accel/kvm: Convert to ram_block_discard_disable()

Discarding memory does not work as expected. At the time this is called,
we cannot have anyone active that relies on discards to work properly.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20200626072248.78761-5-david@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

accel/kvm/kvm-all.c

@@ -40,7 +40,6 @@
 #include "trace.h"
 #include "hw/irq.h"
 #include "sysemu/sev.h"
-#include "sysemu/balloon.h"
 #include "qapi/visitor.h"
 #include "qapi/qapi-types-common.h"
 #include "qapi/qapi-visit-common.h"
@@ -2229,7 +2228,8 @@ static int kvm_init(MachineState *ms)
 
     s->sync_mmu = !!kvm_vm_check_extension(kvm_state, KVM_CAP_SYNC_MMU);
     if (!s->sync_mmu) {
-        qemu_balloon_inhibit(true);
+        ret = ram_block_discard_disable(true);
+        assert(!ret);
     }
 
     return 0;