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-rw-r--r--include/sysemu/kvm.h8
-rw-r--r--include/sysemu/kvm_int.h17
2 files changed, 17 insertions, 8 deletions
diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index 9cf14ca3d5..613d3f7581 100644
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -235,11 +235,11 @@ static inline int kvm_update_guest_debug(CPUState *cpu, unsigned long reinject_t
 
 /* internal API */
 
-int kvm_ioctl(KVMState *s, int type, ...);
+int kvm_ioctl(KVMState *s, unsigned long type, ...);
 
-int kvm_vm_ioctl(KVMState *s, int type, ...);
+int kvm_vm_ioctl(KVMState *s, unsigned long type, ...);
 
-int kvm_vcpu_ioctl(CPUState *cpu, int type, ...);
+int kvm_vcpu_ioctl(CPUState *cpu, unsigned long type, ...);
 
 /**
  * kvm_device_ioctl - call an ioctl on a kvm device
@@ -248,7 +248,7 @@ int kvm_vcpu_ioctl(CPUState *cpu, int type, ...);
  *
  * Returns: -errno on error, nonnegative on success
  */
-int kvm_device_ioctl(int fd, int type, ...);
+int kvm_device_ioctl(int fd, unsigned long type, ...);
 
 /**
  * kvm_vm_check_attr - check for existence of a specific vm attribute
diff --git a/include/sysemu/kvm_int.h b/include/sysemu/kvm_int.h
index 1d8fb1473b..17483ff53b 100644
--- a/include/sysemu/kvm_int.h
+++ b/include/sysemu/kvm_int.h
@@ -122,10 +122,19 @@ struct KVMState
     bool sync_mmu;
     bool guest_state_protected;
     uint64_t manual_dirty_log_protect;
-    /* The man page (and posix) say ioctl numbers are signed int, but
-     * they're not.  Linux, glibc and *BSD all treat ioctl numbers as
-     * unsigned, and treating them as signed here can break things */
-    unsigned irq_set_ioctl;
+    /*
+     * Older POSIX says that ioctl numbers are signed int, but in
+     * practice they are not. (Newer POSIX doesn't specify ioctl
+     * at all.) Linux, glibc and *BSD all treat ioctl numbers as
+     * unsigned, and real-world ioctl values like KVM_GET_XSAVE have
+     * bit 31 set, which means that passing them via an 'int' will
+     * result in sign-extension when they get converted back to the
+     * 'unsigned long' which the ioctl() prototype uses. Luckily Linux
+     * always treats the argument as an unsigned 32-bit int, so any
+     * possible sign-extension is deliberately ignored, but for
+     * consistency we keep to the same type that glibc is using.
+     */
+    unsigned long irq_set_ioctl;
     unsigned int sigmask_len;
     GHashTable *gsimap;
 #ifdef KVM_CAP_IRQ_ROUTING