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From: Dave Hansen <dave.hansen@intel.com>
To: Sean Christopherson <seanjc@google.com>
Cc: Andy Lutomirski <luto@kernel.org>,
	Kuppuswamy Sathyanarayanan 
	<sathyanarayanan.kuppuswamy@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Andi Kleen <ak@linux.intel.com>,
	Kirill Shutemov <kirill.shutemov@linux.intel.com>,
	Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
	Dan Williams <dan.j.williams@intel.com>,
	Raj Ashok <ashok.raj@intel.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Sean Christopherson <sean.j.christopherson@intel.com>
Subject: Re: [RFC v1 05/26] x86/traps: Add #VE support for TDX guest
Date: Fri, 12 Feb 2021 13:06:49 -0800	[thread overview]
Message-ID: <7d0b08c4-5ae7-f914-e217-767a9fae7b78@intel.com> (raw)
In-Reply-To: <YCbq+UEMIsE0NIWI@google.com>

On 2/12/21 12:54 PM, Sean Christopherson wrote:
> Ah, I see what you're thinking.
> 
> Treating an EPT #VE as fatal was also considered as an option.  IIUC it was
> thought that finding every nook and cranny that could access a page, without
> forcing the kernel to pre-accept huge swaths of memory, would be very difficult.
> It'd be wonderful if that's not the case.

We have to manually set up the page table entries for every physical
page of memory (except for the hard-coded early stuff below 8MB or
whatever).  We *KNOW*, 100% before physical memory is accessed.

There aren't nooks and crannies where memory is accessed.  There are a
few, very well-defined choke points which must be crossed before memory
is accessed.  Page table creation, bootmem and the core page allocator
come to mind.

If Linux doesn't have a really good handle on which physical pages are
accessed when, we've got bigger problems on our hands.  Remember, we
even have debugging mechanisms that unmap pages from the kernel when
they're in the allocator.  We know so well that nobody is accessing
those physical addresses that we even tell hypervisors they can toss the
page contents and remove the physical backing (guest free page hinting).

  reply	other threads:[~2021-02-12 21:07 UTC|newest]

