| Message ID | 1502095466-21312-2-git-send-email-longpeng2@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 07.08.2017 10:44, Longpeng(Mike) wrote: > If the vcpu(me) exit due to request a usermode spinlock, then > the spinlock-holder may be preempted in usermode or kernmode. > > But if the vcpu(me) is in kernmode, then the holder must be > preempted in kernmode, so we should choose a vcpu in kernmode > as the most eligible candidate. > > For some architecture(e.g. arm/s390), spin/preempt_in_kernel() > are the same, but they are different for X86. > > Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com> > --- > arch/mips/kvm/mips.c | 10 ++++++++++ > arch/powerpc/kvm/powerpc.c | 10 ++++++++++ > arch/s390/kvm/kvm-s390.c | 10 ++++++++++ > arch/x86/kvm/x86.c | 10 ++++++++++ > include/linux/kvm_host.h | 2 ++ > virt/kvm/arm/arm.c | 10 ++++++++++ > virt/kvm/kvm_main.c | 4 ++++ > 7 files changed, 56 insertions(+) > > diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c > index d4b2ad1..e04e6b3 100644 > --- a/arch/mips/kvm/mips.c > +++ b/arch/mips/kvm/mips.c > @@ -98,6 +98,16 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu) > return !!(vcpu->arch.pending_exceptions); > } > > +bool kvm_arch_vcpu_spin_in_kernel(struct kvm_vcpu *vcpu) > +{ > + return false; > +} > + > +bool kvm_arch_vcpu_preempt_in_kernel(struct kvm_vcpu *vcpu) > +{ > + return false; > +} > + > int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu) > { > return 1; > diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c > index 1a75c0b..c573ddd 100644 > --- a/arch/powerpc/kvm/powerpc.c > +++ b/arch/powerpc/kvm/powerpc.c > @@ -58,6 +58,16 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *v) > return !!(v->arch.pending_exceptions) || kvm_request_pending(v); > } > > +bool kvm_arch_vcpu_spin_in_kernel(struct kvm_vcpu *vcpu) > +{ > + return false; > +} > + > +bool kvm_arch_vcpu_preempt_in_kernel(struct kvm_vcpu *vcpu) > +{ > + return false; > +} > + > int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu) > { > return 1; > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c > index af09d34..f78cdc2 100644 > --- a/arch/s390/kvm/kvm-s390.c > +++ b/arch/s390/kvm/kvm-s390.c > @@ -2447,6 +2447,16 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu) > return kvm_s390_vcpu_has_irq(vcpu, 0); > } > > +bool kvm_arch_vcpu_spin_in_kernel(struct kvm_vcpu *vcpu) > +{ > + return false; > +} > + > +bool kvm_arch_vcpu_preempt_in_kernel(struct kvm_vcpu *vcpu) > +{ > + return false; > +} > + > void kvm_s390_vcpu_block(struct kvm_vcpu *vcpu) > { > atomic_or(PROG_BLOCK_SIE, &vcpu->arch.sie_block->prog20); > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 6c97c82..04c6a1f 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -8435,6 +8435,16 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu) > return kvm_vcpu_running(vcpu) || kvm_vcpu_has_events(vcpu); > } > > +bool kvm_arch_vcpu_spin_in_kernel(struct kvm_vcpu *vcpu) > +{ > + return false; > +} > + > +bool kvm_arch_vcpu_preempt_in_kernel(struct kvm_vcpu *vcpu) > +{ > + return false; > +} > + > int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu) > { > return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE; > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 890b706..9613620 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -798,6 +798,8 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu, > void kvm_arch_hardware_unsetup(void); > void kvm_arch_check_processor_compat(void *rtn); > int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu); > +bool kvm_arch_vcpu_spin_in_kernel(struct kvm_vcpu *vcpu); > +bool kvm_arch_vcpu_preempt_in_kernel(struct kvm_vcpu *vcpu); > int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu); > > #ifndef __KVM_HAVE_ARCH_VM_ALLOC > diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c > index a39a1e1..e45f780 100644 > --- a/virt/kvm/arm/arm.c > +++ b/virt/kvm/arm/arm.c > @@ -416,6 +416,16 