From: Michael Roth <michael.roth@amd.com>
To: Sean Christopherson <seanjc@google.com>
Cc: <kvm@vger.kernel.org>, <linux-coco@lists.linux.dev>,
<linux-mm@kvack.org>, <linux-crypto@vger.kernel.org>,
<x86@kernel.org>, <linux-kernel@vger.kernel.org>,
<tglx@linutronix.de>, <mingo@redhat.com>, <jroedel@suse.de>,
<thomas.lendacky@amd.com>, <hpa@zytor.com>, <ardb@kernel.org>,
<pbonzini@redhat.com>, <vkuznets@redhat.com>,
<jmattson@google.com>, <luto@kernel.org>,
<dave.hansen@linux.intel.com>, <slp@redhat.com>,
<pgonda@google.com>, <peterz@infradead.org>,
<srinivas.pandruvada@linux.intel.com>, <rientjes@google.com>,
<dovmurik@linux.ibm.com>, <tobin@ibm.com>, <bp@alien8.de>,
<vbabka@suse.cz>, <kirill@shutemov.name>, <ak@linux.intel.com>,
<tony.luck@intel.com>,
<sathyanarayanan.kuppuswamy@linux.intel.com>,
<alpergun@google.com>, <jarkko@kernel.org>,
<ashish.kalra@amd.com>, <nikunj.dadhania@amd.com>,
<pankaj.gupta@amd.com>, <liam.merwick@oracle.com>,
<Larry.Dewey@amd.com>
Subject: Re: [PATCH v14 21/22] crypto: ccp: Add the SNP_{PAUSE,RESUME}_ATTESTATION commands
Date: Fri, 26 Apr 2024 20:32:10 -0500 [thread overview]
Message-ID: <20240427013210.ioz7mv3yuu2r5un6@amd.com> (raw)
In-Reply-To: <ZixCYlKn5OYUFWEq@google.com>
On Fri, Apr 26, 2024 at 05:10:10PM -0700, Sean Christopherson wrote:
> On Fri, Apr 26, 2024, Michael Roth wrote:
> > On Fri, Apr 26, 2024 at 12:57:08PM -0700, Sean Christopherson wrote:
> > > On Fri, Apr 26, 2024, Michael Roth wrote:
> > > What is "management"? I assume its some userspace daemon?
> >
> > It could be a daemon depending on cloud provider, but the main example
> > we have in mind is something more basic like virtee[1] being used to
> > interactively perform an update at the command-line. E.g. you point it
> > at the new VLEK, the new cert, and it will handle updating the certs at
> > some known location and issuing the SNP_LOAD_VLEK command. With this
> ^^^^^^^^^^^^^^^^^^^
> > interface, it can take the additional step of PAUSE'ing attestations
> > before performing either update to keep the 2 actions in sync with the
> > guest view.
>
> ...
>
> > > without having to bounce through the kernel. It doesn't even require a push
> > > model, e.g. wrap/redirect the certs with a file that has a "pause" flag and a
> > > sequence counter.
> >
> > We could do something like flag the certificate file itself, it does
> > sounds less painful than the above. But what defines that spec?
>
> Whoever defines "some known location". And it doesn't need to be a file wrapper,
"some known location" is a necessary and simple parameter controlled by
the cloud provider, so it's easy to make a tool like virtee aware of those
what those parameters should be for any particular environment. But it's not
easy to make it aware of a particular providers internal way of synchronizing
guests and certs access. We'd be somewhat dependent of those providers either
providing hooks to allow for better integration, which is "work" that might
encourage them to just brew their own solutions, versus...
Providing a simple reference scheme that's clearly defined, and easily
adoptable across the board, which is "less work", and makes adoption of common
tools/libraries SNP/certs/key management easier because we don't need to
directly involve a provider's internal guest management mechanisms into those
tools.
