From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id D91506B0003 for ; Mon, 18 Jun 2018 10:41:13 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id x17-v6so8647762pfm.18 for ; Mon, 18 Jun 2018 07:41:13 -0700 (PDT) Received: from mga17.intel.com (mga17.intel.com. [192.55.52.151]) by mx.google.com with ESMTPS id u29-v6si15221610pfi.96.2018.06.18.07.41.08 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 18 Jun 2018 07:41:08 -0700 (PDT) Date: Mon, 18 Jun 2018 17:41:06 +0300 From: "Kirill A. Shutemov" Subject: Re: [PATCHv3 16/17] x86/mm: Handle encrypted memory in page_to_virt() and __pa() Message-ID: <20180618144106.2gga6w55zbbnnjhb@black.fi.intel.com> References: <20180612143915.68065-1-kirill.shutemov@linux.intel.com> <20180612143915.68065-17-kirill.shutemov@linux.intel.com> <20180618133455.aumn4wihygvds543@black.fi.intel.com> <48fe7072-e92d-959a-67f7-ded82124f79f@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <48fe7072-e92d-959a-67f7-ded82124f79f@intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: Ingo Molnar , x86@kernel.org, Thomas Gleixner , "H. Peter Anvin" , Tom Lendacky , Kai Huang , Jacob Pan , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Mon, Jun 18, 2018 at 01:59:18PM +0000, Dave Hansen wrote: > On 06/18/2018 06:34 AM, Kirill A. Shutemov wrote: > > On Wed, Jun 13, 2018 at 06:43:08PM +0000, Dave Hansen wrote: > >>> diff --git a/arch/x86/include/asm/mktme.h b/arch/x86/include/asm/mktme.h > >>> index efc0d4bb3b35..d6edcabacfc7 100644 > >>> --- a/arch/x86/include/asm/mktme.h > >>> +++ b/arch/x86/include/asm/mktme.h > >>> @@ -43,6 +43,9 @@ void mktme_disable(void); > >>> void setup_direct_mapping_size(void); > >>> int sync_direct_mapping(void); > >>> > >>> +#define page_to_virt(x) \ > >>> + (__va(PFN_PHYS(page_to_pfn(x))) + page_keyid(x) * direct_mapping_size) > >> > >> This looks like a super important memory management function being > >> defined in some obscure Intel-specific feature header. How does that work? > > > > No magic. It overwrites define in . > > It frankly looks like magic to me. How can this possibly work without > ensuring that asm/mktme.h is #included everywhere on every file compiled > for the entire architecture? asm/mktme.h is included from asm/page.h. It is functionally identical other architectures. > If we look at every definition of page_to_virt() on every architecture > in the kernel, we see it uniquely defined in headers that look rather > generic. I don't see any precedent for feature-specific definitions. I do. m68k and microblaze have different definitions of the macro depending on CONFIG_MMU. On arm64 it depends on CONFIG_SPARSEMEM_VMEMMAP. > > arch/arm64/include/asm/memory.h:#define page_to_virt(page) ((void *)((__page_to_voff(page)) | PAGE_OFFSET)) > > arch/hexagon/include/asm/page.h:#define page_to_virt(page) __va(page_to_phys(page)) > > arch/m68k/include/asm/page_mm.h:#define page_to_virt(page) ({ \ > > arch/m68k/include/asm/page_no.h:#define page_to_virt(page) __va(((((page) - mem_map) << PAGE_SHIFT) + PAGE_OFFSET)) > > arch/microblaze/include/asm/page.h:# define page_to_virt(page) __va(page_to_pfn(page) << PAGE_SHIFT) > > arch/microblaze/include/asm/page.h:# define page_to_virt(page) (pfn_to_virt(page_to_pfn(page))) > > arch/nios2/include/asm/page.h:#define page_to_virt(page) \ > > arch/riscv/include/asm/page.h:#define page_to_virt(page) (pfn_to_virt(page_to_pfn(page))) > > arch/s390/include/asm/page.h:#define page_to_virt(page) pfn_to_virt(page_to_pfn(page)) > > arch/xtensa/include/asm/page.h:#define page_to_virt(page) __va(page_to_pfn(page) << PAGE_SHIFT) > > *If* you do this, I think it 100% *HAS* to be done in a central header, > like x86's page.h. We need a single x86 macro for this, not something > which can and will change based on #include ordering and Kconfig. I don't agree. asm/mktme.h included from the single header -- asm/page.h -- and has clear path to linux/mm.h where the default page_to_virt() is defined. I don't see a reason to move it out of feature-specific header. The default page_to_virt() is perfectly fine without MKTME. And it will be obvious on grep. -- Kirill A. Shutemov