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

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 22 Nov 2023, Paul Durrant wrote:
> On 21/11/2023 22:10, Volodymyr Babchuk wrote:
> > From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
> > 
> > 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.

yes, it should be passed as command line option to QEMU

 
> > 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@xxxxxxxx>
> > Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
> > ---
> >   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;
> >       }
>