When a device is marked for passthrough (via the new property
"xen,passthrough"),
dom0 must not access to the device (i.e not loading a driver), but should
be able to manage the MMIO/interrupt of the passthrough device.
The latter part will allow the toolstack to map MMIO/IRQ when a device
is pass through to a guest.
The property "xen,passthrough" will be translated as 'status="disabled"'
in the device tree to avoid DOM0 using the device. We assume that DOM0 is
able to cope with this property (already the case for Linux).
Rework the function map_device (renamed into handle_device) to:
* For a given device node:
- Give permission to manage IRQ/MMIO for this device
- Retrieve the IRQ configuration (i.e edge/level) from the device
tree
* When the device is not marked for guest passthrough:
- Assign the device to the guest if it's protected by an IOMMU
- Map the IRQs and MMIOs regions to the guest
Signed-off-by: Julien Grall <julien.gr...@linaro.org>
---
Changes in v3:
- This patch was formely "xen/arm: Follow-up to allow DOM0
manage IRQ and MMIO". It has been split in 2 parts [1].
- Update commit title and improve message
- Remove spurious change
[1] https://patches.linaro.org/34669/
---
docs/misc/arm/device-tree/passthrough.txt | 7 ++
xen/arch/arm/device.c | 2 +-
xen/arch/arm/domain_build.c | 102 ++++++++++++++++++++++--------
xen/common/device_tree.c | 6 ++
xen/include/xen/device_tree.h | 11 ++++
5 files changed, 100 insertions(+), 28 deletions(-)
create mode 100644 docs/misc/arm/device-tree/passthrough.txt
diff --git a/docs/misc/arm/device-tree/passthrough.txt
b/docs/misc/arm/device-tree/passthrough.txt
new file mode 100644
index 0000000..04645b3
--- /dev/null
+++ b/docs/misc/arm/device-tree/passthrough.txt
@@ -0,0 +1,7 @@
+Device passthrough
+===================
+
+Any device that will be passthrough to a guest should have a property
+"xen,passthrough" in their device tree node.
+
+The device won't be exposed to DOM0 and therefore no driver will be loaded.
diff --git a/xen/arch/arm/device.c b/xen/arch/arm/device.c
index 1993929..1a01793 100644
--- a/xen/arch/arm/device.c
+++ b/xen/arch/arm/device.c
@@ -30,7 +30,7 @@ int __init device_init(struct dt_device_node *dev, enum
device_match type,
ASSERT(dev != NULL);
- if ( !dt_device_is_available(dev) )
+ if ( !dt_device_is_available(dev) || dt_device_for_passthrough(dev) )
return -ENODEV;
for ( desc = _sdevice; desc != _edevice; desc++ )
diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index f68755f..b48b5d0 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -402,7 +402,7 @@ static int write_properties(struct domain *d, struct
kernel_info *kinfo,
const struct dt_device_node *node)
{
const char *bootargs = NULL;
- const struct dt_property *prop;
+ const struct dt_property *prop, *status = NULL;
int res = 0;
int had_dom0_bootargs = 0;
@@ -457,6 +457,17 @@ static int write_properties(struct domain *d, struct
kernel_info *kinfo,
}
}
+ /* Don't expose the property "xen,passthrough" to the guest */
+ if ( dt_property_name_is_equal(prop, "xen,passthrough") )
+ continue;
+
+ /* Remember and skip the status property as Xen may modify it later */
+ if ( dt_property_name_is_equal(prop, "status") )
+ {
+ status = prop;
+ continue;
+ }
+
res = fdt_property(kinfo->fdt, prop->name, prop_data, prop_len);
xfree(new_data);
@@ -465,6 +476,19 @@ static int write_properties(struct domain *d, struct
kernel_info *kinfo,
return res;
}
+ /*
+ * Override the property "status" to disable the device when it's
+ * marked for passthrough.
