| Message ID | 1344985483-7440-30-git-send-email-agraf@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
> > +/* Please call after prepare_to_enter. This function puts the lazy ee state > + back to normal mode, without actually enabling interrupts. */ > +static inline void kvmppc_lazy_ee_enable(void) > +{ > +#ifdef CONFIG_PPC64 > + /* Only need to enable IRQs by hard enabling them after this */ > + local_paca->irq_happened = 0; > + local_paca->soft_enabled = 1; > +#endif > +} Smells like the above is the right spot for trace_hardirqs_on() an: > - __hard_irq_disable(); > + local_irq_disable(); > if (kvmppc_prepare_to_enter(vcpu)) { > - /* local_irq_enable(); */ > + local_irq_enable(); > run->exit_reason = KVM_EXIT_INTR; > r = -EINTR; > } else { > /* Going back to guest */ > kvm_guest_enter(); > + kvmppc_lazy_ee_enable(); > } > } You should probably do kvmppc_lazy_ee_enable() before guest enter so the CPU doesn't appear to the rest of the world that it has interrupt disabled while it's in the guest. > @@ -1066,8 +1062,6 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) > #endif > ulong ext_msr; > > - preempt_disable(); > - > /* Check if we can run the vcpu at all */ > if (!vcpu->arch.sane) { > kvm_run->exit_reason = KVM_EXIT_INTERNAL_ERROR; > @@ -1081,9 +1075,9 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) > * really did time things so badly, then we just exit again due to > * a host external interrupt. > */ > - __hard_irq_disable(); > + local_irq_disable(); > if (kvmppc_prepare_to_enter(vcpu)) { > - __hard_irq_enable(); > + local_irq_enable(); > kvm_run->exit_reason = KVM_EXIT_INTR; > ret = -EINTR; > goto out; > @@ -1122,7 +1116,7 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) > if (vcpu->arch.shared->msr & MSR_FP) > kvmppc_handle_ext(vcpu, BOOK3S_INTERRUPT_FP_UNAVAIL, MSR_FP); > > - kvm_guest_enter(); > + kvmppc_lazy_ee_enable(); Same. BTW, why do you have two enter path ? Smells like a recipe for disaster :-) ret = __kvmppc_vcpu_run(kvm_run, vcpu); > > @@ -1157,7 +1151,6 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) > > out: > vcpu->mode = OUTSIDE_GUEST_MODE; > - preempt_enable(); > return ret; > } > > diff --git a/arch/powerpc/kvm/book3s_rmhandlers.S b/arch/powerpc/kvm/book3s_rmhandlers.S > index 9ecf6e3..b2f8258 100644 > --- a/arch/powerpc/kvm/book3s_rmhandlers.S > +++ b/arch/powerpc/kvm/book3s_rmhandlers.S > @@ -170,20 +170,21 @@ kvmppc_handler_skip_ins: > * Call kvmppc_handler_trampoline_enter in real mode > * > * On entry, r4 contains the guest shadow MSR > + * MSR.EE has to be 0 when calling this function > */ > _GLOBAL(kvmppc_entry_trampoline) > mfmsr r5 > LOAD_REG_ADDR(r7, kvmppc_handler_trampoline_enter) > toreal(r7) > > - li r9, MSR_RI > - ori r9, r9, MSR_EE > - andc r9, r5, r9 /* Clear EE and RI in MSR value */ > li r6, MSR_IR | MSR_DR > - ori r6, r6, MSR_EE > - andc r6, r5, r6 /* Clear EE, DR and IR in MSR value */ > - MTMSR_EERI(r9) /* Clear EE and RI in MSR */ > - mtsrr0 r7 /* before we set srr0/1 */ > + andc r6, r5, r6 /* Clear DR and IR in MSR value */ > + /* > + * Set EE in HOST_MSR so that it's enabled when we get into our > + * C exit handler function > + */ > + ori r5, r5, MSR_EE > + mtsrr0 r7 > mtsrr1 r6 > RFI > > diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c > index aae535f..2bd190c 100644 > --- a/arch/powerpc/kvm/booke.c > +++ b/arch/powerpc/kvm/booke.c > @@ -486,6 +486,7 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) > ret = -EINTR; > goto out; > } > + kvmppc_lazy_ee_enable(); > > kvm_guest_enter(); Same. > @@ -955,6 +956,7 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu, > } else { > /* Going back to guest */ > kvm_guest_enter(); > + kvmppc_lazy_ee_enable(); > } > } Same. > > diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c > index 053bfef..545c183 100644 > --- a/arch/powerpc/kvm/powerpc.c > +++ b/arch/powerpc/kvm/powerpc.c > @@ -30,6 +30,7 @@ > #include <asm/kvm_ppc.h> > #include <asm/tlbflush.h> > #include <asm/cputhreads.h> > +#include <asm/irqflags.h> > #include "timing.h" > #include "../mm/mmu_decl.h" > > @@ -93,6 +94,19 @@ int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu) > break; > } > > +#ifdef CONFIG_PPC64 > + /* lazy EE magic */ > + hard_irq_disable(); > + if (lazy_irq_pending()) { > + /* Got an interrupt in between, try again */ > + local_irq_enable(); > + local_irq_disable(); > + continue; > + } > + > + trace_hardirqs_on(); > +#endif And move the trace out as I mentioned. Cheers, Ben. > /* Going into guest context! Yay! */ > vcpu->mode = IN_GUEST_MODE; > smp_wmb(); -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 17.08.2012, at 23:47, Benjamin Herrenschmidt wrote: >> >> +/* Please call after prepare_to_enter. This function puts the lazy ee state >> + back to normal mode, without actually enabling interrupts. */ >> +static inline void kvmppc_lazy_ee_enable(void) >> +{ >> +#ifdef CONFIG_PPC64 >> + /* Only need to enable IRQs by hard enabling them after this */ >> + local_paca->irq_happened = 0; >> + local_paca->soft_enabled = 1; >> +#endif >> +} > > Smells like the above is the right spot for trace_hardirqs_on() an: Hrm. Ok :). > >> - __hard_irq_disable(); >> + local_irq_disable(); >> if (kvmppc_prepare_to_enter(vcpu)) { >> - /* local_irq_enable(); */ >> + local_irq_enable(); >> run->exit_reason = KVM_EXIT_INTR; >> r = -EINTR; >> } else { >> /* Going back to guest */ >> kvm_guest_enter(); >> + kvmppc_lazy_ee_enable(); >> } >> } > > You should probably do kvmppc_lazy_ee_enable() before guest enter > so the CPU doesn't appear to the rest of the world that it has > interrupt disabled while it's in the guest. I don't think I understand. The patch adds kvmppc_lazy_ee_enable() right before guest entry here, no? > >> @@ -1066,8 +1062,6 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) >> #endif >> ulong ext_msr; >> >> - preempt_disable(); >> - >> /* Check if we can run the vcpu at all */ >> if (!vcpu->arch.sane) { >> kvm_run->exit_reason = KVM_EXIT_INTERNAL_ERROR; >> @@ -1081,9 +1075,9 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) >> * really did time things so badly, then we just exit again due to >> * a host external interrupt. >> */ >> - __hard_irq_disable(); >> + local_irq_disable(); >> if (kvmppc_prepare_to_enter(vcpu)) { >> - __hard_irq_enable(); >> + local_irq_enable(); >> kvm_run->exit_reason = KVM_EXIT_INTR; >> ret = -EINTR; >> goto out; >> @@ -1122,7 +1116,7 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) >> if (vcpu->arch.shared->msr & MSR_FP) >> kvmppc_handle_ext(vcpu, BOOK3S_INTERRUPT_FP_UNAVAIL, MSR_FP); >> >> - kvm_guest_enter(); >> + kvmppc_lazy_ee_enable(); > > Same. BTW, why do you have two enter path ? Smells like a recipe for > disaster :-) Because this way we can keep r14-r31 in registers ;). But here too we call kvmppc_lazy_ee_enable() right before going into guest context, no? I can't shake off the feeling I don't fully understand your comments :) Alex > > ret = __kvmppc_vcpu_run(kvm_run, vcpu); >> >> @@ -1157,7 +1151,6 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) >> >> out: >> vcpu->mode = OUTSIDE_GUEST_MODE; >> - preempt_enable(); >> return ret; >> } >> >> diff --git a/arch/powerpc/kvm/book3s_rmhandlers.S b/arch/powerpc/kvm/book3s_rmhandlers.S >> index 9ecf6e3..b2f8258 100644 >> --- a/arch/powerpc/kvm/book3s_rmhandlers.S >> +++ b/arch/powerpc/kvm/book3s_rmhandlers.S >> @@ -170,20 +170,21 @@ kvmppc_handler_skip_ins: >> * Call kvmppc_handler_trampoline_enter in real mode >> * >> * On entry, r4 contains the guest shadow MSR >> + * MSR.EE has to be 0 when calling this function >> */ >> _GLOBAL(kvmppc_entry_trampoline) >> mfmsr r5 >> LOAD_REG_ADDR(r7, kvmppc_handler_trampoline_enter) >> toreal(r7) >> >> - li r9, MSR_RI >> - ori r9, r9, MSR_EE >> - andc r9, r5, r9 /* Clear EE and RI in MSR value */ >> li r6, MSR_IR | MSR_DR >> - ori r6, r6, MSR_EE >> - andc r6, r5, r6 /* Clear EE, DR and IR in MSR value */ >> - MTMSR_EERI(r9) /* Clear EE and RI in MSR */ >> - mtsrr0 r7 /* before we set srr0/1 */ >> + andc r6, r5, r6 /* Clear DR and IR