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From:   Pankaj Gupta <pagupta@redhat.com>
To:     linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        qemu-devel@nongnu.org, linux-nvdimm@ml01.01.org
Cc:     jack@suse.cz, stefanha@redhat.com, dan.j.williams@intel.com,
        riel@surriel.com, nilal@redhat.com, kwolf@redhat.com,
        pbonzini@redhat.com, ross.zwisler@intel.com, david@redhat.com,
        xiaoguangrong.eric@gmail.com, hch@infradead.org, mst@redhat.com,
        niteshnarayanlal@hotmail.com, lcapitulino@redhat.com,
        imammedo@redhat.com, eblake@redhat.com, pagupta@redhat.com
Subject: [PATCH] qemu: Add virtio pmem device
Date:   Fri, 31 Aug 2018 19:00:19 +0530
Message-Id: <20180831133019.27579-5-pagupta@redhat.com>
In-Reply-To: <20180831133019.27579-1-pagupta@redhat.com>
References: <20180831133019.27579-1-pagupta@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

 This patch adds virtio-pmem Qemu device.

 This device presents memory address range information to guest
 which is backed by file backend type. It acts like persistent
 memory device for KVM guest. Guest can perform read and 
 persistent write operations on this memory range with the help 
 of DAX capable filesystem.

 Persistent guest writes are assured with the help of virtio 
 based flushing interface. When guest userspace space performs 
 fsync on file fd on pmem device, a flush command is send to 
 Qemu over VIRTIO and host side flush/sync is done on backing 
 image file.

Signed-off-by: Pankaj Gupta <pagupta@redhat.com>
---
Changes from RFC v3:
- Return EIO for host fsync failure instead of errno - Luiz, Stefan
- Change version for inclusion to Qemu 3.1 - Eric

Changes from RFC v2:
- Use aio_worker() to avoid Qemu from hanging with blocking fsync
  call - Stefan
- Use virtio_st*_p() for endianess - Stefan
- Correct indentation in qapi/misc.json - Eric

 hw/virtio/Makefile.objs                     |   3 +
 hw/virtio/virtio-pci.c                      |  44 +++++
 hw/virtio/virtio-pci.h                      |  14 ++
 hw/virtio/virtio-pmem.c                     | 241 ++++++++++++++++++++++++++++
 include/hw/pci/pci.h                        |   1 +
 include/hw/virtio/virtio-pmem.h             |  42 +++++
 include/standard-headers/linux/virtio_ids.h |   1 +
 qapi/misc.json                              |  26 ++-
 8 files changed, 371 insertions(+), 1 deletion(-)
 create mode 100644 hw/virtio/virtio-pmem.c
 create mode 100644 include/hw/virtio/virtio-pmem.h

diff --git a/hw/virtio/Makefile.objs b/hw/virtio/Makefile.objs
index 1b2799cfd8..7f914d45d0 100644
--- a/hw/virtio/Makefile.objs
+++ b/hw/virtio/Makefile.objs
@@ -10,6 +10,9 @@ obj-$(CONFIG_VIRTIO_CRYPTO) += virtio-crypto.o
 obj-$(call land,$(CONFIG_VIRTIO_CRYPTO),$(CONFIG_VIRTIO_PCI)) += virtio-crypto-pci.o
 
 obj-$(CONFIG_LINUX) += vhost.o vhost-backend.o vhost-user.o
+ifeq ($(CONFIG_MEM_HOTPLUG),y)
+obj-$(CONFIG_LINUX) += virtio-pmem.o
+endif
 obj-$(CONFIG_VHOST_VSOCK) += vhost-vsock.o
 endif
 
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 3a01fe90f0..93d3fc05c7 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -2521,6 +2521,49 @@ static const TypeInfo virtio_rng_pci_info = {
     .class_init    = virtio_rng_pci_class_init,
 };
 
