Hi,

"Host Memory Backends" and "Memory devices" queue ("mem"):
 - Kconfig fix for virtio-based memory devices
 - virtio-mem support for suspend+wake-up with plugged memory
 - hostmem fix when specifying "merge=off"
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Merge tag 'mem-2024-09-24' of https://github.com/davidhildenbrand/qemu into staging

Hi,

"Host Memory Backends" and "Memory devices" queue ("mem"):
- Kconfig fix for virtio-based memory devices
- virtio-mem support for suspend+wake-up with plugged memory
- hostmem fix when specifying "merge=off"

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# gpg: Signature made Tue 24 Sep 2024 10:45:39 BST
# gpg:                using RSA key 1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A
# gpg:                issuer "david@redhat.com"
# gpg: Good signature from "David Hildenbrand <david@redhat.com>" [marginal]
# gpg:                 aka "David Hildenbrand <davidhildenbrand@gmail.com>" [full]
# gpg:                 aka "David Hildenbrand <hildenbr@in.tum.de>" [unknown]
# Primary key fingerprint: 1BD9 CAAD 735C 4C3A 460D  FCCA 4DDE 10F7 00FF 835A

* tag 'mem-2024-09-24' of https://github.com/davidhildenbrand/qemu:
  hostmem: Apply merge property after the memory region is initialized
  virtio-mem: Add support for suspend+wake-up with plugged memory
  virtio-mem: Use new Resettable framework instead of LegacyReset
  reset: Add RESET_TYPE_WAKEUP
  reset: Use ResetType for qemu_devices_reset() and MachineClass::reset()
  virtio: kconfig: memory devices are PCI only

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

backends/hostmem.c

@@ -178,7 +178,7 @@ static void host_memory_backend_set_merge(Object *obj, bool value, Error **errp)
         return;
     }
 
-    if (!host_memory_backend_mr_inited(backend) &&
+    if (host_memory_backend_mr_inited(backend) &&
         value != backend->merge) {
         void *ptr = memory_region_get_ram_ptr(&backend->mr);
         uint64_t sz = memory_region_size(&backend->mr);

docs/devel/reset.rst

@@ -44,6 +44,17 @@ The Resettable interface handles reset types with an enum ``ResetType``:
   value on each cold reset, such as RNG seed information, and which they
   must not reinitialize on a snapshot-load reset.
 
+``RESET_TYPE_WAKEUP``
+  If the machine supports waking up from a suspended state and needs to reset
+  its devices during wake-up (from the ``MachineClass::wakeup()`` method), this
+  reset type should be used for such a request. Devices can utilize this reset
+  type to differentiate the reset requested during machine wake-up from other
+  reset requests. For example, RAM content must not be lost during wake-up, and
+  memory devices like virtio-mem that provide additional RAM must not reset
+  such state during wake-ups, but might do so during cold resets. However, this
+  reset type should not be used for wake-up detection, as not every machine
+  type issues a device reset request during wake-up.
+
 ``RESET_TYPE_S390_CPU_NORMAL``
   This is only used for S390 CPU objects; it clears interrupts, stops
   processing, and clears the TLB, but does not touch register contents.
@@ -53,7 +64,6 @@ The Resettable interface handles reset types with an enum ``ResetType``:
   ``RESET_TYPE_S390_CPU_NORMAL`` does and also clears the PSW, prefix,
   FPC, timer and control registers. It does not touch gprs, fprs or acrs.
 
-
 Devices which implement reset methods must treat any unknown ``ResetType``
 as equivalent to ``RESET_TYPE_COLD``; this will reduce the amount of
 existing code we need to change if we add more types in future.

hw/arm/aspeed.c

@@ -1529,12 +1529,12 @@ static void aspeed_machine_bletchley_class_init(ObjectClass *oc, void *data)
     aspeed_machine_class_init_cpus_defaults(mc);
 }
 
-static void fby35_reset(MachineState *state, ShutdownCause reason)
+static void fby35_reset(MachineState *state, ResetType type)
 {
     AspeedMachineState *bmc = ASPEED_MACHINE(state);
     AspeedGPIOState *gpio = &bmc->soc->gpio;
 
-    qemu_devices_reset(reason);
+    qemu_devices_reset(type);
 
     /* Board ID: 7 (Class-1, 4 slots) */
     object_property_set_bool(OBJECT(gpio), "gpioV4", true, &error_fatal);

hw/arm/mps2-tz.c

@@ -1254,7 +1254,7 @@ static void mps2_set_remap(Object *obj, const char *value, Error **errp)
     }
 }
 