in MSR value */ >> + /* >> + * Set EE in HOST_MSR so that it's enabled when we get into our >> + * C exit handler function >> + */ >> + ori r5, r5, MSR_EE >> + mtsrr0 r7 >> mtsrr1 r6 >> RFI >> >> diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c >> index aae535f..2bd190c 100644 >> --- a/arch/powerpc/kvm/booke.c >> +++ b/arch/powerpc/kvm/booke.c >> @@ -486,6 +486,7 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) >> ret = -EINTR; >> goto out; >> } >> + kvmppc_lazy_ee_enable(); >> >> kvm_guest_enter(); > > Same. > >> @@ -955,6 +956,7 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu, >> } else { >> /* Going back to guest */ >> kvm_guest_enter(); >> + kvmppc_lazy_ee_enable(); >> } >> } > > Same. > >> >> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c >> index 053bfef..545c183 100644 >> --- a/arch/powerpc/kvm/powerpc.c >> +++ b/arch/powerpc/kvm/powerpc.c >> @@ -30,6 +30,7 @@ >> #include <asm/kvm_ppc.h> >> #include <asm/tlbflush.h> >> #include <asm/cputhreads.h> >> +#include <asm/irqflags.h> >> #include "timing.h" >> #include "../mm/mmu_decl.h" >> >> @@ -93,6 +94,19 @@ int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu) >> break; >> } >> >> +#ifdef CONFIG_PPC64 >> + /* lazy EE magic */ >> + hard_irq_disable(); >> + if (lazy_irq_pending()) { >> + /* Got an interrupt in between, try again */ >> + local_irq_enable(); >> + local_irq_disable(); >> + continue; >> + } >> + >> + trace_hardirqs_on(); >> +#endif > > And move the trace out as I mentioned. > > Cheers, > Ben. > >> /* Going into guest context! Yay! */ >> vcpu->mode = IN_GUEST_MODE; >> smp_wmb(); > > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h index 59b7c87..5459364 100644 --- a/arch/powerpc/include/asm/kvm_ppc.h +++ b/arch/powerpc/include/asm/kvm_ppc.h @@ -234,5 +234,15 @@ static inline void kvmppc_mmu_flush_icache(pfn_t pfn) } } +/* Please call after prepare_to_enter. This function puts the lazy ee state + back to normal mode, without actually enabling interrupts. */ +static inline void kvmppc_lazy_ee_enable(void) +{ +#ifdef CONFIG_PPC64 + /* Only need to enable IRQs by hard enabling them after this */ + local_paca->irq_happened = 0; + local_paca->soft_enabled = 1; +#endif +} #endif /* __POWERPC_KVM_PPC_H__ */ diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c index 3dec346..e737db8 100644 --- a/arch/powerpc/kvm/book3s_pr.c +++ b/arch/powerpc/kvm/book3s_pr.c @@ -52,8 +52,6 @@ static int kvmppc_handle_ext(struct kvm_vcpu *vcpu, unsigned int exit_nr, #define MSR_USER32 MSR_USER #define MSR_USER64 MSR_USER #define HW_PAGE_SIZE PAGE_SIZE -#define __hard_irq_disable local_irq_disable -#define __hard_irq_enable local_irq_enable #endif void kvmppc_core_vcpu_load(struct kvm_vcpu *vcpu, int cpu) @@ -597,12 +595,10 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu, run->exit_reason = KVM_EXIT_UNKNOWN; run->ready_for_interrupt_injection = 1; - /* We get here with MSR.EE=0, so enable it to be a nice citizen */ - __hard_irq_enable(); + /* We get here with MSR.EE=1 */ trace_kvm_exit(exit_nr, vcpu); kvm_guest_exit(); - preempt_enable(); switch (exit_nr) { case BOOK3S_INTERRUPT_INST_STORAGE: @@ -854,7 +850,6 @@ program_interrupt: } } - preempt_disable(); if (!(r & RESUME_HOST)) { /* To avoid clobbering exit_reason, only check for signals if * we aren't already exiting to userspace for some other @@ -866,14 +861,15 @@ program_interrupt: * and if we really did time things so badly, then we just exit * again due to a host external interrupt. */ - __hard_irq_disable(); + local_irq_disable(); if (kvmppc_prepare_to_enter(vcpu)) { - /* local_irq_enable(); */ + local_irq_enable(); run->exit_reason = KVM_EXIT_INTR; r = -EINTR; } else { /* Going back to guest */ kvm_guest_enter(); + kvmppc_lazy_ee_enable(); } } @@ -1066,8 +1062,6 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) #endif ulong ext_msr; - preempt_disable(); - /* Check if we can run the vcpu at all */ if (!vcpu->arch.sane) { kvm_run->exit_reason = KVM_EXIT_INTERNAL_ERROR; @@ -1081,9 +1075,9 