+/* virtio-pmem-pci */
+
+static void virtio_pmem_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
+{
+    VirtIOPMEMPCI *vpmem = VIRTIO_PMEM_PCI(vpci_dev);
+    DeviceState *vdev = DEVICE(&vpmem->vdev);
+
+    qdev_set_parent_bus(vdev, BUS(&vpci_dev->bus));
+    object_property_set_bool(OBJECT(vdev), true, "realized", errp);
+}
+
+static void virtio_pmem_pci_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    VirtioPCIClass *k = VIRTIO_PCI_CLASS(klass);
+    PCIDeviceClass *pcidev_k = PCI_DEVICE_CLASS(klass);
+    k->realize = virtio_pmem_pci_realize;
+    set_bit(DEVICE_CATEGORY_MISC, dc->categories);
+    pcidev_k->vendor_id = PCI_VENDOR_ID_REDHAT_QUMRANET;
+    pcidev_k->device_id = PCI_DEVICE_ID_VIRTIO_PMEM;
+    pcidev_k->revision = VIRTIO_PCI_ABI_VERSION;
+    pcidev_k->class_id = PCI_CLASS_OTHERS;
+}
+
+static void virtio_pmem_pci_instance_init(Object *obj)
+{
+    VirtIOPMEMPCI *dev = VIRTIO_PMEM_PCI(obj);
+
+    virtio_instance_init_common(obj, &dev->vdev, sizeof(dev->vdev),
+                                TYPE_VIRTIO_PMEM);
+    object_property_add_alias(obj, "memdev", OBJECT(&dev->vdev), "memdev",
+                              &error_abort);
+}
+
+static const TypeInfo virtio_pmem_pci_info = {
+    .name          = TYPE_VIRTIO_PMEM_PCI,
+    .parent        = TYPE_VIRTIO_PCI,
+    .instance_size = sizeof(VirtIOPMEMPCI),
+    .instance_init = virtio_pmem_pci_instance_init,
+    .class_init    = virtio_pmem_pci_class_init,
+};
+
+
 /* virtio-input-pci */
 
 static Property virtio_input_pci_properties[] = {
@@ -2714,6 +2757,7 @@ static void virtio_pci_register_types(void)
     type_register_static(&virtio_balloon_pci_info);
     type_register_static(&virtio_serial_pci_info);
     type_register_static(&virtio_net_pci_info);
+    type_register_static(&virtio_pmem_pci_info);
 #ifdef CONFIG_VHOST_SCSI
     type_register_static(&vhost_scsi_pci_info);
 #endif
diff --git a/hw/virtio/virtio-pci.h b/hw/virtio/virtio-pci.h
index 813082b0d7..fe74fcad3f 100644
--- a/hw/virtio/virtio-pci.h
+++ b/hw/virtio/virtio-pci.h
@@ -19,6 +19,7 @@
 #include "hw/virtio/virtio-blk.h"
 #include "hw/virtio/virtio-net.h"
 #include "hw/virtio/virtio-rng.h"
+#include "hw/virtio/virtio-pmem.h"
 #include "hw/virtio/virtio-serial.h"
 #include "hw/virtio/virtio-scsi.h"
 #include "hw/virtio/virtio-balloon.h"
@@ -57,6 +58,7 @@ typedef struct VirtIOInputHostPCI VirtIOInputHostPCI;
 typedef struct VirtIOGPUPCI VirtIOGPUPCI;
 typedef struct VHostVSockPCI VHostVSockPCI;
 typedef struct VirtIOCryptoPCI VirtIOCryptoPCI;
+typedef struct VirtIOPMEMPCI VirtIOPMEMPCI;
 
 /* virtio-pci-bus */
 
@@ -274,6 +276,18 @@ struct VirtIOBlkPCI {
     VirtIOBlock vdev;
 };
 