Thread overview: 161+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-06  3:02 Test Email sathyanarayanan.kuppuswamy
2021-02-05 23:38 ` [RFC v1 00/26] Add TDX Guest Support Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 01/26] x86/paravirt: Introduce CONFIG_PARAVIRT_XL Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 02/26] x86/cpufeatures: Add TDX Guest CPU feature Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 03/26] x86/cpufeatures: Add is_tdx_guest() interface Kuppuswamy Sathyanarayanan
2021-04-01 21:08   ` Dave Hansen
2021-04-01 21:15     ` Kuppuswamy, Sathyanarayanan
2021-04-01 21:19       ` Dave Hansen
2021-04-01 22:25         ` Kuppuswamy, Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 04/26] x86/tdx: Get TD execution environment information via TDINFO Kuppuswamy Sathyanarayanan
2021-02-08 10:00   ` Peter Zijlstra
2021-02-08 19:10     ` Kuppuswamy, Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 05/26] x86/traps: Add #VE support for TDX guest Kuppuswamy Sathyanarayanan
2021-02-08 10:20   ` Peter Zijlstra
2021-02-08 16:23     ` Andi Kleen
2021-02-08 16:33       ` Peter Zijlstra
2021-02-08 16:46         ` Sean Christopherson
2021-02-08 16:59           ` Peter Zijlstra
2021-02-08 19:05             ` Kuppuswamy, Sathyanarayanan
2021-02-08 16:46         ` Andi Kleen
2021-02-12 19:20   ` Dave Hansen
2021-02-12 19:47   ` Andy Lutomirski
2021-02-12 20:06     ` Sean Christopherson
2021-02-12 20:17       ` Dave Hansen
2021-02-12 20:37         ` Sean Christopherson
2021-02-12 20:46           ` Dave Hansen
2021-02-12 20:54             ` Sean Christopherson
2021-02-12 21:06               ` Dave Hansen [this message]
2021-02-12 21:37                 ` Sean Christopherson
2021-02-12 21:47                   ` Andy Lutomirski
2021-02-12 21:48                     ` Dave Hansen
2021-02-14 19:33                       ` Andi Kleen
2021-02-14 19:54                         ` Andy Lutomirski
2021-02-12 20:20       ` Andy Lutomirski
2021-02-12 20:44         ` Sean Christopherson
2021-02-05 23:38 ` [RFC v1 06/26] x86/tdx: Add HLT " Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 07/26] x86/tdx: Wire up KVM hypercalls Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 08/26] x86/tdx: Add MSR support for TDX guest Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 09/26] x86/tdx: Handle CPUID via #VE Kuppuswamy Sathyanarayanan
2021-02-05 23:42   ` Andy Lutomirski
2021-02-07 14:13     ` Kirill A. Shutemov
2021-02-07 16:01       ` Dave Hansen
2021-02-07 20:29         ` Kirill A. Shutemov
2021-02-07 22:31           ` Dave Hansen
2021-02-07 22:45             ` Andy Lutomirski
2021-02-08 17:10               ` Sean Christopherson
2021-02-08 17:35                 ` Andy Lutomirski
2021-02-08 17:47                   ` Sean Christopherson
2021-03-18 21:30               ` [PATCH v1 1/1] x86/tdx: Add tdcall() and tdvmcall() helper functions Kuppuswamy Sathyanarayanan
2021-03-19 16:55                 ` Sean Christopherson
2021-03-19 17:42                   ` Kuppuswamy, Sathyanarayanan
2021-03-19 18:22                     ` Dave Hansen
2021-03-19 19:58                       ` Kuppuswamy, Sathyanarayanan
2021-03-26 23:38                         ` [PATCH v2 1/1] x86/tdx: Add __tdcall() and __tdvmcall() " Kuppuswamy Sathyanarayanan
2021-04-20 17:36                           ` Dave Hansen
2021-04-20 19:20                             ` Kuppuswamy, Sathyanarayanan
2021-04-20 19:59                               ` Dave Hansen
2021-04-20 23:12                                 ` Kuppuswamy, Sathyanarayanan
2021-04-20 23:42                                   ` Dave Hansen
2021-04-23  1:09                                     ` Kuppuswamy, Sathyanarayanan
2021-04-23  1:21                                       ` Dave Hansen
2021-04-23  1:35                                         ` Andi Kleen
2021-04-23 15:15                                           ` Sean Christopherson
2021-04-23 15:28                                             ` Dan Williams
2021-04-23 15:38                                               ` Andi Kleen
2021-04-23 15:50                                               ` Sean Christopherson
2021-04-23 15:47                                             ` Andi Kleen
2021-04-23 18:18                                             ` Kuppuswamy, Sathyanarayanan
2021-04-20 23:53                                   ` Dan Williams
2021-04-20 23:59                                     ` Kuppuswamy, Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 10/26] x86/io: Allow to override inX() and outX() implementation Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 11/26] x86/tdx: Handle port I/O Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 12/26] x86/tdx: Handle in-kernel MMIO Kuppuswamy Sathyanarayanan
2021-04-01 19:56   ` Dave Hansen
2021-04-01 22:26     ` Sean Christopherson
2021-04-01 22:53       ` Dave Hansen
2021-02-05 23:38 ` [RFC v1 13/26] x86/tdx: Handle MWAIT, MONITOR and WBINVD Kuppuswamy Sathyanarayanan
2021-02-05 23:43   ` Andy Lutomirski
2021-02-05 23:54     ` Kuppuswamy, Sathyanarayanan
2021-02-06  1:05       ` Andy Lutomirski
2021-03-27  0:18         ` [PATCH v1 1/1] " Kuppuswamy Sathyanarayanan
2021-03-27  2:40           ` Andy Lutomirski
2021-03-27  3:40             ` Kuppuswamy, Sathyanarayanan
2021-03-27 16:03               ` Andy Lutomirski
