RE: [PATCH v2 3/3] hw: Set virtio-iommu aw-bits default value on pc_q35_9.0 and arm virt

[Duan, Zhenzhong]

Hi Eric,

>-----Original Message-----
>From: Eric Auger <eric.auger@redhat.com>
>pc_q35_9.0 and arm virt
>
>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.
>
>Of course if aw-bits is set from the command line, the default
>is overriden.
>
>Signed-off-by: Eric Auger <eric.auger@redhat.com>
>
>---
>
>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 +-
> 4 files changed, 17 insertions(+), 2 deletions(-)
>
>diff --git a/hw/arm/virt.c b/hw/arm/virt.c
>index e6ead2c5c8..56539f2fc5 100644
>--- a/hw/arm/virt.c
>+++ b/hw/arm/virt.c
>@@ -2718,10 +2718,16 @@ 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", NULL);
>         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);
>+        }
>+
>         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 803244e5cc..0e2bcb4840 100644
>--- a/hw/i386/pc.c
>+++ b/hw/i386/pc.c
>@@ -1458,6 +1458,8 @@ 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", NULL);
>         /* 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);
>@@ -1466,6 +1468,10 @@ 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", 39);
>+        }
>+
>         g_free(resv_prop_str);
>     }
>
>diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
>index 7870bdbeee..c468e9b13b 100644
>--- a/hw/virtio/virtio-iommu.c
>+++ b/hw/virtio/virtio-iommu.c
>@@ -1529,7 +1529,7 @@ 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),

Not clear if virtio-iommu support other archs besides x86 and arm.
It looks on those archs, aw_bits is default 0 on machine 9.0 above
and will fails the check in realize?

Thanks
Zhenzhong

>     DEFINE_PROP_END_OF_LIST(),
> };
>
>--
>2.41.0