Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752758AbdGHM5c (ORCPT ); Sat, 8 Jul 2017 08:57:32 -0400 Received: from mail-vk0-f66.google.com ([209.85.213.66]:36334 "EHLO mail-vk0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750791AbdGHM53 (ORCPT ); Sat, 8 Jul 2017 08:57:29 -0400 MIME-Version: 1.0 In-Reply-To: <20170707133925.29711.39301.stgit@tlendack-t1.amdoffice.net> References: <20170707133804.29711.1616.stgit@tlendack-t1.amdoffice.net> <20170707133925.29711.39301.stgit@tlendack-t1.amdoffice.net> From: Brian Gerst Date: Sat, 8 Jul 2017 08:57:27 -0400 Message-ID: Subject: Re: [PATCH v9 07/38] x86/mm: Remove phys_to_virt() usage in ioremap() To: Tom Lendacky Cc: linux-arch , linux-efi@vger.kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, "the arch/x86 maintainers" , kexec@lists.infradead.org, Linux Kernel Mailing List , kasan-dev@googlegroups.com, xen-devel@lists.xen.org, Linux-MM , 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 , Thomas Gleixner , Paolo Bonzini Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2085 Lines: 53 On Fri, Jul 7, 2017 at 9:39 AM, 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, the default is to add pagetable > mappings with the encryption bit set unless specifically overridden. The > resulting pagetable mapping from phys_to_virt() will result in a mapping > that has the encryption bit set. With SME, the use of ioremap() is > intended to generate pagetable mappings that do not have the encryption > bit set through the use of the PAGE_KERNEL_IO protection value. > > Rather than special case the SME scenario, remove the ISA range check and > usage of phys_to_virt() and have ISA range mappings continue through the > remaining ioremap() path. > > Signed-off-by: Tom Lendacky > --- > arch/x86/mm/ioremap.c | 7 +------ > 1 file changed, 1 insertion(+), 6 deletions(-) > > diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c > index 4c1b5fd..bfc3e2d 100644 > --- a/arch/x86/mm/ioremap.c > +++ b/arch/x86/mm/ioremap.c > @@ -13,6 +13,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -106,12 +107,6 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr, > } > > /* > - * Don't remap the low PCI/ISA area, it's always mapped.. > - */ > - if (is_ISA_range(phys_addr, last_addr)) > - return (__force void __iomem *)phys_to_virt(phys_addr); > - > - /* > * Don't allow anybody to remap normal RAM that we're using.. > */ > pfn = phys_addr >> PAGE_SHIFT; > Removing this also affects 32-bit, which is more likely to access legacy devices in this range. Put in a check for SME instead (provided you follow my recommendations to not set the SME feature bit on 32-bit even when the processor supports it). -- Brian Gerst