From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Dave Hansen <dave.hansen@intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Tom Lendacky <thomas.lendacky@amd.com>,
Kai Huang <kai.huang@linux.intel.com>,
Jacob Pan <jacob.jun.pan@linux.intel.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org, "Schofield,
Alison" <alison.schofield@intel.com>
Subject: Re: [PATCHv5 10/19] x86/mm: Implement page_keyid() using page_ext
Date: Mon, 23 Jul 2018 12:45:17 +0300 [thread overview]
Message-ID: <20180723094517.7sxt62p3h75htppw@kshutemo-mobl1> (raw)
In-Reply-To: <2166be55-3491-f620-5eb0-6f671a53645f@intel.com>
On Wed, Jul 18, 2018 at 04:38:02PM -0700, Dave Hansen wrote:
> On 07/17/2018 04:20 AM, Kirill A. Shutemov wrote:
> > Store KeyID in bits 31:16 of extended page flags. These bits are unused.
>
> I'd love a two sentence remind of what page_ext is and why you chose to
> use it. Yes, you need this. No, not everybody that you want to review
> this patch set knows what it is or why you chose it.
Okay.
> > page_keyid() returns zero until page_ext is ready.
>
> Is there any implication of this? Or does it not matter because we
> don't run userspace until after page_ext initialization is done?
It matters in sense that we shouldn't reference page_ext before it's
initialized otherwise we will get garbage and crash.
> > page_ext initializer enables static branch to indicate that
>
> "enables a static branch"
>
> > page_keyid() can use page_ext. The same static branch will gate MKTME
> > readiness in general.
>
> Can you elaborate on this a bit? It would also be a nice place to hint
> to the folks working hard on the APIs to ensure she checks this.
Okay.
> > We don't yet set KeyID for the page. It will come in the following
> > patch that implements prep_encrypted_page(). All pages have KeyID-0 for
> > now.
>
> It also wouldn't hurt to mention why you don't use an X86_FEATURE_* for
> this rather than an explicit static branch. I'm sure the x86
> maintainers will be curious.
Sure.
--
Kirill A. Shutemov
next prev parent reply other threads:[~2018-07-23 9:45 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-17 11:20 [PATCHv5 00/19] MKTME enabling Kirill A. Shutemov
2018-07-17 11:20 ` [PATCHv5 01/19] mm: Do no merge VMAs with different encryption KeyIDs Kirill A. Shutemov
2018-07-17 11:20 ` [PATCHv5 02/19] mm: Do not use zero page in encrypted pages Kirill A. Shutemov
2018-07-18 17:36 ` Dave Hansen
2018-07-19 7:16 ` Kirill A. Shutemov
2018-07-19 13:58 ` Dave Hansen
2018-07-20 12:16 ` Kirill A. Shutemov
2018-07-17 11:20 ` [PATCHv5 03/19] mm/ksm: Do not merge pages with different KeyIDs Kirill A. Shutemov
2018-07-18 17:38 ` Dave Hansen
2018-07-19 7:32 ` Kirill A. Shutemov
2018-07-19 14:02 ` Dave Hansen
2018-07-20 12:23 ` Kirill A. Shutemov
2018-07-17 11:20 ` [PATCHv5 04/19] mm/page_alloc: Unify alloc_hugepage_vma() Kirill A. Shutemov
2018-07-18 17:43 ` Dave Hansen
2018-07-17 11:20 ` [PATCHv5 05/19] mm/page_alloc: Handle allocation for encrypted memory Kirill A. Shutemov
