On 10/11/2023 15:42, Volodymyr Babchuk wrote:
Add option to preserve owner when creating an entry in Xen Store. This
may be needed in cases when Qemu is working as device model in a
domain that is Domain-0, e.g. in driver domain.
"owner" parameter for qemu_xen_xs_create() function can have special
value XS_PRESERVE_OWNER, which will make specific implementation to
get original owner of an entry and pass it back to
set_permissions() call.
If QEMU is running in a driver domain then it should know whether the
domid of the domain it is running in and use that. Yes, it is hardcoded
to 0 at the moment but surely a backend domid (which defaults to 0)
could be passed on the command line?
Paul
Signed-off-by: Volodymyr Babchuk <volodymyr_babc...@epam.com>
---
hw/i386/kvm/xen_xenstore.c | 18 ++++++++++++++++++
hw/xen/xen-operations.c | 12 ++++++++++++
include/hw/xen/xen_backend_ops.h | 2 ++
3 files changed, 32 insertions(+)
diff --git a/hw/i386/kvm/xen_xenstore.c b/hw/i386/kvm/xen_xenstore.c
index 660d0b72f9..7b894a9884 100644
--- a/hw/i386/kvm/xen_xenstore.c
+++ b/hw/i386/kvm/xen_xenstore.c
@@ -1572,6 +1572,24 @@ static bool xs_be_create(struct qemu_xs_handle *h,
xs_transaction_t t,
return false;
}
+ if (owner == XS_PRESERVE_OWNER) {
+ GList *perms;
+ char letter;
+
+ err = xs_impl_get_perms(h->impl, 0, t, path, &perms);
+ if (err) {
+ errno = err;
+ return false;
+ }
+
+ if (sscanf(perms->data, "%c%u", &letter, &owner) != 2) {
+ errno = EFAULT;
+ g_list_free_full(perms, g_free);
+ return false;
+ }
+ g_list_free_full(perms, g_free);
+ }
+
perms_list = g_list_append(perms_list,
xs_perm_as_string(XS_PERM_NONE, owner));
perms_list = g_list_append(perms_list,
diff --git a/hw/xen/xen-operations.c b/hw/xen/xen-operations.c
index e00983ec44..1df59b3c08 100644
--- a/hw/xen/xen-operations.c
+++ b/hw/xen/xen-operations.c
@@ -300,6 +300,18 @@ static bool libxenstore_create(struct qemu_xs_handle *h,
xs_transaction_t t,
return false;
}
+ if (owner == XS_PRESERVE_OWNER) {
+ struct xs_permissions *tmp;
+ unsigned int num;
+
+ tmp = xs_get_permissions(h->xsh, 0, path, &num);
+ if (tmp == NULL) {
+ return false;
+ }
+ perms_list[0].id = tmp[0].id;
+ free(tmp);
+ }
+
return xs_set_permissions(h->xsh, t, path, perms_list,
ARRAY_SIZE(perms_list));
}
diff --git a/include/hw/xen/xen_backend_ops.h b/include/hw/xen/xen_backend_ops.h
index 90cca85f52..273e414559 100644
--- a/include/hw/xen/xen_backend_ops.h
+++ b/include/hw/xen/xen_backend_ops.h
@@ -266,6 +266,8 @@ typedef uint32_t xs_transaction_t;
#define XS_PERM_READ 0x01
#define XS_PERM_WRITE 0x02
+#define XS_PRESERVE_OWNER 0xFFFE
+
struct xenstore_backend_ops {
struct qemu_xs_handle *(*open)(void);
void (*close)(struct qemu_xs_handle *h);