+ */
+ if ( dt_device_for_passthrough(node) )
+ res = fdt_property_string(kinfo->fdt, "status", "disabled");
+ else if ( status )
+ res = fdt_property(kinfo->fdt, "status", status->value,
+ status->length);
+
+ if ( res )
+ return res;
+
if ( dt_node_path_is_equal(node, "/chosen") )
{
const struct bootmodule *mod = kinfo->initrd_bootmodule;
@@ -919,8 +943,14 @@ static int make_timer_node(const struct domain *d, void
*fdt,
return res;
}
-/* Map the device in the domain */
-static int map_device(struct domain *d, struct dt_device_node *dev)
+/* For a given device node:
+ * - Give permission to the guest to manage IRQ and MMIO range
+ * - Retrieve the IRQ configuration (i.e edge/level) from device tree
+ * When the device is not marked for guest passthrough:
+ * - Assign the device to the guest if it's protected by an IOMMU
+ * - Map the IRQs and iomem regions to DOM0
+ */
+static int handle_device(struct domain *d, struct dt_device_node *dev)
{
unsigned int nirq;
unsigned int naddr;
@@ -929,13 +959,15 @@ static int map_device(struct domain *d, struct
dt_device_node *dev)
unsigned int irq;
struct dt_raw_irq rirq;
u64 addr, size;
+ bool_t need_mapping = !dt_device_for_passthrough(dev);
nirq = dt_number_of_irq(dev);
naddr = dt_number_of_address(dev);
- DPRINT("%s nirq = %d naddr = %u\n", dt_node_full_name(dev), nirq, naddr);
+ DPRINT("%s passthrough = %d nirq = %d naddr = %u\n",
dt_node_full_name(dev),
+ need_mapping, nirq, naddr);
- if ( dt_device_is_protected(dev) )
+ if ( dt_device_is_protected(dev) && need_mapping )
{
DPRINT("%s setup iommu\n", dt_node_full_name(dev));
res = iommu_assign_dt_device(d, dev);
@@ -947,7 +979,7 @@ static int map_device(struct domain *d, struct
dt_device_node *dev)
}
}
- /* Map IRQs */
+ /* Give permission and map IRQs */
for ( i = 0; i < nirq; i++ )
{
res = dt_device_get_raw_irq(dev, i, &rirq);
@@ -980,22 +1012,34 @@ static int map_device(struct domain *d, struct
dt_device_node *dev)
irq = res;
DPRINT("irq %u = %u\n", i, irq);
- /*
- * Checking the return of vgic_reserve_virq is not
- * necessary. It should not fail except when we try to map
- * twice the IRQ. This can happen if the IRQ is shared
- */
- vgic_reserve_virq(d, irq);
- res = route_irq_to_guest(d, irq, dt_node_name(dev));
+
+ res = irq_permit_access(d, irq);
if ( res )
{
- printk(XENLOG_ERR "Unable to route IRQ %u to domain %u\n",
- irq, d->domain_id);
+ printk(XENLOG_ERR "Unable to permit to dom%u access to IRQ %u\n",
+ d->domain_id, irq);
return res;
}
+
+ if ( need_mapping )
+ {
+ /*
+ * Checking the return of vgic_reserve_virq is not
+ * necessary. It should not fail except when we try to map
+ * twice the IRQ. This can happen if the IRQ is shared
+ */
+ vgic_reserve_virq(d, irq);
+ res = route_irq_to_guest(d, irq, dt_node_name(dev));
+ if ( res )
+ {
+ printk(XENLOG_ERR "Unable to route IRQ %u to domain %u\n",
+ irq, d->domain_id);
+ return res;
+ }
+ }
}
- /* Map the address ranges */
+ /* Give permission and map MMIOs */
for ( i = 0; i < naddr; i++ )
{
res = dt_device_get_address(dev, i, &addr, &size);
@@ -1019,17 +1063,21 @@ static int map_device(struct domain *d, struct
dt_device_node *dev)
addr & PAGE_MASK, PAGE_ALIGN(addr + size) - 1);
return res;
}
- res = map_mmio_regions(d,
- paddr_to_pfn(addr & PAGE_MASK),
- DIV_ROUND_UP(size, PAGE_SIZE),
- paddr_to_pfn(addr & PAGE_MASK));
- if ( res )
+
+ if ( need_mapping )
{
- printk(XENLOG_ERR "Unable to map 0x%"PRIx64
- " - 0x%"PRIx64" in domain %d\n",
- addr & PAGE_MASK, PAGE_ALIGN(addr + size) - 1,
- d->domain_id);
- return res;
+ res = map_mmio_regions(d,
+ paddr_to_pfn(addr & PAGE_MASK),
+ DIV_ROUND_UP(size, PAGE_SIZE),
+ paddr_to_pfn(addr & PAGE_MASK));
+ if ( res )
+ {
+ printk(XENLOG_ERR "Unable to map 0x%"PRIx64
+ " - 0x%"PRIx64" in domain %d\n",
+ addr & PAGE_MASK, PAGE_ALIGN(addr + size) - 1,
+ d->domain_id);
+ return res;
+ }
}
}
@@ -1104,7 +1152,7 @@ static int handle_node(struct domain *d, struct
kernel_info *kinfo,
return 0;
}
- res = map_device(d, node);
+ res = handle_device(d, node);
if ( res)
return res;
diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
index bb9d7ce..ce10574 100644
--- a/xen/common/device_tree.c
+++ b/xen/common/device_tree.c
@@ -1103,6 +1103,12 @@ bool_t dt_device_is_available(const struct
dt_device_node *device)
return 0;
}
+bool_t dt_device_for_passthrough(const struct dt_device_node *device)
+{
+ return (dt_find_property(device, "xen,passthrough", NULL) != NULL);
+
+}
+
static int __dt_parse_phandle_with_args(const struct dt_device_node *np,
const char *list_name,
const char *cells_name,
diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h
index 890d356..caaf65f 100644
--- a/xen/include/xen/device_tree.h
+++ b/xen/include/xen/device_tree.h
@@ -555,6 +555,17 @@ int dt_n_addr_cells(const struct dt_device_node *np);
bool_t dt_device_is_available(const struct dt_device_node *device);
/**
+ * dt_device_for_passthrough - Check if a device will be used for
+ * passthrough later
+ *
+ * @device: Node to check
+ *
+ * Return true if the property "xen,passthrough" is present in the node,
+ * false otherwise.
+ */
+bool_t dt_device_for_passthrough(const struct dt_device_node *device);
+
+/**
* dt_match_node - Tell if a device_node has a matching of dt_device_match
* @matches: array of dt_device_match structures to search in
* @node: the dt_device_node structure to match against
--
2.1.4
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