Re: [PATCH v2 4/6] xen_pvdev: Do not assume Dom0 when creating a directory

[Paul Durrant <xadimgnik@gmail.com>]

On 21/11/2023 22:10, Volodymyr Babchuk wrote:
> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
> 
> Instead of forcing the owner to domid 0, use XS_PRESERVE_OWNER to
> inherit the owner of the directory.

Ah... so that's why the previous patch is there.

This is not the right way to fix it. The QEMU Xen support is *assuming* 
that QEMU is either running in, or emulating, dom0. In the emulation 
case this is probably fine, but the 'real Xen' case it should be using 
the correct domid for node creation. I guess this could either be 
supplied on the command line or discerned by reading the local domain 
'domid' node.

> 
> Note that for other than Dom0 domain (non toolstack domain) the
> "driver_domain" property should be set in domain config file for the
> toolstack to create required directories in advance.
> 
> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
> Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@epam.com>
> ---
>   hw/xen/xen_pvdev.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/xen/xen_pvdev.c b/hw/xen/xen_pvdev.c
> index c5ad71e8dc..42bdd4f6c8 100644
> --- a/hw/xen/xen_pvdev.c
> +++ b/hw/xen/xen_pvdev.c
> @@ -60,7 +60,8 @@ void xen_config_cleanup(void)
>   
>   int xenstore_mkdir(char *path, int p)
>   {
> -    if (!qemu_xen_xs_create(xenstore, 0, 0, xen_domid, p, path)) {
> +    if (!qemu_xen_xs_create(xenstore, 0, XS_PRESERVE_OWNER,
> +                            xen_domid, p, path)) {
>           xen_pv_printf(NULL, 0, "xs_mkdir %s: failed\n", path);
>           return -1;
>       }