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Re: [Qemu-ppc] [PATCH] spapr_pci: turn IOMMU root into an I/O region
From: |
Alexey Kardashevskiy |
Subject: |
Re: [Qemu-ppc] [PATCH] spapr_pci: turn IOMMU root into an I/O region |
Date: |
Wed, 27 Aug 2014 21:29:55 +1000 |
User-agent: |
Mozilla/5.0 (X11; Linux i686 on x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0 |
On 08/27/2014 08:57 PM, Alexander Graf wrote:
>
>
> On 26.08.14 18:40, Greg Kurz wrote:
>> On sPAPR, virtio devices are connected to the PCI bus and use MSI-X.
>> Commit cc943c36faa192cd4b32af8fe5edb31894017d35 has modified MSI-X
>> so that writes are made using the bus master address space.
>> Unfortunately, the MSI-X notification hits unassigned_mem_write and
>> never reaches the guest... The most visible effect is that all
>> virtio devices are non-fonctionnal on sPAPR. :(
>>
>> This patch plugs the MSI memory ops to the root IOMMU region, and
>> virtio devices work again. I am not sure this is the right way to
>> fix: please comment and enlight !
>>
>> Signed-off-by: Greg Kurz <address@hidden>
>> ---
>> hw/ppc/spapr_pci.c | 5 +++--
>> 1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
>> index 9ed39a9..b638a3c 100644
>> --- a/hw/ppc/spapr_pci.c
>> +++ b/hw/ppc/spapr_pci.c
>> @@ -599,8 +599,9 @@ static void spapr_phb_realize(DeviceState *dev, Error
>> **errp)
>> */
>> sprintf(namebuf, "%s.iommu-root", sphb->dtbusname);
>>
>> - memory_region_init(&sphb->iommu_root, OBJECT(sphb),
>> - namebuf, UINT64_MAX);
>> + memory_region_init_io(&sphb->iommu_root, OBJECT(sphb),
>> + &spapr_msi_ops, spapr,
>> + namebuf, UINT64_MAX);
>
> This will turn all unallocated accesses in iommu_root into calls to
> spapr_msi_ops, no?
It should not, the window is small.
> Can't we instead just populate the iommu_root memory region with the MSI
> subregion?
Makes sense to me. Having one global MSI window sounds like my bug, I just
did not any good reason for having it per PHB :)
--
Alexey