intc/gic: Extract some reusable vGIC code

Some functions previously used only by vGICv2 are useful also for vGICv3
implementation. Untie them from GICState and make accessible from within
other modules:
- kvm_arm_gic_set_irq()
- kvm_gic_supports_attr() - moved to common code and renamed to
  kvm_device_check_attr()
- kvm_gic_access() - turned into GIC-independent kvm_device_access().
  Data pointer changed to void * because some GICv3 registers are
  64-bit wide

Some of these changes are not used right now, but they will be helpful for
implementing live migration.

Actually kvm_dist_get() and kvm_dist_put() could also be made reusable, but
they would require two extra parameters (s->dev_fd and s->num_cpu) as well as
lots of typecasts of 's' to DeviceState * and back to GICState *. This makes
the code very ugly so i decided to stop at this point. I tried also an
approach with making a base class for all possible GICs, but it would contain
only three variables (dev_fd, cpu_num and irq_num), and accessing them through
the rest of the code would be again tedious (either ugly casts or qemu-style
separate object pointer). So i disliked it too.

Signed-off-by: Pavel Fedin <p.fedin@samsung.com>
Tested-by: Ashok kumar <ashoks@broadcom.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 2ef56d1dd64ffb75ed02a10dcdaf605e5b8ff4f8.1441784344.git.p.fedin@samsung.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

kvm-all.c

@@ -24,6 +24,7 @@
 #include "qemu/atomic.h"
 #include "qemu/option.h"
 #include "qemu/config-file.h"
+#include "qemu/error-report.h"
 #include "hw/hw.h"
 #include "hw/pci/msi.h"
 #include "hw/s390x/adapter.h"
@@ -2008,6 +2009,39 @@ int kvm_vm_check_attr(KVMState *s, uint32_t group, uint64_t attr)
     return ret ? 0 : 1;
 }
 
+int kvm_device_check_attr(int dev_fd, uint32_t group, uint64_t attr)
+{
+    struct kvm_device_attr attribute = {
+        .group = group,
+        .attr = attr,
+        .flags = 0,
+    };
+
+    return kvm_device_ioctl(dev_fd, KVM_HAS_DEVICE_ATTR, &attribute) ? 0 : 1;
+}
+
+void kvm_device_access(int fd, int group, uint64_t attr,
+                       void *val, bool write)
+{
+    struct kvm_device_attr kvmattr;
+    int err;
+
+    kvmattr.flags = 0;
+    kvmattr.group = group;
+    kvmattr.attr = attr;
+    kvmattr.addr = (uintptr_t)val;
+
+    err = kvm_device_ioctl(fd,
+                           write ? KVM_SET_DEVICE_ATTR : KVM_GET_DEVICE_ATTR,
+                           &kvmattr);
+    if (err < 0) {
+        error_report("KVM_%s_DEVICE_ATTR failed: %s\n"
+                     "Group %d attr 0x%016" PRIx64, write ? "SET" : "GET",
+                     strerror(-err), group, attr);
+        abort();
+    }
+}
+
 int kvm_has_sync_mmu(void)
 {
     return kvm_check_extension(kvm_state, KVM_CAP_SYNC_MMU);