KVM: x86: Stuff vCPU's PAT with default value at RESET, not creation

Move the stuffing of the vCPU's PAT to the architectural "default" value
from kvm_arch_vcpu_create() to kvm_vcpu_reset(), guarded by !init_event,
to better capture that the default value is the value "Following Power-up
or Reset".  E.g. setting PAT only during creation would break if KVM were
to expose a RESET ioctl() to userspace (which is unlikely, but that's not
a good reason to have unintuitive code).

No functional change.

Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20240605231918.2915961-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: sean-jc

arch/x86/kvm/x86.c

@@ -12260,8 +12260,6 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 	vcpu->arch.maxphyaddr = cpuid_query_maxphyaddr(vcpu);
 	vcpu->arch.reserved_gpa_bits = kvm_vcpu_reserved_gpa_bits_raw(vcpu);
 
-	vcpu->arch.pat = MSR_IA32_CR_PAT_DEFAULT;
-
 	kvm_async_pf_hash_reset(vcpu);
 
 	vcpu->arch.perf_capabilities = kvm_caps.supported_perf_cap;
@@ -12427,6 +12425,8 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 	if (!init_event) {
 		vcpu->arch.smbase = 0x30000;
 
+		vcpu->arch.pat = MSR_IA32_CR_PAT_DEFAULT;
+
 		vcpu->arch.msr_misc_features_enables = 0;
 		vcpu->arch.ia32_misc_enable_msr = MSR_IA32_MISC_ENABLE_PEBS_UNAVAIL |
 						  MSR_IA32_MISC_ENABLE_BTS_UNAVAIL;