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| author | Bharat Bhushan <r65777@freescale.com> | 2011-03-25 10:32:13 +0530 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2011-05-11 07:57:04 -0400 |
| commit | 09000adb86550d2895b64faa52e64eaec3cae7b2 (patch) | |
| tree | e2a932b4735b1296e2df760fea26030286f9daaa /arch/powerpc/kvm/timing.c | |
| parent | 7c5625227ff8c81953e953d8e25c3eba2ab0aeb3 (diff) | |
| download | kernel_samsung_smdk4412-09000adb86550d2895b64faa52e64eaec3cae7b2.tar.gz kernel_samsung_smdk4412-09000adb86550d2895b64faa52e64eaec3cae7b2.tar.bz2 kernel_samsung_smdk4412-09000adb86550d2895b64faa52e64eaec3cae7b2.zip | |
KVM: PPC: Fix issue clearing exit timing counters
Following dump is observed on host when clearing the exit timing counters
[root@p1021mds kvm]# echo -n 'c' > vm1200_vcpu0_timing
INFO: task echo:1276 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
echo D 0ff5bf94 0 1276 1190 0x00000000
Call Trace:
[c2157e40] [c0007908] __switch_to+0x9c/0xc4
[c2157e50] [c040293c] schedule+0x1b4/0x3bc
[c2157e90] [c04032dc] __mutex_lock_slowpath+0x74/0xc0
[c2157ec0] [c00369e4] kvmppc_init_timing_stats+0x20/0xb8
[c2157ed0] [c0036b00] kvmppc_exit_timing_write+0x84/0x98
[c2157ef0] [c00b9f90] vfs_write+0xc0/0x16c
[c2157f10] [c00ba284] sys_write+0x4c/0x90
[c2157f40] [c000e320] ret_from_syscall+0x0/0x3c
The vcpu->mutex is used by kvm_ioctl_* (KVM_RUN etc) and same was
used when clearing the stats (in kvmppc_init_timing_stats()). What happens
is that when the guest is idle then it held the vcpu->mutx. While the
exiting timing process waits for guest to release the vcpu->mutex and
a hang state is reached.
Now using seprate lock for exit timing stats.
Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
Acked-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/powerpc/kvm/timing.c')
| -rw-r--r-- | arch/powerpc/kvm/timing.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/arch/powerpc/kvm/timing.c b/arch/powerpc/kvm/timing.c index a021f5827a3..18f40fd3e98 100644 --- a/arch/powerpc/kvm/timing.c +++ b/arch/powerpc/kvm/timing.c @@ -34,8 +34,8 @@ void kvmppc_init_timing_stats(struct kvm_vcpu *vcpu) { int i; - /* pause guest execution to avoid concurrent updates */ - mutex_lock(&vcpu->mutex); + /* Take a lock to avoid concurrent updates */ + mutex_lock(&vcpu->arch.exit_timing_lock); vcpu->arch.last_exit_type = 0xDEAD; for (i = 0; i < __NUMBER_OF_KVM_EXIT_TYPES; i++) { @@ -49,7 +49,7 @@ void kvmppc_init_timing_stats(struct kvm_vcpu *vcpu) vcpu->arch.timing_exit.tv64 = 0; vcpu->arch.timing_last_enter.tv64 = 0; - mutex_unlock(&vcpu->mutex); + mutex_unlock(&vcpu->arch.exit_timing_lock); } static void add_exit_timing(struct kvm_vcpu *vcpu, u64 duration, int type) @@ -65,6 +65,8 @@ static void add_exit_timing(struct kvm_vcpu *vcpu, u64 duration, int type) return; } + mutex_lock(&vcpu->arch.exit_timing_lock); + vcpu->arch.timing_count_type[type]++; /* sum */ @@ -93,6 +95,8 @@ static void add_exit_timing(struct kvm_vcpu *vcpu, u64 duration, int type) vcpu->arch.timing_min_duration[type] = duration; if (unlikely(duration > vcpu->arch.timing_max_duration[type])) vcpu->arch.timing_max_duration[type] = duration; + + mutex_unlock(&vcpu->arch.exit_timing_lock); } void kvmppc_update_timing_stats(struct kvm_vcpu *vcpu) |