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From: Paolo Bonzini <pbonzini@redhat.com>
To: Peter Xu <peterx@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	Sean Christopherson <sean.j.christopherson@intel.com>
Subject: Re: [PATCH 0/3] KVM: x86: cleanup and fixes for debug register accesses
Date: Mon, 4 May 2020 21:20:05 +0200	[thread overview]
Message-ID: <06dcafe8-8278-a818-ad76-36f3bbbcc0a2@redhat.com> (raw)
In-Reply-To: <20200504185530.GE6299@xz-x1>

On 04/05/20 20:55, Peter Xu wrote:
> On Mon, May 04, 2020 at 11:55:55AM -0400, Paolo Bonzini wrote:
>> The purpose of this series is to get rid of the get_dr6 accessor
>> and, on Intel, of set_dr6 as well.  This is done mostly in patch 2,
>> since patch 3 is only the resulting cleanup.  Patch 1 is a related
>> bug fix that I found while inspecting the code.
> 
> Reviewed-by: Peter Xu <peterx@redhat.com>
> 
> (Btw, the db_interception() change in patch 2 seems to be a real fix to me)

It should be okay because vcpu->arch.dr6 is not used on AMD.

However I think a kvm_update_dr6 call is missing in
kvm_deliver_exception_payload, and kvm_vcpu_check_breakpoint should use
kvm_queue_exception_p.  I'll fix all of those.

> I have that in my list, but I don't know it's "sorely" needed. :) It was low
> after I knew the fact that we've got one test in kvm-unit-test, but I can for
> sure do that earlier.
> 
> I am wondering whether we still want a test in selftests if there's a similar
> test in kvm-unit-test already.  For this one I guess at least the guest debug
> test is still missing.

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.

Paolo


  reply	other threads:[~2020-05-04 19:20 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-04 15:55 [PATCH 0/3] KVM: x86: cleanup and fixes for debug register accesses Paolo Bonzini
2020-05-04 15:55 ` [PATCH 1/3] KVM: SVM: fill in kvm_run->debug.arch.dr[67] Paolo Bonzini
2020-05-06 23:42   ` Sasha Levin
2020-05-04 15:55 ` [PATCH 2/3] KVM: SVM: keep DR6 synchronized with vcpu->arch.dr6 Paolo Bonzini
2020-05-04 15:55 ` [PATCH 3/3] KVM: x86: simplify dr6 accessors in kvm_x86_ops Paolo Bonzini
2020-05-04 18:55 ` [PATCH 0/3] KVM: x86: cleanup and fixes for debug register accesses Peter Xu
2020-05-04 19:20   ` Paolo Bonzini [this message]
2020-05-04 23:49     ` Peter Xu
2020-05-05 11:36       ` Paolo Bonzini

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