[PATCH v8 03/20] multi-process: setup PCI host bridge for remote device

[Jagannathan Raman <jag.raman@oracle.com>]

PCI host bridge is setup for the remote device process. It is
implemented using remote-pcihost object. It is an extension of the PCI
host bridge setup by QEMU.
Remote-pcihost configures a PCI bus which could be used by the remote
PCI device to latch on to.

Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
---
 MAINTAINERS                  |  8 +++++
 hw/pci-host/Makefile.objs    |  1 +
 hw/pci-host/remote.c         | 76 ++++++++++++++++++++++++++++++++++++++++++++
 include/hw/pci-host/remote.h | 30 +++++++++++++++++
 4 files changed, 115 insertions(+)
 create mode 100644 hw/pci-host/remote.c
 create mode 100644 include/hw/pci-host/remote.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 0886eb3..d781a28 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3035,6 +3035,14 @@ S: Maintained
 F: hw/semihosting/
 F: include/hw/semihosting/
 
+Multi-process QEMU
+M: Jagannathan Raman <jag.raman@oracle.com>
+M: Elena Ufimtseva <elena.ufimtseva@oracle.com>
+M: John G Johnson <john.g.johnson@oracle.com>
+S: Maintained
+F: hw/pci-host/remote.c
+F: include/hw/pci-host/remote.h
+
 Build and test automation
 -------------------------
 Build and test automation
diff --git a/hw/pci-host/Makefile.objs b/hw/pci-host/Makefile.objs
index e422e0a..daf9007 100644
--- a/hw/pci-host/Makefile.objs
+++ b/hw/pci-host/Makefile.objs
@@ -18,6 +18,7 @@ common-obj-$(CONFIG_XEN_IGD_PASSTHROUGH) += xen_igd_pt.o
 common-obj-$(CONFIG_PCI_EXPRESS_Q35) += q35.o
 common-obj-$(CONFIG_PCI_EXPRESS_GENERIC_BRIDGE) += gpex.o
 common-obj-$(CONFIG_PCI_EXPRESS_XILINX) += xilinx-pcie.o
+common-obj-$(CONFIG_MPQEMU) += remote.o
 
 common-obj-$(CONFIG_PCI_EXPRESS_DESIGNWARE) += designware.o
 obj-$(CONFIG_POWERNV) += pnv_phb4.o pnv_phb4_pec.o
diff --git a/hw/pci-host/remote.c b/hw/pci-host/remote.c
new file mode 100644
index 0000000..03c8e99
--- /dev/null
+++ b/hw/pci-host/remote.c
@@ -0,0 +1,76 @@
+/*
+ * Remote PCI host device
+ *
+ * Unlike PCI host devices that model physical hardware, the purpose
+ * of this PCI host is to host multi-process QEMU devices.
+ *
+ * Multi-process QEMU extends the PCI host of a QEMU machine into a
+ * remote process. Any PCI device attached to the remote process is
+ * visible in the QEMU guest. This allows existing QEMU device models
+ * to be reused in the remote process.
+ *
+ * This PCI host is purely a container for PCI devices. It's fake in the
+ * sense that the guest never sees this PCI host and has no way of
+ * accessing it. It's job is just to provide the environment that QEMU
+ * PCI device models need when running in a remote process.
+ *
+ * Copyright © 2018, 2020 Oracle and/or its affiliates.
+ *
+ * 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 "qemu/osdep.h"
+#include "qemu-common.h"
+
+#include "hw/pci/pci.h"
+#include "hw/pci/pci_host.h"
+#include "hw/pci/pcie_host.h"
+#include "hw/qdev-properties.h"
+#include "hw/pci-host/remote.h"
+#include "exec/memory.h"
+
+static const char *remote_pcihost_root_bus_path(PCIHostState *host_bridge,
+                                                PCIBus *rootbus)
+{
+    return "0000:00";
+}
+
+static void remote_pcihost_realize(DeviceState *dev, Error **errp)
+{
+    char *busname = g_strdup_printf("remote-pci-%ld", (unsigned long)getpid());
+    PCIHostState *pci = PCI_HOST_BRIDGE(dev);
+    RemotePCIHost *s = REMOTE_HOST_DEVICE(dev);
+
+    pci->bus = pci_root_bus_new(DEVICE(s), busname,
+                                s->mr_pci_mem, s->mr_sys_io,
+                                0, TYPE_PCIE_BUS);
+}
+
+static void remote_pcihost_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    PCIHostBridgeClass *hc = PCI_HOST_BRIDGE_CLASS(klass);
+
+    hc->root_bus_path = remote_pcihost_root_bus_path;
+    dc->realize = remote_pcihost_realize;
+
+    dc->user_creatable = false;
+    set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
+    dc->fw_name = "pci";
+}
+
+static const TypeInfo remote_pcihost_info = {
+    .name = TYPE_REMOTE_HOST_DEVICE,
+    .parent = TYPE_PCIE_HOST_BRIDGE,
+    .instance_size = sizeof(RemotePCIHost),
+    .class_init = remote_pcihost_class_init,
+};
+
+static void remote_pcihost_register(void)
+{
+    type_register_static(&remote_pcihost_info);
+}
+
+type_init(remote_pcihost_register)
diff --git a/include/hw/pci-host/remote.h b/include/hw/pci-host/remote.h
new file mode 100644
index 0000000..bab6d3c
--- /dev/null
+++ b/include/hw/pci-host/remote.h
@@ -0,0 +1,30 @@
+/*
+ * PCI Host for remote device
+ *
+ * Copyright © 2018, 2020 Oracle and/or its affiliates.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef REMOTE_PCIHOST_H
+#define REMOTE_PCIHOST_H
+
+#include "exec/memory.h"
+#include "hw/pci/pcie_host.h"
+
+#define TYPE_REMOTE_HOST_DEVICE "remote-pcihost"
+#define REMOTE_HOST_DEVICE(obj) \
+    OBJECT_CHECK(RemotePCIHost, (obj), TYPE_REMOTE_HOST_DEVICE)
+
+typedef struct RemotePCIHost {
+    /*< private >*/
+    PCIExpressHost parent_obj;
+    /*< public >*/
+
+    MemoryRegion *mr_pci_mem;
+    MemoryRegion *mr_sys_io;
+} RemotePCIHost;
+
+#endif
-- 
1.8.3.1