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Re: [PATCH v3 04/23] xen/arm: vIOMMU: add generic vIOMMU framework
- To: Milan Djokic <milan_djokic@xxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Julien Grall <julien@xxxxxxx>
- Date: Tue, 14 Apr 2026 15:15:38 +0900
- Cc: Rahul Singh <rahul.singh@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Bertrand Marquis <bertrand.marquis@xxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Anthony PERARD <anthony.perard@xxxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>
- Delivery-date: Tue, 14 Apr 2026 20:24:36 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
Hi Milan,
On 31/03/2026 10:52, Milan Djokic wrote:
From: Rahul Singh <rahul.singh@xxxxxxx>
This patch adds basic framework for vIOMMU.
Signed-off-by: Rahul Singh <rahul.singh@xxxxxxx>
Signed-off-by: Milan Djokic <milan_djokic@xxxxxxxx>
---
xen/arch/arm/dom0less-build.c | 2 +
xen/arch/arm/domain.c | 33 +++++++++++++
xen/arch/arm/domain_build.c | 2 +
xen/arch/arm/include/asm/viommu.h | 70 ++++++++++++++++++++++++++++
xen/drivers/passthrough/Kconfig | 5 ++
xen/drivers/passthrough/arm/Makefile | 1 +
xen/drivers/passthrough/arm/viommu.c | 48 +++++++++++++++++++
xen/include/public/arch-arm.h | 5 ++
xen/include/public/domctl.h | 4 +-
9 files changed, 168 insertions(+), 2 deletions(-)
create mode 100644 xen/arch/arm/include/asm/viommu.h
create mode 100644 xen/drivers/passthrough/arm/viommu.c
diff --git a/xen/arch/arm/dom0less-build.c b/xen/arch/arm/dom0less-build.c
index 4181c10538..067835e5d0 100644
--- a/xen/arch/arm/dom0less-build.c
+++ b/xen/arch/arm/dom0less-build.c
@@ -23,6 +23,7 @@
#include <asm/arm64/sve.h>
#include <asm/domain_build.h>
#include <asm/firmware/sci.h>
+#include <asm/viommu.h>
#include <asm/grant_table.h>
#include <asm/setup.h>
@@ -317,6 +318,7 @@ int __init arch_parse_dom0less_node(struct dt_device_node *node,
uint32_t val;
d_cfg->arch.gic_version = XEN_DOMCTL_CONFIG_GIC_NATIVE;
+ d_cfg->arch.viommu_type = viommu_get_type();
d_cfg->flags |= XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_hap;
if ( domu_dt_sci_parse(node, d_cfg) )
diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 94b9858ad2..241f87386b 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -28,6 +28,7 @@
#include <asm/tee/tee.h>
#include <asm/vfp.h>
#include <asm/vgic.h>
+#include <asm/viommu.h>
#include <asm/vtimer.h>
#include "vpci.h"
@@ -550,6 +551,14 @@ int arch_sanitise_domain_config(struct
xen_domctl_createdomain *config)
return -EINVAL;
}
+ /* Check config structure padding */
+ if ( config->arch.pad )
+ {
+ dprintk(XENLOG_INFO,
+ "Invalid input config, padding must be zero\n");
+ return -EINVAL;
+ }
+
/* Check feature flags */
if ( sve_vl_bits > 0 )
{
@@ -626,6 +635,21 @@ int arch_sanitise_domain_config(struct
xen_domctl_createdomain *config)
return -EINVAL;
}
+ if ( !(config->flags & XEN_DOMCTL_CDF_iommu) &&
+ config->arch.viommu_type != XEN_DOMCTL_CONFIG_VIOMMU_NONE )
+ {
+ dprintk(XENLOG_INFO,
+ "vIOMMU requested while iommu not enabled for domain\n");
+ return -EINVAL;
+ }
+
+ if ( config->arch.viommu_type != XEN_DOMCTL_CONFIG_VIOMMU_NONE )
+ {
+ dprintk(XENLOG_INFO,
+ "vIOMMU type requested not supported by the platform or
Xen\n");
+ return -EINVAL;
+ }
+
return sci_domain_sanitise_config(config);
}
@@ -721,6 +745,9 @@ int arch_domain_create(struct domain *d,
if ( (rc = sci_domain_init(d, config)) != 0 )
goto fail;
+ if ( (rc = domain_viommu_init(d, config->arch.viommu_type)) != 0 )
+ goto fail;
+
return 0;
fail:
@@ -965,6 +992,7 @@ enum {
PROG_pci = 1,
PROG_sci,
PROG_tee,
+ PROG_viommu,
I am not entirely sure about the position. Is the intention to
relinquish the viommu state *after* the devices are detached? If so, it
would be better to move this call just after 'PROG_pci' and add a
comment indicating the dependency.
