On 5/18/22 15:25, Like Xu wrote:
From: Like Xu <likexu@xxxxxxxxxxx>
Similar to "kvm->arch.msr_filter", KVM should guarantee that vCPUs will
see either the previous filter or the new filter when user space calls
KVM_SET_PMU_EVENT_FILTER ioctl with the vCPU running so that guest
pmu events with identical settings in both the old and new filter have
deterministic behavior.
Fixes: 66bb8a065f5a ("KVM: x86: PMU Event Filter")
Signed-off-by: Like Xu <likexu@xxxxxxxxxxx>
Reviewed-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
Please always include the call trace where SRCU is not taken. The ones
I reconstructed always end up at a place inside srcu_read_lock/unlock:
reprogram_gp_counter/reprogram_fixed_counter
amd_pmu_set_msr
kvm_set_msr_common
svm_set_msr
__kvm_set_msr
kvm_set_msr_ignored_check
kvm_set_msr_with_filter
kvm_emulate_wrmsr**
emulator_set_msr_with_filter**
kvm_set_msr
emulator_set_msr**
do_set_msr
__msr_io
msr_io
ioctl(KVM_SET_MSRS)**
intel_pmu_set_msr
kvm_set_msr_common
vmx_set_msr (see svm_set_msr)
reprogram_counter
global_ctrl_changed
intel_pmu_set_msr (see above)
kvm_pmu_handle_event
vcpu_enter_guest**
kvm_pmu_incr_counter
kvm_pmu_trigger_event
nested_vmx_run**
kvm_skip_emulated_instruction**
x86_emulate_instruction**
reprogram_fixed_counters
intel_pmu_set_msr (see above)
Paolo
arch/x86/kvm/pmu.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index f189512207db..24624654e476 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -246,8 +246,9 @@ static bool check_pmu_event_filter(struct kvm_pmc *pmc)
struct kvm *kvm = pmc->vcpu->kvm;
bool allow_event = true;
__u64 key;
- int idx;
+ int idx, srcu_idx;
+ srcu_idx = srcu_read_lock(&kvm->srcu);
filter = srcu_dereference(kvm->arch.pmu_event_filter, &kvm->srcu);
if (!filter)
goto out;
@@ -270,6 +271,7 @@ static bool check_pmu_event_filter(struct kvm_pmc *pmc)
}
out:
+ srcu_read_unlock(&kvm->srcu, srcu_idx);
return allow_event;
}
