kvm: Allow arch to set sigmask length

MIPS/Linux is unusual in having 128 signals rather than just 64 like
most other architectures. This means its sigmask is 16 bytes instead of
8, so allow arches to override the sigmask->len value passed to the
KVM_SET_SIGNAL_MASK ioctl in kvm_set_signal_mask() by calling
kvm_set_sigmask_len() from kvm_arch_init(). Otherwise default to 8
bytes.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: Sanjay Lal <sanjayl@kymasys.com>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

include/sysemu/kvm.h

@@ -325,6 +325,8 @@ int kvm_check_extension(KVMState *s, unsigned int extension);
 uint32_t kvm_arch_get_supported_cpuid(KVMState *env, uint32_t function,
                                       uint32_t index, int reg);
 
+void kvm_set_sigmask_len(KVMState *s, unsigned int sigmask_len);
+
 #if !defined(CONFIG_USER_ONLY)
 int kvm_physical_memory_addr_from_host(KVMState *s, void *ram_addr,
                                        hwaddr *phys_addr);

kvm-all.c

@@ -99,6 +99,7 @@ struct KVMState
      * 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;
+    unsigned int sigmask_len;
 #ifdef KVM_CAP_IRQ_ROUTING
     struct kvm_irq_routing *irq_routes;
     int nr_allocated_irq_routes;
@@ -1397,6 +1398,8 @@ int kvm_init(MachineClass *mc)
     assert(TARGET_PAGE_SIZE <= getpagesize());
     page_size_init();
 
+    s->sigmask_len = 8;
+
 #ifdef KVM_CAP_SET_GUEST_DEBUG
     QTAILQ_INIT(&s->kvm_sw_breakpoints);
 #endif
@@ -1575,6 +1578,11 @@ int kvm_init(MachineClass *mc)
     return ret;
 }
 
+void kvm_set_sigmask_len(KVMState *s, unsigned int sigmask_len)
+{
+    s->sigmask_len = sigmask_len;
+}
+
 static void kvm_handle_io(uint16_t port, void *data, int direction, int size,
                           uint32_t count)
 {
@@ -2095,6 +2103,7 @@ void kvm_remove_all_breakpoints(CPUState *cpu)
 
 int kvm_set_signal_mask(CPUState *cpu, const sigset_t *sigset)
 {
+    KVMState *s = kvm_state;
     struct kvm_signal_mask *sigmask;
     int r;
 
@@ -2104,7 +2113,7 @@ int kvm_set_signal_mask(CPUState *cpu, const sigset_t *sigset)
 
     sigmask = g_malloc(sizeof(*sigmask) + sizeof(*sigset));
 
-    sigmask->len = 8;
+    sigmask->len = s->sigmask_len;
     memcpy(sigmask->sigset, sigset, sizeof(*sigset));
     r = kvm_vcpu_ioctl(cpu, KVM_SET_SIGNAL_MASK, sigmask);
     g_free(sigmask);