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Maarten Lankhorst

2013-Aug-11 06:17 UTC

[Nouveau] Fixing nouveau for >4k PAGE_SIZE

Op 11-08-13 07:36, Benjamin Herrenschmidt schreef:> On Sun, 2013-08-11 at 10:41 +1000, Benjamin Herrenschmidt wrote:
>> Now, to do that, I need a better understanding of the various things
>> in there since I'm not familiar with nouveau at all. What I think
I've
>> figured out is with a few questions, it would be awesome if you could
>> answer them so I can have a shot at fixing it all :-)
> Ok, a few more questions :-)
>
>  - in struct nouveau_mm_node, what unit are "offset" and
"length" ?Depends on the context. It's re-used a few times. In case of nouveau_vm
it's multiples of 1<<12, which is the smallest unit
a card can address.> They *seem* to be hard wired to be in units of 4k (regardless of either
> of system page size) which I assume means card small page size, but
> "offset" is in bytes ? At least according to my parsing of the
code in
> nouveau_vm_map_at().
Correct.> The big question then is whether that represents card address space or
> system address space... I assume the former right ? So a function like
> nouveau_vm_map_at() is solely concerned with mapping a piece of card
> address space in the card VM and thus shouldn't be concerned by the
> system PAGE_SIZE at all, right ?Former, but the code entangles system PAGE_SIZE and card PAGE_SIZE/SHIFT/MASK in
some cases.
> IE. The only one we should actually care about here is
> nouveau_vm_map_sg_table() or am I missing an important piece of the
> puzzle ?nouveau_vm_map_sg too.

nouveau_vm_map is special, and also used to map VRAM into BAR1/BAR3 by
subdev/bar code.> Additionally, nv41.c has only map_sg() callbacks, no map() callbacks,
> should I assume that means that nouveau_vm_map() and nouveau_vm_map_at()
> will never be called on these ?Correct. all cards before the nv50 family have no real vm. the BAR used for vram
is just an identity mapping,
not the entirety of VRAM may be accessible to the
system.>  - In vm/base.c this construct appears regulary:
>
>     struct nouveau_gpuobj *pgt = vm->pgt[pde].obj[big];
>
> Which makes me believe we have separate page tables for small vs. large
> pages (in card mmu) (though I assume big is always 0 on nv40 unless
> missed something, I want to make sure I'm not breaking everything
> else...).
>
> Thus I assume that each "pte" in a "big" page table
maps a page size
> of 1 << vmm->lpg_shift, is that correct ?Correct, nv50+ are the only ones that support large
pages.> vmm->pgt_bits is always the same however, thus I assume that PDEs always
> map the same amount of space, but regions for large pages just have
> fewer PTEs, which seem to correspond to what the code does here:
>
> 	u32 pte  = (offset & ((1 << vmm->pgt_bits) - 1)) >>
bits;
>
> - My basic idea is to move the card page vs system PAGE breakdown
> up into vm/base.c, which seems reasonably simple in the case of
> nouveau_vm_map_sg_table() since we only call vmm->map_sg for one PTE at
> a time, but things get a bit trickier with nouveau_vm_map_sg which
> passes the whole page list down.
>
> Following my idea would mean essentially also making it operate one PTE
> at a time, thus potentially reducing the performance of the map
> operations.
>
> One option is to special case the PAGE_SIZE==12 case to keep the
> existing behaviour and operate in "reduced" (one PTE per call)
> mode in the other case but I dislike special casing like that (bitrots,
> one code path gets untested/unfixed, etc...)
>
> Another option would be to make struct nouveau_mem *mem ->pages always
> be an array of 4k (ie, create a breakdown when constructing that list),
> but I have yet to figure out what the impact would be (where that stuff
> gets created) and whether this is realistic at all...
>
>  - struct nouveau_mem is called "node" in various places (in
> nouveau_ttm) which is confusing. What is the relationship between
> nouveau_mem, nouveau_mm and nouveau_mm_node ? nouveau_mem seems to be
> having things such as "offset" in multiple of PAGE_SIZE, but have
a
> "page_shift" member that appears to match the buffer object
page_shift,
> hence seem to indicate that it is a card page shift...
>
> Would it be possible, maybe, to add comments next to the fields in
> those various data structure indicating in which units they are ?
>
>  - Similar confusion arises with things like struct ttm_mem_reg *mem.
> For example, in nouveau_ttm.c, I see statements like:
>
> 	ret = nouveau_vm_get(man->priv, mem->num_pages << 12,
node->page_shift,
> 			     NV_MEM_ACCESS_RW, &node->vma[0]);
>
> Which seems to indicate that mem->num_pages is in multiple of 4k always,
> though I would have though that a ttm object was in multiple of
> PAGE_SIZE, am I wrong ?
>
> Especially since the same object is later populated using:
>
> 	mem->start   = node->vma[0].offset >> PAGE_SHIFT;
>
> So the "start" member is in units of PAGE_SHIFT here, not 12.
>
> So I'm still a bit confused :-)
>The fun has been doubled because TTM expects PAGE units, so some of the
PAGE_SHIFT's are
genuine. Some may be a result of PAGE_SHIFT == 12, so honestly I don't know
the specific ones.

