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Re: [Qemu-devel] [PATCH 17/21] introduce memory_region_get_address() and


From: Blue Swirl
Subject: Re: [Qemu-devel] [PATCH 17/21] introduce memory_region_get_address() and use it in kvm/ioapic
Date: Thu, 25 Apr 2013 18:37:19 +0000

On Tue, Apr 23, 2013 at 8:29 AM, Igor Mammedov <address@hidden> wrote:
> kvm/ioapic is relying on the fact that SysBus device
> maps mmio regions with offset counted from start of system memory.
> But if ioapic's region is moved to another sub-region which doesn't
> start at the beginning of system memory then using offset isn't correct.

But base_address in only initialized once, never changed. Does this
patch matter now?

The correct solution would be to track changes to APICBASE register at
PIIX3 chipset level and adjust mapping and KVM base also from there.

>
> Fix kvm/ioapic by providing and using helper function that returns
> absolute region address in respective address space.
>
> Signed-off-by: Igor Mammedov <address@hidden>
> ---
> Note:
>   next patch "move IOAPIC to ICC bus" converts IOAPICs to ICCDevice
>   and breaks SysBus device assumption used by kvm/ioapic.
> ---
>  hw/i386/kvm/ioapic.c  |    2 +-
>  include/exec/memory.h |   10 ++++++++++
>  memory.c              |   11 +++++++++++
>  3 files changed, 22 insertions(+), 1 deletions(-)
>
> diff --git a/hw/i386/kvm/ioapic.c b/hw/i386/kvm/ioapic.c
> index a3bd519..b80d41a 100644
> --- a/hw/i386/kvm/ioapic.c
> +++ b/hw/i386/kvm/ioapic.c
> @@ -96,7 +96,7 @@ static void kvm_ioapic_put(IOAPICCommonState *s)
>
>      kioapic->id = s->id;
>      kioapic->ioregsel = s->ioregsel;
> -    kioapic->base_address = s->busdev.mmio[0].addr;
> +    kioapic->base_address = memory_region_get_address(&s->io_memory);
>      kioapic->irr = s->irr;
>      for (i = 0; i < IOAPIC_NUM_PINS; i++) {
>          kioapic->redirtbl[i].bits = s->ioredtbl[i];
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index 9e88320..954f353 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -706,6 +706,16 @@ void memory_region_set_enabled(MemoryRegion *mr, bool 
> enabled);
>  void memory_region_set_address(MemoryRegion *mr, hwaddr addr);
>
>  /*
> + * memory_region_get_address: get current the address of a region
> + *
> + * Returns the absolute address of a region.
> + * May be used on regions that are currently part of a memory hierarchy.
> + *
> + * @mr: the region being queried
> + */
> +hwaddr memory_region_get_address(MemoryRegion *mr);
> +
> +/*
>   * memory_region_set_alias_offset: dynamically update a memory alias's offset
>   *
>   * Dynamically updates the offset into the target region that an alias points
> diff --git a/memory.c b/memory.c
> index 75ca281..0651050 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -1413,6 +1413,17 @@ void memory_region_set_address(MemoryRegion *mr, 
> hwaddr addr)
>      memory_region_transaction_commit();
>  }
>
> +hwaddr memory_region_get_address(MemoryRegion *mr)
> +{
> +    hwaddr addr = mr->addr;
> +
> +    while (mr->parent) {
> +        mr = mr->parent;
> +        addr += mr->addr;
> +    }
> +    return addr;
> +}
> +
>  void memory_region_set_alias_offset(MemoryRegion *mr, hwaddr offset)
>  {
>      assert(mr->alias);
> --
> 1.7.1
>



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