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Date: Sun, 29 Jan 2017 12:07:48 +0000
From: Marc Zyngier <marc.zyngier@....com>
To: Jintack Lim <jintack@...columbia.edu>
Cc: <pbonzini@...hat.com>, <rkrcmar@...hat.com>,
<christoffer.dall@...aro.org>, <linux@...linux.org.uk>,
<catalin.marinas@....com>, <will.deacon@....com>,
<andre.przywara@....com>, <kvm@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<kvmarm@...ts.cs.columbia.edu>, <linux-kernel@...r.kernel.org>
Subject: Re: [RFC v2 05/10] KVM: arm/arm64: Initialize the emulated EL1 physical timer
On Fri, Jan 27 2017 at 01:04:55 AM, Jintack Lim <jintack@...columbia.edu> 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 | 9 +++++++--
> 4 files changed, 25 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,
> +};
At some point, we'll have to make that discoverable/configurable. Maybe
the time for a discoverable arch timer has come (see below).
> +
> 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 e95d4f6..d9e9697 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,
> @@ -104,6 +109,7 @@ 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) {
> @@ -117,6 +123,7 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
> }
>
> cpu_vtimer_irq = &default_vtimer_irq;
> + cpu_ptimer_irq = &default_ptimer_irq;
> break;
> }
>
> @@ -130,5 +137,5 @@ 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 69f648b..a364593 100644
> --- a/include/kvm/arm_arch_timer.h
> +++ b/include/kvm/arm_arch_timer.h
> @@ -59,7 +59,8 @@ 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 f72005a..0f6e935 100644
> --- a/virt/kvm/arm/arch_timer.c
> +++ b/virt/kvm/arm/arch_timer.c
> @@ -329,9 +329,11 @@ 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
> @@ -339,7 +341,8 @@ 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
> @@ -348,6 +351,7 @@ 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;
> @@ -369,6 +373,7 @@ void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
> struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
>
> update_vtimer_cntvoff(vcpu, kvm_phys_timer_read());
> + vcpu_ptimer(vcpu)->cntvoff = 0;
This is quite contentious, IMHO. Do we really want to expose the delta
between the virtual and physical counters? That's a clear indication to
the guest that it is virtualized. I"m not sure it matters, but I think
we should at least make a conscious choice, and maybe give the
opportunity to userspace to select the desired behaviour.
>
> INIT_WORK(&timer->expired, kvm_timer_inject_irq_work);
> hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
Thanks,
M.
--
Jazz is not dead. It just smells funny.
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