Benjamin Herrenschmidt

2013-Aug-11 07:06 UTC

head link

[Nouveau] Fixing nouveau for >4k PAGE_SIZE

On Sun, 2013-08-11 at 08:17 +0200, Maarten Lankhorst
wrote:> > So I'm still a bit confused :-)
> >
> The fun has been doubled because TTM expects PAGE units, so some of
> the PAGE_SHIFT's are
> genuine. Some may be a result of PAGE_SHIFT == 12, so honestly I don't
> know the specific ones.
Right, and the other way around too :-)

I think I found at least two cases where "12" was used where it should
have been PAGE_SHIFT (basically ttm_mem_reg->num_pages). This
is only the tip of the iceberg, so this isn't a formal patch submission,
but I would appreciate your thought as to whether the below is correct
(and thus I'm on the right track) :

--- a/drivers/gpu/drm/nouveau/nouveau_sgdma.c
+++ b/drivers/gpu/drm/nouveau/nouveau_sgdma.c
@@ -31,7 +31,7 @@ nv04_sgdma_bind(struct ttm_tt *ttm, struct ttm_mem_reg *mem)
 {
        struct nouveau_sgdma_be *nvbe = (struct nouveau_sgdma_be *)ttm;
        struct nouveau_mem *node = mem->mm_node;
-       u64 size = mem->num_pages << 12;
+       u64 size = mem->num_pages << PAGE_SHIFT;
 
        if (ttm->sg) {
                node->sg = ttm->sg;
diff --git a/drivers/gpu/drm/nouveau/nouveau_ttm.c b/drivers/gpu/drm/nouveau/nou
index 19e3757..f0629de 100644
--- a/drivers/gpu/drm/nouveau/nouveau_ttm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_ttm.c
@@ -252,8 +252,8 @@ nv04_gart_manager_new(struct ttm_mem_type_manager *man,
 
        node->page_shift = 12;
 
-       ret = nouveau_vm_get(man->priv, mem->num_pages << 12,
node->page_shift,
-                            NV_MEM_ACCESS_RW, &node->vma[0]);
+       ret = nouveau_vm_get(man->priv, mem->num_pages <<
PAGE_SHIFT,
+                            node->page_shift, NV_MEM_ACCESS_RW,
&node->vma[0]);
        if (ret) {
                kfree(node);

Thanks !

Cheers,
Ben.

Benjamin Herrenschmidt

2013-Aug-11 08:04 UTC

head link

[Nouveau] Fixing nouveau for >4k PAGE_SIZE

On Sun, 2013-08-11 at 17:06 +1000, Benjamin Herrenschmidt wrote:
> I think I found at least two cases where "12" was used where it
should
> have been PAGE_SHIFT (basically ttm_mem_reg->num_pages). This
> is only the tip of the iceberg, so this isn't a formal patch
submission,
> but I would appreciate your thought as to whether the below is correct
> (and thus I'm on the right track) :
This patch (which needs cleanups, and probably be broken down for
bisectability) makes it work for me. I've disabled nouveau_dri for now
as this has its own problems related to Ajax recent gallium endian
changes.

Note the horrible duplication of nouveau_vm_map_sg...

