KVM: selftests: Slightly simplify memstress_setup_nested()

Instead of calling memstress_setup_ept_mappings() only in the first
iteration in the loop, move it before the loop.

The call needed to happen within the loop before commit e40e72f
("KVM: selftests: Stop passing VMX metadata to TDP mapping functions"),
as memstress_setup_ept_mappings() used to take in a pointer to vmx_pages
and pass it into tdp_identity_map_1g() (to get the EPT root GPA). This
is no longer the case, as tdp_identity_map_1g() gets the EPT root
through stage2 MMU.

Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Link: https://patch.msgid.link/20260113171456.2097312-1-yosry.ahmed@linux.dev
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: yosrym93

tools/testing/selftests/kvm/lib/x86/memstress.c

@@ -110,16 +110,13 @@ void memstress_setup_nested(struct kvm_vm *vm, int nr_vcpus, struct kvm_vcpu *vc
 	TEST_REQUIRE(kvm_cpu_has_tdp());
 
 	vm_enable_tdp(vm);
+	memstress_setup_ept_mappings(vm);
 	for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
 		if (kvm_cpu_has(X86_FEATURE_VMX))
 			vcpu_alloc_vmx(vm, &nested_gva);
 		else
 			vcpu_alloc_svm(vm, &nested_gva);
 
-		/* The EPTs are shared across vCPUs, setup the mappings once */
-		if (vcpu_id == 0)
-			memstress_setup_ept_mappings(vm);
-
 		/*
 		 * Override the vCPU to run memstress_l1_guest_code() which will
 		 * bounce it into L2 before calling memstress_guest_code().