From: Dave Airlie <airlied@gmail.com>
To: dri-devel@lists.freedesktop.org
Cc: nouveau@lists.freedesktop.org
Subject: [PATCH 1/3] nouveau/vmm: rewrite pte tracker using a struct and bitfields.
Date: Tue, 3 Feb 2026 15:25:25 +1000 [thread overview]
Message-ID: <20260203052823.2220053-2-airlied@gmail.com> (raw)
In-Reply-To: <20260203052823.2220053-1-airlied@gmail.com>
From: Dave Airlie <airlied@redhat.com>
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.
Signed-off-by: Dave Airlie <airlied@redhat.com>
---
drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c | 41 ++++++++++---------
drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.h | 14 +++++--
2 files changed, 31 insertions(+), 24 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
index f95c58b67633..efc334f6104c 100644
--- 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 4586a425dbe4..a6312a0e6b84 100644
--- 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 *,
--
2.52.0
next prev parent reply other threads:[~2026-02-03 5:28 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-03 5:25 nouveau/vmm: fix switching between small and large PTEs Dave Airlie
2026-02-03 5:25 ` Dave Airlie [this message]
2026-02-03 5:25 ` [PATCH 2/3] nouveau/vmm: increase size of vmm pte tracker struct to u32 Dave Airlie
2026-02-03 5:25 ` [PATCH 3/3] nouveau/vmm: start tracking if the LPT PTE is valid. (v6) Dave Airlie
-- strict thread matches above, loose matches on Subject: below --
2026-02-04 3:00 [PATCH 0/3] nouveau/vmm: fix switching between small and large PTEs (series v2) Dave Airlie
2026-02-04 3:00 ` [PATCH 1/3] nouveau/vmm: rewrite pte tracker using a struct and bitfields Dave Airlie
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