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *v) > && !v->arch.power_off && !v->arch.pause); > } > > +bool kvm_arch_vcpu_spin_in_kernel(struct kvm_vcpu *vcpu) > +{ > + return false; > +} > + > +bool kvm_arch_vcpu_preempt_in_kernel(struct kvm_vcpu *vcpu) > +{ > + return false; > +} Is the differentiation really necessary? Can't you cache for x86 in all scenarios and simply introduce kvm_arch_vcpu_in_kernel() ? Otherwise, we have complexity that might just be avoided (e.g. kvm_arch_vcpu_spin_in_kernel must only be called on the loaded VCPU) > + > /* Just ensure a guest exit from a particular CPU */ > static void exit_vm_noop(void *info) > { > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index f3f7427..0d0527b 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -2324,12 +2324,14 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me) > { > struct kvm *kvm = me->kvm; > struct kvm_vcpu *vcpu; > + bool in_kern; > int last_boosted_vcpu = me->kvm->last_boosted_vcpu; > int yielded = 0; > int try = 3; > int pass; > int i; > > + in_kern = kvm_arch_vcpu_spin_in_kernel(me); > kvm_vcpu_set_in_spin_loop(me, true); > /* > * We boost the priority of a VCPU that is runnable but not > @@ -2351,6 +2353,8 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me) > continue; > if (swait_active(&vcpu->wq) && !kvm_arch_vcpu_runnable(vcpu)) > continue; > + if (in_kern && !kvm_arch_vcpu_preempt_in_kernel(vcpu)) > + continue; > if (!kvm_vcpu_eligible_for_directed_yield(vcpu)) > continue; > >
On 2017/8/7 16:55, David Hildenbrand wrote: > On 07.08.2017 10:44, Longpeng(Mike) wrote: >> If the vcpu(me) exit due to request a usermode spinlock, then >> the spinlock-holder may be preempted in usermode or kernmode. >> >> But if the vcpu(me) is in kernmode, then the holder must be >> preempted in kernmode, so we should choose a vcpu in kernmode >> as the most eligible candidate. >> >> For some architecture(e.g. arm/s390), spin/preempt_in_kernel() >> are the same, but they are different for X86. >> >> Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com> >> --- >> arch/mips/kvm/mips.c | 10 ++++++++++ >> arch/powerpc/kvm/powerpc.c | 10 ++++++++++ >> arch/s390/kvm/kvm-s390.c | 10 ++++++++++ >> arch/x86/kvm/x86.c | 10 ++++++++++ >> include/linux/kvm_host.h | 2 ++ >> virt/kvm/arm/arm.c | 10 ++++++++++ >> virt/kvm/kvm_main.c | 4 ++++ >> 7 files changed, 56 insertions(+) >> >> diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c >> index d4b2ad1..e04e6b3 100644 >> --- a/arch/mips/kvm/mips.c >> +++ b/arch/mips/kvm/mips.c >> @@ -98,6 +98,16 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu) >> return !!(vcpu->arch.pending_exceptions); >> } >> >> +bool kvm_arch_vcpu_spin_in_kernel(struct kvm_vcpu *vcpu) >> +{ >> + return false; >> +} >> + >> +bool kvm_arch_vcpu_preempt_in_kernel(struct kvm_vcpu *vcpu) >> +{ >> + return false; >> +} >> + >> int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu) >> { >> return 1; >> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c >> index 1a75c0b..c573ddd 100644 >> --- a/arch/powerpc/kvm/powerpc.c >> +++ b/arch/powerpc/kvm/powerpc.c >> @@ -58,6 +58,16 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *v) >> return !!(v->arch.pending_exceptions) || kvm_request_pending(v); >> } >> >> +bool kvm_arch_vcpu_spin_in_kernel(struct kvm_vcpu *vcpu) >> +{ >> + return false; >> +} >> + >> +bool kvm_arch_vcpu_preempt_in_kernel(struct kvm_vcpu *vcpu) >> +{ >> + return false; >> +} >> + >> int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu) >> { >> return 1; >> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c >> index af09d34..f78cdc2 100644 >> --- a/arch/s390/kvm/kvm-s390.c >> +++ b/arch/s390/kvm/kvm-s390.c >> @@ -2447,6 +2447,16 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu) >> return kvm_s390_vcpu_has_irq(vcpu, 0); >> } >> >> +bool kvm_arch_vcpu_spin_in_kernel(struct kvm_vcpu *vcpu) >> +{ >> + return false; >> +} >> + >> +bool kvm_arch_vcpu_preempt_in_kernel(struct kvm_vcpu *vcpu) >> +{ >> + return