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From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Ashish Kalra <Ashish.Kalra@amd.com>,
	tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com,
	joro@8bytes.org, bp@suse.de, thomas.lendacky@amd.com,
	x86@kernel.org, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org, srutherford@google.com,
	venu.busireddy@oracle.com, brijesh.singh@amd.com
Subject: Re: [PATCH v13 08/12] KVM: X86: Introduce KVM_HC_PAGE_ENC_STATUS hypercall
Date: Tue, 20 Apr 2021 17:24:37 +0000
Message-ID: <YH8OVZTZG7rOstr0@google.com> (raw)
In-Reply-To: <6e6b4e8c-bbfa-fd58-c1e8-895a157762fe@redhat.com>

On Tue, Apr 20, 2021, Paolo Bonzini wrote:
> On 15/04/21 17:57, Ashish Kalra wrote:
> > From: Ashish Kalra <ashish.kalra@amd.com>
> > 
> > This hypercall is used by the SEV guest to notify a change in the page
> > encryption status to the hypervisor. The hypercall should be invoked
> > only when the encryption attribute is changed from encrypted -> decrypted
> > and vice versa. By default all guest pages are considered encrypted.
> > 
> > The hypercall exits to userspace to manage the guest shared regions and
> > integrate with the userspace VMM's migration code.
> 
> I think this should be exposed to userspace as a capability, rather than as
> a CPUID bit.  Userspace then can enable the capability and set the CPUID bit
> if it wants.
> 
> The reason is that userspace could pass KVM_GET_SUPPORTED_CPUID to
> KVM_SET_CPUID2 and the hypercall then would break the guest.

Right, and that's partly why I was advocating that KVM emulate the MSR as a nop.

  reply index

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-15 15:52 [PATCH v13 00/12] Add AMD SEV guest live migration support Ashish Kalra
2021-04-15 15:53 ` [PATCH v13 01/12] KVM: SVM: Add KVM_SEV SEND_START command Ashish Kalra
2021-04-20  8:50   ` Paolo Bonzini
2021-04-15 15:53 ` [PATCH v13 02/12] KVM: SVM: Add KVM_SEND_UPDATE_DATA command Ashish Kalra
2021-04-15 15:54 ` [PATCH v13 03/12] KVM: SVM: Add KVM_SEV_SEND_FINISH command Ashish Kalra
2021-04-15 15:54 ` [PATCH v13 04/12] KVM: SVM: Add support for KVM_SEV_RECEIVE_START command Ashish Kalra
2021-04-20  8:38   ` Paolo Bonzini
2021-04-20  9:18     ` Paolo Bonzini
2021-04-15 15:55 ` [PATCH v13 05/12] KVM: SVM: Add KVM_SEV_RECEIVE_UPDATE_DATA command Ashish Kalra
2021-04-20  8:40   ` Paolo Bonzini
2021-04-20  8:43     ` Paolo Bonzini
2021-04-15 15:55 ` [PATCH v13 06/12] KVM: SVM: Add KVM_SEV_RECEIVE_FINISH command Ashish Kalra
2021-04-15 15:56 ` [PATCH v13 07/12] KVM: x86: Add AMD SEV specific Hypercall3 Ashish Kalra
2021-04-15 15:57 ` [PATCH v13 08/12] KVM: X86: Introduce KVM_HC_PAGE_ENC_STATUS hypercall Ashish Kalra
2021-04-20 11:10   ` Paolo Bonzini
2021-04-20 17:24     ` Sean Christopherson [this message]
2021-04-15 15:57 ` [PATCH v13 09/12] mm: x86: Invoke hypercall when page encryption status is changed Ashish Kalra
2021-04-20  9:39   ` Paolo Bonzini
2021-04-21 10:05   ` Borislav Petkov
2021-04-21 12:00     ` Paolo Bonzini
2021-04-21 14:09       ` Borislav Petkov
2021-04-21 12:12     ` Ashish Kalra
2021-04-21 13:50       ` Brijesh Singh
2021-04-21 13:52       ` Borislav Petkov
2021-04-15 15:58 ` [PATCH v13 10/12] KVM: x86: Introduce new KVM_FEATURE_SEV_LIVE_MIGRATION feature & Custom MSR Ashish Kalra
2021-04-19 23:06   ` Sean Christopherson
2021-04-20 10:49     ` Paolo Bonzini
2021-04-20  9:47   ` Paolo Bonzini
2021-04-15 15:58 ` [PATCH v13 11/12] EFI: Introduce the new AMD Memory Encryption GUID Ashish Kalra
2021-04-15 16:01 ` [PATCH v13 12/12] x86/kvm: Add guest support for detecting and enabling SEV Live Migration feature Ashish Kalra
2021-04-20 10:52   ` Paolo Bonzini
2021-04-21 14:44   ` Borislav Petkov
2021-04-21 15:22     ` Ashish Kalra
2021-04-21 15:32       ` Borislav Petkov
2021-04-21 15:38     ` Paolo Bonzini
2021-04-21 18:48       ` Ashish Kalra
2021-04-21 19:19         ` Ashish Kalra
2021-04-16 21:43 ` [PATCH v13 00/12] Add AMD SEV guest live migration support Steve Rutherford
2021-04-19 14:40   ` Ashish Kalra
2021-04-20 11:11 ` Paolo Bonzini
2021-04-20 18:51   ` Borislav Petkov
2021-04-20 19:08     ` Paolo Bonzini
2021-04-20 20:28       ` Borislav Petkov

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