The MMIO region size required to support virtualized environments with
large PCI BAR regions can exceed the hardcoded limit configured in QEMU.
For example, a VM with multiple NVIDIA Grace-Hopper GPUs passed through
requires more MMIO memory than the amount provided by VIRT_HIGH_PCIE_MMIO
(currently 512GB). Instead of updating VIRT_HIGH_PCIE_MMIO, introduce a
new parameter, highmem-mmio-size, that specifies the MMIO size required
to support the VM configuration.
Example usage with 1TB MMIO region size:
-machine virt,gic-version=3,highmem-mmio-size=1T
Signed-off-by: Matthew R. Ochs <mo...@nvidia.com>
Reviewed-by: Gavin Shan <gs...@redhat.com>
---
v3: - Updated highmem-mmio-size description
v2: - Add unit suffix to example in commit message
- Use existing "high memory region" terminology
- Resolve minor braces nit
docs/system/arm/virt.rst | 4 ++++
hw/arm/virt.c | 38 ++++++++++++++++++++++++++++++++++++++
2 files changed, 42 insertions(+)
diff --git a/docs/system/arm/virt.rst b/docs/system/arm/virt.rst
index e67e7f0f7c50..20b14c22b659 100644
--- a/docs/system/arm/virt.rst
+++ b/docs/system/arm/virt.rst
@@ -138,6 +138,10 @@ highmem-mmio
Set ``on``/``off`` to enable/disable the high memory region for PCI MMIO.
The default is ``on``.
+highmem-mmio-size
+ Set the high memory region size for PCI MMIO. Must be a power-of-2 and
+ greater than or equal to the default size.
+
gic-version
Specify the version of the Generic Interrupt Controller (GIC) to provide.
Valid values are:
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 49eb0355ef0c..d8d62df43f04 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -2773,6 +2773,36 @@ static void virt_set_highmem_mmio(Object *obj, bool
value, Error **errp)
vms->highmem_mmio = value;
}
+static void virt_get_highmem_mmio_size(Object *obj, Visitor *v, const char
*name,
+ void *opaque, Error **errp)
+{
+ uint64_t size = extended_memmap[VIRT_HIGH_PCIE_MMIO].size;
+
+ visit_type_size(v, name, &size, errp);
+}
+
+static void virt_set_highmem_mmio_size(Object *obj, Visitor *v, const char
*name,
+ void *opaque, Error **errp)
+{
+ uint64_t size;
+
+ if (!visit_type_size(v, name, &size, errp)) {
+ return;
+ }
+
+ if (!is_power_of_2(size)) {
+ error_setg(errp, "highmem_mmio_size is not a power-of-2");
+ return;
+ }
+
+ if (size < extended_memmap[VIRT_HIGH_PCIE_MMIO].size) {
+ error_setg(errp, "highmem_mmio_size is less than the default (%lu)",
+ extended_memmap[VIRT_HIGH_PCIE_MMIO].size);
+ return;
+ }
+
+ extended_memmap[VIRT_HIGH_PCIE_MMIO].size = size;
+}
static bool virt_get_its(Object *obj, Error **errp)
{
@@ -3446,6 +3476,14 @@ static void virt_machine_class_init(ObjectClass *oc,
void *data)
"Set on/off to enable/disable high "
"memory region for PCI MMIO");
+ object_class_property_add(oc, "highmem-mmio-size", "size",
+ virt_get_highmem_mmio_size,
+ virt_set_highmem_mmio_size,
+ NULL, NULL);
+ object_class_property_set_description(oc, "highmem-mmio-size",
+ "Set the high memory region size "
+ "for PCI MMIO");
+
object_class_property_add_str(oc, "gic-version", virt_get_gic_version,
virt_set_gic_version);
object_class_property_set_description(oc, "gic-version",
--
2.46.0