2018-07-18 23:03 ` Dave Hansen
2018-07-19 8:27 ` Kirill A. Shutemov
2018-07-19 14:05 ` Dave Hansen
2018-07-20 12:25 ` Kirill A. Shutemov
2018-07-26 14:25 ` Michal Hocko
2018-07-17 11:20 ` [PATCHv5 06/19] mm/khugepaged: Handle encrypted pages Kirill A. Shutemov
2018-07-18 23:11 ` Dave Hansen
2018-07-19 8:59 ` Kirill A. Shutemov
2018-07-19 14:13 ` Dave Hansen
2018-07-20 12:29 ` Kirill A. Shutemov
2018-07-17 11:20 ` [PATCHv5 07/19] x86/mm: Mask out KeyID bits from page table entry pfn Kirill A. Shutemov
2018-07-18 23:13 ` Dave Hansen
2018-07-19 9:54 ` Kirill A. Shutemov
2018-07-19 14:19 ` Dave Hansen
2018-07-20 12:31 ` Kirill A. Shutemov
2018-07-17 11:20 ` [PATCHv5 08/19] x86/mm: Introduce variables to store number, shift and mask of KeyIDs Kirill A. Shutemov
2018-07-18 23:19 ` Dave Hansen
2018-07-19 10:21 ` Kirill A. Shutemov
2018-07-19 12:37 ` Thomas Gleixner
2018-07-19 13:12 ` Kirill A. Shutemov
2018-07-19 13:18 ` Thomas Gleixner
2018-07-19 13:23 ` Kirill A. Shutemov
2018-07-19 13:40 ` Thomas Gleixner
2018-07-20 12:34 ` Kirill A. Shutemov
2018-07-20 13:17 ` Thomas Gleixner
2018-07-20 13:40 ` Kirill A. Shutemov
2018-07-19 14:23 ` Dave Hansen
2018-07-20 12:34 ` Kirill A. Shutemov
2018-07-31 0:08 ` Kai Huang
2018-07-17 11:20 ` [PATCHv5 09/19] x86/mm: Preserve KeyID on pte_modify() and pgprot_modify() Kirill A. Shutemov
2018-07-18 23:30 ` Dave Hansen
2018-07-20 12:42 ` Kirill A. Shutemov
2018-07-17 11:20 ` [PATCHv5 10/19] x86/mm: Implement page_keyid() using page_ext Kirill A. Shutemov
2018-07-18 23:38 ` Dave Hansen
2018-07-23 9:45 ` Kirill A. Shutemov [this message]
2018-07-23 17:22 ` Alison Schofield
2018-07-17 11:20 ` [PATCHv5 11/19] x86/mm: Implement vma_keyid() Kirill A. Shutemov
2018-07-18 23:40 ` Dave Hansen
2018-07-23 9:47 ` Kirill A. Shutemov
2018-07-17 11:20 ` [PATCHv5 12/19] x86/mm: Implement prep_encrypted_page() and arch_free_page() Kirill A. Shutemov
2018-07-18 23:53 ` Dave Hansen
2018-07-23 9:50 ` Kirill A. Shutemov
2018-07-17 11:20 ` [PATCHv5 13/19] x86/mm: Rename CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING Kirill A. Shutemov
2018-07-17 11:20 ` [PATCHv5 14/19] x86/mm: Allow to disable MKTME after enumeration Kirill A. Shutemov
2018-07-17 11:20 ` [PATCHv5 15/19] x86/mm: Detect MKTME early Kirill A. Shutemov
2018-07-17 11:20 ` [PATCHv5 16/19] x86/mm: Calculate direct mapping size Kirill A. Shutemov
2018-07-17 11:20 ` [PATCHv5 17/19] x86/mm: Implement sync_direct_mapping() Kirill A. Shutemov
2018-07-19 0:01 ` Dave Hansen
2018-07-23 10:04 ` Kirill A. Shutemov
2018-07-23 12:25 ` Dave Hansen
2018-07-17 11:20 ` [PATCHv5 18/19] x86/mm: Handle encrypted memory in page_to_virt() and __pa() Kirill A. Shutemov
2018-07-18 22:21 ` Thomas Gleixner
2018-07-23 10:12 ` Kirill A. Shutemov
2018-07-26 17:26 ` Dave Hansen
2018-07-27 13:49 ` Kirill A. Shutemov
2018-07-17 11:20 ` [PATCHv5 19/19] x86: Introduce CONFIG_X86_INTEL_MKTME Kirill A. Shutemov
2018-08-15 7:48 ` Pavel Machek
2018-08-17 9:24 ` Kirill A. Shutemov
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