[PATCH v2 05/31] x86/virt/tdx: Extend tdx_page_array to support IOMMU_MT

Xu Yilun
2026-03-27T16:22:52Z

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

Add a dedicated allocation helper for IOMMU_MT. Fortunately put_page()
works well for both single pages and multi-order folios, simplifying the
cleanup logic for all allocation methods.

Signed-off-by: Xu Yilun <yilun.xu@linux.intel.com>
---
arch/x86/include/asm/tdx.h | 2 +
arch/x86/virt/vmx/tdx/tdx.c | 90 +++++++++++++++++++++++++++++++++++--
2 files changed, 89 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index 9173a432b312..d5f1d7b7d1e7 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -175,6 +175,8 @@ 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 6c4ed80e8e5a..2b17e0f73dac 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -275,8 +275,15 @@ static int tdx_page_array_populate(struct tdx_page_array *array,
TDX_PAGE_ARRAY_MAX_NENTS);

entries = 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;
}
@@ -286,7 +293,7 @@ static void tdx_free_pages_bulk(unsigned int nr_pages, struct page **pages)
int 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,
@@ -463,6 +470,10 @@ 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);
@@ -555,6 +566,79 @@ tdx_page_array_alloc_contig(unsigned int nr_pages)
return tdx_page_array_alloc(nr_pages, tdx_alloc_pages_contig, NULL);
}

+static int tdx_alloc_pages_iommu_mt(unsigned int nr_pages, struct page **pages,
+ void *data)
+{
+ unsigned int iq_order = (unsigned int)(long)data;
+ struct folio *t_iq, *t_ctxiq;
+ int ret;
+
+ /* TODO: folio_alloc_node() is preferred, but need numa info */
+ t_iq = folio_alloc(GFP_KERNEL | __GFP_ZERO, iq_order);
+ if (!t_iq)
+ return -ENOMEM;
+
+ t_ctxiq = folio_alloc(GFP_KERNEL | __GFP_ZERO, iq_order);
+ if (!t_ctxiq) {
+ ret = -ENOMEM;
+ goto out_t_iq;
+ }
+
+ ret = tdx_alloc_pages_bulk(nr_pages - 2, pages + 2, NULL);
+ if (ret)
+ goto out_t_ctxiq;
+
+ pages[0] = folio_page(t_iq, 0);
+ pages[1] = folio_page(t_ctxiq, 0);
+
+ return 0;
+
+out_t_ctxiq:
+ folio_put(t_ctxiq);
+out_t_iq:
+ folio_put(t_iq);
+
+ return ret;
+}
+
+/**
+ * tdx_page_array_create_iommu_mt() - Create a page array for IOMMU Memory Tables
+ * @iq_order: The allocation order for the IOMMU Invalidation Queue.
+ * @nr_mt_pages: Number of additional order-0 pages for the MT.
+ *
+ * Allocate and populate a specialized tdx_page_array for IOMMU_MT structures.
+ * The resulting array consists of two multi-order folios (at index 0 and 1)
+ * followed by the requested number of order-0 pages.
+ *
+ * Return: Fully populated tdx_page_array or NULL on failure.
+ */
+struct tdx_page_array *
+tdx_page_array_create_iommu_mt(unsigned int iq_order, unsigned int nr_mt_pages)
+{
+ unsigned int nr_pages = nr_mt_pages + 2;
+ struct tdx_page_array *array;
+ int populated;
+
+ if (nr_pages > TDX_PAGE_ARRAY_MAX_NENTS)
+ return NULL;
+
+ array = tdx_page_array_alloc(nr_pages, tdx_alloc_pages_iommu_mt,
+ (void *)(long)iq_order);
+ if (!array)
+ return NULL;
+
+ populated = tdx_page_array_populate(array, 0);
+ if (populated != nr_pages)
+ goto out_free;
+
+ return array;
+
+out_free:
+ tdx_page_array_free(array);
+ return NULL;
+}
+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