> e.g. put the cert in a directory along with a lock. Actually, IIUC, there doesn't
> even need to be a separate lock file. I know very little about userspace programming,
> but common sense and a quick search tells me that file locks are a solved problem.
>
> E.g. it took me ~5 minutes of Googling to come up with this, which AFAICT does
> exactly what you want.
>
> touch ~/vlek.cert
> (
> flock -e 200
> echo "Locked the cert, sleeping for 10 seconds"
> sleep 10
> echo "Igor, it's alive!!!!!!"
> ) 200< vlek.cert
>
> touch ~/vlek.cert
> (
> flock -s 201
> echo "Got me a shared lock, no updates for you!"
> ) 201< vlek.cert
>
Hmm... I did completely miss this option. But I think there are still some
issues here. IIUC you're suggesting (for example):
"Management":
a) writelock vlek.cert
b) perform SNP_LOAD_VLEK and update vlek.cert contents
c) unlock vlek.cert
"QEMU":
a) readlock vlek.cert
b) copy cert into guest buffer
c) unlock vlek.cert
The issue is that after "QEMU" unlocks and return the cert to KVM we'll
have:
"KVM"
a) return from EXT_GUEST_REQ exit to userspace
b) issue the attestation report to firmware
c) return the attestation report and cert to the guest
Between a) and b), "Management" can complete another entire update, but
the cert that it passes back to the guest will be stale relative to the
key used to sign the attestation report.
If we need to take more time to explore other options it's not
absolutely necessary to have the kernel solve this now. But every userspace
will need to solve it in some way so it seemed like it might be nice to
have a simple reference implementation to start with.
-Mike
next prev parent reply other threads:[~2024-04-27 1:32 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-21 18:01 [PATCH v14 00/22] Add AMD Secure Nested Paging (SEV-SNP) Hypervisor Support Michael Roth
2024-04-21 18:01 ` [PATCH v14 01/22] KVM: SEV: Select KVM_GENERIC_PRIVATE_MEM when CONFIG_KVM_AMD_SEV=y Michael Roth
2024-04-21 18:01 ` [PATCH v14 02/22] KVM: SEV: Add support to handle AP reset MSR protocol Michael Roth
2024-04-21 18:01 ` [PATCH v14 03/22] KVM: SEV: Add GHCB handling for Hypervisor Feature Support requests Michael Roth
2024-04-24 20:21 ` Sean Christopherson
2024-04-25 20:52 ` Michael Roth
2024-04-25 21:55 ` Sean Christopherson
2024-04-21 18:01 ` [PATCH v14 04/22] KVM: SEV: Add initial SEV-SNP support Michael Roth
2024-04-21 18:01 ` [PATCH v14 05/22] KVM: SEV: Add KVM_SEV_SNP_LAUNCH_START command Michael Roth
2024-04-24 23:26 ` Sean Christopherson
2024-04-21 18:01 ` [PATCH v14 06/22] KVM: SEV: Add KVM_SEV_SNP_LAUNCH_UPDATE command Michael Roth
2024-04-24 23:58 ` Sean Christopherson
2024-04-21 18:01 ` [PATCH v14 07/22] KVM: SEV: Add KVM_SEV_SNP_LAUNCH_FINISH command Michael Roth
2024-04-21 18:01 ` [PATCH v14 08/22] KVM: SEV: Add support to handle GHCB GPA register VMGEXIT Michael Roth
2024-04-21 18:01 ` [PATCH v14 09/22] KVM: SEV: Add support to handle MSR based Page State Change VMGEXIT Michael Roth
2024-04-24 20:59 ` Sean Christopherson