I think to fix it "cleanly" we probably need to slightly change the
->map_sg API to the vmmr. However, I do have a question whose answer
might make things a LOT easier if "yes" can make things a lot easier:

Can we guarantee that that such an sg object (I assume this is always
a ttm_bo getting placed in the "TT" memory, correct ?) has an
alignment
in *card VM space* that is a multiple of the *system page size* ? Ie,
can we make that happen easily ?

For example, if my system page size is 64k, can we guarantee that it
will always be mapped in the card at a virtual address that is 64k
aligned ?

If that is the case, then we *know* that a given page in the page list
passed to nouveau_vm_map_sg() will never cross a pde boundary (will
always be fully contained in the bottom level of the page table). That
allows to simplify the code a bit, and maybe to write a unified function
that can still pass down page lists to the vmmr....

On the other hand, if we have to handle misalignment, then we may as
well stick to 1 PTE at a time like my patch does to avoid horrible
complications.

Cheers,
Ben.

diff --git a/drivers/gpu/drm/nouveau/core/engine/fifo/nv40.c
b/drivers/gpu/drm/nouveau/core/engine/fifo/nv40.c
index 5c7433d..c314a5f 100644
--- a/drivers/gpu/drm/nouveau/core/engine/fifo/nv40.c
+++ b/drivers/gpu/drm/nouveau/core/engine/fifo/nv40.c
@@ -190,8 +190,8 @@ nv40_fifo_chan_ctor(struct nouveau_object *parent,
 	if (size < sizeof(*args))
 		return -EINVAL;
 
-	ret = nouveau_fifo_channel_create(parent, engine, oclass, 0, 0xc00000,
-					  0x1000, args->pushbuf,
+	ret = nouveau_fifo_channel_create(parent, engine, oclass, 0, 0x800000,
+					  0x10000, args->pushbuf,
 					  (1ULL << NVDEV_ENGINE_DMAOBJ) |
 					  (1ULL << NVDEV_ENGINE_SW) |
 					  (1ULL << NVDEV_ENGINE_GR) |
diff --git a/drivers/gpu/drm/nouveau/core/subdev/vm/base.c
b/drivers/gpu/drm/nouveau/core/subdev/vm/base.c
index ef3133e..5833851 100644
--- a/drivers/gpu/drm/nouveau/core/subdev/vm/base.c
+++ b/drivers/gpu/drm/nouveau/core/subdev/vm/base.c
@@ -84,10 +84,11 @@ nouveau_vm_map_sg_table(struct nouveau_vma *vma, u64 delta,
u64 length,
 {
 	struct nouveau_vm *vm = vma->vm;
 	struct nouveau_vmmgr *vmm = vm->vmm;
-	int big = vma->node->type != vmm->spg_shift;
+	u32 shift = vma->node->type;
+	int big = shift != vmm->spg_shift;
 	u32 offset = vma->node->offset + (delta >> 12);
-	u32 bits = vma->node->type - 12;
-	u32 num  = length >> vma->node->type;
+	u32 bits = shift - 12;
+	u32 num  = length >> shift;
 	u32 pde  = (offset >> vmm->pgt_bits) - vm->fpde;
 	u32 pte  = (offset & ((1 << vmm->pgt_bits) - 1)) >> bits;
 	u32 max  = 1 << (vmm->pgt_bits - bits);
@@ -98,7 +99,7 @@ nouveau_vm_map_sg_table(struct nouveau_vma *vma, u64 delta,
u64 length,
 
 	for_each_sg(mem->sg->sgl, sg, mem->sg->nents, i) {
 		struct nouveau_gpuobj *pgt = vm->pgt[pde].obj[big];
-		sglen = sg_dma_len(sg) >> PAGE_SHIFT;
+		sglen = sg_dma_len(sg) >> shift;
 
 		end = pte + sglen;
 		if (unlikely(end >= max))
@@ -106,7 +107,7 @@ nouveau_vm_map_sg_table(struct nouveau_vma *vma, u64 delta,
u64 length,
 		len = end - pte;
 
 		for (m = 0; m < len; m++) {
-			dma_addr_t addr = sg_dma_address(sg) + (m << PAGE_SHIFT);
+			dma_addr_t addr = sg_dma_address(sg) + (m << shift);
 
