From: Thomas Gleixner <tglx@linutronix.de>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Dave Hansen <dave.hansen@intel.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
x86@kernel.org, "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
Subject: Re: [PATCHv5 08/19] x86/mm: Introduce variables to store number, shift and mask of KeyIDs
Date: Thu, 19 Jul 2018 15:40:41 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.21.1807191539370.1602@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20180719132312.75lduymla2uretax@kshutemo-mobl1>
On Thu, 19 Jul 2018, Kirill A. Shutemov wrote:
> On Thu, Jul 19, 2018 at 03:18:03PM +0200, Thomas Gleixner wrote:
> > On Thu, 19 Jul 2018, Kirill A. Shutemov wrote:
> > > On Thu, Jul 19, 2018 at 02:37:35PM +0200, Thomas Gleixner wrote:
> > > > On Thu, 19 Jul 2018, Kirill A. Shutemov wrote:
> > > > > On Wed, Jul 18, 2018 at 04:19:10PM -0700, Dave Hansen wrote:
> > > > > > > } else {
> > > > > > > /*
> > > > > > > * Reset __PHYSICAL_MASK.
> > > > > > > @@ -591,6 +592,9 @@ static void detect_tme(struct cpuinfo_x86 *c)
> > > > > > > * between CPUs.
> > > > > > > */
> > > > > > > physical_mask = (1ULL << __PHYSICAL_MASK_SHIFT) - 1;
> > > > > > > + mktme_keyid_mask = 0;
> > > > > > > + mktme_keyid_shift = 0;
> > > > > > > + mktme_nr_keyids = 0;
> > > > > > > }
> > > > > >
> > > > > > Should be unnecessary. These are zeroed by the compiler.
> > > > >
> > > > > No. detect_tme() called for each CPU in the system.
> > > >
> > > > And then the variables are cleared out while other CPUs can access them?
> > > > How is that supposed to work?
> > >
> > > This code path only matter in patalogical case: when MKTME configuation is
> > > inconsitent between CPUs. Basically if BIOS screwed things up we disable
> > > MKTME.
> >
> > I still don't see how that's supposed to work.
> >
> > When the inconsistent CPU is brought up _AFTER_ MKTME is enabled, then how
> > does clearing the variables help? It does not magically make all the other
> > stuff go away.
>
> We don't actually enable MKTME in kernel. BIOS does. Kernel makes choose
> to use it or not. Current design targeted to be used by userspace.
> So until init we don't have any other stuff to go away. We can just
> pretend that MKTME was never there.
Hotplug is not guaranteed to happen _BEFORE_ init. Think about physical
hotplug.
Thanks,
tglx
next prev parent reply other threads:[~2018-07-19 13:41 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 [this message]
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
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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