Re: [PATCH v2 04/16] kvm: Return number of free memslots

Philippe Mathieu-Daudé <philmd@xxxxxxxxxx> · Tue, 29 Aug 2023 00:26:24 +0200

On 25/8/23 15:21, David Hildenbrand wrote:
Let's return the number of free slots instead of only checking if there
is a free slot. While at it, check all address spaces, which will also
consider SMM under x86 correctly.

Make the stub return UINT_MAX, such that we can call the function
unconditionally.

This is a preparation for memory devices that consume multiple memslots.

Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
  accel/kvm/kvm-all.c      | 33 ++++++++++++++++++++-------------
  accel/stubs/kvm-stub.c   |  4 ++--
  hw/mem/memory-device.c   |  2 +-
  include/sysemu/kvm.h     |  2 +-
  include/sysemu/kvm_int.h |  1 +
  5 files changed, 25 insertions(+), 17 deletions(-)

diff --git a/accel/stubs/kvm-stub.c b/accel/stubs/kvm-stub.c
index 235dc661bc..f39997d86e 100644
--- a/accel/stubs/kvm-stub.c
+++ b/accel/stubs/kvm-stub.c
@@ -109,9 +109,9 @@ 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 UINT_MAX;

Isn't it clearer returning 0 here and keeping kvm_enabled() below?

  }
  
  void kvm_init_cpu_signals(CPUState *cpu)
diff --git a/hw/mem/memory-device.c b/hw/mem/memory-device.c
index 667d56bd29..7c24685796 100644
--- a/hw/mem/memory-device.c
+++ b/hw/mem/memory-device.c
@@ -59,7 +59,7 @@ static void memory_device_check_addable(MachineState *ms, MemoryRegion *mr,
      const uint64_t size = memory_region_size(mr);
  
      /* we will need a new memory slot for kvm and vhost */
-    if (kvm_enabled() && !kvm_has_free_slot(ms)) {
+    if (!kvm_get_free_memslots()) {

(here)

          error_setg(errp, "hypervisor has no free memory slots left");
          return;
      }


diff --git a/include/sysemu/kvm_int.h b/include/sysemu/kvm_int.h
index 511b42bde5..8b09e78b12 100644
--- a/include/sysemu/kvm_int.h
+++ b/include/sysemu/kvm_int.h
@@ -40,6 +40,7 @@ typedef struct KVMMemoryUpdate {
  typedef struct KVMMemoryListener {
      MemoryListener listener;
      KVMSlot *slots;
+    int nr_used_slots;

Preferably using 'unsigned' here:

Reviewed-by: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>








