kvm: svm: fix potential get_num_contig_pages overflow

get_num_contig_pages() could potentially overflow int so make its type
consistent with its usage.
Reported-by: Cfir Cohen <cfir@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm.c

@@ -6422,11 +6422,11 @@ static int sev_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
 	return ret;
 }
 
-static int get_num_contig_pages(int idx, struct page **inpages,
-				unsigned long npages)
+static unsigned long get_num_contig_pages(unsigned long idx,
+				struct page **inpages, unsigned long npages)
 {
 	unsigned long paddr, next_paddr;
-	int i = idx + 1, pages = 1;
+	unsigned long i = idx + 1, pages = 1;
 
 	/* find the number of contiguous pages starting from idx */
 	paddr = __sme_page_pa(inpages[idx]);
@@ -6445,12 +6445,12 @@ static int get_num_contig_pages(int idx, struct page **inpages,
 
 static int sev_launch_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
 {
-	unsigned long vaddr, vaddr_end, next_vaddr, npages, size;
+	unsigned long vaddr, vaddr_end, next_vaddr, npages, pages, size, i;
 	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
 	struct kvm_sev_launch_update_data params;
 	struct sev_data_launch_update_data *data;
 	struct page **inpages;
-	int i, ret, pages;
+	int ret;
 
 	if (!sev_guest(kvm))
 		return -ENOTTY;