linux-kernel - Re: [PATCH 0/3] KVM: x86: cleanup and fixes for debug register accesses

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Date:   Tue, 5 May 2020 13:36:15 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Peter Xu <peterx@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: Re: [PATCH 0/3] KVM: x86: cleanup and fixes for debug register
 accesses

On 05/05/20 01:49, Peter Xu wrote:
>> The guest debugging test would basically cover the gdbstub case, which
>> is different from kvm-unit-tests.  It would run similar tests to
>> kvm-unit-tests, but #DB and #BP exceptions would be replaced by
>> KVM_EXIT_DEBUG, and MOVs to DR would be replaced by KVM_SET_GUEST_DEBUG.
>>
>> It could also cover exception payload support in KVM_GET_VCPU_EVENTS,
>> but that is more complicated because it would require support for
>> exceptions in the selftests.
>
> Yep, I guess the in-guest debug test will still need the exception support,
> though I also guess we don't need that when we have the kvm unit test

We can still use it in order to test for example live migration with
pending debug exceptions (KVM_GET_VCPU_EVENTS), but it's less important
indeed.

Paolo