Re:Re: [PATCH] KVM: arm/arm64 : add lpi info in vgic-debug
peng.hao2 at zte.com.cn
peng.hao2 at zte.com.cn
Fri Mar 23 06:33:53 PDT 2018
>On 23/03/18 10:36, Peng Hao wrote:
>> Add lpi debug info to vgic-stat.
>> the printed info like this:
>> SPI 287 0 000001 0 0 0 160 -1
>> LPI 8192 2 000100 0 0 0 160 -1
>>
>> Signed-off-by: Peng Hao <peng.hao2 at zte.com.cn>
>> ---
>> virt/kvm/arm/vgic/vgic-debug.c | 61 ++++++++++++++++++++++++++++++++++++++----
>> 1 file changed, 56 insertions(+), 5 deletions(-)
>>
>> diff --git a/virt/kvm/arm/vgic/vgic-debug.c b/virt/kvm/arm/vgic/vgic-debug.c
>> index 10b3817..444115e 100644
>> --- a/virt/kvm/arm/vgic/vgic-debug.c
>> +++ b/virt/kvm/arm/vgic/vgic-debug.c
>> @@ -36,9 +36,12 @@
>> struct vgic_state_iter {
>> int nr_cpus;
>> int nr_spis;
>> + int nr_lpis;
>> int dist_id;
>> int vcpu_id;
>> int intid;
>> + int lpi_print_count;
>> + struct vgic_irq **lpi_irqs;
>> };
>>
>> static void iter_next(struct vgic_state_iter *iter)
>> @@ -52,6 +55,40 @@ static void iter_next(struct vgic_state_iter *iter)
>> if (iter->intid == VGIC_NR_PRIVATE_IRQS &&
>> ++iter->vcpu_id < iter->nr_cpus)
>> iter->intid = 0;
>> +
>> + if (iter->intid >= VGIC_NR_PRIVATE_IRQS + iter->nr_spis) {
>> + if (iter->lpi_print_count < iter->nr_lpis)
>> + iter->intid = iter->lpi_irqs[iter->lpi_print_count]->intid;
>> + iter->lpi_print_count++;
>> + }
>> +}
>> +
>> +static void vgic_debug_get_lpis(struct kvm *kvm, struct vgic_state_iter *iter)
>> +{
>> + struct vgic_dist *dist = &kvm->arch.vgic;
>> + int i = 0;
>> + struct vgic_irq *irq = NULL, **lpi_irqs;
>> +
>> +again:
>> + iter->nr_lpis = dist->lpi_list_count;
>> + lpi_irqs = kmalloc_array(iter->nr_lpis, sizeof(irq), GFP_KERNEL);
>> + if (!lpi_irqs) {
>> + iter->nr_lpis = 0;
>> + return;
>> + }
>> + spin_lock(&dist->lpi_list_lock);
>> + if (iter->nr_lpis != dist->lpi_list_count) {
>> + kfree(lpi_irqs);
>> + spin_unlock(&dist->lpi_list_lock);
>> + goto again;
>> + }
>Why do we need an exact count? It is fine to have a transient count, and
>the debug code should be able to come with that without performing this
>terrible loop.
yeah, it is enough to have a rough count for debug code .
>We also already have some code that snapshot the the LPIs (see
>vgic_copy_lpi_list), so please consider reusing that instead.
I can't reuse vgic_copy_lpi_list. It snapshots based on LPI's target vcpu.
>> +
>> + list_for_each_entry(irq, &dist->lpi_list_head, lpi_list) {
>> + vgic_get_irq_kref(irq);
>> + lpi_irqs[i++] = irq;
>> + }
>> + spin_unlock(&dist->lpi_list_lock);
>> + iter->lpi_irqs = lpi_irqs;
>Messing with the internals of the refcounts is really a bad idea. Please
>use vgic_get_irq() in conjunction with the above, and allow it to fail
>gracefully.
vgic_get_irq require intid as input and vgic_get_lpi that vgic_get_irq calling will traverse the lpi_list with holding lpi_list_lock again,
but here I has held lpi_list_lock. So I think calling vgic_get_irq_kref is safe with holding the
lpi_list_lock.
