nouveau/vmm: rewrite pte tracker using a struct and bitfields.

I want to increase the counters here and start tracking LPTs as well
as there are certain situations where userspace with mixed page sizes
can cause ref/unrefs to live longer so need better reference counting.

This should be entirely non-functional.

Reviewed-by: Mary Guillemard <mary@mary.zone>
Tested-by: Mary Guillemard <mary@mary.zone>
Tested-by: Mel Henning <mhenning@darkrefraction.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://patch.msgid.link/20260204030208.2313241-2-airlied@gmail.com

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
index f95c58b67633e151c1bcae11373f2bcd3a12cd12..efc334f6104c7ebc5e2e78c0cbed2bcf4a5537b4 100644 (file)
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
@@ -53,7 +53,7 @@ nvkm_vmm_pt_new(const struct nvkm_vmm_desc *desc, bool sparse,
                }
        }
 
-       if (!(pgt = kzalloc(sizeof(*pgt) + lpte, GFP_KERNEL)))
+       if (!(pgt = kzalloc(sizeof(*pgt) + (sizeof(pgt->pte[0]) * lpte), GFP_KERNEL)))
                return NULL;
        pgt->page = page ? page->shift : 0;
        pgt->sparse = sparse;
@@ -208,7 +208,7 @@ nvkm_vmm_unref_sptes(struct nvkm_vmm_iter *it, struct nvkm_vmm_pt *pgt,
         */
        for (lpti = ptei >> sptb; ptes; spti = 0, lpti++) {
                const u32 pten = min(sptn - spti, ptes);
-               pgt->pte[lpti] -= pten;
+               pgt->pte[lpti].s.sptes -= pten;
                ptes -= pten;
        }
 
@@ -218,9 +218,9 @@ nvkm_vmm_unref_sptes(struct nvkm_vmm_iter *it, struct nvkm_vmm_pt *pgt,
 
        for (ptei = pteb = ptei >> sptb; ptei < lpti; pteb = ptei) {
                /* Skip over any LPTEs that still have valid SPTEs. */
-               if (pgt->pte[pteb] & NVKM_VMM_PTE_SPTES) {
+               if (pgt->pte[pteb].s.sptes) {
                        for (ptes = 1, ptei++; ptei < lpti; ptes++, ptei++) {
-                               if (!(pgt->pte[ptei] & NVKM_VMM_PTE_SPTES))
+                               if (!(pgt->pte[ptei].s.sptes))
                                        break;
                        }
                        continue;
@@ -232,14 +232,14 @@ nvkm_vmm_unref_sptes(struct nvkm_vmm_iter *it, struct nvkm_vmm_pt *pgt,
                 *
                 * Determine how many LPTEs need to transition state.
                 */
-               pgt->pte[ptei] &= ~NVKM_VMM_PTE_VALID;
+               pgt->pte[ptei].s.spte_valid = false;
                for (ptes = 1, ptei++; ptei < lpti; ptes++, ptei++) {
-                       if (pgt->pte[ptei] & NVKM_VMM_PTE_SPTES)
+                       if (pgt->pte[ptei].s.sptes)
                                break;
-                       pgt->pte[ptei] &= ~NVKM_VMM_PTE_VALID;
+                       pgt->pte[ptei].s.spte_valid = false;
                }
 
-               if (pgt->pte[pteb] & NVKM_VMM_PTE_SPARSE) {
+               if (pgt->pte[pteb].s.sparse) {
                        TRA(it, "LPTE %05x: U -> S %d PTEs", pteb, ptes);
                        pair->func->sparse(vmm, pgt->pt[0], pteb, ptes);
                } else
@@ -307,7 +307,7 @@ nvkm_vmm_ref_sptes(struct nvkm_vmm_iter *it, struct nvkm_vmm_pt *pgt,
         */
        for (lpti = ptei >> sptb; ptes; spti = 0, lpti++) {
                const u32 pten = min(sptn - spti, ptes);
-               pgt->pte[lpti] += pten;
+               pgt->pte[lpti].s.sptes += pten;
                ptes -= pten;
        }
 
