hw/arm/virt: Support for virtio-mem-pci

This supports virtio-mem-pci device on "virt" platform, by simply
following the implementation on x86.

   * This implements the hotplug handlers to support virtio-mem-pci
     device hot-add, while the hot-remove isn't supported as we have
     on x86.

   * The block size is 512MB on ARM64 instead of 128MB on x86.

   * It has been passing the tests with various combinations like 64KB
     and 4KB page sizes on host and guest, different memory device
     backends like normal, transparent huge page and HugeTLB, plus
     migration.

Co-developed-by: David Hildenbrand <david@redhat.com>
Co-developed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Message-id: 20220111063329.74447-3-gshan@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

3 files changed, 74 insertions, 1 deletions

diff --git a/hw/arm/Kconfig b/hw/arm/Kconfig
index c459c897cc..2e0049196d 100644
--- a/hw/arm/Kconfig
+++ b/hw/arm/Kconfig
@@ -28,6 +28,7 @@ config ARM_VIRT
     select ACPI_HW_REDUCED
     select ACPI_APEI
     select ACPI_VIOT
+    select VIRTIO_MEM_SUPPORTED
 
 config CHEETAH
     bool
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 177db1da12..a76d86b592 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -71,9 +71,11 @@
 #include "hw/arm/smmuv3.h"
 #include "hw/acpi/acpi.h"
 #include "target/arm/internals.h"
+#include "hw/mem/memory-device.h"
 #include "hw/mem/pc-dimm.h"
 #include "hw/mem/nvdimm.h"
 #include "hw/acpi/generic_event_device.h"
+#include "hw/virtio/virtio-mem-pci.h"
 #include "hw/virtio/virtio-iommu.h"
 #include "hw/char/pl011.h"
 #include "qemu/guest-random.h"
@@ -2501,6 +2503,64 @@ static void virt_memory_plug(HotplugHandler *hotplug_dev,
                          dev, &error_abort);
 }
 
+static void virt_virtio_md_pci_pre_plug(HotplugHandler *hotplug_dev,
+                                        DeviceState *dev, Error **errp)
+{
+    HotplugHandler *hotplug_dev2 = qdev_get_bus_hotplug_handler(dev);
+    Error *local_err = NULL;
+
+    if (!hotplug_dev2 && dev->hotplugged) {
+        /*
+         * Without a bus hotplug handler, we cannot control the plug/unplug
+         * order. We should never reach this point when hotplugging on ARM.
+         * However, it's nice to add a safety net, similar to what we have
+         * on x86.
+         */
+        error_setg(errp, "hotplug of virtio based memory devices not supported"
+                   " on this bus.");
+        return;
+    }
+    /*
+     * First, see if we can plug this memory device at all. If that
+     * succeeds, branch of to the actual hotplug handler.
+     */
+    memory_device_pre_plug(MEMORY_DEVICE(dev), MACHINE(hotplug_dev), NULL,
+                           &local_err);
+    if (!local_err && hotplug_dev2) {
+        hotplug_handler_pre_plug(hotplug_dev2, dev, &local_err);
+    }
+    error_propagate(errp, local_err);
+}
+
+static void virt_virtio_md_pci_plug(HotplugHandler *hotplug_dev,
+                                    DeviceState *dev, Error **errp)
+{
+    HotplugHandler *hotplug_dev2 = qdev_get_bus_hotplug_handler(dev);
+    Error *local_err = NULL;
+
+    /*
+     * Plug the memory device first and then branch off to the actual
+     * hotplug handler. If that one fails, we can easily undo the memory
+     * device bits.
+     */
+    memory_device_plug(MEMORY_DEVICE(dev), MACHINE(hotplug_dev));
+    if (hotplug_dev2) {
+        hotplug_handler_plug(hotplug_dev2, dev, &local_err);
+        if (local_err) {
+            memory_device_unplug(MEMORY_DEVICE(dev), MACHINE(hotplug_dev));
+        }
+    }
+    error_propagate(errp, local_err);
+}
+
+static void virt_virtio_md_pci_unplug_request(HotplugHandler *hotplug_dev,
+                                              DeviceState *dev, Error **errp)
+{
+    /* We don't support hot unplug of virtio based memory devices */
+    error_setg(errp, "virtio based memory devices cannot be unplugged.");
+}
+
+
 static void virt_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
                                             DeviceState *dev, Error **errp)
 {
@@ -2508,6 +2568,8 @@ static void virt_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
 
     if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
         virt_memory_pre_plug(hotplug_dev, dev, errp);
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI)) {
+        virt_virtio_md_pci_pre_plug(hotplug_dev, dev, errp);
     } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI)) {
         hwaddr db_start = 0, db_end = 0;
         char *resv_prop_str;
@@ -2559,6 +2621,11 @@ static void virt_machine_device_plug_cb(HotplugHandler *hotplug_dev,
     if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
         virt_memory_plug(hotplug_dev, dev, errp);
     }
+
+    if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI)) {
+        virt_virtio_md_pci_plug(hotplug_dev, dev, errp);
+    }
+
     if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI)) {
         PCIDevice *pdev = PCI_DEVICE(dev);
 
@@ -2615,6 +2682,8 @@ static void virt_machine_device_unplug_request_cb(HotplugHandler *hotplug_dev,
 {
     if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
         virt_dimm_unplug_request(hotplug_dev, dev, errp);
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI)) {
+        virt_virtio_md_pci_unplug_request(hotplug_dev, dev, errp);
     } else {
         error_setg(errp, "device unplug request for unsupported device"
                    " type: %s", object_get_typename(OBJECT(dev)));
@@ -2639,6 +2708,7 @@ static HotplugHandler *virt_machine_get_hotplug_handler(MachineState *machine,
 
     if (device_is_dynamic_sysbus(mc, dev) ||
         object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM) ||
+        object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MEM_PCI) ||
         object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI)) {
         return HOTPLUG_HANDLER(machine);
     }
diff --git a/hw/virtio/virtio-mem.c b/hw/virtio/virtio-mem.c
index 1ca45336dc..f55dcf61f2 100644
--- a/hw/virtio/virtio-mem.c
+++ b/hw/virtio/virtio-mem.c
@@ -146,7 +146,7 @@ static bool virtio_mem_has_shared_zeropage(RAMBlock *rb)
  * The memory block size corresponds mostly to the section size.
  *
  * This allows e.g., to add 20MB with a section size of 128MB on x86_64, and
- * a section size of 1GB on arm64 (as long as the start address is properly
+ * a section size of 512MB on arm64 (as long as the start address is properly
  * aligned, similar to ordinary DIMMs).
  *
  * We can change this at any time and maybe even make it configurable if
@@ -155,6 +155,8 @@ static bool virtio_mem_has_shared_zeropage(RAMBlock *rb)
  */
 #if defined(TARGET_X86_64) || defined(TARGET_I386)
 #define VIRTIO_MEM_USABLE_EXTENT (2 * (128 * MiB))
+#elif defined(TARGET_ARM)
+#define VIRTIO_MEM_USABLE_EXTENT (2 * (512 * MiB))
 #else
 #error VIRTIO_MEM_USABLE_EXTENT not defined
 #endif