From: Fabiano Rosas farosas@linux.ibm.com
[ Upstream commit 9981bace85d816ed8724ac46e49285e8488d29e6 ]
At debugfs/kvm/<pid>/vcpu0/timings we show how long each part of the code takes to run:
$ cat /sys/kernel/debug/kvm/*-*/vcpu0/timings rm_entry: 123785 49398892 118 4898 rm_intr: 123780 6075890 22 390 rm_exit: 0 0 0 0 <-- NOK guest: 123780 46732919988 402 9997638 cede: 0 0 0 0 <-- OK, no cede napping in P9
The "rm_exit" is always showing zero because it is the last one and end_timing does not increment the counter of the previous entry.
We can fix it by calling accumulate_time again instead of end_timing. That way the counter gets incremented. The rest of the arithmetic can be ignored because there are no timing points after this and the accumulators are reset before the next round.
Signed-off-by: Fabiano Rosas farosas@linux.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20220525130554.2614394-2-farosas@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/kvm/book3s_hv_p9_entry.c | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_hv_p9_entry.c b/arch/powerpc/kvm/book3s_hv_p9_entry.c index a28e5b3daabd..f7591b6c92d1 100644 --- a/arch/powerpc/kvm/book3s_hv_p9_entry.c +++ b/arch/powerpc/kvm/book3s_hv_p9_entry.c @@ -438,15 +438,6 @@ void restore_p9_host_os_sprs(struct kvm_vcpu *vcpu, EXPORT_SYMBOL_GPL(restore_p9_host_os_sprs);
#ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING -static void __start_timing(struct kvm_vcpu *vcpu, struct kvmhv_tb_accumulator *next) -{ - struct kvmppc_vcore *vc = vcpu->arch.vcore; - u64 tb = mftb() - vc->tb_offset_applied; - - vcpu->arch.cur_activity = next; - vcpu->arch.cur_tb_start = tb; -} - static void __accumulate_time(struct kvm_vcpu *vcpu, struct kvmhv_tb_accumulator *next) { struct kvmppc_vcore *vc = vcpu->arch.vcore; @@ -478,8 +469,8 @@ static void __accumulate_time(struct kvm_vcpu *vcpu, struct kvmhv_tb_accumulator curr->seqcount = seq + 2; }
-#define start_timing(vcpu, next) __start_timing(vcpu, next) -#define end_timing(vcpu) __start_timing(vcpu, NULL) +#define start_timing(vcpu, next) __accumulate_time(vcpu, next) +#define end_timing(vcpu) __accumulate_time(vcpu, NULL) #define accumulate_time(vcpu, next) __accumulate_time(vcpu, next) #else #define start_timing(vcpu, next) do {} while (0)