Currently we allocate all 3 levels of radix3 page tables using nvkm_gsp_mem_ctor(), which uses dma_alloc_coherent() for allocating all of the relevant memory. This can end up failing in scenarios where the system has very high memory fragmentation, and we can't find enough contiguous memory to allocate level 2 of the page table.

Currently, this can result in runtime PM issues on systems where memory fragmentation is high - as we'll fail to allocate the page table for our suspend/resume buffer:

kworker/10:2: page allocation failure: order:7, mode:0xcc0(GFP_KERNEL), nodemask=(null),cpuset=/,mems_allowed=0 CPU: 10 PID: 479809 Comm: kworker/10:2 Not tainted 6.8.6-201.ChopperV6.fc39.x86_64 #1 Hardware name: SLIMBOOK Executive/Executive, BIOS N.1.10GRU06 02/02/2024 Workqueue: pm pm_runtime_work Call Trace: <TASK> dump_stack_lvl+0x64/0x80 warn_alloc+0x165/0x1e0 ? __alloc_pages_direct_compact+0xb3/0x2b0 __alloc_pages_slowpath.constprop.0+0xd7d/0xde0 __alloc_pages+0x32d/0x350 __dma_direct_alloc_pages.isra.0+0x16a/0x2b0 dma_direct_alloc+0x70/0x270 nvkm_gsp_radix3_sg+0x5e/0x130 [nouveau] r535_gsp_fini+0x1d4/0x350 [nouveau] nvkm_subdev_fini+0x67/0x150 [nouveau] nvkm_device_fini+0x95/0x1e0 [nouveau] nvkm_udevice_fini+0x53/0x70 [nouveau] nvkm_object_fini+0xb9/0x240 [nouveau] nvkm_object_fini+0x75/0x240 [nouveau] nouveau_do_suspend+0xf5/0x280 [nouveau] nouveau_pmops_runtime_suspend+0x3e/0xb0 [nouveau] pci_pm_runtime_suspend+0x67/0x1e0 ? __pfx_pci_pm_runtime_suspend+0x10/0x10 __rpm_callback+0x41/0x170 ? __pfx_pci_pm_runtime_suspend+0x10/0x10 rpm_callback+0x5d/0x70 ? __pfx_pci_pm_runtime_suspend+0x10/0x10 rpm_suspend+0x120/0x6a0 pm_runtime_work+0x98/0xb0 process_one_work+0x171/0x340 worker_thread+0x27b/0x3a0 ? __pfx_worker_thread+0x10/0x10 kthread+0xe5/0x120 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x31/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1b/0x30

Luckily, we don't actually need to allocate coherent memory for the page table thanks to being able to pass the GPU a radix3 page table for suspend/resume data. So, let's rewrite nvkm_gsp_radix3_sg() to use the sg allocator for level 2. We continue using coherent allocations for lvl0 and 1, since they only take a single page.

V2: * Don't forget to actually jump to the next scatterlist when we reach the end of the scatterlist we're currently on when writing out the page table for level 2

Signed-off-by: Lyude Paul lyude@redhat.com Cc: stable@vger.kernel.org --- .../gpu/drm/nouveau/include/nvkm/subdev/gsp.h | 4 +- .../gpu/drm/nouveau/nvkm/subdev/gsp/r535.c | 77 ++++++++++++------- 2 files changed, 54 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/include/nvkm/subdev/gsp.h b/drivers/gpu/drm/nouveau/include/nvkm/subdev/gsp.h index 6f5d376d8fcc1..a11d16a16c3b2 100644 --- a/drivers/gpu/drm/nouveau/include/nvkm/subdev/gsp.h +++ b/drivers/gpu/drm/nouveau/include/nvkm/subdev/gsp.h @@ -15,7 +15,9 @@ struct nvkm_gsp_mem { };

struct nvkm_gsp_radix3 { - struct nvkm_gsp_mem mem[3]; + struct nvkm_gsp_mem lvl0; + struct nvkm_gsp_mem lvl1; + struct sg_table lvl2; };

int nvkm_gsp_sg(struct nvkm_device *, u64 size, struct sg_table *); diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c index 9858c1438aa7f..fd4e80ba6adfc 100644 --- a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c @@ -1624,7 +1624,7 @@ r535_gsp_wpr_meta_init(struct nvkm_gsp *gsp) meta->magic = GSP_FW_WPR_META_MAGIC; meta->revision = GSP_FW_WPR_META_REVISION;

