Re: [Qemu-arm] [Qemu-devel] [PATCH for-4.2 v10 14/15] virtio-iommu-pci: Add virtio iommu pci support

[Auger Eric]

Hi Michael,

On 8/1/19 3:06 PM, Michael S. Tsirkin wrote:
> On Thu, Aug 01, 2019 at 02:15:03PM +0200, Auger Eric wrote:
>> Hi Michael,
>>
>> On 7/30/19 9:35 PM, Michael S. Tsirkin wrote:
>>> On Tue, Jul 30, 2019 at 07:21:36PM +0200, Eric Auger wrote:
>>>> This patch adds virtio-iommu-pci, which is the pci proxy for
>>>> the virtio-iommu device.
>>>>
>>>> Signed-off-by: Eric Auger <address@hidden>
>>>
>>> This part I'm not sure we should merge just yet.  The reason being I
>>> think we should limit it to mmio where DT can be used to describe iommu
>>> topology. For PCI I don't see why we shouldn't always expose this
>>> in the config space, and I think it's preferable not to
>>> need to support a mix of DT,ACPI and PCI as options.
>>
>> For context, some discussion related to this topic already arose on v7
>> revision of the driver:
>>
>> [1] Re: [PATCH v7 0/7] Add virtio-iommu driver
>> https://lore.kernel.org/linux-pci/87a7ioby9u.fsf@morokweng.localdomain/
>>
>> Some additional thoughts.
>>
>> First considering DT boot.
>>
>> THE DT description features an iommu-map property in the
>> pci-host-ecam-generic node that describes which RIDs are handled by the
>> virtio-iommu and a possible offset/mask to be applied inbetween the RID
>> and the streamID at the input of the IOMMU
>> (Documentation/devicetree/bindings/pci/pci-iommu.txt)
>>
>> As far as I understand when a DMA capable device is setup, its DMA
>> configuration is built using that call chain:
>>
>> pci_dma_configure
>> |_ of_dma_configure
>>    |_ of_iommu_configure
>>       |_ of_pci_iommu_init
>>          |_ of_map_rid
>>
>> I understand you would like the iommu-map/iommu-map-mask info to be
>> exposed directly into the config space of the device instead of inside
>> the DT or IORT table. Assuming a module is initialized sufficiently
>> early to retrieve this info, we would need the resulting info to be
>> consolidated to allow pci_dma_configure chain to work seemlessly. This
>> sounds a significant impact on above kernel infrastructure.
> 
> I don't really know what consolidated means.
> It is pretty common for IOMMUs to expose config through
> PCI registers. This typically happens as a fixup.
I meant: instead of retrieving the info through the of_* code you need
to interoperate with the module to retrieve the same info and detect
when you need to take that path instead of the of one.
> 
> I would write a tiny driver to do exactly that,
> and run it from the fixup.
> 
> 
>> This comes in addition to the development of the "small module that
>> loads early and pokes at the IOMMU sufficiently to get the data about
>> which devices use the IOMMU out of it using standard virtio config
>> space" evoked in [1] + the definition of the data formats to be put in
>> the very cfg space.
> 
> That last part is true but that's exactly why I propose we
> wait on this patch a bit.
> 
>> With ACPI I understand we have the same kind of infrastructure:
>> drivers/acpi/arm64/iort.c currently extracts the mapping between RC RIDs
>> and IOMMU streamids
>>
>> pci_dma_configure(
>> |_ acpi_dma_configure
>>    |_ iort_iommu_configure
>>       |_ iort_pci_iommu_init
>>          |_ iort_node_map_id
>>             |_ iort_id_map
>>
>> Maybe I fail to see the easy and right way to do the integration at
>> kernel level but I am a bit frightened by the efforts that would be
>> requested to follow your suggestion, whereas the DT infra is ready and
>> fully upstreamed to accept the use case.
> 
> Did you take a look at drivers/pci/quirks.c and how these run?
> I think it's just a question of adding DECLARE_PCI_FIXUP_CLASS_EARLY
> and running your hook from there.
I will do and trace the code.
> 
> 
>> For ACPI I agree AFAIK IORT was primarily defined by ARM, for ARM but we
>> prototyped IORT integration with x86 and it worked for pc machine
>> without major trouble.
>>
>> I sent the kernel and qemu patches prototyping this IORT integration:
>>
>> https://github.com/eauger/linux/tree/virtio-iommu-v0.9-iort-x86
>> https://github.com/eauger/qemu/tree/v3.1.0-rc3-virtio-iommu-v0.9-x86
>>
>> There ACPI IORT was built for PC machine and the integration effort at
>> both kernel and QEMU level was low. This work would need to be rebased
>> and depends on kernel ACPI related patches that are not yet upstreamed
>> though.
>>
>> Thanks
>>
>> Eric
> 
> In the end it might turn out you are right.  But it does us no harm to
> delay this just a bit, and for now limit things to ARM where it's
> already used and where alternatives exist.
So if my understanding is correct, at the moment you would accept a DT
integration using MMIO. Is that correct? Meanwhile we can prototype your
suggestion.