-static void mps2_machine_reset(MachineState *machine, ShutdownCause reason)
+static void mps2_machine_reset(MachineState *machine, ResetType type)
 {
     MPS2TZMachineState *mms = MPS2TZ_MACHINE(machine);
 
@@ -1264,7 +1264,7 @@ static void mps2_machine_reset(MachineState *machine, ShutdownCause reason)
      * reset see the correct mapping.
      */
     remap_memory(mms, mms->remap);
-    qemu_devices_reset(reason);
+    qemu_devices_reset(type);
 }
 
 static void mps2tz_class_init(ObjectClass *oc, void *data)

hw/core/reset.c

@@ -170,11 +170,8 @@ void qemu_unregister_resettable(Object *obj)
     resettable_container_remove(get_root_reset_container(), obj);
 }
 
-void qemu_devices_reset(ShutdownCause reason)
+void qemu_devices_reset(ResetType type)
 {
-    ResetType type = (reason == SHUTDOWN_CAUSE_SNAPSHOT_LOAD) ?
-        RESET_TYPE_SNAPSHOT_LOAD : RESET_TYPE_COLD;
-
     /* Reset the simulation */
     resettable_reset(OBJECT(get_root_reset_container()), type);
 }

hw/hppa/machine.c

@@ -642,12 +642,12 @@ static void machine_HP_C3700_init(MachineState *machine)
     machine_HP_common_init_tail(machine, pci_bus, translate);
 }
 
-static void hppa_machine_reset(MachineState *ms, ShutdownCause reason)
+static void hppa_machine_reset(MachineState *ms, ResetType type)
 {
     unsigned int smp_cpus = ms->smp.cpus;
     int i;
 
-    qemu_devices_reset(reason);
+    qemu_devices_reset(type);
 
     /* Start all CPUs at the firmware entry point.
      *  Monarch CPU will initialize firmware, secondary CPUs

hw/i386/microvm.c

@@ -462,7 +462,7 @@ static void microvm_machine_state_init(MachineState *machine)
     microvm_devices_init(mms);
 }
 
-static void microvm_machine_reset(MachineState *machine, ShutdownCause reason)
+static void microvm_machine_reset(MachineState *machine, ResetType type)
 {
     MicrovmMachineState *mms = MICROVM_MACHINE(machine);
     CPUState *cs;
@@ -475,7 +475,7 @@ static void microvm_machine_reset(MachineState *machine, ShutdownCause reason)
         mms->kernel_cmdline_fixed = true;
     }
 
-    qemu_devices_reset(reason);
+    qemu_devices_reset(type);
 
     CPU_FOREACH(cs) {
         cpu = X86_CPU(cs);

hw/i386/pc.c

@@ -1712,12 +1712,12 @@ static void pc_machine_initfn(Object *obj)
     qemu_add_machine_init_done_notifier(&pcms->machine_done);
 }
 
-static void pc_machine_reset(MachineState *machine, ShutdownCause reason)
+static void pc_machine_reset(MachineState *machine, ResetType type)
 {
     CPUState *cs;
     X86CPU *cpu;
 
-    qemu_devices_reset(reason);
+    qemu_devices_reset(type);
 
     /* Reset APIC after devices have been reset to cancel
      * any changes that qemu_devices_reset() might have done.
@@ -1732,7 +1732,7 @@ static void pc_machine_reset(MachineState *machine, ShutdownCause reason)
 static void pc_machine_wakeup(MachineState *machine)
 {
     cpu_synchronize_all_states();
-    pc_machine_reset(machine, SHUTDOWN_CAUSE_NONE);
+    pc_machine_reset(machine, RESET_TYPE_WAKEUP);
     cpu_synchronize_all_post_reset();
 }
 

hw/ppc/pegasos2.c

@@ -291,14 +291,14 @@ static void pegasos2_superio_write(uint8_t addr, uint8_t val)
     cpu_physical_memory_write(PCI1_IO_BASE + 0x3f1, &val, 1);
 }
 
-static void pegasos2_machine_reset(MachineState *machine, ShutdownCause reason)
+static void pegasos2_machine_reset(MachineState *machine, ResetType type)
 {
     Pegasos2MachineState *pm = PEGASOS2_MACHINE(machine);
     void *fdt;
     uint64_t d[2];
     int sz;
 
