Re: [PATCH v5 3/4] hw: Set virtio-iommu aw-bits default value on pc_q35 and arm virt

[Eric Auger]

Hi Igor,

On 2/29/24 10:20, Igor Mammedov wrote:
> On Thu, 15 Feb 2024 09:42:13 +0100
> Eric Auger <eric.auger@redhat.com> wrote:
>
>> Currently the default input range can extend to 64 bits. On x86,
>> when the virtio-iommu protects vfio devices, the physical iommu
>> may support only 39 bits. Let's set the default to 39, as done
>> for the intel-iommu. On ARM we set 48b as a default (matching
>> SMMUv3 SMMU_IDR5.VAX == 0).
>>
>> We use hw_compat_8_2 to handle the compatibility for machines
>> before 9.0 which used to have a virtio-iommu default input range
>> of 64 bits.
> so we have different defaults per target/machine
> while open codding fixup in _pre_plug_ works it's
> a bit unexpected place to manage defaults and
> avoid adding 0 magic.
>
> How about using compat machinery instead to set
> machine dependent defaults:
> For example:
>
> pc_i440fx_machine_options(MachineClass *m)
> {
> ...
> +    compat_props_add(m->compat_props, 
> pc_compat_defaults,pc_compat_defaults_len);
>  }
Yes I can go this way.
>
>> Of course if aw-bits is set from the command line, the default
>> is overriden.
>>
>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>> Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
>> Tested-by: Yanghang Liu<yanghliu@redhat.com>
>>
>> ---
>>
>> v3 -> v4:
>> - update the qos test to relax the check on the max input IOVA
>>
>> v2 -> v3:
>> - collected Zhenzhong's R-b
>> - use &error_abort instead of NULL error handle
>>   on object_property_get_uint() call (Cédric)
>> - use VTD_HOST_AW_39BIT (Cédric)
>>
>> v1 -> v2:
>> - set aw-bits to 48b on ARM
>> - use hw_compat_8_2 to handle the compat for older machines
>>   which used 64b as a default
>> ---
>>  hw/arm/virt.c                   | 6 ++++++
>>  hw/core/machine.c               | 5 ++++-
>>  hw/i386/pc.c                    | 6 ++++++
>>  hw/virtio/virtio-iommu.c        | 2 +-
>>  tests/qtest/virtio-iommu-test.c | 2 +-
>>  5 files changed, 18 insertions(+), 3 deletions(-)
>>
>> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
>> index 368c2a415a..0994f2a560 100644
>> --- a/hw/arm/virt.c
>> +++ b/hw/arm/virt.c
>> @@ -2716,10 +2716,16 @@ static void 
>> virt_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
>>      } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI)) {
>>          virtio_md_pci_pre_plug(VIRTIO_MD_PCI(dev), MACHINE(hotplug_dev), 
>> errp);
>>      } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI)) {
>> +        uint8_t aw_bits = object_property_get_uint(OBJECT(dev),
>> +                                                   "aw-bits", &error_abort);
>>          hwaddr db_start = 0, db_end = 0;
>>          QList *reserved_regions;
>>          char *resv_prop_str;
>>  
>> +        if (!aw_bits) {
>> +            qdev_prop_set_uint8(dev, "aw-bits", 48);
> s/48/macro name/?
with compats it becomes a string.  So I cannot directly reuse X86_64 VTD
or ARM SMMU macros. I would introduce a dummy VIRTIO_IOMMU string which
does not sound really helpful.
>
>> +        }
>>
>>
>>          if (vms->iommu != VIRT_IOMMU_NONE) {
>>              error_setg(errp, "virt machine does not support multiple 
>> IOMMUs");
>>              return;
>> diff --git a/hw/core/machine.c b/hw/core/machine.c
>> index fb5afdcae4..70ac96954c 100644
>> --- a/hw/core/machine.c
