Re: [Qemu-devel] [PATCH for-4.2 v10 11/15] virtio-iommu: Expose the IOAPIC MSI reserved region when relevant

[Auger Eric <eric.auger@redhat.com>]

Hi Kevin, Michael,

On 7/31/19 1:20 AM, Tian, Kevin wrote:
>> From: Michael S. Tsirkin [mailto:mst@redhat.com]
>> Sent: Wednesday, July 31, 2019 3:38 AM
>>
>> On Tue, Jul 30, 2019 at 07:21:33PM +0200, Eric Auger wrote:
>>> We introduce a new msi_bypass field which indicates whether
>>> the IOAPIC MSI window [0xFEE00000 - 0xFEEFFFFF] must be exposed
> 
> it's not good to call it IOAPIC MSI window. any write to this range, either
> from IOAPIC or PCI device, is interpreted by the platform as interrupt
> request. I'd call it "x86 interrupt address range".
Thank you for the clarification. I will reword the commit message as
suggested.
> 
>>> as a reserved region. By default the field is set to true at
>>> instantiation time. Later on we will introduce a property at
>>> virtio pci proxy level to turn it off.
>>>
>>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>>>
>>> ---
>>>
>>> v8 -> v9:
>>> - pass IOAPIC_RANGE_END to virtio_iommu_register_resv_region
>>> - take into account the change in the struct virtio_iommu_probe_resv_mem
>>>   definition
>>> - We just introduce the field here. A property will be introduced later on
>>>   at pci proxy level.
>>> ---
>>>  hw/virtio/virtio-iommu.c         | 36 ++++++++++++++++++++++++++++++++
>>>  include/hw/virtio/virtio-iommu.h |  1 +
>>>  2 files changed, 37 insertions(+)
>>>
>>> diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
>>> index 66be9a4627..74038288b0 100644
>>> --- a/hw/virtio/virtio-iommu.c
>>> +++ b/hw/virtio/virtio-iommu.c
>>> @@ -39,6 +39,9 @@
>>>  #define VIOMMU_DEFAULT_QUEUE_SIZE 256
>>>  #define VIOMMU_PROBE_SIZE 512
>>>
>>> +#define IOAPIC_RANGE_START      (0xfee00000)
>>> +#define IOAPIC_RANGE_END        (0xfeefffff)
>>> +
>>>  #define SUPPORTED_PROBE_PROPERTIES (\
>>>      1 << VIRTIO_IOMMU_PROBE_T_RESV_MEM)
>>>
>>
>> Sorry where are these numbers coming from?
> 
> this is architecturally defined in x86 SDM.
> 
>> Does this really work on all platforms?
> 
> x86 only. 
Yes, the initial goal was to allow the x86 integration. Maybe I should allow
the machine to pass reserved regions as device properties instead.

As integration with pc/q35 is beyond the scope of this initial series,
maybe I should remove that patch?

Thanks

Eric
> 
>> With all guests?
> 
> yes.
> 
>>
>>> @@ -100,6 +103,30 @@ static void
>> virtio_iommu_detach_endpoint_from_domain(viommu_endpoint *ep)
>>>      ep->domain = NULL;
>>>  }
>>>
>>> +static void virtio_iommu_register_resv_region(viommu_endpoint *ep,
>>> +                                              uint8_t subtype,
>>> +                                              uint64_t start, uint64_t end)
>>> +{
>>> +    viommu_interval *interval;
>>> +    struct virtio_iommu_probe_resv_mem *resv_reg_prop;
>>> +    size_t prop_size = sizeof(struct virtio_iommu_probe_resv_mem);
>>> +    size_t value_size = prop_size -
>>> +                sizeof(struct virtio_iommu_probe_property);
>>> +
>>> +    interval = g_malloc0(sizeof(*interval));
>>> +    interval->low = start;
>>> +    interval->high = end;
>>> +
>>> +    resv_reg_prop = g_malloc0(prop_size);
>>> +    resv_reg_prop->head.type = VIRTIO_IOMMU_PROBE_T_RESV_MEM;
>>> +    resv_reg_prop->head.length = cpu_to_le64(value_size);
>>> +    resv_reg_prop->subtype = cpu_to_le64(subtype);
>>> +    resv_reg_prop->start = cpu_to_le64(start);
>>> +    resv_reg_prop->end = cpu_to_le64(end);
>>> +
>>> +    g_tree_insert(ep->reserved_regions, interval, resv_reg_prop);
>>> +}
>>> +
>>>  static viommu_endpoint *virtio_iommu_get_endpoint(VirtIOIOMMU *s,
>>>                                                    uint32_t ep_id)
>>>  {
>>> @@ -117,6 +144,12 @@ static viommu_endpoint
>> *virtio_iommu_get_endpoint(VirtIOIOMMU *s,
>>>      ep->reserved_regions =
>> g_tree_new_full((GCompareDataFunc)interval_cmp,
>>>                                              NULL, (GDestroyNotify)g_free,
>>>                                              (GDestroyNotify)g_free);
>>> +    if (s->msi_bypass) {
>>> +        virtio_iommu_register_resv_region(ep,
>> VIRTIO_IOMMU_RESV_MEM_T_MSI,
>>> +                                          IOAPIC_RANGE_START,
>>> +                                          IOAPIC_RANGE_END);
>>> +    }
>>> +
>>>      return ep;
>>>  }
>>>
>>> @@ -822,6 +855,9 @@ static void virtio_iommu_set_status(VirtIODevice
>> *vdev, uint8_t status)
>>>
>>>  static void virtio_iommu_instance_init(Object *obj)
>>>  {
>>> +    VirtIOIOMMU *s = VIRTIO_IOMMU(obj);
>>> +
>>> +    s->msi_bypass = true;
>>>  }
>>>
>>>  static const VMStateDescription vmstate_virtio_iommu = {
>>> diff --git a/include/hw/virtio/virtio-iommu.h b/include/hw/virtio/virtio-
>> iommu.h
>>> index f55f48d304..56c8b4e57f 100644
>>> --- a/include/hw/virtio/virtio-iommu.h
>>> +++ b/include/hw/virtio/virtio-iommu.h
>>> @@ -59,6 +59,7 @@ typedef struct VirtIOIOMMU {
>>>      GTree *domains;
>>>      QemuMutex mutex;
>>>      GTree *endpoints;
>>> +    bool msi_bypass;
>>>  } VirtIOIOMMU;
>>>
>>>  #endif
>>> --
>>> 2.20.1