linux-kernel - [RESEND PATCH 03/13] KVM: x86: Refactor kvm_vcpu_do

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Date:   Thu, 22 Aug 2019 18:06:59 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [RESEND PATCH 03/13] KVM: x86: Refactor kvm_vcpu_do_singlestep() to remove out param

Return the single-step emulation result directly instead of via an out
param.  Presumably at some point in the past kvm_vcpu_do_singlestep()
could be called with *r==EMULATE_USER_EXIT, but that is no longer the
case, i.e. all callers are happy to overwrite their own return variable.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/kvm/x86.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c6de5bc4fa5e..fe847f8eb947 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6377,7 +6377,7 @@ static int kvm_vcpu_check_hw_bp(unsigned long addr, u32 type, u32 dr7,
 	return dr6;
 }
 
-static void kvm_vcpu_do_singlestep(struct kvm_vcpu *vcpu, int *r)
+static int kvm_vcpu_do_singlestep(struct kvm_vcpu *vcpu)
 {
 	struct kvm_run *kvm_run = vcpu->run;
 
@@ -6386,10 +6386,10 @@ static void kvm_vcpu_do_singlestep(struct kvm_vcpu *vcpu, int *r)
 		kvm_run->debug.arch.pc = vcpu->arch.singlestep_rip;
 		kvm_run->debug.arch.exception = DB_VECTOR;
 		kvm_run->exit_reason = KVM_EXIT_DEBUG;
-		*r = EMULATE_USER_EXIT;
-	} else {
-		kvm_queue_exception_p(vcpu, DB_VECTOR, DR6_BS);
+		return EMULATE_USER_EXIT;
 	}
+	kvm_queue_exception_p(vcpu, DB_VECTOR, DR6_BS);
+	return EMULATE_DONE;
 }
 
 int kvm_skip_emulated_instruction(struct kvm_vcpu *vcpu)
@@ -6410,7 +6410,7 @@ int kvm_skip_emulated_instruction(struct kvm_vcpu *vcpu)
 	 * that sets the TF flag".
 	 */
 	if (unlikely(rflags & X86_EFLAGS_TF))
-		kvm_vcpu_do_singlestep(vcpu, &r);
+		r = kvm_vcpu_do_singlestep(vcpu);
 	return r == EMULATE_DONE;
 }
 EXPORT_SYMBOL_GPL(kvm_skip_emulated_instruction);
@@ -6613,7 +6613,7 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
 		vcpu->arch.emulate_regs_need_sync_to_vcpu = false;
 		kvm_rip_write(vcpu, ctxt->eip);
 		if (r == EMULATE_DONE && ctxt->tf)
-			kvm_vcpu_do_singlestep(vcpu, &r);
+			r = kvm_vcpu_do_singlestep(vcpu);
 		if (!ctxt->have_exception ||
 		    exception_type(ctxt->exception.vector) == EXCPT_TRAP)
 			__kvm_set_rflags(vcpu, ctxt->eflags);
-- 
2.22.0