From: Sean Christopherson <sean.j.christopherson@intel.com>
Date: Thu, 5 Sep 2019 14:22:55 -0700
Subject: KVM: x86: Add kvm_emulate_{rd,wr}msr() to consolidate VXM/SVM code
Git-commit: 1edce0a9eb239b7a2768d10cf7d21dd83e269d5b
Patch-mainline: v5.4-rc1
References: bsc#1164343

Move RDMSR and WRMSR emulation into common x86 code to consolidate
nearly identical SVM and VMX code.

Note, consolidating RDMSR introduces an extra indirect call, i.e.
retpoline, due to reaching {svm,vmx}_get_msr() via kvm_x86_ops, but a
guest kernel likely has bigger problems if increasing the latency of
RDMSR VM-Exits by ~70 cycles has a measurable impact on overall VM
performance.  E.g. the only recurring RDMSR VM-Exits (after booting) on
my system running Linux 5.2 in the guest are for MSR_IA32_TSC_ADJUST via
arch_cpu_idle_enter().

No functional change intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
 arch/x86/include/asm/kvm_host.h |  2 ++
 arch/x86/kvm/svm.c              | 29 ++---------------------------
 arch/x86/kvm/vmx/vmx.c          | 29 ++---------------------------
 arch/x86/kvm/x86.c              | 35 +++++++++++++++++++++++++++++++++++
 4 files changed, 41 insertions(+), 54 deletions(-)

--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1330,6 +1330,8 @@ void kvm_enable_efer_bits(u64);
 bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);
 int kvm_get_msr(struct kvm_vcpu *vcpu, u32 index, u64 *data);
 int kvm_set_msr(struct kvm_vcpu *vcpu, u32 index, u64 data);
+int kvm_emulate_rdmsr(struct kvm_vcpu *vcpu);
+int kvm_emulate_wrmsr(struct kvm_vcpu *vcpu);
 
 struct x86_emulate_ctxt;
 
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -4232,23 +4232,7 @@ static int svm_get_msr(struct kvm_vcpu *
 
 static int rdmsr_interception(struct vcpu_svm *svm)
 {
-	u32 ecx = kvm_rcx_read(&svm->vcpu);
-	struct msr_data msr_info;
-
-	msr_info.index = ecx;
-	msr_info.host_initiated = false;
-	if (svm_get_msr(&svm->vcpu, &msr_info)) {
-		trace_kvm_msr_read_ex(ecx);
-		kvm_inject_gp(&svm->vcpu, 0);
-		return 1;
-	} else {
-		trace_kvm_msr_read(ecx, msr_info.data);
-
-		kvm_rax_write(&svm->vcpu, msr_info.data & 0xffffffff);
-		kvm_rdx_write(&svm->vcpu, msr_info.data >> 32);
-		svm->next_rip = kvm_rip_read(&svm->vcpu) + 2;
-		return kvm_skip_emulated_instruction(&svm->vcpu);
-	}
+	return kvm_emulate_rdmsr(&svm->vcpu);
 }
 
 static int svm_set_vm_cr(struct kvm_vcpu *vcpu, u64 data)
@@ -4438,17 +4422,7 @@ static int svm_set_msr(struct kvm_vcpu *
 
 static int wrmsr_interception(struct vcpu_svm *svm)
 {
-	u32 ecx = kvm_rcx_read(&svm->vcpu);
-	u64 data = kvm_read_edx_eax(&svm->vcpu);
-
-	if (kvm_set_msr(&svm->vcpu, ecx, data)) {
-		trace_kvm_msr_write_ex(ecx, data);
-		kvm_inject_gp(&svm->vcpu, 0);
-		return 1;
-	} else {
-		trace_kvm_msr_write(ecx, data);
-		return kvm_skip_emulated_instruction(&svm->vcpu);
-	}
+	return kvm_emulate_wrmsr(&svm->vcpu);
 }
 
 static int msr_interception(struct vcpu_svm *svm)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1432,6 +1432,41 @@ int kvm_set_msr(struct kvm_vcpu *vcpu, u
 }
 EXPORT_SYMBOL_GPL(kvm_set_msr);
 
+int kvm_emulate_rdmsr(struct kvm_vcpu *vcpu)
+{
+	u32 ecx = kvm_rcx_read(vcpu);
+	u64 data;
+
+	if (kvm_get_msr(vcpu, ecx, &data)) {
+		trace_kvm_msr_read_ex(ecx);
+		kvm_inject_gp(vcpu, 0);
+		return 1;
+	}
+
+	trace_kvm_msr_read(ecx, data);
+
+	kvm_rax_write(vcpu, data & -1u);
+	kvm_rdx_write(vcpu, (data >> 32) & -1u);
+	return kvm_skip_emulated_instruction(vcpu);
+}
+EXPORT_SYMBOL_GPL(kvm_emulate_rdmsr);
+
+int kvm_emulate_wrmsr(struct kvm_vcpu *vcpu)
+{
+	u32 ecx = kvm_rcx_read(vcpu);
+	u64 data = kvm_read_edx_eax(vcpu);
+
+	if (kvm_set_msr(vcpu, ecx, data)) {
+		trace_kvm_msr_write_ex(ecx, data);
+		kvm_inject_gp(vcpu, 0);
+		return 1;
+	}
+
+	trace_kvm_msr_write(ecx, data);
+	return kvm_skip_emulated_instruction(vcpu);
+}
+EXPORT_SYMBOL_GPL(kvm_emulate_wrmsr);
+
 /*
  * Adapt set_msr() to msr_io()'s calling convention
  */