[RFC,02/15] kvm: Return number of free memslots

Commit Message

David Hildenbrand Oct. 13, 2021, 10:33 a.m. UTC

Let's return the number of free slots instead of only checking if there
is a free slot. Required to support memory devices that consume multiple
memslots.

Signed-off-by: David Hildenbrand <[e-mail]>
---
 accel/kvm/kvm-all.c    | 24 +++++++++++-------------
 accel/stubs/kvm-stub.c |  4 ++--
 hw/mem/memory-device.c |  2 +-
 include/sysemu/kvm.h   |  2 +-
 4 files changed, 15 insertions(+), 17 deletions(-)

Patch

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index db8d83b137..0846be835e 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -103,6 +103,7 @@  struct KVMState
     AccelState parent_obj;
 
     int nr_slots;
+    int nr_free_slots;
     int fd;
     int vmfd;
     int coalesced_mmio;
@@ -245,6 +246,13 @@  int kvm_get_max_memslots(void)
     return s->nr_slots;
 }
 
+unsigned int kvm_get_free_memslots(void)
+{
+    KVMState *s = kvm_state;
+
+    return s->nr_free_slots;
+}
+
 /* Called with KVMMemoryListener.slots_lock held */
 static KVMSlot *kvm_get_free_slot(KVMMemoryListener *kml)
 {
@@ -260,19 +268,6 @@  static KVMSlot *kvm_get_free_slot(KVMMemoryListener *kml)
     return NULL;
 }
 
-bool kvm_has_free_slot(MachineState *ms)
-{
-    KVMState *s = KVM_STATE(ms->accelerator);
-    bool result;
-    KVMMemoryListener *kml = &s->memory_listener;
-
-    kvm_slots_lock();
-    result = !!kvm_get_free_slot(kml);
-    kvm_slots_unlock();
-
-    return result;
-}
-
 /* Called with KVMMemoryListener.slots_lock held */
 static KVMSlot *kvm_alloc_slot(KVMMemoryListener *kml)
 {
@@ -1410,6 +1405,7 @@  static void kvm_set_phys_mem(KVMMemoryListener *kml,
             }
             start_addr += slot_size;
             size -= slot_size;
+            kvm_state->nr_free_slots++;
         } while (size);
         goto out;
     }
@@ -1435,6 +1431,7 @@  static void kvm_set_phys_mem(KVMMemoryListener *kml,
         ram_start_offset += slot_size;
         ram += slot_size;
         size -= slot_size;
+        kvm_state->nr_free_slots--;
     } while (size);
 
 out:
@@ -2364,6 +2361,7 @@  static int kvm_init(MachineState *ms)
     if (!s->nr_slots) {
         s->nr_slots = 32;
     }
+    s->nr_free_slots = s->nr_slots;
 
     s->nr_as = kvm_check_extension(s, KVM_CAP_MULTI_ADDRESS_SPACE);
     if (s->nr_as <= 1) {
diff --git a/accel/stubs/kvm-stub.c b/accel/stubs/kvm-stub.c
index 5b1d00a222..cbaeb7c656 100644
--- a/accel/stubs/kvm-stub.c
+++ b/accel/stubs/kvm-stub.c
@@ -133,9 +133,9 @@  int kvm_irqchip_remove_irqfd_notifier_gsi(KVMState *s, EventNotifier *n,
     return -ENOSYS;
 }
 
-bool kvm_has_free_slot(MachineState *ms)
+unsigned int kvm_get_free_memslots(void)
 {
-    return false;
+    return 0;
 }
 
 void kvm_init_cpu_signals(CPUState *cpu)
diff --git a/hw/mem/memory-device.c b/hw/mem/memory-device.c
index d9f8301711..9045ead33e 100644
--- a/hw/mem/memory-device.c
+++ b/hw/mem/memory-device.c
@@ -73,7 +73,7 @@  static void memory_device_check_addable(MachineState *ms, uint64_t size,
     uint64_t used_region_size = 0;
 
     /* we will need a new memory slot for kvm and vhost */
-    if (kvm_enabled() && !kvm_has_free_slot(ms)) {
+    if (kvm_enabled() && !kvm_get_free_memslots()) {
         error_setg(errp, "hypervisor has no free memory slots left");
         return;
     }
diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index a1ab1ee12d..c18be3cbd5 100644
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -211,7 +211,7 @@  typedef struct Notifier Notifier;
 
 /* external API */
 
-bool kvm_has_free_slot(MachineState *ms);
+unsigned int kvm_get_free_memslots(void);
 bool kvm_has_sync_mmu(void);
 int kvm_has_vcpu_events(void);
 int kvm_has_robust_singlestep(void);