 			vmm->map_sg(vma, pgt, mem, pte, 1, &addr);
 			num--;
@@ -121,7 +122,7 @@ nouveau_vm_map_sg_table(struct nouveau_vma *vma, u64 delta,
u64 length,
 		}
 		if (m < sglen) {
 			for (; m < sglen; m++) {
-				dma_addr_t addr = sg_dma_address(sg) + (m << PAGE_SHIFT);
+				dma_addr_t addr = sg_dma_address(sg) + (m << shift);
 
 				vmm->map_sg(vma, pgt, mem, pte, 1, &addr);
 				num--;
@@ -136,6 +137,7 @@ finish:
 	vmm->flush(vm);
 }
 
+#if PAGE_SHIFT == 12
 void
 nouveau_vm_map_sg(struct nouveau_vma *vma, u64 delta, u64 length,
 		  struct nouveau_mem *mem)
@@ -143,10 +145,11 @@ nouveau_vm_map_sg(struct nouveau_vma *vma, u64 delta, u64
length,
 	struct nouveau_vm *vm = vma->vm;
 	struct nouveau_vmmgr *vmm = vm->vmm;
 	dma_addr_t *list = mem->pages;
-	int big = vma->node->type != vmm->spg_shift;
+	u32 shift = vma->node->type;
+	int big = shift != vmm->spg_shift;
 	u32 offset = vma->node->offset + (delta >> 12);
-	u32 bits = vma->node->type - 12;
-	u32 num  = length >> vma->node->type;
+	u32 bits = shift - 12;
+	u32 num  = length >> shift;
 	u32 pde  = (offset >> vmm->pgt_bits) - vm->fpde;
 	u32 pte  = (offset & ((1 << vmm->pgt_bits) - 1)) >> bits;
 	u32 max  = 1 << (vmm->pgt_bits - bits);
@@ -173,6 +176,52 @@ nouveau_vm_map_sg(struct nouveau_vma *vma, u64 delta, u64
length,
 
 	vmm->flush(vm);
 }
+#else
+void
+nouveau_vm_map_sg(struct nouveau_vma *vma, u64 delta, u64 length,
+		  struct nouveau_mem *mem)
+{
+	struct nouveau_vm *vm = vma->vm;
+	struct nouveau_vmmgr *vmm = vm->vmm;
+	dma_addr_t *list = mem->pages;
+	u32 shift = vma->node->type;
+	int big = shift != vmm->spg_shift;
+	u32 offset = vma->node->offset + (delta >> 12);
+	u32 bits = shift - 12;
+	u32 num  = length >> shift;
+	u32 pde  = (offset >> vmm->pgt_bits) - vm->fpde;
+	u32 pte  = (offset & ((1 << vmm->pgt_bits) - 1)) >> bits;
+	u32 max  = 1 << (vmm->pgt_bits - bits);
+	u32 sub_cnt = 1 << (PAGE_SHIFT - shift);
+	u32 sub_rem = 0;
+	u64 phys = 0;
+
+
+	/* XXX This will not work for a big mapping ! */
+	WARN_ON_ONCE(big);
+
+	while (num) {
+		struct nouveau_gpuobj *pgt = vm->pgt[pde].obj[big];
+
+		if (sub_rem == 0) {
+			phys = *(list++);
+			sub_rem = sub_cnt;
+		}
+		vmm->map_sg(vma, pgt, mem, pte, 1, &phys);
+
+		num  -= 1;
+		pte  += 1;
+		sub_rem -= 1;
+		phys += 1 << shift;
+		if (unlikely(pte >= max)) {
+			pde++;
+			pte = 0;
+		}
+	}
+
+	vmm->flush(vm);
+}
+#endif
 
