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

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Message-ID: <X8U3YeoIg1m2NW9x@google.com>
Date:   Mon, 30 Nov 2020 18:18:09 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Tom Lendacky <thomas.lendacky@....com>
Cc:     Paolo Bonzini <pbonzini@...hat.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>
Subject: Re: [RFC PATCH 00/35] SEV-ES hypervisor support

On Mon, Nov 30, 2020, Tom Lendacky wrote:
> 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.

Ya, that probably makes sense.  I suspect the easiest way to resolve these
conflicts will be to land the SEV-ES series and then tweak things as needed for
TDX.  Easiest in the sense that it should be fairly obvious what can be covered
by guest_state_protected and what needs a dedicated flag.