| Message ID | 1447201710-10229-11-git-send-email-benh@kernel.crashing.org |
|---|---|
| State | New |
| Headers | show |
On Wed, Nov 11, 2015 at 11:27:23AM +1100, Benjamin Herrenschmidt wrote: > 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 <benh@kernel.crashing.org> Reviewed-by: David Gibson <david@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 00fae60..83e6c07 100644 > --- a/target-ppc/excp_helper.c > +++ b/target-ppc/excp_helper.c > @@ -662,8 +662,12 @@ 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 57da931..12af61c 100644 > --- a/target-ppc/helper_regs.h > +++ b/target-ppc/helper_regs.h > @@ -114,8 +114,8 @@ 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; > }
diff --git a/target-ppc/excp_helper.c b/target-ppc/excp_helper.c index 00fae60..83e6c07 100644 --- a/target-ppc/excp_helper.c +++ b/target-ppc/excp_helper.c @@ -662,8 +662,12 @@ 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 57da931..12af61c 100644 --- a/target-ppc/helper_regs.h +++ b/target-ppc/helper_regs.h @@ -114,8 +114,8 @@ 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; }
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 <benh@kernel.crashing.org> --- target-ppc/excp_helper.c | 8 ++++++-- target-ppc/helper_regs.h | 4 ++-- 2 files changed, 8 insertions(+), 4 deletions(-)