gpu: nvgpu: Fix several issues with the buddy allocator

The issues are:

1. Non-fixed allocs must take into account explicit PTE size
   requests. Previously the PTE size was determines from the
   allocation size which was incorect. To do this, the PTE size
   is now plumbed through all GPU VA allocations. This is what
   the new alloc_pte() op does.

2. Fix buddy PTE size assignment. This changes a '<=' into a
   '<' in the buddy allocation logic. Effectively this is now
   leaving the PTE size for buddy blocks equal to the PDE block
   size as 'ANY'.

   This prevents a buddy block of PDE size which has yet to be
   allocated from having a specific PDE size. Without this its
   possible to do a fixed alloc that fails unexpectedly due to
   mismatching PDE sizes.

   Consider two PDE block sized fixed allocs that are contained
   in one buddy twice the size of a PDE block. Let's call these
   fixed allocs S and B (small and big). Let's assume that two
   fixed allocs are done, each targeting S and B, in that order.
   With the current logic the first alloc, when we create the
   two buddies S and B, causes both S and B to have a PTE size of
   SMALL. Now when the second alloc happens we attempt to find
   a buddy B with a PTE size of either BIG or ANY. But we cannot
   becasue B already has size SMALL. This casues us to appear
   like we have a conflicting fixed alloc despite this not being
   the case.

3. Misc cleanups & bug fixes:
   - Clean up some MISRA issues
   - Delete an extraneous unlock that could have caused a
     deadlock.

Bug 200105199

Change-Id: Ib5447ec6705a5a289ac0cf3d5e90c79b5d67582d
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1768582
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 18 insertions, 6 deletions

diff --git a/drivers/gpu/nvgpu/common/mm/vm_area.c b/drivers/gpu/nvgpu/common/mm/vm_area.c
index c2c0d569..d096de5d 100644
--- a/drivers/gpu/nvgpu/common/mm/vm_area.c
+++ b/drivers/gpu/nvgpu/common/mm/vm_area.c
@@ -99,11 +99,22 @@ int nvgpu_vm_area_alloc(struct vm_gk20a *vm, u32 pages, u32 page_size,
         struct nvgpu_allocator *vma;
         struct nvgpu_vm_area *vm_area;
         u64 vaddr_start = 0;
+        u64 our_addr = *addr;
         u32 pgsz_idx = GMMU_PAGE_SIZE_SMALL;
 
+        /*
+         * If we have a fixed address then use the passed address in *addr. This
+         * corresponds to the o_a field in the IOCTL. But since we do not
+         * support specific alignments in the buddy allocator we ignore the
+         * field if it isn't a fixed offset.
+         */
+        if ((flags & NVGPU_VM_AREA_ALLOC_FIXED_OFFSET) != 0U) {
+                our_addr = *addr;
+        }
+
         nvgpu_log(g, gpu_dbg_map,
-                  "ADD vm_area: pgsz=%#-8x pages=%-9u addr=%#-14llx flags=0x%x",
-                  page_size, pages, *addr, flags);
+                  "ADD vm_area: pgsz=%#-8x pages=%-9u a/o=%#-14llx flags=0x%x",
+                  page_size, pages, our_addr, flags);
 
         for (; pgsz_idx < GMMU_NR_PAGE_SIZES; pgsz_idx++) {
                 if (vm->gmmu_page_sizes[pgsz_idx] == page_size) {
@@ -133,14 +144,15 @@ int nvgpu_vm_area_alloc(struct vm_gk20a *vm, u32 pages, u32 page_size,
 
         vma = vm->vma[pgsz_idx];
         if (flags & NVGPU_VM_AREA_ALLOC_FIXED_OFFSET) {
-                vaddr_start = nvgpu_alloc_fixed(vma, *addr,
+                vaddr_start = nvgpu_alloc_fixed(vma, our_addr,
                                                 (u64)pages *
                                                 (u64)page_size,
                                                 page_size);
         } else {
-                vaddr_start = nvgpu_alloc(vma,
-                                          (u64)pages *
-                                          (u64)page_size);
+                vaddr_start = nvgpu_alloc_pte(vma,
+                                              (u64)pages *
+                                              (u64)page_size,
+                                              page_size);
         }
 
         if (!vaddr_start) {