From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f71.google.com (mail-pl0-f71.google.com [209.85.160.71]) by kanga.kvack.org (Postfix) with ESMTP id 9BEF56B0003 for ; Fri, 15 Jun 2018 12:06:17 -0400 (EDT) Received: by mail-pl0-f71.google.com with SMTP id z5-v6so5526516pln.20 for ; Fri, 15 Jun 2018 09:06:17 -0700 (PDT) Received: from mga09.intel.com (mga09.intel.com. [134.134.136.24]) by mx.google.com with ESMTPS id k7-v6si6643877pgt.235.2018.06.15.09.06.15 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 15 Jun 2018 09:06:16 -0700 (PDT) Date: Fri, 15 Jun 2018 19:06:13 +0300 From: "Kirill A. Shutemov" Subject: Re: [PATCHv3 07/17] x86/mm: Preserve KeyID on pte_modify() and pgprot_modify() Message-ID: <20180615160613.arntdivl5gdpfwfw@black.fi.intel.com> References: <20180612143915.68065-1-kirill.shutemov@linux.intel.com> <20180612143915.68065-8-kirill.shutemov@linux.intel.com> <8c31f6d2-6512-2726-763e-6dd1cbb0350a@intel.com> <20180615125720.r755xaegvfcqfr6x@black.fi.intel.com> <645a4ca8-ae77-dcdd-0cbc-0da467fc210d@intel.com> <20180615152731.3y6rre7g66rmncxr@black.fi.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Fri, Jun 15, 2018 at 03:31:57PM +0000, Dave Hansen wrote: > On 06/15/2018 08:27 AM, Kirill A. Shutemov wrote: > > On Fri, Jun 15, 2018 at 01:43:03PM +0000, Dave Hansen wrote: > >> On 06/15/2018 05:57 AM, Kirill A. Shutemov wrote: > >>>>> +#define _PAGE_CHG_MASK (PTE_PFN_MASK_MAX | _PAGE_PCD | _PAGE_PWT | \ > >>>>> _PAGE_SPECIAL | _PAGE_ACCESSED | _PAGE_DIRTY | \ > >>>>> _PAGE_SOFT_DIRTY) > >>>>> #define _HPAGE_CHG_MASK (_PAGE_CHG_MASK | _PAGE_PSE) > >>>> This makes me a bit nervous. We have some places (here) where we > >>>> pretend that the KeyID is part of the paddr and then other places like > >>>> pte_pfn() where it's not. > >>> Other option is to include KeyID mask into _PAGE_CHG_MASK. But it means > >>> _PAGE_CHG_MASK would need to reference *two* variables: physical_mask and > >>> mktme_keyid_mask. I mentioned this in the commit message. > >> > >> Why can't it be one variable with a different name that's populated by > >> OR'ing physical_mask and mktme_keyid_mask together? > > > > My point is that we don't need variables at all here. > > > > Architecture defines range of bits in PTE used for PFN. MKTME reduces the > > number of bits for PFN. PTE_PFN_MASK_MAX represents the original > > architectural range, before MKTME stole these bits. > > > > PTE_PFN_MASK_MAX is constant -- on x86-64 bits 51:12 -- regardless of > > MKTME support. > > Then please just rename the make PTE__MASK where > includes both the concept of a physical address and a MKTME keyID. Just > don't call it a pfn if it is not used in physical addressing. I have no idea what such concept should be called. I cannot come with anything better than PTE_PFN_MASK_MAX. Do you? -- Kirill A. Shutemov