> > }
> >
>> static void iter_init(struct kvm *kvm, struct vgic_state_iter *iter,
>> @@ -64,6 +101,8 @@ static void iter_init(struct kvm *kvm, struct vgic_state_iter *iter,
>> iter->nr_cpus = nr_cpus;
>> iter->nr_spis = kvm->arch.vgic.nr_spis;
>>
>> + if (vgic_supports_direct_msis(kvm) && !pos)
>> + vgic_debug_get_lpis(kvm, iter);
>> /* Fast forward to the right position if needed */
>> while (pos--)
>> iter_next(iter);
>> @@ -73,7 +112,9 @@ static bool end_of_vgic(struct vgic_state_iter *iter)
>> {
>> return iter->dist_id > 0 &&
>> iter->vcpu_id == iter->nr_cpus &&
>> - (iter->intid - VGIC_NR_PRIVATE_IRQS) == iter->nr_spis;
>> + (iter->intid - VGIC_NR_PRIVATE_IRQS) >= iter->nr_spis &&
>> + ((iter->nr_lpis == 0) ||
>> + (iter->lpi_print_count == iter->nr_lpis + 1));
>> }
>>
>> static void *vgic_debug_start(struct seq_file *s, loff_t *pos)
>> @@ -130,6 +171,7 @@ static void vgic_debug_stop(struct seq_file *s, void *v)
>>
>> mutex_lock(&kvm->lock);
>> iter = kvm->arch.vgic.iter;
>> + kfree(iter->lpi_irqs);
>> kfree(iter);
>> kvm->arch.vgic.iter = NULL;
>> mutex_unlock(&kvm->lock);
>> @@ -154,7 +196,7 @@ static void print_header(struct seq_file *s, struct vgic_irq *irq,
>> struct kvm_vcpu *vcpu)
>> {
>> int id = 0;
>> - char *hdr = "SPI ";
>> + char *hdr = "S/LPI ";
>>
>> if (vcpu) {
>> hdr = "VCPU";
>> @@ -162,7 +204,10 @@ static void print_header(struct seq_file *s, struct vgic_irq *irq,
>> }
>>
>> seq_printf(s, "\n");
>> - seq_printf(s, "%s%2d TYP ID TGT_ID PLAEHC HWID TARGET SRC PRI VCPU_ID\n", hdr, id);
>> + if (vcpu)
>> + seq_printf(s, "%s%2d TYP ID TGT_ID PLAEHC HWID TARGET SRC PRI VCPU_ID\n", hdr, id);
>> + else
>> + seq_printf(s, "%s TYP ID TGT_ID PLAEHC HWID TARGET SRC PRI VCPU_ID\n", hdr);
>This feels like an unnecessary change. But if you really want that kind
>of detail, change your "S/LPI" to say something more generic, such as
>"Global".
I modify this just for aligned print output. "Global" is great.
>> seq_printf(s, "---------------------------------------------------------------\n");> }
>>
>> @@ -174,8 +219,10 @@ static void print_irq_state(struct seq_file *s, struct vgic_irq *irq,
>> type = "SGI";
>> else if (irq->intid < VGIC_NR_PRIVATE_IRQS)
>> type = "PPI";
>> - else
>> + else if (irq->intid < VGIC_MAX_SPI)
>> type = "SPI";
>> + else if (irq->intid >= VGIC_MIN_LPI)
>> + type = "LPI";
>>
>> if (irq->intid ==0 || irq->intid == VGIC_NR_PRIVATE_IRQS)
>> print_header(s, irq, vcpu);
>> @@ -220,7 +267,9 @@ static int vgic_debug_show(struct seq_file *s, void *v)
>> if (!kvm->arch.vgic.initialized)
>> return 0;
>>
>> - if (iter->vcpu_id < iter->nr_cpus) {
>> + if (iter->intid >= VGIC_MIN_LPI)
>> + irq = iter->lpi_irqs[iter->lpi_print_count - 1];
>> + else if (iter->vcpu_id < iter->nr_cpus) {
>> vcpu = kvm_get_vcpu(kvm, iter->vcpu_id);
>> irq = &vcpu->arch.vgic_cpu.private_irqs[iter->intid];
>> } else {
>> @@ -230,6 +279,8 @@ static int vgic_debug_show(struct seq_file *s, void *v)
>> spin_lock(&irq->irq_lock);
>> print_irq_state(s, irq, vcpu);
>> spin_unlock(&irq->irq_lock);
>> + if (iter->intid >= VGIC_MIN_LPI)
>> + vgic_put_irq(kvm, irq);
>If you adopt the scheme I outlined above, you can have a balanced
>get/put behaviour, irrespective of the interrupt type, and a much nicer
>result.
yeah, "if (iter->intid >= VGIC_MIN_LPI)" is unnecessary.
>> return 0;
>> }
>>
>Thanks,
> M.
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