Thanks

Eric
> 
> 
>>>
>>>> ---
>>>>
>>>> v8 -> v9:
>>>> - add the msi-bypass property
>>>> - create virtio-iommu-pci.c
>>>> ---
>>>>  hw/virtio/Makefile.objs          |  1 +
>>>>  hw/virtio/virtio-iommu-pci.c     | 88 ++++++++++++++++++++++++++++++++
>>>>  include/hw/pci/pci.h             |  1 +
>>>>  include/hw/virtio/virtio-iommu.h |  1 +
>>>>  qdev-monitor.c                   |  1 +
>>>>  5 files changed, 92 insertions(+)
>>>>  create mode 100644 hw/virtio/virtio-iommu-pci.c
>>>>
>>>> diff --git a/hw/virtio/Makefile.objs b/hw/virtio/Makefile.objs
>>>> index f42e4dd94f..80ca719f1c 100644
>>>> --- a/hw/virtio/Makefile.objs
>>>> +++ b/hw/virtio/Makefile.objs
>>>> @@ -27,6 +27,7 @@ obj-$(CONFIG_VIRTIO_INPUT_HOST) += 
>>>> virtio-input-host-pci.o
>>>>  obj-$(CONFIG_VIRTIO_INPUT) += virtio-input-pci.o
>>>>  obj-$(CONFIG_VIRTIO_RNG) += virtio-rng-pci.o
>>>>  obj-$(CONFIG_VIRTIO_BALLOON) += virtio-balloon-pci.o
>>>> +obj-$(CONFIG_VIRTIO_IOMMU) += virtio-iommu-pci.o
>>>>  obj-$(CONFIG_VIRTIO_9P) += virtio-9p-pci.o
>>>>  obj-$(CONFIG_VIRTIO_SCSI) += virtio-scsi-pci.o
>>>>  obj-$(CONFIG_VIRTIO_BLK) += virtio-blk-pci.o
>>>> diff --git a/hw/virtio/virtio-iommu-pci.c b/hw/virtio/virtio-iommu-pci.c
>>>> new file mode 100644
>>>> index 0000000000..f9977096bd
>>>> --- /dev/null
>>>> +++ b/hw/virtio/virtio-iommu-pci.c
>>>> @@ -0,0 +1,88 @@
>>>> +/*
>>>> + * Virtio IOMMU PCI Bindings
>>>> + *
>>>> + * Copyright (c) 2019 Red Hat, Inc.
>>>> + * Written by Eric Auger
>>>> + *
>>>> + *  This program is free software; you can redistribute it and/or modify
>>>> + *  it under the terms of the GNU General Public License version 2 or
>>>> + *  (at your option) any later version.
>>>> + */
>>>> +
>>>> +#include "qemu/osdep.h"
>>>> +
>>>> +#include "virtio-pci.h"
>>>> +#include "hw/virtio/virtio-iommu.h"
>>>> +
>>>> +typedef struct VirtIOIOMMUPCI VirtIOIOMMUPCI;
>>>> +
>>>> +/*
>>>> + * virtio-iommu-pci: This extends VirtioPCIProxy.
>>>> + *
>>>> + */
>>>> +#define VIRTIO_IOMMU_PCI(obj) \
>>>> +        OBJECT_CHECK(VirtIOIOMMUPCI, (obj), TYPE_VIRTIO_IOMMU_PCI)
>>>> +
>>>> +struct VirtIOIOMMUPCI {
>>>> +    VirtIOPCIProxy parent_obj;
>>>> +    VirtIOIOMMU vdev;
>>>> +};
>>>> +
>>>> +static Property virtio_iommu_pci_properties[] = {
>>>> +    DEFINE_PROP_UINT32("class", VirtIOPCIProxy, class_code, 0),
>>>> +    DEFINE_PROP_BOOL("msi-bypass", VirtIOIOMMUPCI, vdev.msi_bypass, true),
>>>> +    DEFINE_PROP_END_OF_LIST(),
>>>> +};
>>>> +
>>>> +static void virtio_iommu_pci_realize(VirtIOPCIProxy *vpci_dev, Error 
>>>> **errp)
>>>> +{
>>>> +    VirtIOIOMMUPCI *dev = VIRTIO_IOMMU_PCI(vpci_dev);
>>>> +    DeviceState *vdev = DEVICE(&dev->vdev);
>>>> +
>>>> +    qdev_set_parent_bus(vdev, BUS(&vpci_dev->bus));
>>>> +    object_property_set_link(OBJECT(dev),
>>>> +                             OBJECT(pci_get_bus(&vpci_dev->pci_dev)),
>>>> +                             "primary-bus", errp);
>>>> +    object_property_set_bool(OBJECT(vdev), true, "realized", errp);
>>>> +}
>>>> +
>>>> +static void virtio_iommu_pci_class_init(ObjectClass *klass, void *data)
>>>> +{
>>>> +    DeviceClass *dc = DEVICE_CLASS(klass);
>>>> +    VirtioPCIClass *k = VIRTIO_PCI_CLASS(klass);