-    qemu_devices_reset(reason);
+    qemu_devices_reset(type);
     if (!pm->vof) {
         return; /* Firmware should set up machine so nothing to do */
     }

hw/ppc/pnv.c

@@ -709,13 +709,13 @@ static void pnv_powerdown_notify(Notifier *n, void *opaque)
     }
 }
 
-static void pnv_reset(MachineState *machine, ShutdownCause reason)
+static void pnv_reset(MachineState *machine, ResetType type)
 {
     PnvMachineState *pnv = PNV_MACHINE(machine);
     IPMIBmc *bmc;
     void *fdt;
 
-    qemu_devices_reset(reason);
+    qemu_devices_reset(type);
 
     /*
      * The machine should provide by default an internal BMC simulator.

hw/ppc/spapr.c

@@ -1725,7 +1725,7 @@ void spapr_check_mmu_mode(bool guest_radix)
     }
 }
 
-static void spapr_machine_reset(MachineState *machine, ShutdownCause reason)
+static void spapr_machine_reset(MachineState *machine, ResetType type)
 {
     SpaprMachineState *spapr = SPAPR_MACHINE(machine);
     PowerPCCPU *first_ppc_cpu;
@@ -1733,7 +1733,7 @@ static void spapr_machine_reset(MachineState *machine, ShutdownCause reason)
     void *fdt;
     int rc;
 
-    if (reason != SHUTDOWN_CAUSE_SNAPSHOT_LOAD) {
+    if (type != RESET_TYPE_SNAPSHOT_LOAD) {
         /*
          * Record-replay snapshot load must not consume random, this was
          * already replayed from initial machine reset.
@@ -1762,7 +1762,7 @@ static void spapr_machine_reset(MachineState *machine, ShutdownCause reason)
         spapr_setup_hpt(spapr);
     }
 
-    qemu_devices_reset(reason);
+    qemu_devices_reset(type);
 
     spapr_ovec_cleanup(spapr->ov5_cas);
     spapr->ov5_cas = spapr_ovec_new();

hw/s390x/s390-virtio-ccw.c

@@ -440,7 +440,7 @@ static void s390_pv_prepare_reset(S390CcwMachineState *ms)
     s390_pv_prep_reset();
 }
 
-static void s390_machine_reset(MachineState *machine, ShutdownCause reason)
+static void s390_machine_reset(MachineState *machine, ResetType type)
 {
     S390CcwMachineState *ms = S390_CCW_MACHINE(machine);
     enum s390_reset reset_type;
@@ -472,7 +472,7 @@ static void s390_machine_reset(MachineState *machine, ShutdownCause reason)
          * Device reset includes CPU clear resets so this has to be
          * done AFTER the unprotect call above.
          */
-        qemu_devices_reset(reason);
+        qemu_devices_reset(type);
         s390_crypto_reset();
 
         /* configure and start the ipl CPU only */

hw/virtio/Kconfig

@@ -16,6 +16,7 @@ config VIRTIO_PCI
     default y if PCI_DEVICES
     depends on PCI
     select VIRTIO
+    select VIRTIO_MD_SUPPORTED
 
 config VIRTIO_MMIO
     bool
@@ -35,10 +36,17 @@ config VIRTIO_CRYPTO
     default y
     depends on VIRTIO
 
+# not all virtio transports support memory devices; if none does,
+# no need to include the code
+config VIRTIO_MD_SUPPORTED
+    bool
+
 config VIRTIO_MD
     bool
+    depends on VIRTIO_MD_SUPPORTED
     select MEM_DEVICE
 
+# selected by the board if it has the required support code
 config VIRTIO_PMEM_SUPPORTED
     bool
 
@@ -46,9 +54,11 @@ config VIRTIO_PMEM
     bool
     default y
     depends on VIRTIO
+    depends on VIRTIO_MD_SUPPORTED
     depends on VIRTIO_PMEM_SUPPORTED
     select VIRTIO_MD
 
+# selected by the board if it has the required support code
 config VIRTIO_MEM_SUPPORTED
     bool
 
@@ -57,6 +67,7 @@ config VIRTIO_MEM
     default y
     depends on VIRTIO
     depends on LINUX
+    depends on VIRTIO_MD_SUPPORTED
     depends on VIRTIO_MEM_SUPPORTED
     select VIRTIO_MD
 

hw/virtio/virtio-mem.c

@@ -890,6 +890,9 @@ static uint64_t virtio_mem_get_features(VirtIODevice *vdev, uint64_t features,
     if (vmem->unplugged_inaccessible == ON_OFF_AUTO_ON) {
         virtio_add_feature(&features, VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE);
     }
+    if (qemu_wakeup_suspend_enabled()) {
+        virtio_add_feature(&features, VIRTIO_MEM_F_PERSISTENT_SUSPEND);
+    }
     return features;
 }
 
