[Qemu-devel] [patch 16/24] QEMU/KVM: device and disk hot-add

[Marcelo Tosatti <mtosatti@redhat.com>]

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Add monitor command to hot-add PCI devices (nic and storage).

Syntax is:

pci_add pcibus nic|storage params

It returns the bus slot and function for the newly added device on success.

It is possible to attach a disk to a device after PCI initialization via
the drive_add command. If so, a manual scan of the SCSI bus on the guest 
is necessary.

Save QEMUMachine necessary for drive_init.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Index: kvm-userspace.hotplug2/qemu/Makefile.target
===================================================================
--- kvm-userspace.hotplug2.orig/qemu/Makefile.target
+++ kvm-userspace.hotplug2/qemu/Makefile.target
@@ -579,6 +579,8 @@ OBJS+= hypercall.o
 # virtio devices
 OBJS += virtio.o virtio-net.o virtio-blk.o
 
+OBJS += device-hotplug.o
+
 ifeq ($(TARGET_BASE_ARCH), i386)
 # Hardware support
 OBJS+= ide.o pckbd.o ps2.o vga.o $(SOUND_HW) dma.o
Index: kvm-userspace.hotplug2/qemu/hw/device-hotplug.c
===================================================================
--- /dev/null
+++ kvm-userspace.hotplug2/qemu/hw/device-hotplug.c
@@ -0,0 +1,158 @@
+#include "hw.h"
+#include "boards.h"
+#include "pci.h"
+#include "net.h"
+#include "sysemu.h"
+#include "pc.h"
+#include "console.h"
+
+static PCIDevice *qemu_system_hot_add_nic(const char *opts, int bus_nr)
+{
+    int ret;
+    char buf[4096];
+    PCIBus *pci_bus;
+
+    pci_bus = pci_find_bus (bus_nr);
+    if (!pci_bus) {
+        term_printf ("Can't find pci_bus %d\n", bus_nr);
+        return NULL;
+    }
+
+    memset (buf, 0, sizeof (buf));
+
+    strcpy (buf, "nic,");
+    strncat (buf, opts, sizeof (buf) - strlen (buf) - 1);
+
+    ret = net_client_init (buf);
+    if (ret < 0 || !nd_table[ret].model)
+        return NULL;
+    return pci_nic_init (pci_bus, &nd_table[ret], -1);
+}
+
+static int add_init_drive(const char *opts)
+{
+    int drive_opt_idx, drive_idx;
+    int ret = -1;
+
+    drive_opt_idx = drive_add(NULL, "%s", opts);
+    if (!drive_opt_idx)
+        return ret;
+
+    drive_idx = drive_init(&drives_opt[drive_opt_idx], 0, current_machine);
+    if (drive_idx == -1) {
+        drive_remove(drive_opt_idx);
+        return ret;
+    }
+
+    return drive_idx;
+}
+
+void drive_hot_add(int pcibus, const char *devfn_string, const char *opts)
+{
+    int drive_idx, type, bus;
+    int devfn;
+    int success = 0;
+    PCIDevice *dev;
+
+    devfn = strtoul(devfn_string, NULL, 0);
+
+    dev = pci_find_device(pcibus, PCI_SLOT(devfn));
+    if (!dev) {
+        term_printf("no pci device with devfn %d (slot %d)\n", devfn,
+                    PCI_SLOT(devfn));
+        return;
+    }
+
+    drive_idx = add_init_drive(opts);
+    if (drive_idx < 0)
+        return;
+    type = drives_table[drive_idx].type;
+    bus = drive_get_max_bus (type);
+
+    switch (type) {
+    case IF_SCSI:
+        success = 1;
+        lsi_scsi_attach (dev, drives_table[drive_idx].bdrv,
+                         drives_table[drive_idx].unit);
+        break;
+    default:
+        term_printf("Can't hot-add drive to type %d\n", type);
+    }
+
+    if (success)
+        term_printf("OK bus %d, unit %d\n", drives_table[drive_idx].bus,
+                                            drives_table[drive_idx].unit);
+    return;
+}
+
+static PCIDevice *qemu_system_hot_add_storage(const char *opts, int bus_nr)
+{
+    void *opaque = NULL;
+    PCIBus *pci_bus;
+    int type = -1, drive_idx = -1;
+    char buf[128];
+
+    pci_bus = pci_find_bus(bus_nr);
+    if (!pci_bus) {
+        term_printf("Can't find pci_bus %d\n", bus_nr);
+        return NULL;
+    }
+
+    if (get_param_value(buf, sizeof(buf), "if", opts)) {
+        if (!strcmp(buf, "scsi"))
+            type = IF_SCSI;
+        else if (!strcmp(buf, "virtio")) {
+            type = IF_VIRTIO;
+        }
+    } else {
+        term_printf("no if= specified\n");
+        return NULL;
+    }
+
+    if (get_param_value(buf, sizeof(buf), "file", opts)) {
+        drive_idx = add_init_drive(opts);
+        if (drive_idx < 0)
+            return NULL;
+    } else if (type == IF_VIRTIO) {
+        term_printf("virtio requires a backing file/device.\n");
+        return NULL;
+    }
+
+    switch (type) {
+    case IF_SCSI:
+        opaque = lsi_scsi_init (pci_bus, -1);
+        if (drive_idx >= 0)
+            lsi_scsi_attach (opaque, drives_table[drive_idx].bdrv,
+                             drives_table[drive_idx].unit);
+        break;
+    case IF_VIRTIO:
+        opaque = virtio_blk_init (pci_bus, 0x1AF4, 0x1001,
+                                  drives_table[drive_idx].bdrv);
+        break;
+    default:
+        term_printf ("type %s not a hotpluggable PCI device.\n", buf);
+    }
+
+    return opaque;
+}
+
+void device_hot_add(int pcibus, const char *type, const char *opts)
+{
+    PCIDevice *dev = NULL;
+
+    if (strcmp(type, "nic") == 0)
+        dev = qemu_system_hot_add_nic(opts, pcibus);
+    else if (strcmp(type, "storage") == 0)
+        dev = qemu_system_hot_add_storage(opts, pcibus);
+    else
+        term_printf("invalid type: %s\n", type);
+
+    if (dev) {
+        qemu_system_device_hot_add(PCI_SLOT(dev->devfn), 1);
+        term_printf("OK bus %d, slot %d, function %d (devfn %d)\n",
+                    pci_bus_num(dev->bus), PCI_SLOT(dev->devfn),
+                    PCI_FUNC(dev->devfn), dev->devfn);
+    } else
+        term_printf("failed to add %s\n", opts);
+}
+
Index: kvm-userspace.hotplug2/qemu/monitor.c
===================================================================
--- kvm-userspace.hotplug2.orig/qemu/monitor.c
+++ kvm-userspace.hotplug2/qemu/monitor.c
@@ -1359,6 +1359,12 @@ static term_cmd_t term_cmds[] = {
     { "migrate_set_speed", "s", do_migrate_set_speed,
       "value", "set maximum speed (in bytes) for migrations" },
     { "cpu_set", "is", do_cpu_set_nr, "cpu [online|offline]", "change cpu state" },
+    { "drive_add", "iss", drive_hot_add, "pcibus pcidevfn [file=file][,if=type][,bus=n]\n"
+                                        "[,unit=m][,media=d][index=i]\n"
+                                        "[,cyls=c,heads=h,secs=s[,trans=t]]\n"
+                                        "[snapshot=on|off][,cache=on|off]",
+                                        "add drive to PCI storage controller" },
+    { "pci_add", "iss", device_hot_add, "bus nic|storage [[vlan=n][,macaddr=addr][,model=type]] [file=file][,if=type][,bus=nr]...", "hot-add PCI device" },
     { NULL, NULL, },
 };
 
