From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f199.google.com (mail-io0-f199.google.com [209.85.223.199]) by kanga.kvack.org (Postfix) with ESMTP id E88796B03FE for ; Wed, 21 Jun 2017 09:55:12 -0400 (EDT) Received: by mail-io0-f199.google.com with SMTP id k93so3822537ioi.1 for ; Wed, 21 Jun 2017 06:55:12 -0700 (PDT) Received: from NAM03-DM3-obe.outbound.protection.outlook.com (mail-dm3nam03on0075.outbound.protection.outlook.com. [104.47.41.75]) by mx.google.com with ESMTPS id i186si1404979ioi.150.2017.06.21.06.55.11 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 21 Jun 2017 06:55:11 -0700 (PDT) Subject: Re: [PATCH v7 07/36] x86/mm: Don't use phys_to_virt in ioremap() if SME is active References: <20170616184947.18967.84890.stgit@tlendack-t1.amdoffice.net> <20170616185104.18967.7867.stgit@tlendack-t1.amdoffice.net> From: Tom Lendacky Message-ID: <859437c0-d190-240e-6aa5-5edb0b63aa9e@amd.com> Date: Wed, 21 Jun 2017 08:54:57 -0500 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Thomas Gleixner Cc: linux-arch@vger.kernel.org, linux-efi@vger.kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, x86@kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, xen-devel@lists.xen.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Brijesh Singh , Toshimitsu Kani , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Matt Fleming , Alexander Potapenko , "H. Peter Anvin" , Larry Woodman , Jonathan Corbet , Joerg Roedel , "Michael S. Tsirkin" , Ingo Molnar , Andrey Ryabinin , Dave Young , Rik van Riel , Arnd Bergmann , Konrad Rzeszutek Wilk , Borislav Petkov , Andy Lutomirski , Boris Ostrovsky , Dmitry Vyukov , Juergen Gross , Paolo Bonzini On 6/21/2017 2:37 AM, Thomas Gleixner wrote: > On Fri, 16 Jun 2017, Tom Lendacky wrote: >> Currently there is a check if the address being mapped is in the ISA >> range (is_ISA_range()), and if it is then phys_to_virt() is used to >> perform the mapping. When SME is active, however, this will result >> in the mapping having the encryption bit set when it is expected that >> an ioremap() should not have the encryption bit set. So only use the >> phys_to_virt() function if SME is not active >> >> Reviewed-by: Borislav Petkov >> Signed-off-by: Tom Lendacky >> --- >> arch/x86/mm/ioremap.c | 7 +++++-- >> 1 file changed, 5 insertions(+), 2 deletions(-) >> >> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c >> index 4c1b5fd..a382ba9 100644 >> --- a/arch/x86/mm/ioremap.c >> +++ b/arch/x86/mm/ioremap.c >> @@ -13,6 +13,7 @@ >> #include >> #include >> #include >> +#include >> >> #include >> #include >> @@ -106,9 +107,11 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr, >> } >> >> /* >> - * Don't remap the low PCI/ISA area, it's always mapped.. >> + * Don't remap the low PCI/ISA area, it's always mapped. >> + * But if SME is active, skip this so that the encryption bit >> + * doesn't get set. >> */ >> - if (is_ISA_range(phys_addr, last_addr)) >> + if (is_ISA_range(phys_addr, last_addr) && !sme_active()) >> return (__force void __iomem *)phys_to_virt(phys_addr); > > More thoughts about that. > > Making this conditional on !sme_active() is not the best idea. I'd rather > remove that whole thing and make it unconditional so the code pathes get > always exercised and any subtle wreckage is detected on a broader base and > not only on that hard to access and debug SME capable machine owned by Joe > User. Ok, that sounds good. I'll remove the check and usage of phys_to_virt() and update the changelog with additional detail about that. Thanks, Tom > > Thanks, > > tglx > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org