On 14.03.2016 17:56, Cédric Le Goater wrote: > From: Benjamin Herrenschmidt <b...@kernel.crashing.org> > > This helper is only used by the various instructions that can alter > MSR and not interrupts. Add a comment to that effect to the interrupt > code as well in case somebody wants to change this > > Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org> > Reviewed-by: David Gibson <da...@gibson.dropbear.id.au> > --- > target-ppc/excp_helper.c | 8 ++++++-- > target-ppc/helper_regs.h | 4 ++-- > 2 files changed, 8 insertions(+), 4 deletions(-) > > diff --git a/target-ppc/excp_helper.c b/target-ppc/excp_helper.c > index c890853d861b..37d4721db63b 100644 > --- a/target-ppc/excp_helper.c > +++ b/target-ppc/excp_helper.c > @@ -666,8 +666,12 @@ static inline void powerpc_excp(PowerPCCPU *cpu, int > excp_model, int excp) > } > } > #endif > - /* XXX: we don't use hreg_store_msr here as already have treated > - * any special case that could occur. Just store MSR and update > hflags > + /* We don't use hreg_store_msr here as already have treated > + * any special case that could occur. Just store MSR and update hflags > + * > + * Note: We *MUST* not use hreg_store_msr() as-is anyway because it > + * will prevent setting of the HV bit which some exceptions might need > + * to do. > */ > env->msr = new_msr & env->msr_mask; > hreg_compute_hflags(env); > diff --git a/target-ppc/helper_regs.h b/target-ppc/helper_regs.h > index 271fddf17f0a..844240d1a755 100644 > --- a/target-ppc/helper_regs.h > +++ b/target-ppc/helper_regs.h > @@ -75,8 +75,8 @@ static inline int hreg_store_msr(CPUPPCState *env, > target_ulong value, > excp = 0; > value &= env->msr_mask; > #if !defined(CONFIG_USER_ONLY) > - if (!alter_hv) { > - /* mtmsr cannot alter the hypervisor state */ > + /* Neither mtmsr nor guest state can alter HV */ > + if (!alter_hv || !(env->msr & MSR_HVB)) { > value &= ~MSR_HVB; > value |= env->msr & MSR_HVB; > }
Reviewed-by: Thomas Huth <th...@redhat.com>