Re: [RFC 4/8] KVM: arm/arm64: Initialize the emulated EL1 physical timer

[Jintack Lim]

On Tue, Jan 10, 2017 at 2:34 PM, Christoffer Dall
<christoffer.dall@xxxxxxxxxx> wrote:
> On Tue, Jan 10, 2017 at 12:03:00PM -0500, Jintack Lim wrote:
>> On Mon, Jan 9, 2017 at 7:02 AM, Christoffer Dall
>> <christoffer.dall@xxxxxxxxxx> wrote:
>> > On Mon, Dec 26, 2016 at 12:12:02PM -0500, Jintack Lim wrote:
>> >> Initialize the emulated EL1 physical timer with the default irq number.
>> >>
>> >> Signed-off-by: Jintack Lim <jintack@xxxxxxxxxxxxxxx>
>> >> ---
>> >>  arch/arm/kvm/reset.c         |  9 ++++++++-
>> >>  arch/arm64/kvm/reset.c       |  9 ++++++++-
>> >>  include/kvm/arm_arch_timer.h |  3 ++-
>> >>  virt/kvm/arm/arch_timer.c    | 12 ++++++++++--
>> >>  4 files changed, 28 insertions(+), 5 deletions(-)
>> >>
>> >> diff --git a/arch/arm/kvm/reset.c b/arch/arm/kvm/reset.c
>> >> index 4b5e802..1da8b2d 100644
>> >> --- a/arch/arm/kvm/reset.c
>> >> +++ b/arch/arm/kvm/reset.c
>> >> @@ -37,6 +37,11 @@
>> >>       .usr_regs.ARM_cpsr = SVC_MODE | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT,
>> >>  };
>> >>
>> >> +static const struct kvm_irq_level cortexa_ptimer_irq = {
>> >> +     { .irq = 30 },
>> >> +     .level = 1,
>> >> +};
>> >> +
>> >>  static const struct kvm_irq_level cortexa_vtimer_irq = {
>> >>       { .irq = 27 },
>> >>       .level = 1,
>> >> @@ -58,6 +63,7 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
>> >>  {
>> >>       struct kvm_regs *reset_regs;
>> >>       const struct kvm_irq_level *cpu_vtimer_irq;
>> >> +     const struct kvm_irq_level *cpu_ptimer_irq;
>> >>
>> >>       switch (vcpu->arch.target) {
>> >>       case KVM_ARM_TARGET_CORTEX_A7:
>> >> @@ -65,6 +71,7 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
>> >>               reset_regs = &cortexa_regs_reset;
>> >>               vcpu->arch.midr = read_cpuid_id();
>> >>               cpu_vtimer_irq = &cortexa_vtimer_irq;
>> >> +             cpu_ptimer_irq = &cortexa_ptimer_irq;
>> >>               break;
>> >>       default:
>> >>               return -ENODEV;
>> >> @@ -77,5 +84,5 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
>> >>       kvm_reset_coprocs(vcpu);
>> >>
>> >>       /* Reset arch_timer context */
>> >> -     return kvm_timer_vcpu_reset(vcpu, cpu_vtimer_irq);
>> >> +     return kvm_timer_vcpu_reset(vcpu, cpu_vtimer_irq, cpu_ptimer_irq);
>> >>  }
>> >> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
>> >> index 5bc4608..74322c2 100644
>> >> --- a/arch/arm64/kvm/reset.c
>> >> +++ b/arch/arm64/kvm/reset.c
>> >> @@ -46,6 +46,11 @@
>> >>                       COMPAT_PSR_I_BIT | COMPAT_PSR_F_BIT),
>> >>  };
>> >>
>> >> +static const struct kvm_irq_level default_ptimer_irq = {
>> >> +     .irq    = 30,
>> >> +     .level  = 1,
>> >> +};
>> >> +
>> >>  static const struct kvm_irq_level default_vtimer_irq = {
>> >>       .irq    = 27,
>> >>       .level  = 1,
>> >> @@ -110,6 +115,7 @@ int kvm_arch_dev_ioctl_check_extension(struct kvm *kvm, long ext)
>> >>  int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
>> >>  {
>> >>       const struct kvm_irq_level *cpu_vtimer_irq;
>> >> +     const struct kvm_irq_level *cpu_ptimer_irq;
>> >>       const struct kvm_regs *cpu_reset;
>> >>
>> >>       switch (vcpu->arch.target) {
>> >> @@ -123,6 +129,7 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
>> >>               }
>> >>
>> >>               cpu_vtimer_irq = &default_vtimer_irq;
>> >> +             cpu_ptimer_irq = &default_ptimer_irq;
>> >>               break;
>> >>       }
>> >>
>> >> @@ -136,5 +143,5 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
>> >>       kvm_pmu_vcpu_reset(vcpu);
>> >>
>> >>       /* Reset timer */
