Commit c4d53e56 authored by Dave Airlie's avatar Dave Airlie
Browse files

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: default avatarMary Guillemard <mary@mary.zone>
Tested-by: default avatarMary Guillemard <mary@mary.zone>
Tested-by: default avatarMel Henning <mhenning@darkrefraction.com>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
Link: https://patch.msgid.link/20260204030208.2313241-2-airlied@gmail.com
parent 750817a7

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c

+21 −20
Original line number Diff line number Diff line
@@ -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 {

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.h

+10 −4
Original line number Diff line number Diff line
@@ -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 *,