+/*
+ * virtio-pmem-pci: This extends VirtioPCIProxy.
+ */
+#define TYPE_VIRTIO_PMEM_PCI "virtio-pmem-pci"
+#define VIRTIO_PMEM_PCI(obj) \
+        OBJECT_CHECK(VirtIOPMEMPCI, (obj), TYPE_VIRTIO_PMEM_PCI)
+
+struct VirtIOPMEMPCI {
+    VirtIOPCIProxy parent_obj;
+    VirtIOPMEM vdev;
+};
+
 /*
  * virtio-balloon-pci: This extends VirtioPCIProxy.
  */
diff --git a/hw/virtio/virtio-pmem.c b/hw/virtio/virtio-pmem.c
new file mode 100644
index 0000000000..69ae4c0a50
--- /dev/null
+++ b/hw/virtio/virtio-pmem.c
@@ -0,0 +1,241 @@
+/*
+ * Virtio pmem device
+ *
+ * Copyright (C) 2018 Red Hat, Inc.
+ * Copyright (C) 2018 Pankaj Gupta <pagupta@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qemu-common.h"
+#include "qemu/error-report.h"
+#include "hw/virtio/virtio-access.h"
+#include "hw/virtio/virtio-pmem.h"
+#include "hw/mem/memory-device.h"
+#include "block/aio.h"
+#include "block/thread-pool.h"
+
+typedef struct VirtIOPMEMresp {
+    int ret;
+} VirtIOPMEMResp;
+
+typedef struct VirtIODeviceRequest {
+    VirtQueueElement elem;
+    int fd;
+    VirtIOPMEM *pmem;
+    VirtIOPMEMResp resp;
+} VirtIODeviceRequest;
+
+static int worker_cb(void *opaque)
+{
+    VirtIODeviceRequest *req = opaque;
+    int err = 0;
+
+    /* flush raw backing image */
+    err = fsync(req->fd);
+    if (err != 0) {
+        err = EIO;
+    }
+    req->resp.ret = err;
+
+    return 0;
+}
+
+static void done_cb(void *opaque, int ret)
+{
+    VirtIODeviceRequest *req = opaque;
+    int len = iov_from_buf(req->elem.in_sg, req->elem.in_num, 0,
+                              &req->resp, sizeof(VirtIOPMEMResp));
+
+    /* Callbacks are serialized, so no need to use atomic ops.  */
+    virtqueue_push(req->pmem->rq_vq, &req->elem, len);
+    virtio_notify((VirtIODevice *)req->pmem, req->pmem->rq_vq);
+    g_free(req);
+}
+
+static void virtio_pmem_flush(VirtIODevice *vdev, VirtQueue *vq)
+{
+    VirtIODeviceRequest *req;
+    VirtIOPMEM *pmem = VIRTIO_PMEM(vdev);
+    HostMemoryBackend *backend = MEMORY_BACKEND(pmem->memdev);
+    ThreadPool *pool = aio_get_thread_pool(qemu_get_aio_context());
+
+    req = virtqueue_pop(vq, sizeof(VirtIODeviceRequest));
+    if (!req) {
+        virtio_error(vdev, "virtio-pmem missing request data");
+        return;
+    }
+
+    if (req->elem.out_num < 1 || req->elem.in_num < 1) {
+        virtio_error(vdev, "virtio-pmem request not proper");
+        g_free(req);
+        return;
+    }
+    req->fd = memory_region_get_fd(&backend->mr);
+    req->pmem = pmem;
+    thread_pool_submit_aio(pool, worker_cb, req, done_cb, req);
+}
+
+static void virtio_pmem_get_config(VirtIODevice *vdev, uint8_t *config)
+{
+    VirtIOPMEM *pmem = VIRTIO_PMEM(vdev);
+    struct virtio_pmem_config *pmemcfg = (struct virtio_pmem_config *) config;
+
+    virtio_stq_p(vdev, &pmemcfg->start, pmem->start);
+    virtio_stq_p(vdev, &pmemcfg->size, pmem->size);
+}
+
+static uint64_t virtio_pmem_get_features(VirtIODevice *vdev, uint64_t features,
+                                        Error **errp)
+{
+    return features;
+}
+
+static void virtio_pmem_realize(DeviceState *dev, Error **errp)
+{
+    VirtIODevice   *vdev   = VIRTIO_DEVICE(dev);
+    VirtIOPMEM     *pmem   = VIRTIO_PMEM(dev);
+    MachineState   *ms     = MACHINE(qdev_get_machine());
+    uint64_t align;
+    Error *local_err = NULL;
+    MemoryRegion *mr;
+
+    if (!pmem->memdev) {
+        error_setg(errp, "virtio-pmem memdev not set");
+        return;
+    }
+
+    mr  = host_memory_backend_get_memory(pmem->memdev);
+    align = memory_region_get_alignment(mr);
+    pmem->size = QEMU_ALIGN_DOWN(memory_region_size(mr), align);
+    pmem->start = memory_device_get_free_addr(ms, NULL, align, pmem->size,
+                                                               &local_err);
+    if (local_err) {
+        error_setg(errp, "Can't get free address in mem device");
+        return;
+    }
+    memory_region_init_alias(&pmem->mr, OBJECT(pmem),
+                             "virtio_pmem-memory", mr, 0, pmem->size);
+    memory_device_plug_region(ms, &pmem->mr, pmem->start);
+
+    host_memory_backend_set_mapped(pmem->memdev, true);
+    virtio_init(vdev, TYPE_VIRTIO_PMEM, VIRTIO_ID_PMEM,
+                                          sizeof(struct virtio_pmem_config));
+    pmem->rq_vq = virtio_add_queue(vdev, 128, virtio_pmem_flush);
+}
+
+static void virtio_mem_check_memdev(Object *obj, const char *name, Object *val,
+                                    Error **errp)
+{
+    if (host_memory_backend_is_mapped(MEMORY_BACKEND(val))) {
+        char *path = object_get_canonical_path_component(val);
+        error_setg(errp, "Can't use already busy memdev: %s", path);
+        g_free(path);
+        return;
+    }
+
+    qdev_prop_allow_set_link_before_realize(obj, name, val, errp);
+}
+
+static const char *virtio_pmem_get_device_id(VirtIOPMEM *vm)
+{
+    Object *obj = OBJECT(vm);
+    DeviceState *parent_dev;
+
+    /* always use the ID of the proxy device */
+    if (obj->parent && object_dynamic_cast(obj->parent, TYPE_DEVICE)) {
+        parent_dev = DEVICE(obj->parent);
+        return parent_dev->id;
+    }
+    return NULL;
+}
+
+static void virtio_pmem_md_fill_device_info(const MemoryDeviceState *md,
+                                           MemoryDeviceInfo *info)
+{
+    VirtioPMemDeviceInfo *vi = g_new0(VirtioPMemDeviceInfo, 1);
+    VirtIOPMEM *vm = VIRTIO_PMEM(md);
+    const char *id = virtio_pmem_get_device_id(vm);
+
+    if (id) {
+        vi->has_id = true;
+        vi->id = g_strdup(id);
+    }
+
+    vi->start = vm->start;
+    vi->size = vm->size;
+    vi->memdev = object_get_canonical_path(OBJECT(vm->memdev));
+
+    info->u.virtio_pmem.data = vi;
+    info->type = MEMORY_DEVICE_INFO_KIND_VIRTIO_PMEM;
+}
+
+static uint64_t virtio_pmem_md_get_addr(const MemoryDeviceState *md)
+{
+    VirtIOPMEM *vm = VIRTIO_PMEM(md);
+
+    return vm->start;
+}
+
+static uint64_t virtio_pmem_md_get_plugged_size(const MemoryDeviceState *md)
+{
+    VirtIOPMEM *vm = VIRTIO_PMEM(md);
+
+    return vm->size;
+}
+
+static uint64_t virtio_pmem_md_get_region_size(const MemoryDeviceState *md)
+{
+    VirtIOPMEM *vm = VIRTIO_PMEM(md);
+
+    return vm->size;
+}
+
+static void virtio_pmem_instance_init(Object *obj)
+{
+    VirtIOPMEM *vm = VIRTIO_PMEM(obj);
+    object_property_add_link(obj, "memdev", TYPE_MEMORY_BACKEND,
+                                (Object **)&vm->memdev,
+                                (void *) virtio_mem_check_memdev,
+                                OBJ_PROP_LINK_STRONG,
+                                &error_abort);
+}
+
+
+static void virtio_pmem_class_init(ObjectClass *klass, void *data)
+{
+    VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
+    MemoryDeviceClass *mdc = MEMORY_DEVICE_CLASS(klass);
+
+    vdc->realize      =  virtio_pmem_realize;
+    vdc->get_config   =  virtio_pmem_get_config;
+    vdc->get_features =  virtio_pmem_get_features;
+
+    mdc->get_addr         = virtio_pmem_md_get_addr;
+    mdc->get_plugged_size = virtio_pmem_md_get_plugged_size;
+    mdc->get_region_size  = virtio_pmem_md_get_region_size;
+    mdc->fill_device_info = virtio_pmem_md_fill_device_info;
+}
+
+static TypeInfo virtio_pmem_info = {
+    .name          = TYPE_VIRTIO_PMEM,
+    .parent        = TYPE_VIRTIO_DEVICE,
+    .class_init    = virtio_pmem_class_init,
+    .instance_size = sizeof(VirtIOPMEM),
+    .instance_init = virtio_pmem_instance_init,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_MEMORY_DEVICE },
+        { }
+  },
+};
+
+static void virtio_register_types(void)
+{
+    type_register_static(&virtio_pmem_info);
+}
+
+type_init(virtio_register_types)
diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
index 990d6fcbde..28829b6437 100644
--- a/include/hw/pci/pci.h
+++ b/include/hw/pci/pci.h
@@ -85,6 +85,7 @@ extern bool pci_available;
 #define PCI_DEVICE_ID_VIRTIO_RNG         0x1005
 #define PCI_DEVICE_ID_VIRTIO_9P          0x1009
 #define PCI_DEVICE_ID_VIRTIO_VSOCK       0x1012
+#define PCI_DEVICE_ID_VIRTIO_PMEM        0x1013
 
