| Message ID | 20230610061520.3026530-3-reijiw@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: arm64: PMU: Disallow vPMU on non-uniform PMUVer systems | expand |
On Fri, Jun 09, 2023 at 11:15:20PM -0700, Reiji Watanabe wrote: > Disallow userspace from configuring vPMU for guests on systems > where the PMUVer is not uniform across all PEs. > KVM has not been advertising PMUv3 to the guests with vPMU on > such systems anyway, and such systems would be extremely > uncommon and unlikely to even use KVM. Ok... Now your changes are starting to make sense. This patch is rather relevant context for interpreting the other PMU fix [*], so I'd recommend you send this as a combined series going forward. [*] https://lore.kernel.org/kvmarm/20230610194510.4146549-1-reijiw@google.com/ > diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h > index eef17de966da..af1fe2b53fbb 100644 > --- a/include/kvm/arm_pmu.h > +++ b/include/kvm/arm_pmu.h > @@ -105,6 +105,14 @@ void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu); > > u8 kvm_arm_pmu_get_pmuver_limit(void); > > +static inline void kvm_arm_set_support_pmu_v3(void) > +{ > + u8 pmuver = kvm_arm_pmu_get_pmuver_limit(); > + > + if (pmu_v3_is_supported(pmuver)) > + static_branch_enable(&kvm_arm_pmu_available); > +} > + > #else > struct kvm_pmu { > }; > @@ -114,6 +122,8 @@ static inline bool kvm_arm_support_pmu_v3(void) > return false; > } > > +static inline void kvm_arm_set_support_pmu_v3(void) {}; > + nit: Give this thing a more generic name (e.g. kvm_pmu_init()) in case we wind up needing more boot-time PMU initialization. -- Thanks, Oliver
Hi Oliver, On Sat, Jun 10, 2023 at 07:32:42PM -0700, Oliver Upton wrote: > On Fri, Jun 09, 2023 at 11:15:20PM -0700, Reiji Watanabe wrote: > > Disallow userspace from configuring vPMU for guests on systems > > where the PMUVer is not uniform across all PEs. > > KVM has not been advertising PMUv3 to the guests with vPMU on > > such systems anyway, and such systems would be extremely > > uncommon and unlikely to even use KVM. > > Ok... Now your changes are starting to make sense. This patch is rather > relevant context for interpreting the other PMU fix [*], so I'd > recommend you send this as a combined series going forward. Sure, I will include the patch [*] in this series. > > [*] https://lore.kernel.org/kvmarm/20230610194510.4146549-1-reijiw@google.com/ > > > diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h > > index eef17de966da..af1fe2b53fbb 100644 > > --- a/include/kvm/arm_pmu.h > > +++ b/include/kvm/arm_pmu.h > > @@ -105,6 +105,14 @@ void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu); > > > > u8 kvm_arm_pmu_get_pmuver_limit(void); > > > > +static inline void kvm_arm_set_support_pmu_v3(void) > > +{ > > + u8 pmuver = kvm_arm_pmu_get_pmuver_limit(); > > + > > + if (pmu_v3_is_supported(pmuver)) > > + static_branch_enable(&kvm_arm_pmu_available); > > +} > > + > > #else > > struct kvm_pmu { > > }; > > @@ -114,6 +122,8 @@ static inline bool kvm_arm_support_pmu_v3(void) > > return false; > > } > > > > +static inline void kvm_arm_set_support_pmu_v3(void) {}; > > + > > nit: Give this thing a more generic name (e.g. kvm_pmu_init()) in case > we wind up needing more boot-time PMU initialization. Sure, thank you for the suggestion! Thank you, Reiji
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 14391826241c..21901fbd6e4d 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -1960,6 +1960,7 @@ static int __init init_subsystems(void) goto out; kvm_register_perf_callbacks(NULL); + kvm_arm_set_support_pmu_v3(); out: if (err) diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c index 5d2903f52a5f..45b84cf22026 100644 --- a/arch/arm64/kvm/pmu-emul.c +++ b/arch/arm64/kvm/pmu-emul.c @@ -684,9 +684,6 @@ void kvm_host_pmu_init(struct arm_pmu *pmu) entry->arm_pmu = pmu; list_add_tail(&entry->entry, &arm_pmus); - if (list_is_singular(&arm_pmus)) - static_branch_enable(&kvm_arm_pmu_available); - out_unlock: mutex_unlock(&arm_pmus_lock); } diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h index eef17de966da..af1fe2b53fbb 100644 --- a/include/kvm/arm_pmu.h +++ b/include/kvm/arm_pmu.h @@ -105,6 +105,14 @@ void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu); u8 kvm_arm_pmu_get_pmuver_limit(void); +static inline void kvm_arm_set_support_pmu_v3(void) +{ + u8 pmuver = kvm_arm_pmu_get_pmuver_limit(); + + if (pmu_v3_is_supported(pmuver)) + static_branch_enable(&kvm_arm_pmu_available); +} + #else struct kvm_pmu { }; @@ -114,6 +122,8 @@ static inline bool kvm_arm_support_pmu_v3(void) return false; } +static inline void kvm_arm_set_support_pmu_v3(void) {}; + #define kvm_arm_pmu_irq_initialized(v) (false) static inline u64 kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu, u64 select_idx)
Disallow userspace from configuring vPMU for guests on systems where the PMUVer is not uniform across all PEs. KVM has not been advertising PMUv3 to the guests with vPMU on such systems anyway, and such systems would be extremely uncommon and unlikely to even use KVM. Signed-off-by: Reiji Watanabe <reijiw@google.com> --- arch/arm64/kvm/arm.c | 1 + arch/arm64/kvm/pmu-emul.c | 3 --- include/kvm/arm_pmu.h | 10 ++++++++++ 3 files changed, 11 insertions(+), 3 deletions(-)