linux-kernel - [PATCH v14 12/13] KVM: nVMX: Add helper to check the vmcs01 MSR bitmap for MSR pass-through

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Date:   Fri,  6 Nov 2020 09:16:36 +0800
From:   Yang Weijiang <weijiang.yang@...el.com>
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        pbonzini@...hat.com, sean.j.christopherson@...el.com,
        jmattson@...gle.com
Cc:     yu.c.zhang@...ux.intel.com, Yang Weijiang <weijiang.yang@...el.com>
Subject: [PATCH v14 12/13] KVM: nVMX: Add helper to check the vmcs01 MSR bitmap for MSR pass-through

Add a helper to perform the check on the vmcs01/l01 MSR bitmap when
disabling interception of an MSR for L2.  This reduces the boilerplate
for the existing cases, and will be used heavily in a future patch for
CET MSRs.

Co-developed-by: Sean Christopherson <sean.j.christopherson@...el.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
Signed-off-by: Yang Weijiang <weijiang.yang@...el.com>
---
 arch/x86/kvm/vmx/nested.c | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 89af692deb7e..8abc7bdd94f7 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -544,6 +544,17 @@ static void nested_vmx_disable_intercept_for_msr(unsigned long *msr_bitmap_l1,
 	}
 }
 
+static void nested_vmx_cond_disable_intercept_for_msr(struct kvm_vcpu *vcpu, u32 msr,
+						      unsigned long *bitmap_12,
+						      unsigned long *bitmap_02,
+						      int type)
+{
+	if (msr_write_intercepted_l01(vcpu, msr))
+		return;
+
+	nested_vmx_disable_intercept_for_msr(bitmap_12, bitmap_02, msr, type);
+}
+
 static inline void enable_x2apic_msr_intercepts(unsigned long *msr_bitmap)
 {
 	int msr;
@@ -640,17 +651,13 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct kvm_vcpu *vcpu,
 	 *    updated to reflect this when L1 (or its L2s) actually write to
 	 *    the MSR.
 	 */
-	if (!msr_write_intercepted_l01(vcpu, MSR_IA32_SPEC_CTRL))
-		nested_vmx_disable_intercept_for_msr(
-					msr_bitmap_l1, msr_bitmap_l0,
-					MSR_IA32_SPEC_CTRL,
-					MSR_TYPE_R | MSR_TYPE_W);
+	nested_vmx_cond_disable_intercept_for_msr(vcpu, MSR_IA32_SPEC_CTRL,
+						  msr_bitmap_l1, msr_bitmap_l0,
+						  MSR_TYPE_R | MSR_TYPE_W);
 
-	if (!msr_write_intercepted_l01(vcpu, MSR_IA32_PRED_CMD))
-		nested_vmx_disable_intercept_for_msr(
-					msr_bitmap_l1, msr_bitmap_l0,
-					MSR_IA32_PRED_CMD,
-					MSR_TYPE_W);
+	nested_vmx_cond_disable_intercept_for_msr(vcpu, MSR_IA32_PRED_CMD,
+						  msr_bitmap_l1, msr_bitmap_l0,
+						  MSR_TYPE_W);
 
 	kvm_vcpu_unmap(vcpu, &to_vmx(vcpu)->nested.msr_bitmap_map, false);
 
-- 
2.17.2