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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: Fri, 20 Jul 2018 15:17:54 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.21.1807201511560.1580@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20180720123415.57m2fqbdjtvnietu@kshutemo-mobl1>

On Fri, 20 Jul 2018, Kirill A. Shutemov wrote:
> On Thu, Jul 19, 2018 at 03:40:41PM +0200, Thomas Gleixner wrote:
> > > > 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.
> 
> Ouch. I didn't think about this. :/
> 
> In this case I don't see how to handle the situation properly.
> Is it okay to WARN() && pray()?

Not really. First of all, you want to do the initial checking on the boot
CPU and then when secondary CPUs are brought up, verify that they have
matching parameters. If they do not, then we should just shut them down
right away before they can touch anything which is TME related and mark
them as 'don't online again'. That needs some extra logic in the hotplug
code, but I already have played with that for different reasons. Stick a
fat comment into that 'not matching' code path for now and I'll give you
the magic for preventing full bringup after polishing it a bit.

Thanks,

	tglx

  reply	other threads:[~2018-07-20 13:18 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 [this message]
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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