Messages in this thread Patch in this message | | | From | Kamal Mostafa <> | Subject | [PATCH 3.19.y-ckt 43/56] KVM: x86: move steal time initialization to vcpu entry time | Date | Tue, 12 Apr 2016 13:59:01 -0700 |
| |
3.19.8-ckt19 -stable review patch. If anyone has any objections, please let me know.
---8<------------------------------------------------------------
From: Marcelo Tosatti <mtosatti@redhat.com>
commit 7cae2bedcbd4680b155999655e49c27b9cf020fa upstream.
As reported at https://bugs.launchpad.net/qemu/+bug/1494350, it is possible to have vcpu->arch.st.last_steal initialized from a thread other than vcpu thread, say the iothread, via KVM_SET_MSRS.
Which can cause an overflow later (when subtracting from vcpu threads sched_info.run_delay).
To avoid that, move steal time accumulation to vcpu entry time, before copying steal time data to guest.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Reviewed-by: David Matlack <dmatlack@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Cc: Liang Chen <liangchen.linux@gmail.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- arch/x86/kvm/x86.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 6d99bc5..18bfb6c 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2068,6 +2068,8 @@ static void accumulate_steal_time(struct kvm_vcpu *vcpu) static void record_steal_time(struct kvm_vcpu *vcpu) { + accumulate_steal_time(vcpu); + if (!(vcpu->arch.st.msr_val & KVM_MSR_ENABLED)) return; @@ -2201,12 +2203,6 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) if (!(data & KVM_MSR_ENABLED)) break; - vcpu->arch.st.last_steal = current->sched_info.run_delay; - - preempt_disable(); - accumulate_steal_time(vcpu); - preempt_enable(); - kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu); break; @@ -2908,7 +2904,6 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) vcpu->cpu = cpu; } - accumulate_steal_time(vcpu); kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu); } -- 2.7.4
| |