 #define PCI_VENDOR_ID_REDHAT             0x1b36
 #define PCI_DEVICE_ID_REDHAT_BRIDGE      0x0001
diff --git a/include/hw/virtio/virtio-pmem.h b/include/hw/virtio/virtio-pmem.h
new file mode 100644
index 0000000000..fda3ee691c
--- /dev/null
+++ b/include/hw/virtio/virtio-pmem.h
@@ -0,0 +1,42 @@
+/*
+ * Virtio pmem Device
+ *
+ * Copyright Red Hat, Inc. 2018
+ * Copyright Pankaj Gupta <pagupta@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * (at your option) any later version.  See the COPYING file in the
+ * top-level directory.
+ */
+
+#ifndef QEMU_VIRTIO_PMEM_H
+#define QEMU_VIRTIO_PMEM_H
+
+#include "hw/virtio/virtio.h"
+#include "exec/memory.h"
+#include "sysemu/hostmem.h"
+#include "standard-headers/linux/virtio_ids.h"
+#include "hw/boards.h"
+#include "hw/i386/pc.h"
+
+#define TYPE_VIRTIO_PMEM "virtio-pmem"
+
+#define VIRTIO_PMEM(obj) \
+        OBJECT_CHECK(VirtIOPMEM, (obj), TYPE_VIRTIO_PMEM)
+
+/* VirtIOPMEM device structure */
+typedef struct VirtIOPMEM {
+    VirtIODevice parent_obj;
+
+    VirtQueue *rq_vq;
+    uint64_t start;
+    uint64_t size;
+    MemoryRegion mr;
+    HostMemoryBackend *memdev;
+} VirtIOPMEM;
+
+struct virtio_pmem_config {
+    uint64_t start;
+    uint64_t size;
+};
+#endif
diff --git a/include/standard-headers/linux/virtio_ids.h b/include/standard-headers/linux/virtio_ids.h
index 6d5c3b2d4f..346389565a 100644
--- a/include/standard-headers/linux/virtio_ids.h
+++ b/include/standard-headers/linux/virtio_ids.h
@@ -43,5 +43,6 @@
 #define VIRTIO_ID_INPUT        18 /* virtio input */
 #define VIRTIO_ID_VSOCK        19 /* virtio vsock transport */
 #define VIRTIO_ID_CRYPTO       20 /* virtio crypto */
+#define VIRTIO_ID_PMEM         25 /* virtio pmem */
 
