| Message ID | 20180417071722.9399-10-david@gibson.dropbear.id.au |
|---|---|
| State | New |
| Headers | show |
| Series | spapr: Cleanups to PAPR mode setup | expand |
On 17.04.2018 09:17, David Gibson wrote: > cpu_ppc_set_papr() removes the EP and HV bits from the MSR mask. While > removing the HV bit makes sense (a cpu in PAPR mode should never be > emulated in hypervisor mode), the EP bit is just bizarre. Although it's > true that a papr mode guest shouldn't be able to change the exception > prefix, the MSR[EP] bit doesn't even exist on the cpus supported for PAPR > mode, so it's pointless to do anything with it here. > > Signed-off-by: David Gibson <david@gibson.dropbear.id.au> > --- > target/ppc/translate_init.c | 9 ++++----- > 1 file changed, 4 insertions(+), 5 deletions(-) > > diff --git a/target/ppc/translate_init.c b/target/ppc/translate_init.c > index 5e89901149..bb5559d799 100644 > --- a/target/ppc/translate_init.c > +++ b/target/ppc/translate_init.c > @@ -8870,12 +8870,11 @@ void cpu_ppc_set_papr(PowerPCCPU *cpu, PPCVirtualHypervisor *vhyp) > > cpu->vhyp = vhyp; > > - /* PAPR always has exception vectors in RAM not ROM. To ensure this, > - * MSR[IP] should never be set. > - * > - * We also disallow setting of MSR_HV > + /* > + * With a virtual hypervisor mode we never allow the CPU to go > + * hypervisor mode itself > */ > - env->msr_mask &= ~((1ull << MSR_EP) | MSR_HVB); > + env->msr_mask &= ~MSR_HVB; > > /* Tell KVM that we're in PAPR mode */ > if (kvm_enabled()) { Looks right. Reviewed-by: Thomas Huth <thuth@redhat.com>
On Fri, Apr 20, 2018 at 08:08:59AM +0200, Thomas Huth wrote: > On 17.04.2018 09:17, David Gibson wrote: > > cpu_ppc_set_papr() removes the EP and HV bits from the MSR mask. While > > removing the HV bit makes sense (a cpu in PAPR mode should never be > > emulated in hypervisor mode), the EP bit is just bizarre. Although it's > > true that a papr mode guest shouldn't be able to change the exception > > prefix, the MSR[EP] bit doesn't even exist on the cpus supported for PAPR > > mode, so it's pointless to do anything with it here. > > > > Signed-off-by: David Gibson <david@gibson.dropbear.id.au> > > --- > > target/ppc/translate_init.c | 9 ++++----- > > 1 file changed, 4 insertions(+), 5 deletions(-) > > > > diff --git a/target/ppc/translate_init.c b/target/ppc/translate_init.c > > index 5e89901149..bb5559d799 100644 > > --- a/target/ppc/translate_init.c > > +++ b/target/ppc/translate_init.c > > @@ -8870,12 +8870,11 @@ void cpu_ppc_set_papr(PowerPCCPU *cpu, PPCVirtualHypervisor *vhyp) > > > > cpu->vhyp = vhyp; > > > > - /* PAPR always has exception vectors in RAM not ROM. To ensure this, > > - * MSR[IP] should never be set. > > - * > > - * We also disallow setting of MSR_HV > > + /* > > + * With a virtual hypervisor mode we never allow the CPU to go > > + * hypervisor mode itself > > */ > > - env->msr_mask &= ~((1ull << MSR_EP) | MSR_HVB); > > + env->msr_mask &= ~MSR_HVB; > > > > /* Tell KVM that we're in PAPR mode */ > > if (kvm_enabled()) { > > Looks right. > > Reviewed-by: Thomas Huth <thuth@redhat.com> Turns out this one is pretty much independent of the rest of the series, so I've merged it to ppc-for-2.13 already.
diff --git a/target/ppc/translate_init.c b/target/ppc/translate_init.c index 5e89901149..bb5559d799 100644 --- a/target/ppc/translate_init.c +++ b/target/ppc/translate_init.c @@ -8870,12 +8870,11 @@ void cpu_ppc_set_papr(PowerPCCPU *cpu, PPCVirtualHypervisor *vhyp) cpu->vhyp = vhyp; - /* PAPR always has exception vectors in RAM not ROM. To ensure this, - * MSR[IP] should never be set. - * - * We also disallow setting of MSR_HV + /* + * With a virtual hypervisor mode we never allow the CPU to go + * hypervisor mode itself */ - env->msr_mask &= ~((1ull << MSR_EP) | MSR_HVB); + env->msr_mask &= ~MSR_HVB; /* Tell KVM that we're in PAPR mode */ if (kvm_enabled()) {
cpu_ppc_set_papr() removes the EP and HV bits from the MSR mask. While removing the HV bit makes sense (a cpu in PAPR mode should never be emulated in hypervisor mode), the EP bit is just bizarre. Although it's true that a papr mode guest shouldn't be able to change the exception prefix, the MSR[EP] bit doesn't even exist on the cpus supported for PAPR mode, so it's pointless to do anything with it here. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> --- target/ppc/translate_init.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)