[PATCH 2/4] KVM: nVMX: remove unnecessary code in prepare_vmcs02

[Paolo Bonzini]

The late vmwrite of the PDPTRs in prepare_vmcs02() is redundant, because
every write it does was already performed by prepare_vmcs02_rare earlier
in the same prepare_vmcs02 call.

In particular:

- load_guest_pdptrs_vmcs12 == true implies that prepare_vmcs02_rare() ran

- the assignment to load_guest_pdptrs_vmcs12 matches the gate in
  prepare_vmcs02_rare(), other than having one that checks
  !hv_evmcs and the other !nested_vmx_is_evmptr12_valid(vmx)

- the condition for the late move is a strict subset of the one in
  prepare_vmcs02_rare(), because the former checks
  nested_cpu_has_ept(vmcs12), which implies enable_ept, and on top
  it narrows it further by ANDing is_pae_paging(vcpu)

Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
 arch/x86/kvm/vmx/nested.c | 13 -------------
 1 file changed, 13 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index c1be8ef882b8..f86a12fc29ec 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2721,14 +2721,10 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	struct hv_enlightened_vmcs *evmcs = nested_vmx_evmcs(vmx);
-	bool load_guest_pdptrs_vmcs12 = false;
 
 	if (vmx->nested.dirty_vmcs12 || nested_vmx_is_evmptr12_valid(vmx)) {
 		prepare_vmcs02_rare(vmx, vmcs12);
 		vmx->nested.dirty_vmcs12 = false;
-
-		load_guest_pdptrs_vmcs12 = !nested_vmx_is_evmptr12_valid(vmx) ||
-			!(evmcs->hv_clean_fields & HV_VMX_ENLIGHTENED_CLEAN_FIELD_GUEST_GRP1);
 	}
 
 	if (vcpu->arch.nested_run_pending &&
@@ -2831,15 +2827,6 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
 	if (enable_ept)
 		vmcs_writel(GUEST_CR3, vmcs12->guest_cr3);
 
-	/* Late preparation of GUEST_PDPTRs now that EFER and CRs are set. */
-	if (load_guest_pdptrs_vmcs12 && nested_cpu_has_ept(vmcs12) &&
-	    is_pae_paging(vcpu)) {
-		vmcs_write64(GUEST_PDPTR0, vmcs12->guest_pdptr0);
-		vmcs_write64(GUEST_PDPTR1, vmcs12->guest_pdptr1);
-		vmcs_write64(GUEST_PDPTR2, vmcs12->guest_pdptr2);
-		vmcs_write64(GUEST_PDPTR3, vmcs12->guest_pdptr3);
-	}
-
 	if ((vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL) &&
 	    kvm_pmu_has_perf_global_ctrl(vcpu_to_pmu(vcpu)) &&
 	    WARN_ON_ONCE(__kvm_emulate_msr_write(vcpu, MSR_CORE_PERF_GLOBAL_CTRL,
-- 
2.52.0