Merge tag 'pull-hv-balloon-20231106' of https://github.com/maciejsszmigiero/qemu into staging

Hyper-V Dynamic Memory protocol driver.

This driver is like virtio-balloon on steroids for Windows guests:
it allows both changing the guest memory allocation via ballooning and
inserting pieces of extra RAM into it on demand from a provided memory
backend via Windows-native Hyper-V Dynamic Memory protocol.

* Preparatory patches to support empty memory devices and ones with
large alignment requirements.

* Revert of recently added "hw/virtio/virtio-pmem: Replace impossible
check by assertion" commit 5960f254dbb4 since this series makes this
situation possible again.

* Protocol definitions.

* Hyper-V DM protocol driver (hv-balloon) base (ballooning only).

* Hyper-V DM protocol driver (hv-balloon) hot-add support.

* qapi query-memory-devices support for the driver.

* qapi HV_BALLOON_STATUS_REPORT event.

* The relevant PC machine plumbing.

* New MAINTAINERS entry for the above.

# -----BEGIN PGP SIGNATURE-----
#
# iQGzBAABCAAdFiEE4ndqq6COJv9aG0oJUrHW6VHQzgcFAmVI81IACgkQUrHW6VHQ
# zgdzTgv+I5eV2R01YLOBBJhBjzxZ4/BUqkuUHNxHpfjuCqEIzPb7FIfoZ4ZyXZFT
# YJdSE4lPeTZLrmmi/Nt6G0rUKDvdCeIgkS2VLHFSsTV8IzcT71BTRGzV0zAjUF5v
# yDH6uzo6e9gmaziIalRjibUxSDjCQmoCifms2rS2DwazADudUp+naGfm+3uyA0gM
# raOfBfRkNZsDqhXg2ayuqPIES75xQONoON9xYPKDAthS48POEbqtWBKuFopr3kXY
# y0eph+NAw+RajCyLYKM3poIgaSu3l4WegInuKQffzqKR8dxrbwPdCmtgo6NSHx0W
# uDfl7FUBnGzrR18VU4ZfTSrF5SVscGwF9EL7uocJen15inJjl1q3G53uZgyGzHLC
# cw8fKMjucmE8njQR2qiMyX0b+T4+9nKO1rykBgTG/+c9prRUVoxYpFCF117Ei0U8
# QzLGACW1oK+LV41bekWAye7w9pShUtFaxffhPbJeZDDGh7q0x61R3Z3yKkA07p46
# /YWWFWUD
# =RAb0
# -----END PGP SIGNATURE-----
# gpg: Signature made Mon 06 Nov 2023 22:08:18 HKT
# gpg:                using RSA key E2776AABA08E26FF5A1B4A0952B1D6E951D0CE07
# gpg: Good signature from "Maciej S. Szmigiero <mail@maciej.szmigiero.name>" [unknown]
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 727A 0D4D DB9E D9F6 039B  ECEF 847F 5E37 90CE 0977
#      Subkey fingerprint: E277 6AAB A08E 26FF 5A1B  4A09 52B1 D6E9 51D0 CE07

* tag 'pull-hv-balloon-20231106' of https://github.com/maciejsszmigiero/qemu:
  MAINTAINERS: Add an entry for Hyper-V Dynamic Memory Protocol
  hw/i386/pc: Support hv-balloon
  qapi: Add HV_BALLOON_STATUS_REPORT event and its QMP query command
  qapi: Add query-memory-devices support to hv-balloon
  Add Hyper-V Dynamic Memory Protocol driver (hv-balloon) hot-add support
  Add Hyper-V Dynamic Memory Protocol driver (hv-balloon) base
  Add Hyper-V Dynamic Memory Protocol definitions
  memory-device: Drop size alignment check
  Revert "hw/virtio/virtio-pmem: Replace impossible check by assertion"
  memory-device: Support empty memory devices

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

2 files changed, 23 insertions, 0 deletions

diff --git a/hw/i386/Kconfig b/hw/i386/Kconfig
index 94772c726b..55850791df 100644
--- a/hw/i386/Kconfig
+++ b/hw/i386/Kconfig
@@ -45,6 +45,7 @@ config PC
     select ACPI_VMGENID
     select VIRTIO_PMEM_SUPPORTED
     select VIRTIO_MEM_SUPPORTED
+    select HV_BALLOON_SUPPORTED
 
 config PC_PCI
     bool
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 6031234a73..1aef21aa2c 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -27,6 +27,7 @@
 #include "hw/i386/pc.h"
 #include "hw/char/serial.h"
 #include "hw/char/parallel.h"
+#include "hw/hyperv/hv-balloon.h"
 #include "hw/i386/fw_cfg.h"
 #include "hw/i386/vmport.h"
 #include "sysemu/cpus.h"
@@ -57,6 +58,7 @@
 #include "hw/i386/kvm/xen_evtchn.h"
 #include "hw/i386/kvm/xen_gnttab.h"
 #include "hw/i386/kvm/xen_xenstore.h"
+#include "hw/mem/memory-device.h"
 #include "e820_memory_layout.h"
 #include "trace.h"
 #include CONFIG_DEVICES
@@ -1422,6 +1424,21 @@ static void pc_memory_unplug(HotplugHandler *hotplug_dev,
     error_propagate(errp, local_err);
 }
 
+static void pc_hv_balloon_pre_plug(HotplugHandler *hotplug_dev,
+                                   DeviceState *dev, Error **errp)
+{
+    /* The vmbus handler has no hotplug handler; we should never end up here. */
+    g_assert(!dev->hotplugged);
+    memory_device_pre_plug(MEMORY_DEVICE(dev), MACHINE(hotplug_dev), NULL,
+                           errp);
+}
+
+static void pc_hv_balloon_plug(HotplugHandler *hotplug_dev,
+                               DeviceState *dev, Error **errp)
+{
+    memory_device_plug(MEMORY_DEVICE(dev), MACHINE(hotplug_dev));
+}
+
 static void pc_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
                                           DeviceState *dev, Error **errp)
 {
@@ -1452,6 +1469,8 @@ static void pc_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
             return;
         }
         pcms->iommu = dev;
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_HV_BALLOON)) {
+        pc_hv_balloon_pre_plug(hotplug_dev, dev, errp);
     }
 }
 
@@ -1464,6 +1483,8 @@ static void pc_machine_device_plug_cb(HotplugHandler *hotplug_dev,
         x86_cpu_plug(hotplug_dev, dev, errp);
     } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI)) {
         virtio_md_pci_plug(VIRTIO_MD_PCI(dev), MACHINE(hotplug_dev), errp);
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_HV_BALLOON)) {
+        pc_hv_balloon_plug(hotplug_dev, dev, errp);
     }
 }
 
@@ -1505,6 +1526,7 @@ static HotplugHandler *pc_get_hotplug_handler(MachineState *machine,
         object_dynamic_cast(OBJECT(dev), TYPE_CPU) ||
         object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI) ||
         object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI) ||
+        object_dynamic_cast(OBJECT(dev), TYPE_HV_BALLOON) ||
         object_dynamic_cast(OBJECT(dev), TYPE_X86_IOMMU_DEVICE)) {
         return HOTPLUG_HANDLER(machine);
     }