- meta->sysmemAddrOfRadix3Elf = gsp->radix3.mem[0].addr; + meta->sysmemAddrOfRadix3Elf = gsp->radix3.lvl0.addr; meta->sizeOfRadix3Elf = gsp->fb.wpr2.elf.size;

meta->sysmemAddrOfBootloader = gsp->boot.fw.addr; @@ -1919,8 +1919,9 @@ nvkm_gsp_sg(struct nvkm_device *device, u64 size, struct sg_table *sgt) static void nvkm_gsp_radix3_dtor(struct nvkm_gsp *gsp, struct nvkm_gsp_radix3 *rx3) { - for (int i = ARRAY_SIZE(rx3->mem) - 1; i >= 0; i--) - nvkm_gsp_mem_dtor(gsp, &rx3->mem[i]); + nvkm_gsp_sg_free(gsp->subdev.device, &rx3->lvl2); + nvkm_gsp_mem_dtor(gsp, &rx3->lvl1); + nvkm_gsp_mem_dtor(gsp, &rx3->lvl0); }

/** @@ -1960,36 +1961,60 @@ static int nvkm_gsp_radix3_sg(struct nvkm_gsp *gsp, struct sg_table *sgt, u64 size, struct nvkm_gsp_radix3 *rx3) { - u64 addr; + struct sg_dma_page_iter sg_dma_iter; + struct scatterlist *sg; + size_t bufsize; + u64 *pte; + int ret, i, page_idx = 0;

- for (int i = ARRAY_SIZE(rx3->mem) - 1; i >= 0; i--) { - u64 *ptes; - size_t bufsize; - int ret, idx; + ret = nvkm_gsp_mem_ctor(gsp, GSP_PAGE_SIZE, &rx3->lvl0); + if (ret) + return ret;

- bufsize = ALIGN((size / GSP_PAGE_SIZE) * sizeof(u64), GSP_PAGE_SIZE); - ret = nvkm_gsp_mem_ctor(gsp, bufsize, &rx3->mem[i]); - if (ret) - return ret; + ret = nvkm_gsp_mem_ctor(gsp, GSP_PAGE_SIZE, &rx3->lvl1); + if (ret) + goto lvl1_fail;

- ptes = rx3->mem[i].data; - if (i == 2) { - struct scatterlist *sgl; + // Allocate level 2 + bufsize = ALIGN((size / GSP_PAGE_SIZE) * sizeof(u64), GSP_PAGE_SIZE); + ret = nvkm_gsp_sg(gsp->subdev.device, bufsize, &rx3->lvl2); + if (ret) + goto lvl2_fail;

- for_each_sgtable_dma_sg(sgt, sgl, idx) { - for (int j = 0; j < sg_dma_len(sgl) / GSP_PAGE_SIZE; j++) - *ptes++ = sg_dma_address(sgl) + (GSP_PAGE_SIZE * j); - } - } else { - for (int j = 0; j < size / GSP_PAGE_SIZE; j++) - *ptes++ = addr + GSP_PAGE_SIZE * j; + // Write the bus address of level 1 to level 0 + pte = rx3->lvl0.data; + *pte = rx3->lvl1.addr; + + // Write the bus address of each page in level 2 to level 1 + pte = rx3->lvl1.data; + for_each_sgtable_dma_page(&rx3->lvl2, &sg_dma_iter, 0) + *pte++ = sg_page_iter_dma_address(&sg_dma_iter); + + // Finally, write the bus address of each page in sgt to level 2 + for_each_sgtable_sg(&rx3->lvl2, sg, i) { + void *sgl_end; + + pte = sg_virt(sg); + sgl_end = (void*)pte + sg->length; + + for_each_sgtable_dma_page(sgt, &sg_dma_iter, page_idx) { + *pte++ = sg_page_iter_dma_address(&sg_dma_iter); + page_idx++; + + // Go to the next scatterlist for level 2 if we've reached the end + if ((void*)pte >= sgl_end) + break; } + }

- size = rx3->mem[i].size; - addr = rx3->mem[i].addr; + if (ret) { +lvl2_fail: + nvkm_gsp_mem_dtor(gsp, &rx3->lvl1); +lvl1_fail: + nvkm_gsp_mem_dtor(gsp, &rx3->lvl0); }

- return 0; + return ret; }

int @@ -2021,7 +2046,7 @@ r535_gsp_fini(struct nvkm_gsp *gsp, bool suspend) sr = gsp->sr.meta.data; sr->magic = GSP_FW_SR_META_MAGIC; sr->revision = GSP_FW_SR_META_REVISION; - sr->sysmemAddrOfSuspendResumeData = gsp->sr.radix3.mem[0].addr; + sr->sysmemAddrOfSuspendResumeData = gsp->sr.radix3.lvl0.addr; sr->sizeOfSuspendResumeData = len;

mbox0 = lower_32_bits(gsp->sr.meta.addr);