linux-kernel - [PATCH 4/7] KVM: x86: Consolidate KVM_GUESTDBG_SINGLESTEP check into the kvm_inject_emulated

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Message-Id: <45cbc005e14ea2a4b9ec803a91af63e364aeb71a.1757416809.git.houwenlong.hwl@antgroup.com>
Date: Wed, 10 Sep 2025 10:49:16 +0800
From: Hou Wenlong <houwenlong.hwl@...group.com>
To: kvm@...r.kernel.org
Cc: Lai Jiangshan <jiangshan.ljs@...group.com>,
	Sean Christopherson <seanjc@...gle.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 4/7] KVM: x86: Consolidate KVM_GUESTDBG_SINGLESTEP check into the kvm_inject_emulated_db()

Use kvm_inject_emulated_db() in kvm_vcpu_do_singlestep() to consolidate
'KVM_GUESTDBG_SINGLESTEP' check into kvm_inject_emulated_db() during
emulation.

No functional change intended.

Suggested-by: Lai Jiangshan <jiangshan.ljs@...group.com>
Signed-off-by: Hou Wenlong <houwenlong.hwl@...group.com>
---
 arch/x86/kvm/x86.c | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5af652916a19..83960214d5d8 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8632,7 +8632,10 @@ 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) {
+	/* Data breakpoints are not supported in emulation for now. */
+	WARN_ON((dr6 & DR6_BS) && (dr6 & DR_TRAP_BITS));
+
+	if (vcpu->guest_debug & (KVM_GUESTDBG_USE_HW_BP | KVM_GUESTDBG_SINGLESTEP)) {
 		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;
@@ -8907,17 +8910,7 @@ static int kvm_vcpu_check_hw_bp(unsigned long addr, u32 type, u32 dr7,
 
 static int kvm_vcpu_do_singlestep(struct kvm_vcpu *vcpu)
 {
-	struct kvm_run *kvm_run = vcpu->run;
-
-	if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) {
-		kvm_run->debug.arch.dr6 = DR6_BS | 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_BS);
-	return 1;
+	return kvm_inject_emulated_db(vcpu, DR6_BS);
 }
 
 int kvm_skip_emulated_instruction(struct kvm_vcpu *vcpu)
-- 
2.31.1