Index: kvm-userspace.hotplug2/qemu/hw/boards.h
===================================================================
--- kvm-userspace.hotplug2.orig/qemu/hw/boards.h
+++ kvm-userspace.hotplug2/qemu/hw/boards.h
@@ -19,6 +19,8 @@ typedef struct QEMUMachine {
 
 int qemu_register_machine(QEMUMachine *m);
 
+extern QEMUMachine *current_machine;
+
 /* Axis ETRAX.  */
 extern QEMUMachine bareetraxfs_machine;
 
Index: kvm-userspace.hotplug2/qemu/sysemu.h
===================================================================
--- kvm-userspace.hotplug2.orig/qemu/sysemu.h
+++ kvm-userspace.hotplug2/qemu/sysemu.h
@@ -176,6 +176,11 @@ extern int drive_init(struct drive_opt *
 /* acpi */
 void qemu_system_cpu_hot_add(int cpu, int state);
 void qemu_system_hot_add_init(char *cpu_model);
+void qemu_system_device_hot_add(int slot, int state);
+
+/* device-hotplug */
+void device_hot_add(int pcibus, const char *type, const char *opts);
+void drive_hot_add(int pcibus, const char *devfn_string, const char *opts);
 
 /* vmchannel devices */
 
Index: kvm-userspace.hotplug2/qemu/vl.c
===================================================================
--- kvm-userspace.hotplug2.orig/qemu/vl.c
+++ kvm-userspace.hotplug2/qemu/vl.c
@@ -7610,6 +7610,7 @@ void qemu_bh_delete(QEMUBH *bh)
 /* machine registration */
 
 QEMUMachine *first_machine = NULL;
+QEMUMachine *current_machine = NULL;
 
 int qemu_register_machine(QEMUMachine *m)
 {
@@ -9767,6 +9768,8 @@ int main(int argc, char **argv)
     machine->init(ram_size, vga_ram_size, boot_devices, ds,
                   kernel_filename, kernel_cmdline, initrd_filename, cpu_model);
 
+    current_machine = machine;
+
     /* init USB devices */
     if (usb_enabled) {
         for(i = 0; i < usb_devices_index; i++) {

--