amd_iommu: Add helpers to walk AMD v1 Page Table format

The current amdvi_page_walk() is designed to be called by the replay()
method. Rather than drastically altering it, introduce helpers to fetch
guest PTEs that will be used by a page walker implementation.

Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20250919213515.917111-8-alejandro.j.jimenez@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 40 insertions, 0 deletions

diff --git a/hw/i386/amd_iommu.h b/hw/i386/amd_iommu.h
index c1170a8202..9f833b297d 100644
--- a/hw/i386/amd_iommu.h
+++ b/hw/i386/amd_iommu.h
@@ -178,6 +178,46 @@
 #define AMDVI_GATS_MODE                 (2ULL <<  12)
 #define AMDVI_HATS_MODE                 (2ULL <<  10)
 
+/* Page Table format */
+
+#define AMDVI_PTE_PR                    (1ULL << 0)
+#define AMDVI_PTE_NEXT_LEVEL_MASK       GENMASK64(11, 9)
+
+#define IOMMU_PTE_PRESENT(pte)          ((pte) & AMDVI_PTE_PR)
+
+/* Using level=0 for leaf PTE at 4K page size */
+#define PT_LEVEL_SHIFT(level)           (12 + ((level) * 9))
+
+/* Return IOVA bit group used to index the Page Table at specific level */
+#define PT_LEVEL_INDEX(level, iova)     (((iova) >> PT_LEVEL_SHIFT(level)) & \
+                                        GENMASK64(8, 0))
+
+/* Return the max address for a specified level i.e. max_oaddr */
+#define PT_LEVEL_MAX_ADDR(x)    (((x) < 5) ? \
+                                ((1ULL << PT_LEVEL_SHIFT((x + 1))) - 1) : \
+                                (~(0ULL)))
+
+/* Extract the NextLevel field from PTE/PDE */
+#define PTE_NEXT_LEVEL(pte)     (((pte) & AMDVI_PTE_NEXT_LEVEL_MASK) >> 9)
+
+/* Take page table level and return default pagetable size for level */
+#define PTE_LEVEL_PAGE_SIZE(level)      (1ULL << (PT_LEVEL_SHIFT(level)))
+
+/*
+ * Return address of lower level page table encoded in PTE and specified by
+ * current level and corresponding IOVA bit group at such level.
+ */
+#define NEXT_PTE_ADDR(pte, level, iova) (((pte) & AMDVI_DEV_PT_ROOT_MASK) + \
+                                        (PT_LEVEL_INDEX(level, iova) * 8))
+
+/*
+ * Take a PTE value with mode=0x07 and return the page size it encodes.
+ */
+#define PTE_LARGE_PAGE_SIZE(pte)    (1ULL << (1 + cto64(((pte) | 0xfffULL))))
+
+/* Return number of PTEs to use for a given page size (expected power of 2) */
+#define PAGE_SIZE_PTE_COUNT(pgsz)       (1ULL << ((ctz64(pgsz) - 12) % 9))
+
 /* IOTLB */
 #define AMDVI_IOTLB_MAX_SIZE 1024
 #define AMDVI_DEVID_SHIFT    36