From: "Andy Lutomirski" <luto@kernel.org>
To: "Dave Hansen" <dave.hansen@intel.com>,
"Sean Christopherson" <seanjc@google.com>
Cc: "Joerg Roedel" <jroedel@suse.de>,
"Yu Zhang" <yu.c.zhang@linux.intel.com>,
"David Hildenbrand" <david@redhat.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Vitaly Kuznetsov" <vkuznets@redhat.com>,
"Wanpeng Li" <wanpengli@tencent.com>,
"Jim Mattson" <jmattson@google.com>,
"Joerg Roedel" <joro@8bytes.org>,
"kvm list" <kvm@vger.kernel.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"Borislav Petkov" <bp@alien8.de>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Andi Kleen" <ak@linux.intel.com>,
"David Rientjes" <rientjes@google.com>,
"Vlastimil Babka" <vbabka@suse.cz>,
"Tom Lendacky" <thomas.lendacky@amd.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
"Ingo Molnar" <mingo@redhat.com>,
"Varad Gautam" <varad.gautam@suse.com>,
"Dario Faggioli" <dfaggioli@suse.com>,
"the arch/x86 maintainers" <x86@kernel.org>,
linux-mm@kvack.org, linux-coco@lists.linux.dev,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
"Sathyanarayanan Kuppuswamy"
<sathyanarayanan.kuppuswamy@linux.intel.com>
Subject: Re: [RFC] KVM: mm: fd-based approach for supporting KVM guest private memory
Date: Thu, 02 Sep 2021 13:42:28 -0700 [thread overview]
Message-ID: <a979ba51-8693-43a0-bebb-b8b1938ff74c@www.fastmail.com> (raw)
In-Reply-To: <ef14702f-4f31-8784-8583-0b79bb7d0a07@intel.com>
On Thu, Sep 2, 2021, at 12:07 PM, Dave Hansen wrote:
> On 9/2/21 11:57 AM, Sean Christopherson wrote:
> > On Thu, Sep 02, 2021, Andy Lutomirski wrote:
> >> On 9/2/21 2:27 AM, Joerg Roedel wrote:
> >>> On Wed, Sep 01, 2021 at 09:07:59AM -0700, Andy Lutomirski wrote:
> >>>> In principle, you could actually initialize a TDX guest with all of its
> >>>> memory shared and all of it mapped in the host IOMMU.
> >>> Not sure how this works in TDX, but in SEV code fetches are always
> >>> treated as encrypted. So this approach would not work with SEV, not to
> >>> speak about attestation, which will not work with this approach either
> >>> :)
> >>>
> >> Oof.
> > TDX is kinda similar. _All_ accesses are private if paging is disabled because
> > the shared bit is either bit 48 or bit 51 in the GPA, i.e. can't be reached if
> > paging is disabled. The vCPU is hardcoded to start in unpaged protected mode,
> > so at least some amount of guest memory needs to be private.
>
> That's a rule we should definitely add to our page table checker. Just
> like how we can look for W+X, we should also look for Shared+X.
>
The only case I can thing of where the TDX vs SEV rule matters is for some mildly crazy user who wants to run user code out of an unencrypted DAX device (or virtio-fs, I guess). We can save that for another year :)
next prev parent reply other threads:[~2021-09-02 20:42 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-24 0:52 [RFC] KVM: mm: fd-based approach for supporting KVM guest private memory Sean Christopherson
2021-08-24 10:48 ` Yu Zhang
2021-08-26 0:35 ` Sean Christopherson
2021-08-26 13:23 ` Yu Zhang
2021-08-26 10:15 ` David Hildenbrand
2021-08-26 17:05 ` Andy Lutomirski
2021-08-26 21:26 ` David Hildenbrand
2021-08-27 18:24 ` Andy Lutomirski
2021-08-27 22:28 ` Sean Christopherson
2021-08-31 19:12 ` David Hildenbrand
2021-08-31 20:45 ` Sean Christopherson
2021-09-01 7:51 ` David Hildenbrand
2021-08-27 2:31 ` Yu Zhang
2021-08-31 19:08 ` David Hildenbrand
2021-08-31 20:01 ` Andi Kleen
2021-08-31 20:15 ` David Hildenbrand
2021-08-31 20:39 ` Andi Kleen
2021-09-01 3:34 ` Yu Zhang
2021-09-01 4:53 ` Andy Lutomirski
2021-09-01 7:12 ` Tian, Kevin
2021-09-01 10:24 ` Yu Zhang
2021-09-01 16:07 ` Andy Lutomirski
2021-09-01 16:27 ` David Hildenbrand
2021-09-02 8:34 ` Yu Zhang
2021-09-02 8:44 ` David Hildenbrand
2021-09-02 11:02 ` Yu Zhang
2021-09-02 8:19 ` Yu Zhang
2021-09-02 18:41 ` Andy Lutomirski
2021-09-07 1:33 ` Yan Zhao
2021-09-02 9:27 ` Joerg Roedel
2021-09-02 18:41 ` Andy Lutomirski
2021-09-02 18:57 ` Sean Christopherson
2021-09-02 19:07 ` Dave Hansen
2021-09-02 20:42 ` Andy Lutomirski [this message]
2021-08-27 22:18 ` Sean Christopherson
2021-08-31 19:07 ` David Hildenbrand
2021-08-31 21:54 ` Sean Christopherson
2021-09-01 8:09 ` David Hildenbrand
2021-09-01 15:54 ` Andy Lutomirski
2021-09-01 16:16 ` David Hildenbrand
2021-09-01 17:09 ` Andy Lutomirski
2021-09-01 16:18 ` James Bottomley
2021-09-01 16:22 ` David Hildenbrand
2021-09-01 16:31 ` James Bottomley
2021-09-01 16:37 ` David Hildenbrand
2021-09-01 16:45 ` James Bottomley
2021-09-01 17:08 ` David Hildenbrand
2021-09-01 17:50 ` Sean Christopherson
2021-09-01 17:53 ` David Hildenbrand
2021-09-01 17:08 ` Andy Lutomirski
2021-09-01 17:13 ` James Bottomley
2021-09-02 10:18 ` Joerg Roedel
2021-09-01 18:24 ` Andy Lutomirski
2021-09-01 19:26 ` Dave Hansen
2021-09-07 15:00 ` Tom Lendacky
2021-09-01 4:58 ` Andy Lutomirski
2021-09-01 7:49 ` David Hildenbrand
2021-09-02 18:47 ` Kirill A. Shutemov
2021-09-02 20:33 ` Sean Christopherson
2021-09-03 19:14 ` Kirill A. Shutemov
2021-09-03 19:15 ` Andy Lutomirski
2021-09-10 17:18 ` Kirill A. Shutemov
2021-09-15 19:58 ` Chao Peng
2021-09-15 13:51 ` David Hildenbrand
2021-09-15 14:29 ` Kirill A. Shutemov
2021-09-15 14:59 ` David Hildenbrand
2021-09-15 15:35 ` David Hildenbrand
2021-09-15 20:04 ` Kirill A. Shutemov
2021-09-15 14:11 ` Kirill A. Shutemov
2021-09-16 7:36 ` Chao Peng
2021-09-16 9:24 ` Paolo Bonzini
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