[PATCH v1 15/26] x86/virt/tdx: Extend tdx_page_array to support IOMMU_MT

Xu Yilun
2025-11-17T02:38:49Z

IOMMU_MT is another TDX Module defined structure similar to HPA_ARRAY_T
and HPA_LIST_INFO. The difference is it supports multi-order contiguous
pages. It adds an additional NUM_PAGES field for every multi-order page
entry.

Add an dedicated allocation helper for IOMMU_MT. Maybe a general
allocation helper for multi-order is better but could postponed until
another user appears.

Signed-off-by: Xu Yilun <yilun.xu@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
arch/x86/include/asm/tdx.h | 2 ++
arch/x86/virt/vmx/tdx/tdx.c | 71 +++++++++++++++++++++++++++++++++++--
2 files changed, 70 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index 1eeb77a6790a..4078fc497779 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -157,6 +157,8 @@ void tdx_page_array_ctrl_leak(struct tdx_page_array *array);
int tdx_page_array_ctrl_release(struct tdx_page_array *array,
unsigned int nr_released,
u64 released_hpa);
+struct tdx_page_array *
+tdx_page_array_create_iommu_mt(unsigned int iq_order, unsigned int nr_mt_pages);

struct tdx_td {
/* TD root structure: */
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index bbf93cad5bf2..46cdb5aaaf68 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -316,8 +316,15 @@ static int tdx_page_array_fill_root(struct tdx_page_array *array,
TDX_PAGE_ARRAY_MAX_NENTS);

entries = (u64 *)page_address(array->root);
- for (i = 0; i < array->nents; i++)
- entries[i] = page_to_phys(array->pages[offset + i]);
+ for (i = 0; i < array->nents; i++) {
+ struct page *page = array->pages[offset + i];
+
+ entries[i] = page_to_phys(page);
+
+ /* Now only for iommu_mt */
+ if (compound_nr(page) > 1)
+ entries[i] |= compound_nr(page);
+ }

return array->nents;
}
@@ -327,7 +334,7 @@ static void tdx_free_pages_bulk(unsigned int nr_pages, struct page **pages)
unsigned long i;

for (i = 0; i < nr_pages; i++)
- __free_page(pages[i]);
+ put_page(pages[i]);
}

static int tdx_alloc_pages_bulk(unsigned int nr_pages, struct page **pages)
@@ -466,6 +473,10 @@ static bool tdx_page_array_validate_release(struct tdx_page_array *array,
struct page *page = array->pages[offset + i];
u64 val = page_to_phys(page);

+ /* Now only for iommu_mt */
+ if (compound_nr(page) > 1)
+ val |= compound_nr(page);
+
if (val != entries[i]) {
pr_err("%s entry[%d] [0x%llx] doesn't match page hpa [0x%llx]\n",
__func__, i, entries[i], val);
@@ -516,6 +527,60 @@ int tdx_page_array_ctrl_release(struct tdx_page_array *array,
}
EXPORT_SYMBOL_GPL(tdx_page_array_ctrl_release);

+struct tdx_page_array *
+tdx_page_array_create_iommu_mt(unsigned int iq_order, unsigned int nr_mt_pages)
+{
+ unsigned int nr_entries = 2 + nr_mt_pages;
+ int ret;
+
+ if (nr_entries > TDX_PAGE_ARRAY_MAX_NENTS)
+ return NULL;
+
+ struct tdx_page_array *array __free(kfree) = kzalloc(sizeof(*array),
+ GFP_KERNEL);
+ if (!array)
+ return NULL;
+
+ struct page *root __free(__free_page) = alloc_page(GFP_KERNEL |
+ __GFP_ZERO);
+ if (!root)
+ return NULL;
+
+ struct page **pages __free(kfree) = kcalloc(nr_entries, sizeof(*pages),
+ GFP_KERNEL);
+ if (!pages)
+ return NULL;
+
+ /* TODO: folio_alloc_node() is preferred, but need numa info */
+ struct folio *t_iq __free(folio_put) = folio_alloc(GFP_KERNEL |
+ __GFP_ZERO,
+ iq_order);
+ if (!t_iq)
+ return NULL;
+
+ struct folio *t_ctxiq __free(folio_put) = folio_alloc(GFP_KERNEL |
+ __GFP_ZERO,
+ iq_order);
+ if (!t_ctxiq)
+ return NULL;
+
+ ret = tdx_alloc_pages_bulk(nr_mt_pages, pages + 2);
+ if (ret)
+ return NULL;
+
+ pages[0] = folio_page(no_free_ptr(t_iq), 0);
+ pages[1] = folio_page(no_free_ptr(t_ctxiq), 0);
+
+ array->nr_pages = nr_entries;
+ array->pages = no_free_ptr(pages);
+ array->root = no_free_ptr(root);
+
+ tdx_page_array_fill_root(array, 0);
+
+ return no_free_ptr(array);
+}
+EXPORT_SYMBOL_GPL(tdx_page_array_create_iommu_mt);
+
#define HPA_LIST_INFO_FIRST_ENTRY GENMASK_U64(11, 3)
#define HPA_LIST_INFO_PFN GENMASK_U64(51, 12)
#define HPA_LIST_INFO_LAST_ENTRY GENMASK_U64(63, 55)
--
2.25.1