Re: [PATCH v2 1/2] x86/dom0: fix restoring %cr3 and the mapcache override on PV build error

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Wed, Jul 31, 2024 at 08:32:03AM +0200, Jan Beulich wrote:
> On 30.07.2024 17:28, Roger Pau Monne wrote:
> > One of the error paths in the PV dom0 builder section that runs on the guest
> > page-tables wasn't restoring the Xen value of %cr3, neither removing the
> > mapcache override.
> 
> s/neither/nor/ ?
> 
> > --- a/xen/arch/x86/pv/dom0_build.c
> > +++ b/xen/arch/x86/pv/dom0_build.c
> > @@ -825,6 +825,8 @@ int __init dom0_construct_pv(struct domain *d,
> >      rc = elf_load_binary(&elf);
> >      if ( rc < 0 )
> >      {
> > +        mapcache_override_current(NULL);
> > +        switch_cr3_cr4(current->arch.cr3, read_cr4());
> >          printk("Failed to load the kernel binary\n");
> >          goto out;
> >      }
> 
> Just below here we have
> 
>     bootstrap_map(NULL);
> 
> This too is wanted in the error case aiui. Happy to move it up immediately
> ahead of the if() while committing, so long as you agree. Then:
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

I'm happy with this, but note there are further instances of error
paths above this one that already don't remove the bootstrap mappings.

Thanks, Roger.