2024-04-25 22:00 ` Michael Roth
2024-04-25 22:13 ` Sean Christopherson
2024-04-26 17:16 ` Michael Roth
2024-04-26 20:14 ` Sean Christopherson
2024-04-26 22:24 ` Michael Roth
2024-04-26 22:48 ` Michael Roth
2024-04-21 18:01 ` [PATCH v14 10/22] KVM: SEV: Add support to handle " Michael Roth
2024-04-21 18:01 ` [PATCH v14 11/22] KVM: SEV: Add support to handle RMP nested page faults Michael Roth
2024-04-21 18:01 ` [PATCH v14 12/22] KVM: SEV: Support SEV-SNP AP Creation NAE event Michael Roth
2024-04-21 18:01 ` [PATCH v14 13/22] KVM: SEV: Add support for GHCB-based termination requests Michael Roth
2024-04-21 18:01 ` [PATCH v14 14/22] KVM: SEV: Implement gmem hook for initializing private pages Michael Roth
2024-04-21 18:01 ` [PATCH v14 15/22] KVM: SEV: Implement gmem hook for invalidating " Michael Roth
2024-04-21 18:01 ` [PATCH v14 16/22] KVM: x86: Implement gmem hook for determining max NPT mapping level Michael Roth
2024-04-25 0:45 ` Sean Christopherson
2024-04-21 18:01 ` [PATCH v14 17/22] KVM: SEV: Avoid WBINVD for HVA-based MMU notifications for SNP Michael Roth
2024-04-25 0:17 ` Sean Christopherson
2024-04-21 18:01 ` [PATCH v14 18/22] KVM: SVM: Add module parameter to enable SEV-SNP Michael Roth
2024-04-21 18:01 ` [PATCH v14 19/22] KVM: SEV: Provide support for SNP_GUEST_REQUEST NAE event Michael Roth
2024-04-21 18:01 ` [PATCH v14 20/22] crypto: ccp: Add the SNP_VLEK_LOAD command Michael Roth
2024-04-21 18:01 ` [PATCH v14 21/22] crypto: ccp: Add the SNP_{PAUSE,RESUME}_ATTESTATION commands Michael Roth
2024-04-25 0:15 ` Sean Christopherson
2024-04-26 17:35 ` Michael Roth
2024-04-26 19:57 ` Sean Christopherson
2024-04-26 21:46 ` Michael Roth
2024-04-27 0:10 ` Sean Christopherson
2024-04-27 1:32 ` Michael Roth [this message]
2024-04-29 14:27 ` Sean Christopherson
2024-04-21 18:01 ` [PATCH v14 22/22] KVM: SEV: Provide support for SNP_EXTENDED_GUEST_REQUEST NAE event Michael Roth
2024-04-25 0:10 ` Sean Christopherson
2024-04-26 17:57 ` Michael Roth
2024-04-23 16:21 ` [PATCH v14 23/22] [SQUASH] KVM: SEV: Add support to handle GHCB GPA register VMGEXIT Michael Roth
2024-04-23 16:21 ` [PATCH v14 24/22] [SQUASH] KVM: SEV: Add support to handle MSR based Page State Change VMGEXIT Michael Roth
2024-04-23 16:21 ` [PATCH v14 25/22] [SQUASH] KVM: SEV: Add support to handle " Michael Roth
2024-04-23 16:21 ` [PATCH v14 26/22] [SQUASH] KVM: SEV: Add support for GHCB-based termination requests Michael Roth
2024-04-23 16:21 ` [PATCH v14 27/22] [SQUASH] KVM: SEV: Provide support for SNP_GUEST_REQUEST NAE event Michael Roth
2024-04-23 16:21 ` [PATCH v14 28/22] [SQUASH] KVM: SEV: Provide support for SNP_EXTENDED_GUEST_REQUEST " Michael Roth
2024-04-23 21:36 ` Jarkko Sakkinen
2024-04-23 16:21 ` [PATCH v14 29/22] [SQUASH] KVM: SEV: Support SEV-SNP AP Creation " Michael Roth
2024-04-23 16:31 ` [PATCH v14 00/22] Add AMD Secure Nested Paging (SEV-SNP) Hypervisor Support Michael Roth
2024-04-24 16:51 ` Paolo Bonzini
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