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Message-ID: <CAHyh4xgq_me42Jv+=6P=NhcyxpjJ4R6zgWGY2HibEc6e09Af2g@mail.gmail.com>
Date: Tue, 10 Jan 2017 12:03:00 -0500
From: Jintack Lim <jintack@...columbia.edu>
To: Christoffer Dall <christoffer.dall@...aro.org>
Cc: kvmarm@...ts.cs.columbia.edu, Marc Zyngier <marc.zyngier@....com>,
Paolo Bonzini <pbonzini@...hat.com>, rkrcmar@...hat.com,
linux@...linux.org.uk, Catalin Marinas <catalin.marinas@....com>,
will.deacon@....com, andre.przywara@....com,
linux-arm-kernel@...ts.infradead.org,
KVM General <kvm@...r.kernel.org>, linux-kernel@...r.kernel.org
Subject: Re: [RFC 4/8] KVM: arm/arm64: Initialize the emulated EL1 physical timer
On Mon, Jan 9, 2017 at 7:02 AM, Christoffer Dall
<christoffer.dall@...aro.org> 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@...columbia.edu>
>> ---
>> 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.
>
> In any case, the comment should explain the rationale as opposed to
> reiterate what the following code line does, or just not be there.
>
>> + ptimer->enabled = 1;
>> +
>> if (vtimer->enabled)
>> return 0;
>>
>> --
>> 1.9.1
>>
>>
>
> Thanks,
> -Christoffer
>
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