false; >> +} >> + >> void kvm_s390_vcpu_block(struct kvm_vcpu *vcpu) >> { >> atomic_or(PROG_BLOCK_SIE, &vcpu->arch.sie_block->prog20); >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >> index 6c97c82..04c6a1f 100644 >> --- a/arch/x86/kvm/x86.c >> +++ b/arch/x86/kvm/x86.c >> @@ -8435,6 +8435,16 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu) >> return kvm_vcpu_running(vcpu) || kvm_vcpu_has_events(vcpu); >> } >> >> +bool kvm_arch_vcpu_spin_in_kernel(struct kvm_vcpu *vcpu) >> +{ >> + return false; >> +} >> + >> +bool kvm_arch_vcpu_preempt_in_kernel(struct kvm_vcpu *vcpu) >> +{ >> + return false; >> +} >> + >> int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu) >> { >> return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE; >> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h >> index 890b706..9613620 100644 >> --- a/include/linux/kvm_host.h >> +++ b/include/linux/kvm_host.h >> @@ -798,6 +798,8 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu, >> void kvm_arch_hardware_unsetup(void); >> void kvm_arch_check_processor_compat(void *rtn); >> int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu); >> +bool kvm_arch_vcpu_spin_in_kernel(struct kvm_vcpu *vcpu); >> +bool kvm_arch_vcpu_preempt_in_kernel(struct kvm_vcpu *vcpu); >> int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu); >> >> #ifndef __KVM_HAVE_ARCH_VM_ALLOC >> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c >> index a39a1e1..e45f780 100644 >> --- a/virt/kvm/arm/arm.c >> +++ b/virt/kvm/arm/arm.c >> @@ -416,6 +416,16 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *v) >> && !v->arch.power_off && !v->arch.pause); >> } >> >> +bool kvm_arch_vcpu_spin_in_kernel(struct kvm_vcpu *vcpu) >> +{ >> + return false; >> +} >> + >> +bool kvm_arch_vcpu_preempt_in_kernel(struct kvm_vcpu *vcpu) >> +{ >> + return false; >> +} > > Is the differentiation really necessary? > > Can't you cache for x86 in all scenarios and simply introduce > kvm_arch_vcpu_in_kernel() ? > For X86 this is necessary, I have no idea how to avoid this, hopes someone could give me some suggestion. :) > Otherwise, we have complexity that might just be avoided (e.g. > kvm_arch_vcpu_spin_in_kernel must only be called on the loaded VCPU) > >> + >> /* Just ensure a guest exit from a particular CPU */ >> static void exit_vm_noop(void *info) >> { >> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c >> index f3f7427..0d0527b 100644 >> --- a/virt/kvm/kvm_main.c >> +++ b/virt/kvm/kvm_main.c >> @@ -2324,12 +2324,14 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me) >> { >> struct kvm *kvm = me->kvm; >> struct kvm_vcpu *vcpu; >> + bool in_kern; >> int last_boosted_vcpu = me->kvm->last_boosted_vcpu; >> int yielded = 0; >> int try = 3; >> int pass; >> int i; >> >> + in_kern = kvm_arch_vcpu_spin_in_kernel(me); >> kvm_vcpu_set_in_spin_loop(me, true); >> /* >> * We boost the priority of a VCPU that is runnable but not >> @@ -2351,6 +2353,8 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me) >> continue; >> if (swait_active(&vcpu->wq) && !kvm_arch_vcpu_runnable(vcpu)) >> continue; >> + if (in_kern && !kvm_arch_vcpu_preempt_in_kernel(vcpu)) >> + continue; >> if (!kvm_vcpu_eligible_for_directed_yield(vcpu)) >> continue; >> >> > >
diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c index d4b2ad1..e04e6b3 100644 --- a/arch/mips/kvm/mips.c +++ b/arch/mips/kvm/mips.c @@ -98,6 +98,16 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu) return !!(vcpu->arch.pending_exceptions); } +bool kvm_arch_vcpu_spin_in_kernel(struct kvm_vcpu *vcpu) +{ + return false; +} + +bool kvm_arch_vcpu_preempt_in_kernel(struct kvm_vcpu *vcpu) +{ + return false; +} + int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu) { return 1; diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c index 1a75c0b..c573ddd 100644 --- a/arch/powerpc/kvm/powerpc.c +++ b/arch/powerpc/kvm/powerpc.c @@ -58,6 +58,16 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *v) return !!