@@ -317,9 +317,9 @@ nvkm_vmm_ref_sptes(struct nvkm_vmm_iter *it, struct nvkm_vmm_pt *pgt,
 
        for (ptei = pteb = ptei >> sptb; ptei < lpti; pteb = ptei) {
                /* Skip over any LPTEs that already have valid SPTEs. */
-               if (pgt->pte[pteb] & NVKM_VMM_PTE_VALID) {
+               if (pgt->pte[pteb].s.spte_valid) {
                        for (ptes = 1, ptei++; ptei < lpti; ptes++, ptei++) {
-                               if (!(pgt->pte[ptei] & NVKM_VMM_PTE_VALID))
+                               if (!pgt->pte[ptei].s.spte_valid)
                                        break;
                        }
                        continue;
@@ -331,14 +331,14 @@ nvkm_vmm_ref_sptes(struct nvkm_vmm_iter *it, struct nvkm_vmm_pt *pgt,
                 *
                 * Determine how many LPTEs need to transition state.
                 */
-               pgt->pte[ptei] |= NVKM_VMM_PTE_VALID;
+               pgt->pte[ptei].s.spte_valid = true;
                for (ptes = 1, ptei++; ptei < lpti; ptes++, ptei++) {
-                       if (pgt->pte[ptei] & NVKM_VMM_PTE_VALID)
+                       if (pgt->pte[ptei].s.spte_valid)
                                break;
-                       pgt->pte[ptei] |= NVKM_VMM_PTE_VALID;
+                       pgt->pte[ptei].s.spte_valid = true;
                }
 
-               if (pgt->pte[pteb] & NVKM_VMM_PTE_SPARSE) {
+               if (pgt->pte[pteb].s.sparse) {
                        const u32 spti = pteb * sptn;
                        const u32 sptc = ptes * sptn;
                        /* The entire LPTE is marked as sparse, we need
@@ -386,7 +386,8 @@ nvkm_vmm_sparse_ptes(const struct nvkm_vmm_desc *desc,
                        pgt->pde[ptei++] = NVKM_VMM_PDE_SPARSE;
        } else
        if (desc->type == LPT) {
-               memset(&pgt->pte[ptei], NVKM_VMM_PTE_SPARSE, ptes);
+               union nvkm_pte_tracker sparse = { .s.sparse = 1 };
+               memset(&pgt->pte[ptei].u, sparse.u, ptes);
        }
 }
 
@@ -398,7 +399,7 @@ nvkm_vmm_sparse_unref_ptes(struct nvkm_vmm_iter *it, bool pfn, u32 ptei, u32 pte
                memset(&pt->pde[ptei], 0x00, sizeof(pt->pde[0]) * ptes);
        else
        if (it->desc->type == LPT)
-               memset(&pt->pte[ptei], 0x00, sizeof(pt->pte[0]) * ptes);
+               memset(&pt->pte[ptei].u, 0x00, sizeof(pt->pte[0]) * ptes);
        return nvkm_vmm_unref_ptes(it, pfn, ptei, ptes);
 }
 
@@ -445,9 +446,9 @@ nvkm_vmm_ref_hwpt(struct nvkm_vmm_iter *it, struct nvkm_vmm_pt *pgd, u32 pdei)
                 * the SPTEs on some GPUs.
                 */
                for (ptei = pteb = 0; ptei < pten; pteb = ptei) {
-                       bool spte = pgt->pte[ptei] & NVKM_VMM_PTE_SPTES;
+                       bool spte = !!pgt->pte[ptei].s.sptes;
                        for (ptes = 1, ptei++; ptei < pten; ptes++, ptei++) {
-                               bool next = pgt->pte[ptei] & NVKM_VMM_PTE_SPTES;
+                               bool next = !!pgt->pte[ptei].s.sptes;
                                if (spte != next)
                                        break;
                        }
@@ -461,7 +462,7 @@ nvkm_vmm_ref_hwpt(struct nvkm_vmm_iter *it, struct nvkm_vmm_pt *pgd, u32 pdei)
                        } else {
                                desc->func->unmap(vmm, pt, pteb, ptes);
                                while (ptes--)
-                                       pgt->pte[pteb++] |= NVKM_VMM_PTE_VALID;
+                                       pgt->pte[pteb++].s.spte_valid = true;
                        }
                }
        } else {

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.h b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.h
index 4586a425dbe4a6b576bfc77c031d48835eac0044..a6312a0e6b8464bae305cd11aefb091b3c9e0928 100644 (file)
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.h
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.h
@@ -4,6 +4,15 @@
 #include <core/memory.h>
 enum nvkm_memory_target;
 
+union nvkm_pte_tracker {
+       u8 u;
+       struct {
+               u8 sparse:1;
+               u8 spte_valid:1;
+               u8 sptes:6;
+       } s;
+};
+
 struct nvkm_vmm_pt {
        /* Some GPUs have a mapping level with a dual page tables to
         * support large and small pages in the same address-range.
@@ -44,10 +53,7 @@ struct nvkm_vmm_pt {
         *
         * This information is used to manage LPTE state transitions.
         */
-#define NVKM_VMM_PTE_SPARSE 0x80
-#define NVKM_VMM_PTE_VALID  0x40
-#define NVKM_VMM_PTE_SPTES  0x3f
-       u8 pte[];
+       union nvkm_pte_tracker pte[];
 };
 
 typedef void (*nvkm_vmm_pxe_func)(struct nvkm_vmm *,