Messages in this thread | | | Date | Fri, 3 Nov 2023 19:34:21 +0100 | Subject | Re: [PATCH 2/4] KVM: s390: vsie: Fix length of facility list shadowed | From | David Hildenbrand <> |
| |
On 03.11.23 18:30, Nina Schoetterl-Glausch wrote: > The length of the facility list accessed when interpretively executing > STFLE is the same as the hosts facility list (in case of format-0) > When shadowing, copy only those bytes. > The memory following the facility list need not be accessible, in which > case we'd wrongly inject a validity intercept. > > Fixes: 66b630d5b7f2 ("KVM: s390: vsie: support STFLE interpretation") > Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com> > --- > arch/s390/include/asm/facility.h | 6 ++++++ > arch/s390/kernel/Makefile | 2 +- > arch/s390/kernel/facility.c | 18 ++++++++++++++++++ > arch/s390/kvm/vsie.c | 12 +++++++++++- > 4 files changed, 36 insertions(+), 2 deletions(-) > create mode 100644 arch/s390/kernel/facility.c > > diff --git a/arch/s390/include/asm/facility.h b/arch/s390/include/asm/facility.h > index 94b6919026df..796007125dff 100644 > --- a/arch/s390/include/asm/facility.h > +++ b/arch/s390/include/asm/facility.h > @@ -111,4 +111,10 @@ static inline void stfle(u64 *stfle_fac_list, int size) > preempt_enable(); > } > > +/** > + * stfle_size - Actual size of the facility list as specified by stfle > + * (number of double words) > + */ > +unsigned int stfle_size(void); > + > #endif /* __ASM_FACILITY_H */ > diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile > index 0df2b88cc0da..0daa81439478 100644 > --- a/arch/s390/kernel/Makefile > +++ b/arch/s390/kernel/Makefile > @@ -41,7 +41,7 @@ obj-y += sysinfo.o lgr.o os_info.o > obj-y += runtime_instr.o cache.o fpu.o dumpstack.o guarded_storage.o sthyi.o > obj-y += entry.o reipl.o kdebugfs.o alternative.o > obj-y += nospec-branch.o ipl_vmparm.o machine_kexec_reloc.o unwind_bc.o > -obj-y += smp.o text_amode31.o stacktrace.o abs_lowcore.o > +obj-y += smp.o text_amode31.o stacktrace.o abs_lowcore.o facility.o > > extra-y += vmlinux.lds > > diff --git a/arch/s390/kernel/facility.c b/arch/s390/kernel/facility.c > new file mode 100644 > index 000000000000..c33a95a562da > --- /dev/null > +++ b/arch/s390/kernel/facility.c > @@ -0,0 +1,18 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright IBM Corp. 2023 > + */ > + > +#include <asm/facility.h> > + > +unsigned int stfle_size(void) > +{ > + static unsigned int size = 0; > + u64 dummy; > + > + if (!size) { > + size = __stfle_asm(&dummy, 1) + 1; > + } > + return size; > +} > +EXPORT_SYMBOL(stfle_size);
Possible races? Should have to use an atomic?
No access to documentation, but sounds plausible.
Acked-by: David Hildenbrand <david@redhat.com>
-- Cheers,
David / dhildenb
| |