diff mbox series

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

Message ID cd3a20960062081d7c911879f509c26aedee89b4.1596217462.git.jag.raman@oracle.com
State New
Headers show
Series Initial support for multi-process qemu | expand

Commit Message

Jagannathan Raman July 31, 2020, 6:20 p.m. UTC
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

Comments

Stefan Hajnoczi Aug. 4, 2020, 10:47 a.m. UTC | #1
On Fri, Jul 31, 2020 at 02:20:10PM -0400, Jagannathan Raman wrote:
> + * 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

s/It's/Its/ :)

> +static void remote_pcihost_realize(DeviceState *dev, Error **errp)
> +{
> +    char *busname = g_strdup_printf("remote-pci-%ld", (unsigned long)getpid());

Why is the pid used here? I don't understand why this helps. If
additional instances are created in this process then the name won't be
unique. The name isn't exposed outside the process, so there is no need
to uniquely identify the process either.

g_free(busname) is missing. A nice way to fix this is:

  g_autofree char *busname = ...

This avoids the need to manually call g_free().
diff mbox series

Patch

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