From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f69.google.com (mail-pg0-f69.google.com [74.125.83.69]) by kanga.kvack.org (Postfix) with ESMTP id 93F8E6B02EE for ; Mon, 24 Apr 2017 11:54:09 -0400 (EDT) Received: by mail-pg0-f69.google.com with SMTP id l30so15683326pgc.15 for ; Mon, 24 Apr 2017 08:54:09 -0700 (PDT) Received: from NAM02-BL2-obe.outbound.protection.outlook.com (mail-bl2nam02on0088.outbound.protection.outlook.com. [104.47.38.88]) by mx.google.com with ESMTPS id g73si19491854pfg.34.2017.04.24.08.54.08 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 24 Apr 2017 08:54:08 -0700 (PDT) Subject: Re: [PATCH v5 09/32] x86/mm: Provide general kernel support for memory encryption References: <20170418211612.10190.82788.stgit@tlendack-t1.amdoffice.net> <20170418211754.10190.25082.stgit@tlendack-t1.amdoffice.net> <0106e3fc-9780-e872-2274-fecf79c28923@intel.com> From: Tom Lendacky Message-ID: <9fc79e28-ad64-1c2f-4c46-a4efcdd550b0@amd.com> Date: Mon, 24 Apr 2017 10:53:58 -0500 MIME-Version: 1.0 In-Reply-To: <0106e3fc-9780-e872-2274-fecf79c28923@intel.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen , 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, linux-mm@kvack.org, iommu@lists.linux-foundation.org Cc: Rik van Riel , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Toshimitsu Kani , Arnd Bergmann , Jonathan Corbet , Matt Fleming , "Michael S. Tsirkin" , Joerg Roedel , Konrad Rzeszutek Wilk , Paolo Bonzini , Larry Woodman , Brijesh Singh , Ingo Molnar , Borislav Petkov , Andy Lutomirski , "H. Peter Anvin" , Andrey Ryabinin , Alexander Potapenko , Dave Young , Thomas Gleixner , Dmitry Vyukov On 4/21/2017 4:52 PM, Dave Hansen wrote: > On 04/18/2017 02:17 PM, Tom Lendacky wrote: >> @@ -55,7 +57,7 @@ static inline void copy_user_page(void *to, void *from, unsigned long vaddr, >> __phys_addr_symbol(__phys_reloc_hide((unsigned long)(x))) >> >> #ifndef __va >> -#define __va(x) ((void *)((unsigned long)(x)+PAGE_OFFSET)) >> +#define __va(x) ((void *)(__sme_clr(x) + PAGE_OFFSET)) >> #endif > > It seems wrong to be modifying __va(). It currently takes a physical > address, and this modifies it to take a physical address plus the SME bits. This actually modifies it to be sure the encryption bit is not part of the physical address. > > How does that end up ever happening? If we are pulling physical > addresses out of the page tables, we use p??_phys(). I'd expect *those* > to be masking off the SME bits. > > Is it these cases? > > pgd_t *base = __va(read_cr3()); > > For those, it seems like we really want to create two modes of reading > cr3. One that truly reads CR3 and another that reads the pgd's physical > address out of CR3. Then you only do the SME masking on the one > fetching a physical address, and the SME bits never leak into __va(). I'll investigate this and see if I can remove the mod to __va(). Thanks, Tom > -- 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