This patch makes legacy backends optional. As was discussed at [1]
this is a solution to a problem when we can't run QEMU as a device
model in a non-privileged domain. This is because legacy backends
assume that they are always running in domain with ID = 0. Actually,
this may prevent running QEMU in a privileged domain with ID not equal
to zero.
With this patch it is possible to provide
"--disable-xen-legacy-backends" configure option to get QEMU binary
that can run in a driver domain. With price of not be able to use
legacy backends of course.
[1]
https://lists.gnu.org/archive/html/qemu-devel/2023-11/msg05022.html
Signed-off-by: Volodymyr Babchuk
---
I am not sure if I made correct changes to build system, so this patch
is tagged as RFC.
Changes in v3:
- New patch in v3
---
hw/9pfs/meson.build | 4 +++-
hw/display/meson.build| 4 +++-
hw/i386/pc.c | 2 ++
hw/usb/meson.build| 5 -
hw/xen/meson.build| 11 ---
hw/xen/xen-hvm-common.c | 2 ++
hw/xenpv/xen_machine_pv.c | 2 ++
meson.build | 5 +
meson_options.txt | 2 ++
scripts/meson-buildoptions.sh | 4
10 files changed, 35 insertions(+), 6 deletions(-)
diff --git a/hw/9pfs/meson.build b/hw/9pfs/meson.build
index 2944ea63c3..e8306ba8d2 100644
--- a/hw/9pfs/meson.build
+++ b/hw/9pfs/meson.build
@@ -15,7 +15,9 @@ fs_ss.add(files(
))
fs_ss.add(when: 'CONFIG_LINUX', if_true: files('9p-util-linux.c'))
fs_ss.add(when: 'CONFIG_DARWIN', if_true: files('9p-util-darwin.c'))
-fs_ss.add(when: 'CONFIG_XEN_BUS', if_true: files('xen-9p-backend.c'))
+if have_xen_legacy_backends
+ fs_ss.add(when: 'CONFIG_XEN_BUS', if_true: files('xen-9p-backend.c'))
+endif
system_ss.add_all(when: 'CONFIG_FSDEV_9P', if_true: fs_ss)
specific_ss.add(when: 'CONFIG_VIRTIO_9P', if_true: files('virtio-9p-device.c'))
diff --git a/hw/display/meson.build b/hw/display/meson.build
index 344dfe3d8c..18d657f6b3 100644
--- a/hw/display/meson.build
+++ b/hw/display/meson.build
@@ -14,7 +14,9 @@ system_ss.add(when: 'CONFIG_PL110', if_true: files('pl110.c'))
system_ss.add(when: 'CONFIG_SII9022', if_true: files('sii9022.c'))
system_ss.add(when: 'CONFIG_SSD0303', if_true: files('ssd0303.c'))
system_ss.add(when: 'CONFIG_SSD0323', if_true: files('ssd0323.c'))
-system_ss.add(when: 'CONFIG_XEN_BUS', if_true: files('xenfb.c'))
+if have_xen_legacy_backends
+ system_ss.add(when: 'CONFIG_XEN_BUS', if_true: files('xenfb.c'))
+endif
system_ss.add(when: 'CONFIG_VGA_PCI', if_true: files('vga-pci.c'))
system_ss.add(when: 'CONFIG_VGA_ISA', if_true: files('vga-isa.c'))
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 29b9964733..91857af428 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1263,7 +1263,9 @@ void pc_basic_device_init(struct PCMachineState *pcms,
pci_create_simple(pcms->bus, -1, "xen-platform");
}
pcms->xenbus = xen_bus_init();
+#ifdef CONFIG_XEN_LEGACY_BACKENDS
xen_be_init();
+#endif
}
#endif
diff --git a/hw/usb/meson.build b/hw/usb/meson.build
index e94149ebde..8d395745b2 100644
--- a/hw/usb/meson.build
+++ b/hw/usb/meson.build
@@ -84,6 +84,9 @@ if libusb.found()
hw_usb_modules += {'host': usbhost_ss}
endif
-system_ss.add(when: ['CONFIG_USB', 'CONFIG_XEN_BUS', libusb], if_true:
files('xen-usb.c'))
+if have_xen_legacy_backends
+ system_ss.add(when: ['CONFIG_USB', 'CONFIG_XEN_BUS', libusb],
+if_true: files('xen-usb.c'))
+endif
modules += { 'hw-usb': hw_usb_modules }
diff --git a/hw/xen/meson.build b/hw/xen/meson.build
index d887fa9ba4..964c3364f2 100644
--- a/hw/xen/meson.build
+++ b/hw/xen/meson.build
@@ -2,11 +2,16 @@ system_ss.add(when: ['CONFIG_XEN_BUS'], if_true: files(
'xen-backend.c',
'xen-bus-helper.c',
'xen-bus.c',
- 'xen-legacy-backend.c',
- 'xen_devconfig.c',
- 'xen_pvdev.c',
))
+if have_xen_legacy_backends
+ system_ss.add(when: ['CONFIG_XEN_BUS'], if_true: files(
+'xen_pvdev.c',
+'xen-legacy-backend.c',
+'xen_devconfig.c',
+ ))
+endif
+
system_ss.add(when: ['CONFIG_XEN', xen], if_true: files(
'xen-operations.c',
))
diff --git a/hw/xen/xen-hvm-common.c b/hw/xen/xen-hvm-common.c
index 565dc39c8f..2e7897dbd2 100644
--- a/hw/xen/xen-hvm-common.c
+++ b/hw/xen/xen-hvm-common.c
@@ -869,7 +869,9 @@ void xen_register_ioreq(XenIOState *state, unsigned int
max_cpus,
xen_bus_init();
+#ifdef CONFIG_XEN_LEGACY_BACKENDS
xen_be_init();
+#endif
return;
diff --git a/hw/xenpv/xen_machine_pv.c b/hw/xenpv/xen_machine_pv.c
index 9f9f137f99..03a55f345c 100644
--- a/hw/xenpv/xen_machine_pv.c
+++ b/hw/xenpv/xen_machine_pv.c
@@ -37,7 +37,9 @@ static void xen_init_pv(MachineState *machine)
setup_xen_backend_ops();
/* Initialize backend core & drivers */
+#ifdef CONFIG_XEN_LEGACY_BACKENDS
xen_be_init();
+#endif
switch (xen_mode) {
case XEN_ATTACH:
diff --git a/meson.build b/meson.build
index ec01f8b138..c8a43dd97d
