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From: Tejun Heo <tj@kernel.org>
To: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Vipin Sharma <vipinsh@google.com>,
	brijesh.singh@amd.com, jon.grimm@amd.com,
	eric.vantassell@amd.com, pbonzini@redhat.com, seanjc@google.com,
	lizefan@huawei.com, hannes@cmpxchg.org, frankja@linux.ibm.com,
	borntraeger@de.ibm.com, corbet@lwn.net, joro@8bytes.org,
	vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com,
	tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
	hpa@zytor.com, gingell@google.com, rientjes@google.com,
	dionnaglaze@google.com, kvm@vger.kernel.org, x86@kernel.org,
	cgroups@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [Patch v4 1/2] cgroup: svm: Add Encryption ID controller
Date: Thu, 21 Jan 2021 10:55:13 -0500	[thread overview]
Message-ID: <YAmj4Q2J9htW2Fe8@mtj.duckdns.org> (raw)
In-Reply-To: <be699d89-1bd8-25ae-fc6f-1e356b768c75@amd.com>

Hello,

On Thu, Jan 21, 2021 at 08:55:07AM -0600, Tom Lendacky wrote:
> The hardware will allow any SEV capable ASID to be run as SEV-ES, however,
> the SEV firmware will not allow the activation of an SEV-ES VM to be
> assigned to an ASID greater than or equal to the SEV minimum ASID value. The
> reason for the latter is to prevent an !SEV-ES ASID starting out as an
> SEV-ES guest and then disabling the SEV-ES VMCB bit that is used by VMRUN.
> This would result in the downgrading of the security of the VM without the
> VM realizing it.
> 
> As a result, you have a range of ASIDs that can only run SEV-ES VMs and a
> range of ASIDs that can only run SEV VMs.

I see. That makes sense. What's the downside of SEV-ES compared to SEV w/o
ES? Are there noticeable performance / feature penalties or is the split
mostly for backward compatibility?

Thanks.

-- 
tejun

  reply	other threads:[~2021-01-21 16:49 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-08  1:28 [Patch v4 0/2] cgroup: KVM: New Encryption IDs cgroup controller Vipin Sharma
2021-01-08  1:28 ` [Patch v4 1/2] cgroup: svm: Add Encryption ID controller Vipin Sharma
2021-01-13 15:19   ` Brijesh Singh
2021-01-15 20:59   ` Tejun Heo
2021-01-15 22:18     ` Vipin Sharma
2021-01-16  3:43       ` Tejun Heo
2021-01-16  4:32         ` Vipin Sharma
2021-01-19 15:51           ` Tejun Heo
2021-01-20  7:13             ` Vipin Sharma
2021-01-20 16:40               ` Tejun Heo
2021-01-20 23:18                 ` Vipin Sharma
2021-01-20 23:32                   ` Tejun Heo
2021-01-22  0:09                     ` Vipin Sharma
2021-01-21 14:55                 ` Tom Lendacky
2021-01-21 15:55                   ` Tejun Heo [this message]
2021-01-21 23:12                     ` Tom Lendacky
2021-01-22  1:25                       ` Sean Christopherson
2021-01-26 20:49                         ` David Rientjes
2021-01-26 22:01                           ` Tejun Heo
2021-01-26 22:02                             ` Tejun Heo
2021-01-27  1:11                             ` Vipin Sharma
2021-01-27 14:10                               ` Tejun Heo
2021-01-08  1:28 ` [Patch v4 2/2] cgroup: svm: Encryption IDs cgroup documentation Vipin Sharma
2021-01-15 21:00   ` Tejun Heo
2021-01-15 21:41     ` Vipin Sharma

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