KVM: limit the number of pages per memory slot

This patch limits the number of pages per memory slot to make
us free from extra care about type issues.

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 169d077..5583063 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -105,6 +105,12 @@ struct kvm_vcpu {
 	struct kvm_vcpu_arch arch;
 };
 
+/*
+ * Some of the bitops functions do not support too long bitmaps.
+ * This number must be determined not to exceed such limits.
+ */
+#define KVM_MEM_MAX_NR_PAGES ((1UL << 31) - 1)
+
 struct kvm_memory_slot {
 	gfn_t base_gfn;
 	unsigned long npages;