>> >> -     return kvm_timer_vcpu_reset(vcpu, cpu_vtimer_irq);
>> >> +     return kvm_timer_vcpu_reset(vcpu, cpu_vtimer_irq, cpu_ptimer_irq);
>> >>  }
>> >> diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h
>> >> index d21652a..04ed9c1 100644
>> >> --- a/include/kvm/arm_arch_timer.h
>> >> +++ b/include/kvm/arm_arch_timer.h
>> >> @@ -61,7 +61,8 @@ struct arch_timer_cpu {
>> >>  int kvm_timer_enable(struct kvm_vcpu *vcpu);
>> >>  void kvm_timer_init(struct kvm *kvm);
>> >>  int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
>> >> -                      const struct kvm_irq_level *irq);
>> >> +                      const struct kvm_irq_level *virt_irq,
>> >> +                      const struct kvm_irq_level *phys_irq);
>> >>  void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu);
>> >>  void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu);
>> >>  void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu);
>> >> diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
>> >> index 3bd6063..ed80864 100644
>> >> --- a/virt/kvm/arm/arch_timer.c
>> >> +++ b/virt/kvm/arm/arch_timer.c
>> >> @@ -339,9 +339,11 @@ void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
>> >>  }
>> >>
>> >>  int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
>> >> -                      const struct kvm_irq_level *irq)
>> >> +                      const struct kvm_irq_level *virt_irq,
>> >> +                      const struct kvm_irq_level *phys_irq)
>> >>  {
>> >>       struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
>> >> +     struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
>> >>
>> >>       /*
>> >>        * The vcpu timer irq number cannot be determined in
>> >> @@ -349,7 +351,8 @@ int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
>> >>        * kvm_vcpu_set_target(). To handle this, we determine
>> >>        * vcpu timer irq number when the vcpu is reset.
>> >>        */
>> >> -     vtimer->irq.irq = irq->irq;
>> >> +     vtimer->irq.irq = virt_irq->irq;
>> >> +     ptimer->irq.irq = phys_irq->irq;
>> >>
>> >>       /*
>> >>        * The bits in CNTV_CTL are architecturally reset to UNKNOWN for ARMv8
>> >> @@ -358,6 +361,7 @@ int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
>> >>        * the ARMv7 architecture.
>> >>        */
>> >>       vtimer->cnt_ctl = 0;
>> >> +     ptimer->cnt_ctl = 0;
>> >>       kvm_timer_update_state(vcpu);
>> >>
>> >>       return 0;
>> >> @@ -477,11 +481,15 @@ void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu)
>> >>  int kvm_timer_enable(struct kvm_vcpu *vcpu)
>> >>  {
>> >>       struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
>> >> +     struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
>> >>       struct irq_desc *desc;
>> >>       struct irq_data *data;
>> >>       int phys_irq;
>> >>       int ret;
>> >>
>> >> +     /* Always enable emulated the EL1 physical timer */
>> >
>> > Dubious comment the way it stands.
>> >
>> > Does the rest of the code really support one timer being enabled while
>> > another one not so?
>>
>> No. The code never check if the physical timer is enabled. I think
>> it's not necessary to set enable bit for this emulated physical timer.
>> We, however, may need to set/check this enable bit later if we decide
>> to give the EL1 physical timer to the guest instead of emulating it.
>>
>
> It hink the semantics of the enable bit before your patches is more "is
> the arch timer code at all enabled and working", so maybe you want to
> preserve that and move the enabled bit out of the per-timer and per-vcpu
> state?

Ok, I'll do that in v2.

Thanks,
Jintack

>
> Thanks,
> -Christoffer
>