[Qemu-devel] Re: [PATCH 4/6] provide in-kernel i8259 chip

[Juan Quintela <quintela@redhat.com>]

Glauber Costa <glommer@redhat.com> wrote:
> On Tue, Sep 29, 2009 at 12:04:54AM +0200, Juan Quintela wrote:
>> Glauber Costa <glommer@redhat.com> wrote:
>> > This patch provides kvm with an in-kernel i8259 chip. We are currently not enabling it.
>> > The code is heavily based on what's in qemu-kvm.git.
>> >
>> > Signed-off-by: Glauber Costa <glommer@redhat.com>
>> > ---
>> >  hw/i8259.c |  103 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> >  hw/pc.h    |    1 +
>> >  kvm-all.c  |   24 ++++++++++++++
>> >  kvm.h      |    2 +
>> >  4 files changed, 130 insertions(+), 0 deletions(-)
>> >
>> > diff --git a/hw/i8259.c b/hw/i8259.c
>> > index 3de22e3..31524f5 100644
>> > --- a/hw/i8259.c
>> > +++ b/hw/i8259.c
>> > @@ -26,6 +26,7 @@
>> >  #include "isa.h"
>> >  #include "monitor.h"
>> >  #include "qemu-timer.h"
>> > +#include "kvm.h"
>> >  
>> >  /* debug PIC */
>> >  //#define DEBUG_PIC
>> > @@ -446,9 +447,77 @@ static uint32_t elcr_ioport_read(void *opaque, uint32_t addr1)
>> >      return s->elcr;
>> >  }
>> >  
>> > +static int kvm_kernel_pic_load_from_user(void *opaque)
>> > +{
>> > +#if defined(TARGET_I386)
>> > +    PicState *s = (void *)opaque;
>> > +    struct kvm_irqchip chip;
>> > +    struct kvm_pic_state *kpic;
>> 
>> It miss:
>>    if (!kvm_enabled() && !kvm_irqchip_enabled()) {
>>       return 0;
>>    }
>> 
>> Or similar logic, otherwise kvm_set_irqchip() is called when kvm_irqchip
>> is not enabled.  Same for save_to_user.
>> 
>> > +    chip.chip_id = (&s->pics_state->pics[0] == s) ?
>> > +                   KVM_IRQCHIP_PIC_MASTER :
>> > +                   KVM_IRQCHIP_PIC_SLAVE;
>> > +    kpic = &chip.chip.pic;
>> > +
>> > +    kpic->last_irr = s->last_irr;
>> > +    kpic->irr = s->irr;
>> > +    kpic->imr = s->imr;
>> > +    kpic->isr = s->isr;
>> > +    kpic->priority_add = s->priority_add;
>> > +    kpic->irq_base = s->irq_base;
>> > +    kpic->read_reg_select = s->read_reg_select;
>> > +    kpic->poll = s->poll;
>> > +    kpic->special_mask = s->special_mask;
>> > +    kpic->init_state = s->init_state;
>> > +    kpic->auto_eoi = s->auto_eoi;
>> > +    kpic->rotate_on_auto_eoi = s->rotate_on_auto_eoi;
>> > +    kpic->special_fully_nested_mode = s->special_fully_nested_mode;
>> > +    kpic->init4 = s->init4;
>> > +    kpic->elcr = s->elcr;
>> > +    kpic->elcr_mask = s->elcr_mask;
>> > +
>> > +    kvm_set_irqchip(&chip);
>> > +#endif
>> > +    return 0;
>> > +}
>> ....
>> >  static const VMStateDescription vmstate_pic = {
>> >      .name = "i8259",
>> >      .version_id = 1,
>> > +    .pre_save = kvm_kernel_pic_save_to_user,
>> > +    .post_load = kvm_kernel_pic_load_from_user,
>> 
>> Let the three version_id fields together, please.
>> 
>> 
>> > +#if defined(KVM_CAP_IRQCHIP) && defined(TARGET_I386)
>> > +static void kvm_i8259_set_irq(void *opaque, int irq, int level)
>> > +{
>> > +    int pic_ret;
>> > +    if (kvm_set_irq(irq, level, &pic_ret)) {
>> > +        if (pic_ret != 0)
>> > +            apic_set_irq_delivered();
>> > +        return;
>> > +    }
>> > +}
>> > +
>> > +static void kvm_pic_init1(int io_addr, PicState *s)
>> > +{
>> > +    vmstate_register(io_addr, &vmstate_pic, s);
>> > +    qemu_register_reset(pic_reset, s);
>> > +}
>> > +
>> > +qemu_irq *kvm_i8259_init(qemu_irq parent_irq)
>> > +{
>> > +    PicState2 *s;
>> > +
>> > +    s = qemu_mallocz(sizeof(PicState2));
>> > +
>> > +    kvm_pic_init1(0x20, &s->pics[0]);
>> > +    kvm_pic_init1(0xa0, &s->pics[1]);
>> > +    s->parent_irq = parent_irq;
>> > +    s->pics[0].pics_state = s;
>> > +    s->pics[1].pics_state = s;
>> > +    isa_pic = s;
>> > +    return qemu_allocate_irqs(kvm_i8259_set_irq, s, 24);
>> > +}
>> > +#endif
>> 
>> I think everything would be nicer if this three functions where merged
>> with the _non_ kvm ones with a kvm_enable() test.  They only differ in
>> 2-3 lines.
> I disagree. I think it is a better solution long term to provide irqchips
> that are completely free of kvm code.

Solutions:
- you copy the file and lives synchronizing the changes
- you export the needed funtions and then implement in the other file
  the kvm bits.
- you merge the kvm and non kvm bits.

I see here a very bad mix :(  The error showed before is due to the bad mix.

I showed 1 error, 1 question of style and 1 suggestion, you only
answered to the suggestion.

Later, Juan.