linux-kernel - Re: [RFC PATCH 00/35] SEV-ES hypervisor support

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Date:   Mon, 30 Nov 2020 21:24:33 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Tom Lendacky <thomas.lendacky@....com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, x86@...nel.org,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Borislav Petkov <bp@...en8.de>, Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Brijesh Singh <brijesh.singh@....com>,
        Xiaoyao Li <xiaoyao.li@...el.com>,
        Isaku Yamahata <isaku.yamahata@...el.com>
Subject: Re: [RFC PATCH 00/35] SEV-ES hypervisor support

On 30/11/20 20:35, Sean Christopherson wrote:
>> Delayed interrupts are fine, since they are injected according to RVI and
>> the posted interrupt descriptor.  I'm thinking more of events (exceptions
>> and interrupts) that caused an EPT violation exit and were recorded in the
>> IDT-vectored info field.
> Ah.  As is, I don't believe KVM has access to this information.  TDX-Module
> handles the actual EPT violation, as well as event reinjection.  The EPT
> violation reported by SEAMRET is synthesized, and IIRC the IDT-vectoring field
> is not readable.
> 
> Regardless, is there an actual a problem with having a "pending" exception that
> isn't reported to userspace?  Obviously the info needs to be migrated, but that
> will be taken care of by virtue of migrating the VMCS.

No problem, I suppose we would just have to get used to not being able 
to look into the state of migrated VMs.

Paolo