[PATCH V2] ARM: KVM: Allow host virtual timer irq number to be different from guest virtual timer irq number
Anup Patel
anup.patel at linaro.org
Fri Apr 26 06:12:57 EDT 2013
Hi Marc,
On 26 April 2013 15:17, Marc Zyngier <marc.zyngier at arm.com> wrote:
> Hi Anup,
>
> On Fri, 26 Apr 2013 12:51:50 +0530, Anup Patel <anup.patel at linaro.org>
> wrote:
>> The arch_timer irq numbers (or PPI number) are implementation dependent
>> so, the host virtual timer irq number can be different from guest
> virtual
>> timer irq number.
>>
>> This patch ensures that host virtual timer irq number is read from DTB
> and
>> guest virtual timer irq is determined based on guest vcpu target type.
>
> One word about communication first: Please keep me cc-ed on anything that
> has to do with with vgic and timers. I'm the author of the code, I intend
> to look after it, and this has some direct impact on the arm64 port. Thank
> you.
Sure, I'll CC you for arch_timer and vgic changes.
>
>> Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar at linaro.org>
>
> Who is the author of this patch? You or Pranavkumar? If it is you, then
> your Signed-off line should be present. If not, then there should be a
> "From:" line at the beginning of the commit message.
I really thought "From" is implicit and the sender of the email is the author.
Pranav has co-authored this patch hence his signed-off by him.
Anyways, I will put signed-off by me and Pranav both.
>
>> ---
>> arch/arm/include/asm/kvm_host.h | 1 +
>> arch/arm/kvm/arch_timer.c | 25 ++++++++++++++++++-------
>> arch/arm/kvm/guest.c | 15 +++++++++++++++
>> 3 files changed, 34 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/arm/include/asm/kvm_host.h
>> b/arch/arm/include/asm/kvm_host.h
>> index 57cb786..cdc0551 100644
>> --- a/arch/arm/include/asm/kvm_host.h
>> +++ b/arch/arm/include/asm/kvm_host.h
>> @@ -43,6 +43,7 @@
>> struct kvm_vcpu;
>> u32 *kvm_vcpu_reg(struct kvm_vcpu *vcpu, u8 reg_num, u32 mode);
>> int kvm_target_cpu(void);
>> +struct kvm_irq_level *kvm_target_timer_irq(struct kvm_vcpu *vcpu);
>> int kvm_reset_vcpu(struct kvm_vcpu *vcpu);
>> void kvm_reset_coprocs(struct kvm_vcpu *vcpu);
>>
>> diff --git a/arch/arm/kvm/arch_timer.c b/arch/arm/kvm/arch_timer.c
>> index 49a7516..521cdb9 100644
>> --- a/arch/arm/kvm/arch_timer.c
>> +++ b/arch/arm/kvm/arch_timer.c
>> @@ -30,7 +30,7 @@
>>
>> static struct timecounter *timecounter;
>> static struct workqueue_struct *wqueue;
>> -static struct kvm_irq_level timer_irq = {
>> +static struct kvm_irq_level host_timer_irq = {
>> .level = 1,
>> };
>>
>> @@ -65,10 +65,21 @@ static void kvm_timer_inject_irq(struct kvm_vcpu
> *vcpu)
>> {
>> struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
>>
>> + /*
>> + * The vcpu timer irq number cannont be determined in
>> + * kvm_timer_vcpu_init() because it is called much before
>> + * kvm_vcpu_set_target(). To handle this, we determin
>> + * vcpu timer irq number when we inject the vcpu timer irq
>> + * first time.
>> + */
>> + if (!timer->irq) {
>> + timer->irq = kvm_target_timer_irq(vcpu);
>> + }
>
> Please, not yet another of these. We already have kvm_vcpu_first_run_init
> that collects all the "do this on first vcpu run" kind of thing.
>
>> timer->cntv_ctl |= ARCH_TIMER_CTRL_IT_MASK;
>> kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
>> - vcpu->arch.timer_cpu.irq->irq,
>> - vcpu->arch.timer_cpu.irq->level);
>> + timer->irq->irq,
>> + timer->irq->level);
>> }
>>
>> static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id)
>> @@ -163,12 +174,12 @@ void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
>> INIT_WORK(&timer->expired, kvm_timer_inject_irq_work);
>> hrtimer_init(&timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
>> timer->timer.function = kvm_timer_expire;
>> - timer->irq = &timer_irq;
>> + timer->irq = NULL;
>> }
>
> So with the above in mind, how about moving the call to
> kvm_timer_vcpu_init into kvm_vcpu_first_run_init, and do the init once and
> for all?
Yes, this would be even more cleaner.
>
>> static void kvm_timer_init_interrupt(void *info)
>> {
>> - enable_percpu_irq(timer_irq.irq, 0);
>> + enable_percpu_irq(host_timer_irq.irq, 0);
>> }
>>
>>
>> @@ -182,7 +193,7 @@ static int kvm_timer_cpu_notify(struct
> notifier_block
>> *self,
>> break;
>> case CPU_DYING:
>> case CPU_DYING_FROZEN:
>> - disable_percpu_irq(timer_irq.irq);
>> + disable_percpu_irq(host_timer_irq.irq);
>> break;
>> }
>>
>> @@ -230,7 +241,7 @@ int kvm_timer_hyp_init(void)
>> goto out;
>> }
>>
>> - timer_irq.irq = ppi;
>> + host_timer_irq.irq = ppi;
>>
>> err = register_cpu_notifier(&kvm_timer_cpu_nb);
>> if (err) {
>> diff --git a/arch/arm/kvm/guest.c b/arch/arm/kvm/guest.c
>> index 152d036..d87b05d 100644
>> --- a/arch/arm/kvm/guest.c
>> +++ b/arch/arm/kvm/guest.c
>> @@ -36,6 +36,11 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
>> { NULL }
>> };
>>
>> +struct kvm_irq_level target_default_timer_irq = {
>> + .irq = 27,
>> + .level = 1,
>> +};
>
> Don't call it default, as it is A15 specific. Also make it static.
Sure, will update this.
>
>> int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
>> {
>> return 0;
>> @@ -197,6 +202,16 @@ int __attribute_const__ kvm_target_cpu(void)
>> }
>> }
>>
>> +struct kvm_irq_level *kvm_target_timer_irq(struct kvm_vcpu *vcpu)
>> +{
>> + switch (vcpu->arch.target) {
>> + case KVM_ARM_TARGET_CORTEX_A15:
>> + return &target_default_timer_irq;
>> + default:
>> + return NULL;
>
> And what do you do once you've returned NULL? Let the kernel crash?
> Also, we now have a second path that tests the target (the first one is in
> reset.c
Actually, this function is expected to be called as part of VCPU init
and if we get NULL then we should fail the VCPU init.
>
> Actually, scratch all the above, and move the irq assignment to reset.c.
> It is probably the best place for it.
Sure, I will try this and send another patch which addresses all comments.
>
> Thanks,
>
> M.
> --
> Fast, cheap, reliable. Pick two.
Regards,
Anup
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