[PATCH v2 21/31] x86/virt/tdx: Add SEAMCALL wrappers for trusted IOMMU setup and clear

Xu Yilun
2026-03-27T16:23:51Z

From: Zhenzhong Duan <zhenzhong.duan@intel.com>

Add SEAMCALLs to setup/clear trusted IOMMU for TDX Connect.

Enable TEE I/O support for a target device requires to setup trusted IOMMU
for the related IOMMU device first, even only for enabling physical secure
links like SPDM/IDE.

TDH.IOMMU.SETUP takes the register base address (VTBAR) to position an
IOMMU device, and outputs an IOMMU_ID as the trusted IOMMU identifier.
TDH.IOMMU.CLEAR takes the IOMMU_ID to reverse the setup.

More information see Intel TDX Connect ABI Specification [1]
Section 3.2 TDX Connect Host-Side (SEAMCALL) Interface Functions.

[1]: https://cdrdv2.intel.com/v1/dl/getContent/858625

Co-developed-by: Xu Yilun <yilun.xu@linux.intel.com>
Signed-off-by: Xu Yilun <yilun.xu@linux.intel.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
---
arch/x86/include/asm/tdx.h | 2 ++
arch/x86/virt/vmx/tdx/tdx.h | 2 ++
arch/x86/virt/vmx/tdx/tdx.c | 32 ++++++++++++++++++++++++++++++--
3 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index d7605235aa9b..a59e0e43e465 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -245,6 +245,8 @@ u64 tdh_mem_page_remove(struct tdx_td *td, u64 gpa, u64 level, u64 *ext_err1, u6
u64 tdh_phymem_cache_wb(bool resume);
u64 tdh_phymem_page_wbinvd_tdr(struct tdx_td *td);
u64 tdh_phymem_page_wbinvd_hkid(u64 hkid, struct page *page);
+u64 tdh_iommu_setup(u64 vtbar, struct tdx_page_array *iommu_mt, u64 *iommu_id);
+u64 tdh_iommu_clear(u64 iommu_id, struct tdx_page_array *iommu_mt);
#else
static inline void tdx_init(void) { }
static inline int tdx_cpu_enable(void) { return -ENODEV; }
diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
index a26fe94c07ff..b25c418f6e61 100644
--- a/arch/x86/virt/vmx/tdx/tdx.h
+++ b/arch/x86/virt/vmx/tdx/tdx.h
@@ -62,6 +62,8 @@
#define TDH_SYS_CONFIG SEAMCALL_LEAF_VER(TDH_SYS_CONFIG_V0, 1)
#define TDH_EXT_INIT 60
#define TDH_EXT_MEM_ADD 61
+#define TDH_IOMMU_SETUP 128
+#define TDH_IOMMU_CLEAR 129

/* TDX page types */
#define PT_NDA 0x0
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index 294f36048c03..790713881f1f 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -2084,8 +2084,8 @@ static inline u64 tdx_tdr_pa(struct tdx_td *td)
return page_to_phys(td->tdr_page);
}

-static u64 __maybe_unused __seamcall_ir_resched(sc_func_t sc_func, u64 fn,
- struct tdx_module_args *args)
+static u64 __seamcall_ir_resched(sc_func_t sc_func, u64 fn,
+ struct tdx_module_args *args)
{
struct tdx_module_args _args;
u64 r;
@@ -2478,3 +2478,31 @@ void tdx_cpu_flush_cache_for_kexec(void)
}
EXPORT_SYMBOL_FOR_KVM(tdx_cpu_flush_cache_for_kexec);
#endif
+
+u64 tdh_iommu_setup(u64 vtbar, struct tdx_page_array *iommu_mt, u64 *iommu_id)
+{
+ struct tdx_module_args args = {
+ .rcx = vtbar,
+ .rdx = virt_to_phys(iommu_mt->root),
+ };
+ u64 r;
+
+ tdx_clflush_page_array(iommu_mt);
+
+ r = seamcall_ret_ir_resched(TDH_IOMMU_SETUP, &args);
+
+ *iommu_id = args.rcx;
+ return r;
+}
+EXPORT_SYMBOL_FOR_MODULES(tdh_iommu_setup, "tdx-host");
+
+u64 tdh_iommu_clear(u64 iommu_id, struct tdx_page_array *iommu_mt)
+{
+ struct tdx_module_args args = {
+ .rcx = iommu_id,
+ .rdx = virt_to_phys(iommu_mt->root),
+ };
+
+ return seamcall_ret_ir_resched(TDH_IOMMU_CLEAR, &args);
+}
+EXPORT_SYMBOL_FOR_MODULES(tdh_iommu_clear, "tdx-host");
--
2.25.1