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

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Message-ID: <38e89899-cf58-3a39-1d09-3ce963140a57@amd.com>
Date:   Mon, 30 Nov 2020 10:06:37 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>
Cc:     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>
Subject: Re: [RFC PATCH 00/35] SEV-ES hypervisor support

On 11/30/20 9:31 AM, Paolo Bonzini wrote:
> On 16/09/20 02:19, Sean Christopherson wrote:
>>
>> TDX also selectively blocks/skips portions of other ioctl()s so that the
>> TDX code itself can yell loudly if e.g. .get_cpl() is invoked.  The event
>> injection restrictions are due to direct injection not being allowed
>> (except
>> for NMIs); all IRQs have to be routed through APICv (posted interrupts) and
>> exception injection is completely disallowed.
>>
>>    kvm_vcpu_ioctl_x86_get_vcpu_events:
>>     if (!vcpu->kvm->arch.guest_state_protected)
>>              events->interrupt.shadow =
>> kvm_x86_ops.get_interrupt_shadow(vcpu);
> 
> Perhaps an alternative implementation can enter the vCPU with immediate
> exit until no events are pending, and then return all zeroes?

SEV-SNP has support for restricting injections, but SEV-ES does not.
Perhaps a new boolean, guest_restricted_injection, can be used instead of
basing it on guest_state_protected.

Thanks,
Tom

> 
> Paolo
>