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

Yang Weijiang
2020-11-06T01:06:44Z

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@intel.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Yang Weijiang <weijiang.yang@intel.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