arm/arm64: kvm: drop inappropriate use of kvm_is_mmio_pfn()

commit 07a9748c upstream.

Instead of using kvm_is_mmio_pfn() to decide whether a host region
should be stage 2 mapped with device attributes, add a new static
function kvm_is_device_pfn() that disregards RAM pages with the
reserved bit set, as those should usually not be mapped as device
memory.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

arch/arm/kvm/mmu.c

@@ -644,6 +644,11 @@ static bool kvm_is_write_fault(struct kvm_vcpu *vcpu)
 	return kvm_vcpu_dabt_iswrite(vcpu);
 }
 
+static bool kvm_is_device_pfn(unsigned long pfn)
+{
+	return !pfn_valid(pfn);
+}
+
 static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 			  gfn_t gfn, struct kvm_memory_slot *memslot,
 			  unsigned long fault_status)
@@ -684,7 +689,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	if (is_error_pfn(pfn))
 		return -EFAULT;
 
-	if (kvm_is_mmio_pfn(pfn))
+	if (kvm_is_device_pfn(pfn))
 		mem_type = PAGE_S2_DEVICE;
 
 	new_pte = pfn_pte(pfn, mem_type);