 #endif /* _LINUX_VIRTIO_IDS_H */
diff --git a/qapi/misc.json b/qapi/misc.json
index d450cfef21..517376b866 100644
--- a/qapi/misc.json
+++ b/qapi/misc.json
@@ -2907,6 +2907,29 @@
           }
 }
 
+##
+# @VirtioPMemDeviceInfo:
+#
+# VirtioPMem state information
+#
+# @id: device's ID
+#
+# @start: physical address, where device is mapped
+#
+# @size: size of memory that the device provides
+#
+# @memdev: memory backend linked with device
+#
+# Since: 3.1
+##
+{ 'struct': 'VirtioPMemDeviceInfo',
+  'data': { '*id': 'str',
+            'start': 'size',
+            'size': 'size',
+            'memdev': 'str'
+          }
+}
+
 ##
 # @MemoryDeviceInfo:
 #
@@ -2916,7 +2939,8 @@
 ##
 { 'union': 'MemoryDeviceInfo',
   'data': { 'dimm': 'PCDIMMDeviceInfo',
-            'nvdimm': 'PCDIMMDeviceInfo'
+            'nvdimm': 'PCDIMMDeviceInfo',
+	    'virtio-pmem': 'VirtioPMemDeviceInfo'
           }
 }
 
-- 
2.14.3