[Qemu-devel] [PATCH 4/5] backdoor: [softmmu] Add QEMU-side proxy to "libbackdoor.a"

["Lluís Vilanova" <vilanova@ac.upc.edu>]

Uses a virtual device to proxy uses of the backdoor communication channel to the
user-provided code.

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
---
 Makefile.objs           |    1 
 backdoor/qemu/softmmu.c |  124 +++++++++++++++++++++++++++++++++++++++++++++++
 hw/pci.h                |    1 
 3 files changed, 126 insertions(+), 0 deletions(-)
 create mode 100644 backdoor/qemu/softmmu.c

diff --git a/Makefile.objs b/Makefile.objs
index d39074d..5f54d10 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -398,6 +398,7 @@ $(trace-obj-y): $(GENERATED_HEADERS)
 # backdoor
 
 backdoor-nested-$(CONFIG_USER_ONLY) += user.o
+backdoor-nested-$(CONFIG_SOFTMMU) += softmmu.o
 
 backdoor-obj-y += $(addprefix backdoor/qemu/, $(backdoor-nested-y))
 
diff --git a/backdoor/qemu/softmmu.c b/backdoor/qemu/softmmu.c
new file mode 100644
index 0000000..fdd3a25
--- /dev/null
+++ b/backdoor/qemu/softmmu.c
@@ -0,0 +1,124 @@
+/*
+ * QEMU-side management of backdoor channels in softmmu emulation.
+ *
+ * Copyright (C) 2011 Lluís Vilanova <vilanova@ac.upc.edu>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "hw/pci.h"
+#include "backdoor/qemu/qemu-backdoor.h"
+
+
+#define PAGE_SIZE TARGET_PAGE_SIZE
+#define CTRL_BYTES sizeof(uint64_t)
+
+
+typedef struct State
+{
+    PCIDevice dev;
+
+    uint8_t pages;
+    uint64_t size;
+
+    uint64_t cmd;
+
+    void *data_ptr;
+    MemoryRegion data;
+    MemoryRegion control;
+} State;
+
+
+static uint64_t control_io_read(void *opaque, target_phys_addr_t addr, unsigned size)
+{
+    State *s = opaque;
+
+    uint64_t res = ldq_p(&s->size);
+    uint8_t *resb = (uint8_t*)&res;
+    return resb[addr % CTRL_BYTES];
+}
+
+static void control_io_write(void *opaque, target_phys_addr_t addr, uint64_t data, unsigned size)
+{
+    State *s = opaque;
+
+    uint8_t *cmdb = (uint8_t*)&s->cmd;
+    cmdb[addr % CTRL_BYTES] = (uint8_t)data;
+
+    if ((addr + size) % CTRL_BYTES == 0) {
+        qemu_backdoor(ldq_p(&s->cmd), s->data_ptr);
+    }
+}
+
+static const MemoryRegionOps control_ops = {
+    .read = control_io_read,
+    .write = control_io_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .impl = {
+        .min_access_size = 1,
+        .max_access_size = 1,
+    },
+};
+
+
+static int init(PCIDevice *dev)
+{
+    State *s = DO_UPCAST(State, dev, dev);
+
+    if (s->pages < 1) {
+        fprintf(stderr, "error: backdoor: "
+                "the data channel must have one or more pages\n");
+        return -1;
+    }
+    s->size = s->pages * PAGE_SIZE;
+
+    pci_set_word(s->dev.config + PCI_COMMAND,
+                 PCI_COMMAND_IO | PCI_COMMAND_MEMORY);
+
+    memory_region_init_io(&s->control, &control_ops, s, "backdoor.control",
+                          PAGE_SIZE);
+    pci_register_bar(&s->dev, 0, PCI_BASE_ADDRESS_SPACE_MEMORY, &s->control);
+
+    memory_region_init_ram(&s->data, &s->dev.qdev, "backdoor.data",
+                           s->size);
+    pci_register_bar(&s->dev, 1, PCI_BASE_ADDRESS_SPACE_MEMORY, &s->data);
+    s->data_ptr = qemu_get_ram_ptr(s->data.ram_addr);
+
+    qemu_backdoor_init(s->size);
+
+    return 0;
+}
+
+static int fini(PCIDevice *dev)
+{
+    State *s = DO_UPCAST(State, dev, dev);
+
+    memory_region_destroy(&s->data);
+    memory_region_destroy(&s->control);
+
+    return 0;
+}
+
+
+static PCIDeviceInfo info = {
+    .qdev.name  = "backdoor",
+    .qdev.desc  = "Backdoor communication channel",
+    .qdev.size  = sizeof(State),
+    .init       = init,
+    .exit       = fini,
+    .vendor_id  = PCI_VENDOR_ID_REDHAT_QUMRANET,
+    .device_id  = PCI_DEVICE_ID_BACKDOOR,
+    .class_id   = PCI_CLASS_MEMORY_RAM,
+    .qdev.props = (Property[]) {
+        DEFINE_PROP_UINT8("pages", State, pages, 1),
+        DEFINE_PROP_END_OF_LIST(),
+    }
+};
+
+static void register_device(void)
+{
+    pci_qdev_register(&info);
+}
+
+device_init(register_device)
diff --git a/hw/pci.h b/hw/pci.h
index 86a81c8..4d7d161 100644
--- a/hw/pci.h
+++ b/hw/pci.h
@@ -75,6 +75,7 @@
 #define PCI_DEVICE_ID_VIRTIO_BLOCK       0x1001
 #define PCI_DEVICE_ID_VIRTIO_BALLOON     0x1002
 #define PCI_DEVICE_ID_VIRTIO_CONSOLE     0x1003
+#define PCI_DEVICE_ID_BACKDOOR           0x1004
 
 #define FMT_PCIBUS                      PRIx64