAL_MEMORY: > case EFI_PERSISTENT_MEMORY: > - pr_warn(FW_BUG "requested region covers kernel memory @ %pa\n", &phys); > - return NULL; > + if (memblock_is_map_memory(phys) || > + !memblock_is_region_memory(phys, size)) { > + pr_warn(FW_BUG "requested region covers kernel memory @ %pa\n", &phys); > + return NULL; > + } > + /* > + * Mapping kernel memory is permitted if the region in > + * question is covered by a single memblock with the > + * NOMAP attribute set: this enables the use of ACPI > + * table overrides passed via initramfs, which are > + * reserved in memory using arch_reserve_mem_area() > + * below. As this particular use case only requires > + * read access, fall through to the R/O mapping case. > + */ > + fallthrough; > > case EFI_RUNTIME_SERVICES_CODE: > /* > @@ -388,3 +401,8 @@ int apei_claim_sea(struct pt_regs *regs) > > return err; > } > + > +void arch_reserve_mem_area(acpi_physical_address addr, size_t size) > +{ > + memblock_mark_nomap(addr, size); > +} > diff --git a/include/linux/acpi.h b/include/linux/acpi.h > index 1e4cdc6c7ae2..64ae25c59d55 100644 > --- a/include/linux/acpi.h > +++ b/include/linux/acpi.h > @@ -958,7 +958,7 @@ void acpi_os_set_prepare_extended_sleep(int (*func)(u8 sleep_state, > acpi_status acpi_os_prepare_extended_sleep(u8 sleep_state, > u32 val_a, u32 val_b); > > -#ifdef CONFIG_X86 > +#ifndef CONFIG_IA64 > void arch_reserve_mem_area(acpi_physical_address addr, size_t size); > #else > static inline void arch_reserve_mem_area(acpi_physical_address addr,