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[PATCH v4 1/6] hw/xen: Set XenBackendInstance in the XenDevice before re
From: |
Volodymyr Babchuk |
Subject: |
[PATCH v4 1/6] hw/xen: Set XenBackendInstance in the XenDevice before realizing it |
Date: |
Sat, 2 Dec 2023 01:41:21 +0000 |
From: David Woodhouse <dwmw@amazon.co.uk>
This allows a XenDevice implementation to know whether it was created
by QEMU, or merely discovered in XenStore after the toolstack created
it. This will allow us to create frontend/backend nodes only when we
should, rather than unconditionally attempting to overwrite them from
a driver domain which doesn't have privileges to do so.
As an added benefit, it also means we no longer have to call the
xen_backend_set_device() function from the device models immediately
after calling qdev_realize_and_unref(). Even though we could make
the argument that it's safe to do so, and the pointer to the unreffed
device *will* actually still be valid, it still made my skin itch to
look at it.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
---
hw/block/xen-block.c | 3 +--
hw/char/xen_console.c | 2 +-
hw/net/xen_nic.c | 2 +-
hw/xen/xen-backend.c | 15 +--------------
hw/xen/xen-bus.c | 4 ++++
include/hw/xen/xen-backend.h | 2 --
include/hw/xen/xen-bus.h | 2 ++
7 files changed, 10 insertions(+), 20 deletions(-)
diff --git a/hw/block/xen-block.c b/hw/block/xen-block.c
index 6d64ede94f..c2ac9db4a2 100644
--- a/hw/block/xen-block.c
+++ b/hw/block/xen-block.c
@@ -1081,13 +1081,12 @@ static void xen_block_device_create(XenBackendInstance
*backend,
blockdev->iothread = iothread;
blockdev->drive = drive;
+ xendev->backend = backend;
if (!qdev_realize_and_unref(DEVICE(xendev), BUS(xenbus), errp)) {
error_prepend(errp, "realization of device %s failed: ", type);
goto fail;
}
-
- xen_backend_set_device(backend, xendev);
return;
fail:
diff --git a/hw/char/xen_console.c b/hw/char/xen_console.c
index 5cbee2f184..bef8a3a621 100644
--- a/hw/char/xen_console.c
+++ b/hw/char/xen_console.c
@@ -600,8 +600,8 @@ static void xen_console_device_create(XenBackendInstance
*backend,
goto fail;
}
+ xendev->backend = backend;
if (qdev_realize_and_unref(DEVICE(xendev), BUS(xenbus), errp)) {
- xen_backend_set_device(backend, xendev);
goto done;
}
diff --git a/hw/net/xen_nic.c b/hw/net/xen_nic.c
index af4ba3f1e6..afa10c96e8 100644
--- a/hw/net/xen_nic.c
+++ b/hw/net/xen_nic.c
@@ -627,8 +627,8 @@ static void xen_net_device_create(XenBackendInstance
*backend,
net->dev = number;
memcpy(&net->conf.macaddr, &mac, sizeof(mac));
+ xendev->backend = backend;
if (qdev_realize_and_unref(DEVICE(xendev), BUS(xenbus), errp)) {
- xen_backend_set_device(backend, xendev);
return;
}
diff --git a/hw/xen/xen-backend.c b/hw/xen/xen-backend.c
index b9bf70a9f5..b2e753ebc8 100644
--- a/hw/xen/xen-backend.c
+++ b/hw/xen/xen-backend.c
@@ -88,19 +88,6 @@ static void xen_backend_list_add(XenBackendInstance *backend)
QLIST_INSERT_HEAD(&backend_list, backend, entry);
}
-static XenBackendInstance *xen_backend_list_find(XenDevice *xendev)
-{
- XenBackendInstance *backend;
-
- QLIST_FOREACH(backend, &backend_list, entry) {
- if (backend->xendev == xendev) {
- return backend;
- }
- }
-
- return NULL;
-}
-
bool xen_backend_exists(const char *type, const char *name)
{
const XenBackendImpl *impl = xen_backend_table_lookup(type);
@@ -170,7 +157,7 @@ XenDevice *xen_backend_get_device(XenBackendInstance
*backend)
bool xen_backend_try_device_destroy(XenDevice *xendev, Error **errp)
{
- XenBackendInstance *backend = xen_backend_list_find(xendev);
+ XenBackendInstance *backend = xendev->backend;
const XenBackendImpl *impl;
if (!backend) {
diff --git a/hw/xen/xen-bus.c b/hw/xen/xen-bus.c
index 4973e7d9c9..dd0171ab98 100644
--- a/hw/xen/xen-bus.c
+++ b/hw/xen/xen-bus.c
@@ -1079,6 +1079,10 @@ static void xen_device_realize(DeviceState *dev, Error
**errp)
}
}
+ if (xendev->backend) {
+ xen_backend_set_device(xendev->backend, xendev);
+ }
+
xendev->exit.notify = xen_device_exit;
qemu_add_exit_notifier(&xendev->exit);
return;
diff --git a/include/hw/xen/xen-backend.h b/include/hw/xen/xen-backend.h
index 0f01631ae7..ea080ba7c9 100644
--- a/include/hw/xen/xen-backend.h
+++ b/include/hw/xen/xen-backend.h
@@ -10,8 +10,6 @@
#include "hw/xen/xen-bus.h"
-typedef struct XenBackendInstance XenBackendInstance;
-
typedef void (*XenBackendDeviceCreate)(XenBackendInstance *backend,
QDict *opts, Error **errp);
typedef void (*XenBackendDeviceDestroy)(XenBackendInstance *backend,
diff --git a/include/hw/xen/xen-bus.h b/include/hw/xen/xen-bus.h
index 334ddd1ff6..7647c4c38e 100644
--- a/include/hw/xen/xen-bus.h
+++ b/include/hw/xen/xen-bus.h
@@ -14,9 +14,11 @@
#include "qom/object.h"
typedef struct XenEventChannel XenEventChannel;
+typedef struct XenBackendInstance XenBackendInstance;
struct XenDevice {
DeviceState qdev;
+ XenBackendInstance *backend;
domid_t frontend_id;
char *name;
struct qemu_xs_handle *xsh;
--
2.42.0
- [PATCH v4 0/6] xen-arm: add support for virtio-pci, Volodymyr Babchuk, 2023/12/01
- [PATCH v4 3/6] xen: decouple generic xen code from legacy backends codebase, Volodymyr Babchuk, 2023/12/01
- [PATCH v4 5/6] xen_arm: set mc->max_cpus to GUEST_MAX_VCPUS, Volodymyr Babchuk, 2023/12/01
- [PATCH v4 6/6] xen_arm: Add virtual PCIe host bridge support, Volodymyr Babchuk, 2023/12/01
- [PATCH v4 2/6] xen: backends: don't overwrite XenStore nodes created by toolstack, Volodymyr Babchuk, 2023/12/01
- [PATCH v4 1/6] hw/xen: Set XenBackendInstance in the XenDevice before realizing it,
Volodymyr Babchuk <=
- [RFC PATCH v4 4/6] xen: add option to disable legacy backends, Volodymyr Babchuk, 2023/12/01