KVM: VMX: Ignore MKTME KeyID bits when intercepting #PF for allow_smaller_maxphyaddr

Use the raw/true host.MAXPHYADDR when deciding whether or not KVM must
intercept #PFs when allow_smaller_maxphyaddr is enabled, as any adjustments
the kernel makes to boot_cpu_data.x86_phys_bits to account for MKTME KeyID
bits do not apply to the guest physical address space.  I.e. the KeyID are
off-limits for host physical addresses, but are not reserved for GPAs as
far as hardware is concerned.

Signed-off-by: Tao Su <tao1.su@linux.intel.com>
Link: https://lore.kernel.org/r/20240319031111.495006-1-tao1.su@linux.intel.com
[sean: massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: taosu-linux

arch/x86/kvm/vmx/vmx.h

@@ -15,6 +15,7 @@
 #include "vmx_ops.h"
 #include "../cpuid.h"
 #include "run_flags.h"
+#include "../mmu.h"
 
 #define MSR_TYPE_R	1
 #define MSR_TYPE_W	2
@@ -719,7 +720,8 @@ static inline bool vmx_need_pf_intercept(struct kvm_vcpu *vcpu)
 	if (!enable_ept)
 		return true;
 
-	return allow_smaller_maxphyaddr && cpuid_maxphyaddr(vcpu) < boot_cpu_data.x86_phys_bits;
+	return allow_smaller_maxphyaddr &&
+	       cpuid_maxphyaddr(vcpu) < kvm_get_shadow_phys_bits();
 }
 
 static inline bool is_unrestricted_guest(struct kvm_vcpu *vcpu)