>>>> +    PCIDeviceClass *pcidev_k = PCI_DEVICE_CLASS(klass);
>>>> +    k->realize = virtio_iommu_pci_realize;
>>>> +    set_bit(DEVICE_CATEGORY_MISC, dc->categories);
>>>> +    dc->props = virtio_iommu_pci_properties;
>>>> +    pcidev_k->vendor_id = PCI_VENDOR_ID_REDHAT_QUMRANET;
>>>> +    pcidev_k->device_id = PCI_DEVICE_ID_VIRTIO_IOMMU;
>>>> +    pcidev_k->revision = VIRTIO_PCI_ABI_VERSION;
>>>> +    pcidev_k->class_id = PCI_CLASS_OTHERS;
>>>> +}
>>>> +
>>>> +static void virtio_iommu_pci_instance_init(Object *obj)
>>>> +{
>>>> +    VirtIOIOMMUPCI *dev = VIRTIO_IOMMU_PCI(obj);
>>>> +
>>>> +    virtio_instance_init_common(obj, &dev->vdev, sizeof(dev->vdev),
>>>> +                                TYPE_VIRTIO_IOMMU);
>>>> +}
>>>> +
>>>> +static const VirtioPCIDeviceTypeInfo virtio_iommu_pci_info = {
>>>> +    .base_name             = TYPE_VIRTIO_IOMMU_PCI,
>>>> +    .generic_name          = "virtio-iommu-pci",
>>>> +    .transitional_name     = "virtio-iommu-pci-transitional",
>>>> +    .non_transitional_name = "virtio-iommu-pci-non-transitional",
>>>> +    .instance_size = sizeof(VirtIOIOMMUPCI),
>>>> +    .instance_init = virtio_iommu_pci_instance_init,
>>>> +    .class_init    = virtio_iommu_pci_class_init,
>>>> +};
>>>> +
>>>> +static void virtio_iommu_pci_register(void)
>>>> +{
>>>> +    virtio_pci_types_register(&virtio_iommu_pci_info);
>>>> +}
>>>> +
>>>> +type_init(virtio_iommu_pci_register)
>>>> +
>>>> +
>>>> diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
>>>> index aaf1b9f70d..492ea7e68d 100644
>>>> --- a/include/hw/pci/pci.h
>>>> +++ b/include/hw/pci/pci.h
>>>> @@ -86,6 +86,7 @@ extern bool pci_available;
>>>>  #define PCI_DEVICE_ID_VIRTIO_9P          0x1009
>>>>  #define PCI_DEVICE_ID_VIRTIO_VSOCK       0x1012
>>>>  #define PCI_DEVICE_ID_VIRTIO_PMEM        0x1013
>>>> +#define PCI_DEVICE_ID_VIRTIO_IOMMU       0x1014
>>>>  
>>>>  #define PCI_VENDOR_ID_REDHAT             0x1b36
>>>>  #define PCI_DEVICE_ID_REDHAT_BRIDGE      0x0001
>>>> diff --git a/include/hw/virtio/virtio-iommu.h 
>>>> b/include/hw/virtio/virtio-iommu.h
>>>> index 56c8b4e57f..893ac65c0b 100644
>>>> --- a/include/hw/virtio/virtio-iommu.h
>>>> +++ b/include/hw/virtio/virtio-iommu.h
>>>> @@ -25,6 +25,7 @@
>>>>  #include "hw/pci/pci.h"
>>>>  
>>>>  #define TYPE_VIRTIO_IOMMU "virtio-iommu-device"
>>>> +#define TYPE_VIRTIO_IOMMU_PCI "virtio-iommu-device-base"
>>>>  #define VIRTIO_IOMMU(obj) \
>>>>          OBJECT_CHECK(VirtIOIOMMU, (obj), TYPE_VIRTIO_IOMMU)
>>>>  
>>>> diff --git a/qdev-monitor.c b/qdev-monitor.c
>>>> index 58222c2211..74cf090c61 100644
>>>> --- a/qdev-monitor.c
>>>> +++ b/qdev-monitor.c
>>>> @@ -63,6 +63,7 @@ static const QDevAlias qdev_alias_table[] = {
>>>>      { "virtio-input-host-ccw", "virtio-input-host", QEMU_ARCH_S390X },
>>>>      { "virtio-input-host-pci", "virtio-input-host",
>>>>              QEMU_ARCH_ALL & ~QEMU_ARCH_S390X },
>>>> +    { "virtio-iommu-pci", "virtio-iommu", QEMU_ARCH_ALL & 
>>>> ~QEMU_ARCH_S390X },
>>>>      { "virtio-keyboard-ccw", "virtio-keyboard", QEMU_ARCH_S390X },
>>>>      { "virtio-keyboard-pci", "virtio-keyboard",
>>>>              QEMU_ARCH_ALL & ~QEMU_ARCH_S390X },
>>>> -- 
>>>> 2.20.1
>>>
>