(v->arch.pending_exceptions) || kvm_request_pending(v); } +bool kvm_arch_vcpu_spin_in_kernel(struct kvm_vcpu *vcpu) +{ + return false; +} + +bool kvm_arch_vcpu_preempt_in_kernel(struct kvm_vcpu *vcpu) +{ + return false; +} + int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu) { return 1; diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index af09d34..f78cdc2 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -2447,6 +2447,16 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu) return kvm_s390_vcpu_has_irq(vcpu, 0); } +bool kvm_arch_vcpu_spin_in_kernel(struct kvm_vcpu *vcpu) +{ + return false; +} + +bool kvm_arch_vcpu_preempt_in_kernel(struct kvm_vcpu *vcpu) +{ + return false; +} + void kvm_s390_vcpu_block(struct kvm_vcpu *vcpu) { atomic_or(PROG_BLOCK_SIE, &vcpu->arch.sie_block->prog20); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 6c97c82..04c6a1f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8435,6 +8435,16 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu) return kvm_vcpu_running(vcpu) || kvm_vcpu_has_events(vcpu); } +bool kvm_arch_vcpu_spin_in_kernel(struct kvm_vcpu *vcpu) +{ + return false; +} + +bool kvm_arch_vcpu_preempt_in_kernel(struct kvm_vcpu *vcpu) +{ + return false; +} + int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu) { return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE; diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 890b706..9613620 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -798,6 +798,8 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu, void kvm_arch_hardware_unsetup(void); void kvm_arch_check_processor_compat(void *rtn); int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu); +bool kvm_arch_vcpu_spin_in_kernel(struct kvm_vcpu *vcpu); +bool kvm_arch_vcpu_preempt_in_kernel(struct kvm_vcpu *vcpu); int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu); #ifndef __KVM_HAVE_ARCH_VM_ALLOC diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c index a39a1e1..e45f780 100644 --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -416,6 +416,16 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *v) && !v->arch.power_off && !v->arch.pause); } +bool kvm_arch_vcpu_spin_in_kernel(struct kvm_vcpu *vcpu) +{ + return false; +} + +bool kvm_arch_vcpu_preempt_in_kernel(struct kvm_vcpu *vcpu) +{ + return false; +} + /* Just ensure a guest exit from a particular CPU */ static void exit_vm_noop(void *info) { diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index f3f7427..0d0527b 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2324,12 +2324,14 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me) { struct kvm *kvm = me->kvm; struct kvm_vcpu *vcpu; + bool in_kern; int last_boosted_vcpu = me->kvm->last_boosted_vcpu; int yielded = 0; int try = 3; int pass; int i; + in_kern = kvm_arch_vcpu_spin_in_kernel(me); kvm_vcpu_set_in_spin_loop(me, true); /* * We boost the priority of a VCPU that is runnable but not @@ -2351,6 +2353,8 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me) continue; if (swait_active(&vcpu->wq) && !kvm_arch_vcpu_runnable(vcpu)) continue; + if (in_kern && !kvm_arch_vcpu_preempt_in_kernel(vcpu)) + continue; if (!kvm_vcpu_eligible_for_directed_yield(vcpu)) continue;
If the vcpu(me) exit due to request a usermode spinlock, then the spinlock-holder may be preempted in usermode or kernmode. But if the vcpu(me) is in kernmode, then the holder must be preempted in kernmode, so we should choose a vcpu in kernmode as the most eligible candidate. For some architecture(e.g. arm/s390), spin/preempt_in_kernel() are the same, but they are different for X86. Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com> --- arch/mips/kvm/mips.c | 10 ++++++++++ arch/powerpc/kvm/powerpc.c | 10 ++++++++++ arch/s390/kvm/kvm-s390.c | 10 ++++++++++ arch/x86/kvm/x86.c | 10 ++++++++++ include/linux/kvm_host.h | 2 ++ virt/kvm/arm/arm.c | 10 ++++++++++ virt/kvm/kvm_main.c | 4 ++++ 7 files changed, 56 insertions(+)