Re: Regression: [PATCH v10 10/12] tools/libxl: use libxenhypfs for setting xen runtime parameters

[Jürgen Groß <jgross@xxxxxxxx>]

On 10.09.20 22:09, Andrew Cooper wrote:
> On 19/05/2020 08:21, Juergen Gross wrote:
> > Instead of xc_set_parameters() use xenhypfs_write() for setting
> > parameters of the hypervisor.
> >
> > Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> Something here isn't right.  XenServer's testing for XSA-304 has shown
> the following bizarre behaviour.
>
> # xl set-parameters ept=
> libxl: error: libxl.c:701:libxl_set_parameters: setting parameters:
> Invalid argument
> cannot set parameters: ept=
> # xl set-parameters ept=exec-sp
> # xl set-parameters ept=no-exec-sp
> libxl: error: libxl.c:701:libxl_set_parameters: setting parameters: No
> space left on device
> cannot set parameters: ept=no-exec-sp
>
> Instrumentation shows that the first two examples here enter
> parse_ept_param_runtime() with the provided string, while the third
> example doesn't.
>
> Given the -ENOSPC, I'm guessing there is some overly small internal
> buffer somewhere in the hyperfs infrastructure ?
Not, really, just a bad test for max length. Patch sent.


Juergen