2021-03-27 22:54                 ` [PATCH v2 " Kuppuswamy Sathyanarayanan
2021-03-29 17:14                   ` Dave Hansen
2021-03-29 21:55                     ` Kuppuswamy, Sathyanarayanan
2021-03-29 22:02                       ` Dave Hansen
2021-03-29 22:09                         ` Kuppuswamy, Sathyanarayanan
2021-03-29 22:12                           ` Dave Hansen
2021-03-29 22:42                             ` Kuppuswamy, Sathyanarayanan
2021-03-29 23:16                             ` [PATCH v3 " Kuppuswamy Sathyanarayanan
2021-03-29 23:23                               ` Andy Lutomirski
2021-03-29 23:37                                 ` Kuppuswamy, Sathyanarayanan
2021-03-29 23:42                                   ` Sean Christopherson
2021-03-29 23:58                                     ` Andy Lutomirski
2021-03-30  2:04                                       ` Andi Kleen
2021-03-30  2:58                                         ` Andy Lutomirski
2021-03-30 15:14                                           ` Sean Christopherson
2021-03-30 16:37                                             ` Andy Lutomirski
2021-03-30 16:57                                               ` Sean Christopherson
2021-04-07 15:24                                                 ` Andi Kleen
2021-03-31 21:09                                           ` [PATCH v4 " Kuppuswamy Sathyanarayanan
2021-03-31 21:49                                             ` Dave Hansen
2021-03-31 22:29                                               ` Kuppuswamy, Sathyanarayanan
2021-03-31 21:53                                             ` Sean Christopherson
2021-03-31 22:00                                               ` Dave Hansen
2021-03-31 22:06                                                 ` Sean Christopherson
2021-03-31 22:11                                                   ` Dave Hansen
2021-03-31 22:28                                                     ` Kuppuswamy, Sathyanarayanan
2021-03-31 22:32                                                       ` Sean Christopherson
2021-03-31 22:34                                                       ` Dave Hansen
2021-04-01  3:28                                                         ` Andi Kleen
2021-04-01  3:46                                                           ` Dave Hansen
2021-04-01  4:24                                                             ` Andi Kleen
2021-04-01  4:51                                                               ` [PATCH v5 " Kuppuswamy Sathyanarayanan
2021-03-29 23:39                                 ` [PATCH v3 " Sean Christopherson
2021-03-29 23:38                               ` Dave Hansen
2021-03-30  4:56           ` [PATCH v1 " Xiaoyao Li
2021-03-30 15:00             ` Andi Kleen
2021-03-30 15:10               ` Dave Hansen
2021-03-30 17:02                 ` Kuppuswamy, Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 14/26] ACPI: tables: Add multiprocessor wake-up support Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 15/26] x86/boot: Add a trampoline for APs booting in 64-bit mode Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 16/26] x86/boot: Avoid #VE during compressed boot for TDX platforms Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 17/26] x86/boot: Avoid unnecessary #VE during boot process Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 18/26] x86/topology: Disable CPU hotplug support for TDX platforms Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 19/26] x86/tdx: Forcefully disable legacy PIC for TDX guests Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 20/26] x86/tdx: Introduce INTEL_TDX_GUEST config option Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 21/26] x86/mm: Move force_dma_unencrypted() to common code Kuppuswamy Sathyanarayanan
2021-04-01 20:06   ` Dave Hansen
2021-04-06 15:37     ` Kirill A. Shutemov
2021-04-06 16:11       ` Dave Hansen
2021-04-06 16:37         ` Kirill A. Shutemov
2021-02-05 23:38 ` [RFC v1 22/26] x86/tdx: Exclude Shared bit from __PHYSICAL_MASK Kuppuswamy Sathyanarayanan
2021-04-01 20:13   ` Dave Hansen
2021-04-06 15:54     ` Kirill A. Shutemov
2021-04-06 16:12       ` Dave Hansen
2021-02-05 23:38 ` [RFC v1 23/26] x86/tdx: Make pages shared in ioremap() Kuppuswamy Sathyanarayanan
2021-04-01 20:26   ` Dave Hansen
2021-04-06 16:00     ` Kirill A. Shutemov
2021-04-06 16:14       ` Dave Hansen
2021-02-05 23:38 ` [RFC v1 24/26] x86/tdx: Add helper to do MapGPA TDVMALL Kuppuswamy Sathyanarayanan
2021-02-05 23:38 ` [RFC v1 25/26] x86/tdx: Make DMA pages shared Kuppuswamy Sathyanarayanan
2021-04-01 21:01   ` Dave Hansen
2021-04-06 16:31     ` Kirill A. Shutemov
2021-04-06 16:38       ` Dave Hansen
2021-04-06 17:16         ` Sean Christopherson
2021-02-05 23:38 ` [RFC v1 26/26] x86/kvm: Use bounce buffers for TD guest Kuppuswamy Sathyanarayanan
2021-04-01 21:17   ` Dave Hansen
2021-02-06  3:04 ` Test Email sathyanarayanan.kuppuswamy
2021-02-06  6:24 ` [RFC v1 00/26] Add TDX Guest Support sathyanarayanan.kuppuswamy
2021-03-31 21:38 ` Kuppuswamy, Sathyanarayanan
2021-04-02  0:02 ` Dave Hansen
2021-04-02  2:48   ` Andi Kleen
2021-04-02 15:27     ` Dave Hansen
2021-04-02 21:32       ` Andi Kleen
2021-04-03 16:26         ` Dave Hansen
2021-04-03 17:28           ` Andi Kleen
2021-04-04 15:02 ` Dave Hansen
2021-04-12 17:24   ` Dan Williams

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