>> +++ b/hw/core/machine.c
>> @@ -30,9 +30,12 @@
>>  #include "exec/confidential-guest-support.h"
>>  #include "hw/virtio/virtio-pci.h"
>>  #include "hw/virtio/virtio-net.h"
>> +#include "hw/virtio/virtio-iommu.h"
>>  #include "audio/audio.h"
>>  
>> -GlobalProperty hw_compat_8_2[] = {};
>> +GlobalProperty hw_compat_8_2[] = {
>> +    { TYPE_VIRTIO_IOMMU_PCI, "aw-bits", "64" },
>> +};
>>  const size_t hw_compat_8_2_len = G_N_ELEMENTS(hw_compat_8_2);
>>  
>>  GlobalProperty hw_compat_8_1[] = {
>> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
>> index 196827531a..ee2d379c90 100644
>> --- a/hw/i386/pc.c
>> +++ b/hw/i386/pc.c
>> @@ -1456,6 +1456,8 @@ static void 
>> pc_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
>>      } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_MD_PCI)) {
>>          virtio_md_pci_pre_plug(VIRTIO_MD_PCI(dev), MACHINE(hotplug_dev), 
>> errp);
>>      } else if (object_dynamic_cast(OBJECT(dev), TYPE_VIRTIO_IOMMU_PCI)) {
>> +        uint8_t aw_bits = object_property_get_uint(OBJECT(dev),
>> +                                                   "aw-bits", &error_abort);
>>          /* Declare the APIC range as the reserved MSI region */
>>          char *resv_prop_str = g_strdup_printf("0xfee00000:0xfeefffff:%d",
>>                                                VIRTIO_IOMMU_RESV_MEM_T_MSI);
>> @@ -1464,6 +1466,10 @@ static void 
>> pc_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
>>          qlist_append_str(reserved_regions, resv_prop_str);
>>          qdev_prop_set_array(dev, "reserved-regions", reserved_regions);
>>  
>> +        if (!aw_bits) {
>> +            qdev_prop_set_uint8(dev, "aw-bits", VTD_HOST_AW_39BIT);
>> +        }
>> +
>>          g_free(resv_prop_str);
>>      }
>>  
>> diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
>> index 8b541de850..2ec5ef3cd1 100644
>> --- a/hw/virtio/virtio-iommu.c
>> +++ b/hw/virtio/virtio-iommu.c
>> @@ -1526,7 +1526,7 @@ static Property virtio_iommu_properties[] = {
>>      DEFINE_PROP_LINK("primary-bus", VirtIOIOMMU, primary_bus,
>>                       TYPE_PCI_BUS, PCIBus *),
>>      DEFINE_PROP_BOOL("boot-bypass", VirtIOIOMMU, boot_bypass, true),
>> -    DEFINE_PROP_UINT8("aw-bits", VirtIOIOMMU, aw_bits, 64),
>> +    DEFINE_PROP_UINT8("aw-bits", VirtIOIOMMU, aw_bits, 0),
> I'd set some valid value here (obviously not universal) and skip
> default property setting for that machine/target
> For example pick x86 one.
Yes the purpose is to have a non null aw_bits value which makes the
virtio-iommu unusable without proper machine integration and puts the
mess on the libqos tests. 
>
>>      DEFINE_PROP_END_OF_LIST(),
>>  };
>>  
>> diff --git a/tests/qtest/virtio-iommu-test.c 
>> b/tests/qtest/virtio-iommu-test.c
>> index 068e7a9e6c..0f36381acb 100644
>> --- a/tests/qtest/virtio-iommu-test.c
>> +++ b/tests/qtest/virtio-iommu-test.c
>> @@ -34,7 +34,7 @@ static void pci_config(void *obj, void *data, 
>> QGuestAllocator *t_alloc)
>>      uint8_t bypass = qvirtio_config_readb(dev, 36);
>>  
>>      g_assert_cmpint(input_range_start, ==, 0);
>> -    g_assert_cmphex(input_range_end, ==, UINT64_MAX);
>> +    g_assert_cmphex(input_range_end, >=, 32);
>>      g_assert_cmpint(domain_range_start, ==, 0);
>>      g_assert_cmpint(domain_range_end, ==, UINT32_MAX);
>>      g_assert_cmpint(bypass, ==, 1);
Thank you for the suggestions

Eric