| Message ID | 20220509120330.3043773-5-tabba@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: arm64: Do not communicate host pmu event changes by accessing hyp data | expand |
Hi Fuad, On Mon, May 09, 2022 at 12:03:30PM +0000, Fuad Tabba wrote: > Now that the pmu code does not access hyp data, reenable it in > protected mode. > > Signed-off-by: Fuad Tabba <tabba@google.com> > --- > arch/arm64/kvm/pmu-emul.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c > index 3dc990ac4f44..11c43bed5f97 100644 > --- a/arch/arm64/kvm/pmu-emul.c > +++ b/arch/arm64/kvm/pmu-emul.c > @@ -774,8 +774,7 @@ void kvm_host_pmu_init(struct arm_pmu *pmu) > { > struct arm_pmu_entry *entry; > > - if (pmu->pmuver == 0 || pmu->pmuver == ID_AA64DFR0_PMUVER_IMP_DEF || > - is_protected_kvm_enabled()) > + if (pmu->pmuver == 0 || pmu->pmuver == ID_AA64DFR0_PMUVER_IMP_DEF) IIUC, you intend to enable the PMU for non-pVM guests, right? Based on the pKVM feature registers + trap handlers I can see that pVM use of the PMU is in fact disabled. It'd be good to state in the commit message what is exactly intended for pVMs and non-pVMs. Since the PMU counters are disabled outright for pVMs, is there any value in context switching between host/guest in this case? -- Thanks, Oliver
Hi Oliver, On Mon, May 9, 2022 at 11:36 PM Oliver Upton <oupton@google.com> wrote: > > Hi Fuad, > > On Mon, May 09, 2022 at 12:03:30PM +0000, Fuad Tabba wrote: > > Now that the pmu code does not access hyp data, reenable it in > > protected mode. > > > > Signed-off-by: Fuad Tabba <tabba@google.com> > > --- > > arch/arm64/kvm/pmu-emul.c | 3 +-- > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c > > index 3dc990ac4f44..11c43bed5f97 100644 > > --- a/arch/arm64/kvm/pmu-emul.c > > +++ b/arch/arm64/kvm/pmu-emul.c > > @@ -774,8 +774,7 @@ void kvm_host_pmu_init(struct arm_pmu *pmu) > > { > > struct arm_pmu_entry *entry; > > > > - if (pmu->pmuver == 0 || pmu->pmuver == ID_AA64DFR0_PMUVER_IMP_DEF || > > - is_protected_kvm_enabled()) > > + if (pmu->pmuver == 0 || pmu->pmuver == ID_AA64DFR0_PMUVER_IMP_DEF) > > IIUC, you intend to enable the PMU for non-pVM guests, right? Based on > the pKVM feature registers + trap handlers I can see that pVM use of the > PMU is in fact disabled. It'd be good to state in the commit message > what is exactly intended for pVMs and non-pVMs. > > Since the PMU counters are disabled outright for pVMs, is there any > value in context switching between host/guest in this case? I will make this clearer in the commit message. PMU won't be supported for protected VMs but should be for non-protected VMs in protected mode. Thanks, /fuad > -- > Thanks, > Oliver
diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c index 3dc990ac4f44..11c43bed5f97 100644 --- a/arch/arm64/kvm/pmu-emul.c +++ b/arch/arm64/kvm/pmu-emul.c @@ -774,8 +774,7 @@ void kvm_host_pmu_init(struct arm_pmu *pmu) { struct arm_pmu_entry *entry; - if (pmu->pmuver == 0 || pmu->pmuver == ID_AA64DFR0_PMUVER_IMP_DEF || - is_protected_kvm_enabled()) + if (pmu->pmuver == 0 || pmu->pmuver == ID_AA64DFR0_PMUVER_IMP_DEF) return; mutex_lock(&arm_pmus_lock);
Now that the pmu code does not access hyp data, reenable it in protected mode. Signed-off-by: Fuad Tabba <tabba@google.com> --- arch/arm64/kvm/pmu-emul.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)