From: Sean Christopherson <seanjc@google.com>
To: Hou Wenlong <houwenlong.hwl@antgroup.com>
Cc: kvm@vger.kernel.org, Lai Jiangshan <jiangshan.ljs@antgroup.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/9] KVM: x86: Set guest DR6 by kvm_queue_exception_p() in instruction emulation
Date: Mon, 11 May 2026 08:42:53 -0700 [thread overview]
Message-ID: <agH4_fcwwIX5_PNs@google.com> (raw)
In-Reply-To: <agH1NMIENm0CIN9t@google.com>
On Mon, May 11, 2026, Sean Christopherson wrote:
> On Mon, May 11, 2026, Sean Christopherson wrote:
> > On Thu, Dec 18, 2025, Hou Wenlong wrote:
> > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > > index ab298bfa7d9f..f33ce947633e 100644
> > > --- a/arch/x86/kvm/x86.c
> > > +++ b/arch/x86/kvm/x86.c
> > > @@ -8925,7 +8925,9 @@ static void inject_emulated_exception(struct kvm_vcpu *vcpu)
> > > {
> > > struct x86_exception *ex = &vcpu->arch.emulate_ctxt->exception;
> > >
> > > - if (ex->vector == PF_VECTOR)
> > > + if (ex->vector == DB_VECTOR)
> > > + kvm_queue_exception_e(vcpu, DB_VECTOR, ex->dr6);
> >
> > This should be kvm_queue_exception_p(). I also think pivoting on DB_VECTOR is
> > the wrong approach.
>
> Gah, never mind, didn't look at the next patch.
Actually, that's a good excuse to provide kvm_inject_emulated_db() in this patch,
even though it doesn't become truly necessary until the next patch. Eliminating
some of the code movement in the next patch will yield a smaller diff, and make
it easier to see that there's change in the !KVM_GUESTDBG_USE_HW_BP case.
@@ -8976,23 +8998,36 @@ static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask)
}
}
-static void kvm_inject_emulated_db(struct kvm_vcpu *vcpu, unsigned long dr6)
+static int kvm_inject_emulated_db(struct kvm_vcpu *vcpu, unsigned long dr6)
{
+ struct kvm_run *kvm_run = vcpu->run;
+
+ if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP) {
+ kvm_run->debug.arch.dr6 = dr6 | DR6_ACTIVE_LOW;
+ kvm_run->debug.arch.pc = kvm_get_linear_rip(vcpu);
+ kvm_run->debug.arch.exception = DB_VECTOR;
+ kvm_run->exit_reason = KVM_EXIT_DEBUG;
+ return 0;
+ }
+
kvm_queue_exception_p(vcpu, DB_VECTOR, dr6);
+ return 1;
}
-static void inject_emulated_exception(struct kvm_vcpu *vcpu)
+static int inject_emulated_exception(struct kvm_vcpu *vcpu)
{
struct x86_exception *ex = &vcpu->arch.emulate_ctxt->exception;
if (ex->vector == DB_VECTOR)
- kvm_inject_emulated_db(vcpu, ex->dr6);
- else if (ex->vector == PF_VECTOR)
+ return kvm_inject_emulated_db(vcpu, ex->dr6);
+
+ if (ex->vector == PF_VECTOR)
kvm_inject_emulated_page_fault(vcpu, ex);
else if (ex->error_code_valid)
kvm_queue_exception_e(vcpu, ex->vector, ex->error_code);
else
kvm_queue_exception(vcpu, ex->vector);
+ return 1;
}
static struct x86_emulate_ctxt *alloc_emulate_ctxt(struct kvm_vcpu *vcpu)
next prev parent reply other threads:[~2026-05-11 15:42 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-18 14:00 [PATCH v2 0/9] KVM: x86: Improve the handling of debug exceptions during instruction emulation Hou Wenlong
2025-12-18 14:00 ` [PATCH v2 1/9] KVM: x86: Capture "struct x86_exception" in inject_emulated_exception() Hou Wenlong
2025-12-18 14:00 ` [PATCH v2 2/9] KVM: x86: Set guest DR6 by kvm_queue_exception_p() in instruction emulation Hou Wenlong
2026-05-11 15:23 ` Sean Christopherson
2026-05-11 15:26 ` Sean Christopherson
2026-05-11 15:42 ` Sean Christopherson [this message]
2025-12-18 14:00 ` [PATCH v2 3/9] KVM: x86: Check guest debug in DR access " Hou Wenlong
2025-12-18 14:00 ` [PATCH v2 4/9] KVM: x86: Only check effective code breakpoint in emulation Hou Wenlong
2025-12-18 14:00 ` [PATCH v2 5/9] KVM: x86: Consolidate KVM_GUESTDBG_SINGLESTEP check into the kvm_inject_emulated_db() Hou Wenlong
2025-12-18 14:00 ` [PATCH v2 6/9] KVM: x86: Move kvm_set_rflags() up before kvm_vcpu_do_singlestep() Hou Wenlong
2025-12-18 14:00 ` [PATCH v2 7/9] KVM: VMX: Refresh 'PENDING_DBG_EXCEPTIONS.BS' bit during instruction emulation Hou Wenlong
2025-12-18 14:00 ` [PATCH v2 8/9] KVM: selftests: Verify guest debug DR7.GD checking " Hou Wenlong
2025-12-18 14:00 ` [PATCH v2 9/9] KVM: selftests: Verify 'BS' bit checking in pending debug exception state during VM-Entry Hou Wenlong
2026-05-11 15:45 ` [PATCH v2 0/9] KVM: x86: Improve the handling of debug exceptions during instruction emulation Sean Christopherson
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