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@xxxxxxxxx>
---
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(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 649d80b5cd6f..003c1cc8e28b 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1328,6 +1328,8 @@ 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;
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 030bc9f7b7a7..b033aebbcd30 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -4220,22 +4220,7 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
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);
- 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)
@@ -4425,17 +4410,7 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
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)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index f4f4114e756f..b98a88dc8ca6 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4866,37 +4866,12 @@ static int handle_cpuid(struct kvm_vcpu *vcpu)
static int handle_rdmsr(struct kvm_vcpu *vcpu)
{
- u32 ecx = kvm_rcx_read(vcpu);
- struct msr_data msr_info;
-
- msr_info.index = ecx;
- msr_info.host_initiated = false;
- if (vmx_get_msr(vcpu, &msr_info)) {
- trace_kvm_msr_read_ex(ecx);
- kvm_inject_gp(vcpu, 0);
- return 1;
- }
-
- trace_kvm_msr_read(ecx, msr_info.data);
-
- kvm_rax_write(vcpu, msr_info.data & -1u);
- kvm_rdx_write(vcpu, (msr_info.data >> 32) & -1u);
- return kvm_skip_emulated_instruction(vcpu);
+ return kvm_emulate_rdmsr(vcpu);
}
static int handle_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) != 0) {
- 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);
+ return kvm_emulate_wrmsr(vcpu);
}
static int handle_tpr_below_threshold(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a67730600803..7cd578d52611 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1434,6 +1434,41 @@ int kvm_set_msr(struct kvm_vcpu *vcpu, u32 index, u64 data)
}
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
*/
--
2.22.0