 void
 nouveau_vm_unmap_at(struct nouveau_vma *vma, u64 delta, u64 length)
diff --git a/drivers/gpu/drm/nouveau/core/subdev/vm/nv04.c
b/drivers/gpu/drm/nouveau/core/subdev/vm/nv04.c
index ed45437..f7e2311 100644
--- a/drivers/gpu/drm/nouveau/core/subdev/vm/nv04.c
+++ b/drivers/gpu/drm/nouveau/core/subdev/vm/nv04.c
@@ -39,14 +39,10 @@ nv04_vm_map_sg(struct nouveau_vma *vma, struct
nouveau_gpuobj *pgt,
 {
 	pte = 0x00008 + (pte * 4);
 	while (cnt) {
-		u32 page = PAGE_SIZE / NV04_PDMA_PAGE;
 		u32 phys = (u32)*list++;
-		while (cnt && page--) {
-			nv_wo32(pgt, pte, phys | 3);
-			phys += NV04_PDMA_PAGE;
-			pte += 4;
-			cnt -= 1;
-		}
+		nv_wo32(pgt, pte, phys | 3);
+		pte += 4;
+		cnt -= 1;
 	}
 }
 
diff --git a/drivers/gpu/drm/nouveau/core/subdev/vm/nv41.c
b/drivers/gpu/drm/nouveau/core/subdev/vm/nv41.c
index 064c762..a78f624 100644
--- a/drivers/gpu/drm/nouveau/core/subdev/vm/nv41.c
+++ b/drivers/gpu/drm/nouveau/core/subdev/vm/nv41.c
@@ -43,14 +43,10 @@ nv41_vm_map_sg(struct nouveau_vma *vma, struct
nouveau_gpuobj *pgt,
 {
 	pte = pte * 4;
 	while (cnt) {
-		u32 page = PAGE_SIZE / NV41_GART_PAGE;
 		u64 phys = (u64)*list++;
-		while (cnt && page--) {
-			nv_wo32(pgt, pte, (phys >> 7) | 1);
-			phys += NV41_GART_PAGE;
-			pte += 4;
-			cnt -= 1;
-		}
+		nv_wo32(pgt, pte, (phys >> 7) | 1);
+		pte += 4;
+		cnt -= 1;
 	}
 }
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c
b/drivers/gpu/drm/nouveau/nouveau_bo.c
index af20fba..694024d 100644
--- a/drivers/gpu/drm/nouveau/nouveau_bo.c
+++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
@@ -226,7 +226,7 @@ nouveau_bo_new(struct drm_device *dev, int size, int align,
 	nvbo->page_shift = 12;
 	if (drm->client.base.vm) {
 		if (!(flags & TTM_PL_FLAG_TT) && size > 256 * 1024)
-			nvbo->page_shift = drm->client.base.vm->vmm->lpg_shift;
+			nvbo->page_shift = lpg_shift;
 	}
 
 	nouveau_bo_fixup_align(nvbo, flags, &align, &size);
diff --git a/drivers/gpu/drm/nouveau/nouveau_sgdma.c
b/drivers/gpu/drm/nouveau/nouveau_sgdma.c
index ca5492a..494cf88 100644
--- a/drivers/gpu/drm/nouveau/nouveau_sgdma.c
+++ b/drivers/gpu/drm/nouveau/nouveau_sgdma.c
@@ -31,7 +31,7 @@ nv04_sgdma_bind(struct ttm_tt *ttm, struct ttm_mem_reg *mem)
 {
 	struct nouveau_sgdma_be *nvbe = (struct nouveau_sgdma_be *)ttm;
 	struct nouveau_mem *node = mem->mm_node;
-	u64 size = mem->num_pages << 12;
+	u64 size = mem->num_pages << PAGE_SHIFT;
 
 	if (ttm->sg) {
 		node->sg = ttm->sg;
diff --git a/drivers/gpu/drm/nouveau/nouveau_ttm.c
b/drivers/gpu/drm/nouveau/nouveau_ttm.c
index 19e3757..f0629de 100644
--- a/drivers/gpu/drm/nouveau/nouveau_ttm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_ttm.c
@@ -252,8 +252,8 @@ nv04_gart_manager_new(struct ttm_mem_type_manager *man,
 
 	node->page_shift = 12;
 
-	ret = nouveau_vm_get(man->priv, mem->num_pages << 12,
node->page_shift,
-			     NV_MEM_ACCESS_RW, &node->vma[0]);
+	ret = nouveau_vm_get(man->priv, mem->num_pages << PAGE_SHIFT,
+			     node->page_shift, NV_MEM_ACCESS_RW, &node->vma[0]);
 	if (ret) {
 		kfree(node);
 		return ret;

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