Hi Luca,
On 07/03/2025 07:58, Luca Fancellu wrote:
When Xen is built without HAS_PASSTHROUGH, there are some parts
in arm where iommu_* functions are called in the codebase, but
their implementation is under xen/drivers/passthrough that is
not built.
So provide some stub for these functions in order to build Xen
when !HAS_PASSTHROUGH, which is the case for example on systems
with MPU support.
For gnttab_need_iommu_mapping() in the Arm part, modify the macro
to use IS_ENABLED for the HAS_PASSTHROUGH Kconfig.
Fixes: 0388a5979b21 ("xen/arm: mpu: Introduce choice between MMU and MPU")
Signed-off-by: Luca Fancellu <luca.fance...@arm.com>
---
v4 changes:
- re-introduced stub for iommu_use_hap_pt, Stefano suggested
it is ok to have it in iommu.h.
- Reworded comment in iommu_domain_init from Jan suggestion
v3 Changes:
- removed stub for iommu_use_hap_pt, another solution will be
done for the instance in common arm code.
- Moved a comment close to the macro it was referred to
- add comment to iommu_domain_init() stub
- modified commit message
- Add fixes tag
v2 Changes:
- modify gnttab_need_iommu_mapping to use IS_ENABLED
- removed macro that didn't allow some of the parameter to be
evaluated
- Changed commit message
---
---
xen/arch/arm/include/asm/grant_table.h | 5 +--
xen/include/xen/iommu.h | 50 +++++++++++++++++++++++++-
2 files changed, 52 insertions(+), 3 deletions(-)
diff --git a/xen/arch/arm/include/asm/grant_table.h
b/xen/arch/arm/include/asm/grant_table.h
index d3c518a926b9..c5d87b60c4df 100644
--- a/xen/arch/arm/include/asm/grant_table.h
+++ b/xen/arch/arm/include/asm/grant_table.h
@@ -73,8 +73,9 @@ int replace_grant_host_mapping(uint64_t gpaddr, mfn_t frame,
#define gnttab_status_gfn(d, t, i) \
page_get_xenheap_gfn(gnttab_status_page(t, i))
-#define gnttab_need_iommu_mapping(d) \
- (is_domain_direct_mapped(d) && is_iommu_enabled(d))
+#define gnttab_need_iommu_mapping(d) \
+ (IS_ENABLED(CONFIG_HAS_PASSTHROUGH) && is_domain_direct_mapped(d) && \
+ is_iommu_enabled(d))
#endif /* __ASM_GRANT_TABLE_H__ */
/*
diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index 77a514019cc6..5ac038521e23 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -110,6 +110,8 @@ extern int8_t iommu_hwdom_reserved;
extern unsigned int iommu_dev_iotlb_timeout;
+#ifdef CONFIG_HAS_PASSTHROUGH
+
int iommu_setup(void);
int iommu_hardware_setup(void);
@@ -122,6 +124,28 @@ int arch_iommu_domain_init(struct domain *d);
void arch_iommu_check_autotranslated_hwdom(struct domain *d);
void arch_iommu_hwdom_init(struct domain *d);
+#else
+
+static inline int iommu_setup(void)
+{
+ return -ENODEV;
+}
+
+static inline int iommu_domain_init(struct domain *d, unsigned int opts)
+{
+ /*
+ * Return as the real iommu_domain_init() would: Success when
+ * !is_iommu_enabled(), following from !iommu_enabled when !HAS_PASSTHROUGH
+ */
+ return 0;
+}
+
+static inline void iommu_hwdom_init(struct domain *d) {}
+
+static inline void iommu_domain_destroy(struct domain *d) {}
+
+#endif /* HAS_PASSTHROUGH */
+
/*
* The following flags are passed to map (applicable ones also to unmap)
* operations, while some are passed back by lookup operations.
@@ -209,6 +233,8 @@ struct msi_msg;
#ifdef CONFIG_HAS_DEVICE_TREE
#include <xen/device_tree.h>
+#ifdef CONFIG_HAS_PASSTHROUGH
+
int iommu_assign_dt_device(struct domain *d, struct dt_device_node *dev);
int iommu_deassign_dt_device(struct domain *d, struct dt_device_node *dev);
int iommu_dt_domain_init(struct domain *d);
@@ -238,6 +264,26 @@ int iommu_do_dt_domctl(struct xen_domctl *domctl, struct
domain *d,
*/
int iommu_remove_dt_device(struct dt_device_node *np);
+#else
+
+static inline int iommu_assign_dt_device(struct domain *d,
+ struct dt_device_node *dev)
+{
+ return -EINVAL;
+}
+
+static inline int iommu_add_dt_device(struct dt_device_node *np)
+{
+ return 1;
I would suggest to add a comment explain what 1 means. IIRC, this means
"no iommu" present.
Other than that:
Acked-by: Julien Grall <jgr...@amazon.com>
Cheers,
--
Julien Grall