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) * really did time things so badly, then we just exit again due to * a host external interrupt. */ - __hard_irq_disable(); + local_irq_disable(); if (kvmppc_prepare_to_enter(vcpu)) { - __hard_irq_enable(); + local_irq_enable(); kvm_run->exit_reason = KVM_EXIT_INTR; ret = -EINTR; goto out; @@ -1122,7 +1116,7 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) if (vcpu->arch.shared->msr & MSR_FP) kvmppc_handle_ext(vcpu, BOOK3S_INTERRUPT_FP_UNAVAIL, MSR_FP); - kvm_guest_enter(); + kvmppc_lazy_ee_enable(); ret = __kvmppc_vcpu_run(kvm_run, vcpu); @@ -1157,7 +1151,6 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) out: vcpu->mode = OUTSIDE_GUEST_MODE; - preempt_enable(); return ret; } diff --git a/arch/powerpc/kvm/book3s_rmhandlers.S b/arch/powerpc/kvm/book3s_rmhandlers.S index 9ecf6e3..b2f8258 100644 --- a/arch/powerpc/kvm/book3s_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_rmhandlers.S @@ -170,20 +170,21 @@ kvmppc_handler_skip_ins: * Call kvmppc_handler_trampoline_enter in real mode * * On entry, r4 contains the guest shadow MSR + * MSR.EE has to be 0 when calling this function */ _GLOBAL(kvmppc_entry_trampoline) mfmsr r5 LOAD_REG_ADDR(r7, kvmppc_handler_trampoline_enter) toreal(r7) - li r9, MSR_RI - ori r9, r9, MSR_EE - andc r9, r5, r9 /* Clear EE and RI in MSR value */ li r6, MSR_IR | MSR_DR - ori r6, r6, MSR_EE - andc r6, r5, r6 /* Clear EE, DR and IR in MSR value */ - MTMSR_EERI(r9) /* Clear EE and RI in MSR */ - mtsrr0 r7 /* before we set srr0/1 */ + andc r6, r5, r6 /* Clear DR and IR in MSR value */ + /* + * Set EE in HOST_MSR so that it's enabled when we get into our + * C exit handler function + */ + ori r5, r5, MSR_EE + mtsrr0 r7 mtsrr1 r6 RFI diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c index aae535f..2bd190c 100644 --- a/arch/powerpc/kvm/booke.c +++ b/arch/powerpc/kvm/booke.c @@ -486,6 +486,7 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) ret = -EINTR; goto out; } + kvmppc_lazy_ee_enable(); kvm_guest_enter(); @@ -955,6 +956,7 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu, } else { /* Going back to guest */ kvm_guest_enter(); + kvmppc_lazy_ee_enable(); } } diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c index 053bfef..545c183 100644 --- a/arch/powerpc/kvm/powerpc.c +++ b/arch/powerpc/kvm/powerpc.c @@ -30,6 +30,7 @@ #include <asm/kvm_ppc.h> #include <asm/tlbflush.h> #include <asm/cputhreads.h> +#include <asm/irqflags.h> #include "timing.h" #include "../mm/mmu_decl.h" @@ -93,6 +94,19 @@ int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu) break; } +#ifdef CONFIG_PPC64 + /* lazy EE magic */ + hard_irq_disable(); + if (lazy_irq_pending()) { + /* Got an interrupt in between, try again */ + local_irq_enable(); + local_irq_disable(); + continue; + } + + trace_hardirqs_on(); +#endif + /* Going into guest context! Yay! */ vcpu->mode = IN_GUEST_MODE; smp_wmb();
Today, we disable preemption while inside guest context, because we need to expose to the world that we are not in a preemptible context. However, during that time we already have interrupts disabled, which would indicate that we are in a non-preemptible context. The reason the checks for irqs_disabled() fail for us though is that we manually control hard IRQs and ignore all the lazy EE framework. Let's stop doing that. Instead, let's always use lazy EE to indicate when we want to disable IRQs, but do a special final switch that gets us into EE disabled, but soft enabled state. That way when we get back out of guest state, we are immediately ready to process interrupts. This simplifies the code drastically and reduces the time that we appear as preempt disabled. Signed-off-by: Alexander Graf <agraf@suse.de> --- arch/powerpc/include/asm/kvm_ppc.h | 10 ++++++++++ arch/powerpc/kvm/book3s_pr.c | 21 +++++++-------------- arch/powerpc/kvm/book3s_rmhandlers.S | 15 ++++++++------- arch/powerpc/kvm/booke.c | 2 ++ arch/powerpc/kvm/powerpc.c | 14 ++++++++++++++ 5 files changed, 41 insertions(+), 21 deletions(-)