From: "Andy Lutomirski" <luto@kernel.org>
To: "James Bottomley" <jejb@linux.ibm.com>,
"David Hildenbrand" <david@redhat.com>,
"Sean Christopherson" <seanjc@google.com>
Cc: "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>,
"Joerg Roedel" <jroedel@suse.de>,
"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>,
"Dave Hansen" <dave.hansen@intel.com>,
"Yu Zhang" <yu.c.zhang@linux.intel.com>
Subject: Re: [RFC] KVM: mm: fd-based approach for supporting KVM guest private memory
Date: Wed, 01 Sep 2021 10:08:33 -0700 [thread overview]
Message-ID: <85b1dabf-f7be-490a-a856-28227a85ab3a@www.fastmail.com> (raw)
In-Reply-To: <bd22ef54224d15ee89130728c408f70da0516eaa.camel@linux.ibm.com>
On Wed, Sep 1, 2021, at 9:18 AM, James Bottomley wrote:
> On Wed, 2021-09-01 at 08:54 -0700, Andy Lutomirski wrote:
> [...]
> > If you want to swap a page on TDX, you can't. Sorry, go directly to
> > jail, do not collect $200.
>
> Actually, even on SEV-ES you can't either. You can read the encrypted
> page and write it out if you want, but unless you swap it back to the
> exact same physical memory location, the encryption key won't work.
> Since we don't guarantee this for swap, I think swap won't actually
> work for any confidential computing environment.
>
> > So I think there are literally zero code paths that currently call
> > try_to_unmap() that will actually work like that on TDX. If we run
> > out of memory on a TDX host, we can kill the guest completely and
> > reclaim all of its memory (which probably also involves killing QEMU
> > or whatever other user program is in charge), but that's really our
> > only option.
>
> I think our only option for swap is guest co-operation. We're going to
> have to inflate a balloon or something in the guest and have the guest
> driver do some type of bounce of the page, where it becomes an
> unencrypted page in the guest (so the host can read it without the
> physical address keying of the encryption getting in the way) but
> actually encrypted with a swap transfer key known only to the guest. I
> assume we can use the page acceptance infrastructure currently being
> discussed elsewhere to do swap back in as well ... the host provides
> the guest with the encrypted swap page and the guest has to decrypt it
> and place it in encrypted guest memory.
I asked David, and he said the PSP offers a swapping mechanism for SEV-ES. I haven’t read the details, but they should all be public.
next prev parent reply other threads:[~2021-09-01 17:09 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
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 [this message]
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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