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| author | Andrew Murray <andrew.murray@arm.com> | 2019-04-09 20:22:15 +0100 |
|---|---|---|
| committer | Marc Zyngier <marc.zyngier@arm.com> | 2019-04-24 15:46:26 +0100 |
| commit | 435e53fb5e21ad1820c5c69f208304c0e5623d01 (patch) | |
| tree | b3ad2d97114ca99f78c6edcc76c7b0e1446df91b /arch/arm64/kvm/sys_regs.c | |
| parent | 3d91befbb3a0fcec6e1eebde45c8074b88cc9441 (diff) | |
| download | lwn-435e53fb5e21ad1820c5c69f208304c0e5623d01.tar.gz lwn-435e53fb5e21ad1820c5c69f208304c0e5623d01.zip | |
arm64: KVM: Enable VHE support for :G/:H perf event modifiers
With VHE different exception levels are used between the host (EL2) and
guest (EL1) with a shared exception level for userpace (EL0). We can take
advantage of this and use the PMU's exception level filtering to avoid
enabling/disabling counters in the world-switch code. Instead we just
modify the counter type to include or exclude EL0 at vcpu_{load,put} time.
We also ensure that trapped PMU system register writes do not re-enable
EL0 when reconfiguring the backing perf events.
This approach completely avoids blackout windows seen with !VHE.
Suggested-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Andrew Murray <andrew.murray@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Diffstat (limited to 'arch/arm64/kvm/sys_regs.c')
| -rw-r--r-- | arch/arm64/kvm/sys_regs.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 12bd72e42b91..9d02643bc601 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -695,6 +695,7 @@ static bool access_pmcr(struct kvm_vcpu *vcpu, struct sys_reg_params *p, val |= p->regval & ARMV8_PMU_PMCR_MASK; __vcpu_sys_reg(vcpu, PMCR_EL0) = val; kvm_pmu_handle_pmcr(vcpu, val); + kvm_vcpu_pmu_restore_guest(vcpu); } else { /* PMCR.P & PMCR.C are RAZ */ val = __vcpu_sys_reg(vcpu, PMCR_EL0) @@ -850,6 +851,7 @@ static bool access_pmu_evtyper(struct kvm_vcpu *vcpu, struct sys_reg_params *p, if (p->is_write) { kvm_pmu_set_counter_event_type(vcpu, p->regval, idx); __vcpu_sys_reg(vcpu, reg) = p->regval & ARMV8_PMU_EVTYPE_MASK; + kvm_vcpu_pmu_restore_guest(vcpu); } else { p->regval = __vcpu_sys_reg(vcpu, reg) & ARMV8_PMU_EVTYPE_MASK; } @@ -875,6 +877,7 @@ static bool access_pmcnten(struct kvm_vcpu *vcpu, struct sys_reg_params *p, /* accessing PMCNTENSET_EL0 */ __vcpu_sys_reg(vcpu, PMCNTENSET_EL0) |= val; kvm_pmu_enable_counter(vcpu, val); + kvm_vcpu_pmu_restore_guest(vcpu); } else { /* accessing PMCNTENCLR_EL0 */ __vcpu_sys_reg(vcpu, PMCNTENSET_EL0) &= ~val; |