Hi Jan,
> -----Original Message-----
> From: Jan Beulich <jbeul...@suse.com>
> Subject: Re: [PATCH][4.17] x86/shadow: drop (replace) bogus assertions
>
> On 14.10.2022 12:30, Roger Pau Monné wrote:
> > On Fri, Oct 14, 2022 at 10:49:55AM +0200, Jan Beulich wrote:
> >> The addition of a call to shadow_blow_tables() from shadow_teardown()
> >> has resulted in the "no vcpus" related assertion becoming triggerable:
> >> If domain_create() fails with at least one page successfully allocated
> >> in the course of shadow_enable(), or if domain_create() succeeds and
> >> the domain is then killed without ever invoking XEN_DOMCTL_max_vcpus.
> >>
> >> The assertion's comment was bogus anyway: Shadow mode has been
> getting
> >> enabled before allocation of vCPU-s for quite some time. Convert the
> >> assertion to a conditional: As long as there are no vCPU-s, there's
> >> nothing to blow away.
> >>
> >> Fixes: e7aa55c0aab3 ("x86/p2m: free the paging memory pool
> preemptively")
> >> Reported-by: Andrew Cooper <andrew.coop...@citrix.com>
> >>
> >> A similar assertion/comment pair exists in _shadow_prealloc(); the
> >> comment is similarly bogus, and the assertion could in principle trigger
> >> e.g. when shadow_alloc_p2m_page() is called early enough. Replace
> those
> >> at the same time by a similar early return, here indicating failure to
> >> the caller (which will generally lead to the domain being crashed in
> >> shadow_prealloc()).
> >
> > It's my understanding we do care about this because a control domain
> > could try to populate the p2m before calling XEN_DOMCTL_max_vcpus,
> and
> > hence could trigger the ASSERT, as otherwise asserting would be fine.
> >
> >> Signed-off-by: Jan Beulich <jbeul...@suse.com>
> >
> > Acked-by: Roger Pau Monné <roger....@citrix.com>
>
> In a discussion amongst maintainers we've settled Andrew's reservations.
> May I please ask for a release-ack for this change, so it can go in (as
> a bug fix on top of the recent batch of XSAs)?
Absolutely. Thanks for noticing.
Release-acked-by: Henry Wang <henry.w...@arm.com>
Kind regards,
Henry
>
> Thanks, Jan
