| Message ID | 1457974600-13828-6-git-send-email-clg@fr.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 14.03.2016 17:56, Cédric Le Goater wrote: > From: Benjamin Herrenschmidt <benh@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 <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 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 <thuth@redhat.com>
On Mon, Mar 14, 2016 at 08:29:10PM +0100, Thomas Huth wrote: > On 14.03.2016 17:56, Cédric Le Goater wrote: > > From: Benjamin Herrenschmidt <benh@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 <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 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 <thuth@redhat.com> This looks correct, but I'm not seeing a strong case for including it before 2.6.
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; }