@@ -902,18 +905,6 @@ static int virtio_mem_validate_features(VirtIODevice *vdev)
     return 0;
 }
 
-static void virtio_mem_system_reset(void *opaque)
-{
-    VirtIOMEM *vmem = VIRTIO_MEM(opaque);
-
-    /*
-     * During usual resets, we will unplug all memory and shrink the usable
-     * region size. This is, however, not possible in all scenarios. Then,
-     * the guest has to deal with this manually (VIRTIO_MEM_REQ_UNPLUG_ALL).
-     */
-    virtio_mem_unplug_all(vmem);
-}
-
 static void virtio_mem_prepare_mr(VirtIOMEM *vmem)
 {
     const uint64_t region_size = memory_region_size(&vmem->memdev->mr);
@@ -1130,7 +1121,7 @@ static void virtio_mem_device_realize(DeviceState *dev, Error **errp)
         vmstate_register_any(VMSTATE_IF(vmem),
                              &vmstate_virtio_mem_device_early, vmem);
     }
-    qemu_register_reset(virtio_mem_system_reset, vmem);
+    qemu_register_resettable(OBJECT(vmem));
 
     /*
      * Set ourselves as RamDiscardManager before the plug handler maps the
@@ -1150,7 +1141,7 @@ static void virtio_mem_device_unrealize(DeviceState *dev)
      * found via an address space anymore. Unset ourselves.
      */
     memory_region_set_ram_discard_manager(&vmem->memdev->mr, NULL);
-    qemu_unregister_reset(virtio_mem_system_reset, vmem);
+    qemu_unregister_resettable(OBJECT(vmem));
     if (vmem->early_migration) {
         vmstate_unregister(VMSTATE_IF(vmem), &vmstate_virtio_mem_device_early,
                            vmem);
@@ -1850,12 +1841,38 @@ static void virtio_mem_unplug_request_check(VirtIOMEM *vmem, Error **errp)
     }
 }
 
+static ResettableState *virtio_mem_get_reset_state(Object *obj)
+{
+    VirtIOMEM *vmem = VIRTIO_MEM(obj);
+    return &vmem->reset_state;
+}
+
+static void virtio_mem_system_reset_hold(Object *obj, ResetType type)
+{
+    VirtIOMEM *vmem = VIRTIO_MEM(obj);
+
+    /*
+     * When waking up from standby/suspend-to-ram, do not unplug any memory.
+     */
+    if (type == RESET_TYPE_WAKEUP) {
+        return;
+    }
+
+    /*
+     * During usual resets, we will unplug all memory and shrink the usable
+     * region size. This is, however, not possible in all scenarios. Then,
+     * the guest has to deal with this manually (VIRTIO_MEM_REQ_UNPLUG_ALL).
+     */
+    virtio_mem_unplug_all(vmem);
+}
+
 static void virtio_mem_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
     VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
     VirtIOMEMClass *vmc = VIRTIO_MEM_CLASS(klass);
     RamDiscardManagerClass *rdmc = RAM_DISCARD_MANAGER_CLASS(klass);
+    ResettableClass *rc = RESETTABLE_CLASS(klass);
 
     device_class_set_props(dc, virtio_mem_properties);
     dc->vmsd = &vmstate_virtio_mem;
@@ -1882,6 +1899,9 @@ static void virtio_mem_class_init(ObjectClass *klass, void *data)
     rdmc->replay_discarded = virtio_mem_rdm_replay_discarded;
     rdmc->register_listener = virtio_mem_rdm_register_listener;
     rdmc->unregister_listener = virtio_mem_rdm_unregister_listener;
+
+    rc->get_state = virtio_mem_get_reset_state;
+    rc->phases.hold = virtio_mem_system_reset_hold;
 }
 
 static const TypeInfo virtio_mem_info = {

hw/virtio/virtio-qmp.c

@@ -450,6 +450,9 @@ static const qmp_virtio_feature_map_t virtio_mem_feature_map[] = {
     FEATURE_ENTRY(VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE, \
             "VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE: Unplugged memory cannot be "
             "accessed"),
+    FEATURE_ENTRY(VIRTIO_MEM_F_PERSISTENT_SUSPEND, \
+            "VIRTIO_MEM_F_PERSISTENT_SUSPND: Plugged memory will remain "
+            "plugged when suspending+resuming"),
     { -1, "" }
 };
 #endif

include/hw/boards.h

@@ -10,6 +10,7 @@
 #include "qemu/module.h"
 #include "qom/object.h"
 #include "hw/core/cpu.h"
+#include "hw/resettable.h"
 
