Re: [PATCH for-4.19] xen/arm: static-shmem: fix "gbase/pbase used uninitialized" build failure

["Oleksii K." <oleksii.kurochko@xxxxxxxxx>]

Hi, 
On Wed, 2024-06-19 at 09:02 +0000, Bertrand Marquis wrote:
> Hi,
> 
> Adding Oleksii for Release ack.
> 
> Cheers
> Bertrand
> 
> > On 19 Jun 2024, at 08:46, Michal Orzel <michal.orzel@xxxxxxx>
> > wrote:
> > 
> > Building Xen with CONFIG_STATIC_SHM=y results in a build failure:
> > 
> > arch/arm/static-shmem.c: In function 'process_shm':
> > arch/arm/static-shmem.c:327:41: error: 'gbase' may be used
> > uninitialized [-Werror=maybe-uninitialized]
> >  327 |         if ( is_domain_direct_mapped(d) && (pbase != gbase)
> > )
> > arch/arm/static-shmem.c:305:17: note: 'gbase' was declared here
> >  305 |         paddr_t gbase, pbase, psize;
> > 
> > This is because the commit cb1ddafdc573 adds a check referencing
> > gbase/pbase variables which were not yet assigned a value. Fix it.
> > 
> > Fixes: cb1ddafdc573 ("xen/arm/static-shmem: Static-shmem should be
> > direct-mapped for direct-mapped domains")
> > Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>
Release-Acked-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>

~ Oleksii
> > ---
> > Rationale for 4.19: this patch fixes a build failure reported by
> > CI:
> > https://gitlab.com/xen-project/xen/-/jobs/7131807878
> > ---
> > xen/arch/arm/static-shmem.c | 13 +++++++------
> > 1 file changed, 7 insertions(+), 6 deletions(-)
> > 
> > diff --git a/xen/arch/arm/static-shmem.c b/xen/arch/arm/static-
> > shmem.c
> > index c434b96e6204..cd48d2896b7e 100644
> > --- a/xen/arch/arm/static-shmem.c
> > +++ b/xen/arch/arm/static-shmem.c
> > @@ -324,12 +324,6 @@ int __init process_shm(struct domain *d,
> > struct kernel_info *kinfo,
> >             printk("%pd: static shared memory bank not found:
> > '%s'", d, shm_id);
> >             return -ENOENT;
> >         }
> > -        if ( is_domain_direct_mapped(d) && (pbase != gbase) )
> > -        {
> > -            printk("%pd: physical address 0x%"PRIpaddr" and guest
> > address 0x%"PRIpaddr" are not direct-mapped.\n",
> > -                   d, pbase, gbase);
> > -            return -EINVAL;
> > -        }
> > 
> >         pbase = boot_shm_bank->start;
> >         psize = boot_shm_bank->size;
> > @@ -353,6 +347,13 @@ int __init process_shm(struct domain *d,
> > struct kernel_info *kinfo,
> >             /* guest phys address is after host phys address */
> >             gbase = dt_read_paddr(cells + addr_cells, addr_cells);
> > 
> > +            if ( is_domain_direct_mapped(d) && (pbase != gbase) )
> > +            {
> > +                printk("%pd: physical address 0x%"PRIpaddr" and
> > guest address 0x%"PRIpaddr" are not direct-mapped.\n",
> > +                       d, pbase, gbase);
> > +                return -EINVAL;
> > +            }
> > +
> >             for ( i = 0; i < PFN_DOWN(psize); i++ )
> >                 if ( !mfn_valid(mfn_add(maddr_to_mfn(pbase), i)) )
> >                 {
> > -- 
> > 2.25.1
> > 
>