linux-kernel - [PATCH 04/10] KVM: x86: Split guts of kvm_update

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Message-Id: <20200502043234.12481-5-sean.j.christopherson@intel.com>
Date:   Fri,  1 May 2020 21:32:28 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...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: [PATCH 04/10] KVM: x86: Split guts of kvm_update_dr7() to separate helper

Move the calculation of the effective DR7 into a separate helper,
__kvm_update_dr7(), and make the helper visible to vendor code.  It will
be used in a future patch to avoid the retpoline associated with
kvm_x86_ops.set_dr7() when stuffing DR7 during nested VMX transitions.

No functional change intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/kvm/x86.c | 11 +----------
 arch/x86/kvm/x86.h | 14 ++++++++++++++
 2 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index eccbfcb6a4e5..8893c42eac9e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1076,16 +1076,7 @@ static void kvm_update_dr6(struct kvm_vcpu *vcpu)
 
 static void kvm_update_dr7(struct kvm_vcpu *vcpu)
 {
-	unsigned long dr7;
-
-	if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP)
-		dr7 = vcpu->arch.guest_debug_dr7;
-	else
-		dr7 = vcpu->arch.dr7;
-	kvm_x86_ops.set_dr7(vcpu, dr7);
-	vcpu->arch.switch_db_regs &= ~KVM_DEBUGREG_BP_ENABLED;
-	if (dr7 & DR7_BP_EN_MASK)
-		vcpu->arch.switch_db_regs |= KVM_DEBUGREG_BP_ENABLED;
+	kvm_x86_ops.set_dr7(vcpu, __kvm_update_dr7(vcpu));
 }
 
 static u64 kvm_dr6_fixed(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 7b5ed8ed628e..75010b22e379 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -236,6 +236,20 @@ static inline void kvm_register_writel(struct kvm_vcpu *vcpu,
 	return kvm_register_write(vcpu, reg, val);
 }
 
+static inline unsigned long __kvm_update_dr7(struct kvm_vcpu *vcpu)
+{
+	unsigned long dr7;
+
+	if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP)
+		dr7 = vcpu->arch.guest_debug_dr7;
+	else
+		dr7 = vcpu->arch.dr7;
+	vcpu->arch.switch_db_regs &= ~KVM_DEBUGREG_BP_ENABLED;
+	if (dr7 & DR7_BP_EN_MASK)
+		vcpu->arch.switch_db_regs |= KVM_DEBUGREG_BP_ENABLED;
+	return dr7;
+}
+
 static inline bool kvm_check_has_quirk(struct kvm *kvm, u64 quirk)
 {
 	return !(kvm->arch.disabled_quirks & quirk);
-- 
2.26.0