PROG_xen,
PROG_page,
PROG_mapping,
@@ -1021,6 +1049,11 @@ int domain_relinquish_resources(struct domain *d)
if (ret )
return ret;
+ PROGRESS(viommu):
+ ret = viommu_relinquish_resources(d);
+ if (ret )
+ return ret;
+
PROGRESS(xen):
ret = relinquish_memory(d, &d->xenpage_list);
if ( ret )
diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index e8795745dd..a51563ee3d 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -35,6 +35,7 @@
#include <asm/arm64/sve.h>
#include <asm/cpufeature.h>
#include <asm/domain_build.h>
+#include <asm/viommu.h>
#include <xen/event.h>
#include <xen/irq.h>
@@ -1946,6 +1947,7 @@ void __init create_dom0(void)
dom0_cfg.arch.nr_spis = vgic_def_nr_spis();
dom0_cfg.arch.tee_type = tee_get_type();
dom0_cfg.max_vcpus = dom0_max_vcpus();
+ dom0_cfg.arch.viommu_type = viommu_get_type();
if ( iommu_enabled )
dom0_cfg.flags |= XEN_DOMCTL_CDF_iommu;
diff --git a/xen/arch/arm/include/asm/viommu.h
b/xen/arch/arm/include/asm/viommu.h
new file mode 100644
index 0000000000..4598f543b8
--- /dev/null
+++ b/xen/arch/arm/include/asm/viommu.h
@@ -0,0 +1,70 @@
+/* SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause) */
+#ifndef __ARCH_ARM_VIOMMU_H__
+#define __ARCH_ARM_VIOMMU_H__
+
+#ifdef CONFIG_ARM_VIRTUAL_IOMMU
+
+#include <xen/lib.h>
+#include <xen/types.h>
+#include <public/xen.h>
+
+struct viommu_ops {
+ /*
+ * Called during domain construction if toolstack requests to enable
+ * vIOMMU support.
+ */
+ int (*domain_init)(struct domain *d);
+
+ /*
+ * Called during domain destruction to free resources used by vIOMMU.
+ */
+ int (*relinquish_resources)(struct domain *d);
+};
+
+struct viommu_desc {
+ /* vIOMMU domains init/free operations described above. */
+ const struct viommu_ops *ops;
+
+ /*
+ * ID of vIOMMU. Corresponds to xen_arch_domainconfig.viommu_type.
+ * Should be one of XEN_DOMCTL_CONFIG_VIOMMU_xxx
+ */
+ uint16_t viommu_type;
Below, you define viommu_type as 'uint8_t'. So shouldn't this also be
'uint8_t'?
+};
+
+int domain_viommu_init(struct domain *d, uint16_t viommu_type);
+int viommu_relinquish_resources(struct domain *d);
+uint16_t viommu_get_type(void);
+
+#else
+
+static inline uint8_t viommu_get_type(void)
+{
+ return XEN_DOMCTL_CONFIG_VIOMMU_NONE;
+}
+
+static inline int domain_viommu_init(struct domain *d, uint16_t viommu_type)
+{
+ if ( likely(viommu_type == XEN_DOMCTL_CONFIG_VIOMMU_NONE) )
+ return 0;
+
+ return -ENODEV;
+}
+
+static inline int viommu_relinquish_resources(struct domain *d)
+{
+ return 0;
+}
+
+#endif /* CONFIG_ARM_VIRTUAL_IOMMU */
+
+#endif /* __ARCH_ARM_VIOMMU_H__ */
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/drivers/passthrough/Kconfig b/xen/drivers/passthrough/Kconfig
index b413c33a4c..3c174bc87b 100644
--- a/xen/drivers/passthrough/Kconfig
+++ b/xen/drivers/passthrough/Kconfig
@@ -35,6 +35,11 @@ config IPMMU_VMSA
(H3 ES3.0, M3-W+, etc) or Gen4 SoCs which IPMMU hardware supports
stage 2
translation table format and is able to use CPU's P2M table as is.