 #define TYPE_MACHINE_SUFFIX "-machine"
 
@@ -257,7 +258,7 @@ struct MachineClass {
     const char *deprecation_reason;
 
     void (*init)(MachineState *state);
-    void (*reset)(MachineState *state, ShutdownCause reason);
+    void (*reset)(MachineState *state, ResetType type);
     void (*wakeup)(MachineState *state);
     int (*kvm_type)(MachineState *machine, const char *arg);
     int (*hvf_get_physical_address_range)(MachineState *machine);

include/hw/resettable.h

@@ -29,6 +29,7 @@ typedef struct ResettableState ResettableState;
  * Types of reset.
  *
  * + Cold: reset resulting from a power cycle of the object.
+ * + Wakeup: reset resulting from a wake-up from a suspended state.
  *
  * TODO: Support has to be added to handle more types. In particular,
  * ResettableState structure needs to be expanded.
@@ -36,6 +37,7 @@ typedef struct ResettableState ResettableState;
 typedef enum ResetType {
     RESET_TYPE_COLD,
     RESET_TYPE_SNAPSHOT_LOAD,
+    RESET_TYPE_WAKEUP,
     RESET_TYPE_S390_CPU_INITIAL,
     RESET_TYPE_S390_CPU_NORMAL,
 } ResetType;

include/hw/virtio/virtio-mem.h

@@ -14,6 +14,7 @@
 #define HW_VIRTIO_MEM_H
 
 #include "standard-headers/linux/virtio_mem.h"
+#include "hw/resettable.h"
 #include "hw/virtio/virtio.h"
 #include "qapi/qapi-types-misc.h"
 #include "sysemu/hostmem.h"
@@ -115,6 +116,9 @@ struct VirtIOMEM {
 
     /* listeners to notify on plug/unplug activity. */
     QLIST_HEAD(, RamDiscardListener) rdl_list;
+
+    /* State of the resettable container */
+    ResettableState reset_state;
 };
 
 struct VirtIOMEMClass {

include/sysemu/reset.h

@@ -27,6 +27,7 @@
 #ifndef QEMU_SYSEMU_RESET_H
 #define QEMU_SYSEMU_RESET_H
 
+#include "hw/resettable.h"
 #include "qapi/qapi-events-run-state.h"
 
 typedef void QEMUResetHandler(void *opaque);
@@ -110,7 +111,7 @@ void qemu_unregister_reset(QEMUResetHandler *func, void *opaque);
 
 /**
  * qemu_devices_reset: Perform a complete system reset
- * @reason: reason for the reset
+ * @reason: type of the reset
  *
  * This function performs the low-level work needed to do a complete reset
  * of the system (calling all the callbacks registered with
@@ -121,6 +122,6 @@ void qemu_unregister_reset(QEMUResetHandler *func, void *opaque);
  * If you want to trigger a system reset from, for instance, a device
  * model, don't use this function. Use qemu_system_reset_request().
  */
-void qemu_devices_reset(ShutdownCause reason);
+void qemu_devices_reset(ResetType type);
 
 #endif

system/runstate.c

@@ -32,6 +32,7 @@
 #include "exec/cpu-common.h"
 #include "gdbstub/syscalls.h"
 #include "hw/boards.h"
+#include "hw/resettable.h"
 #include "migration/misc.h"
 #include "migration/postcopy-ram.h"
 #include "monitor/monitor.h"
@@ -507,15 +508,23 @@ static int qemu_debug_requested(void)
 void qemu_system_reset(ShutdownCause reason)
 {
     MachineClass *mc;
+    ResetType type;
 
     mc = current_machine ? MACHINE_GET_CLASS(current_machine) : NULL;
 
     cpu_synchronize_all_states();
 
+    switch (reason) {
+    case SHUTDOWN_CAUSE_SNAPSHOT_LOAD:
+        type = RESET_TYPE_SNAPSHOT_LOAD;
+        break;
+    default:
+        type = RESET_TYPE_COLD;
+    }
     if (mc && mc->reset) {
-        mc->reset(current_machine, reason);
+        mc->reset(current_machine, type);
     } else {
-        qemu_devices_reset(reason);
+        qemu_devices_reset(type);
     }
     switch (reason) {
     case SHUTDOWN_CAUSE_NONE: