From: Peter Xu <peterx@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH v2 8/9] KVM: x86, SVM: isolate vcpu->arch.dr6 from vmcb->save.dr6
Date: Thu, 7 May 2020 15:28:08 -0400 [thread overview]
Message-ID: <20200507192808.GK228260@xz-x1> (raw)
In-Reply-To: <20200507115011.494562-9-pbonzini@redhat.com>
On Thu, May 07, 2020 at 07:50:10AM -0400, Paolo Bonzini wrote:
> diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> index 1a547e3ac0e5..9a2a62e5afeb 100644
> --- a/arch/x86/kvm/svm/nested.c
> +++ b/arch/x86/kvm/svm/nested.c
> @@ -633,10 +633,18 @@ static int nested_svm_intercept_db(struct vcpu_svm *svm)
>
> reflected_db:
> /*
> - * Synchronize guest DR6 here just like in db_interception; it will
> - * be moved into the nested VMCB by nested_svm_vmexit.
> + * Synchronize guest DR6 here just like in kvm_deliver_exception_payload;
> + * it will be moved into the nested VMCB by nested_svm_vmexit. Once
> + * exceptions will be moved to svm_check_nested_events, all this stuff
> + * will just go away and we could just return NESTED_EXIT_HOST
> + * unconditionally. db_interception will queue the exception, which
> + * will be processed by svm_check_nested_events if a nested vmexit is
> + * required, and we will just use kvm_deliver_exception_payload to copy
> + * the payload to DR6 before vmexit.
> */
> - svm->vcpu.arch.dr6 = dr6;
> + WARN_ON(svm->vcpu.arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT);
> + svm->vcpu.arch.dr6 &= ~(DR_TRAP_BITS | DR6_RTM);
> + svm->vcpu.arch.dr6 |= dr6 & ~DR6_FIXED_1;
I failed to figure out what the above calculation is going to do... E.g., I
think the old "BT|BS|BD" bits in the old arch.dr6 cache will be leftover even
if none of them is set in save.dr6, while we shouldn't?
Thanks,
--
Peter Xu
next prev parent reply other threads:[~2020-05-07 19:28 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-07 11:50 [PATCH v2 0/9] KVM_SET_GUEST_DEBUG tests and fixes, DR accessors cleanups Paolo Bonzini
2020-05-07 11:50 ` [PATCH v2 1/9] KVM: X86: Declare KVM_CAP_SET_GUEST_DEBUG properly Paolo Bonzini
2020-05-07 11:50 ` [PATCH v2 2/9] KVM: x86: fix DR6 delivery for various cases of #DB injection Paolo Bonzini
2020-05-07 11:50 ` [PATCH v2 3/9] KVM: X86: Set RTM for DB_VECTOR too for KVM_EXIT_DEBUG Paolo Bonzini
2020-05-07 11:50 ` [PATCH v2 4/9] KVM: X86: Fix single-step with KVM_SET_GUEST_DEBUG Paolo Bonzini
2020-05-07 11:50 ` [PATCH v2 5/9] KVM: selftests: Add KVM_SET_GUEST_DEBUG test Paolo Bonzini
2020-05-07 11:50 ` [PATCH v2 6/9] KVM: nSVM: trap #DB and #BP to userspace if guest debugging is on Paolo Bonzini
2020-05-07 18:22 ` Peter Xu
2020-05-07 11:50 ` [PATCH v2 7/9] KVM: SVM: keep DR6 synchronized with vcpu->arch.dr6 Paolo Bonzini
2020-05-07 18:22 ` Peter Xu
2020-05-07 22:21 ` Paolo Bonzini
2020-05-07 11:50 ` [PATCH v2 8/9] KVM: x86, SVM: isolate vcpu->arch.dr6 from vmcb->save.dr6 Paolo Bonzini
2020-05-07 19:28 ` Peter Xu [this message]
2020-05-07 22:33 ` Paolo Bonzini
2020-05-08 15:32 ` Peter Xu
2020-05-09 13:28 ` Paolo Bonzini
2020-05-11 16:15 ` Peter Xu
2020-05-07 11:50 ` [PATCH 9/9] KVM: VMX: pass correct DR6 for GD userspace exit Paolo Bonzini
2020-05-07 16:18 ` Peter Xu
2020-05-07 16:21 ` Paolo Bonzini
2020-05-07 16:38 ` Peter Xu
2020-05-07 17:42 ` Paolo Bonzini
2020-05-07 18:05 ` Peter Xu
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