+config ARM_VIRTUAL_IOMMU
+ bool "Virtual IOMMU Support (UNSUPPORTED)" if UNSUPPORTED
+ help
+ Support virtual IOMMU infrastructure to implement vIOMMU.
+
endif
config AMD_IOMMU
diff --git a/xen/drivers/passthrough/arm/Makefile
b/xen/drivers/passthrough/arm/Makefile
index c5fb3b58a5..c3783188e3 100644
--- a/xen/drivers/passthrough/arm/Makefile
+++ b/xen/drivers/passthrough/arm/Makefile
@@ -2,3 +2,4 @@ obj-y += iommu.o iommu_helpers.o iommu_fwspec.o
obj-$(CONFIG_ARM_SMMU) += smmu.o
obj-$(CONFIG_IPMMU_VMSA) += ipmmu-vmsa.o
obj-$(CONFIG_ARM_SMMU_V3) += smmu-v3.o
+obj-$(CONFIG_ARM_VIRTUAL_IOMMU) += viommu.o
diff --git a/xen/drivers/passthrough/arm/viommu.c
b/xen/drivers/passthrough/arm/viommu.c
new file mode 100644
index 0000000000..7ab6061e34
--- /dev/null
+++ b/xen/drivers/passthrough/arm/viommu.c
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause) */
+
+#include <xen/errno.h>
+#include <xen/init.h>
+#include <xen/types.h>
+
+#include <asm/viommu.h>
+
+const struct viommu_desc __read_mostly *cur_viommu;
You don't seem to define 'cur_viommmu' in the header. So shouldn't this
be 'static'? Also, AFAICT, 'cur_viommu' would be set only once at boot.
So rather than using __read_mostly, you probably want to use
'__ro_after_init'.
+
+int domain_viommu_init(struct domain *d, uint16_t viommu_type)
+{
+ if ( viommu_type == XEN_DOMCTL_CONFIG_VIOMMU_NONE )
+ return 0;
+
+ if ( !cur_viommu )
+ return -ENODEV;
+
+ if ( cur_viommu->viommu_type != viommu_type )
+ return -EINVAL;
+
+ return cur_viommu->ops->domain_init(d);
+}
+
+int viommu_relinquish_resources(struct domain *d)
+{
+ if ( !cur_viommu )
+ return 0;
+
+ return cur_viommu->ops->relinquish_resources(d);
+}
+
+uint16_t viommu_get_type(void)
+{
+ if ( !cur_viommu )
+ return XEN_DOMCTL_CONFIG_VIOMMU_NONE;
+
+ return cur_viommu->viommu_type;
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/include/public/arch-arm.h b/xen/include/public/arch-arm.h
index cd563cf706..d4953d40fd 100644
--- a/xen/include/public/arch-arm.h
+++ b/xen/include/public/arch-arm.h
@@ -330,6 +330,8 @@ DEFINE_XEN_GUEST_HANDLE(vcpu_guest_context_t);
#define XEN_DOMCTL_CONFIG_ARM_SCI_NONE 0
#define XEN_DOMCTL_CONFIG_ARM_SCI_SCMI_SMC 1
+#define XEN_DOMCTL_CONFIG_VIOMMU_NONE 0
+
struct xen_arch_domainconfig {
/* IN/OUT */
uint8_t gic_version;
@@ -355,6 +357,9 @@ struct xen_arch_domainconfig {
uint32_t clock_frequency;
/* IN */
uint8_t arm_sci_type;
+ /* IN */
+ uint8_t viommu_type;
+ uint16_t pad;
};
#endif /* __XEN__ || __XEN_TOOLS__ */
diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
index 8f6708c0a7..23124547f3 100644
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -30,9 +30,9 @@
* fields) don't require a change of the version.
* Stable ops are NOT covered by XEN_DOMCTL_INTERFACE_VERSION!
*
- * Last version bump: Xen 4.19
+ * Last version bump: Xen 4.22
*/
-#define XEN_DOMCTL_INTERFACE_VERSION 0x00000017
+#define XEN_DOMCTL_INTERFACE_VERSION 0x00000018
/*
* NB. xen_domctl.domain is an IN/OUT parameter for this operation.
Cheers,
--
Julien Grall
|
