gpu: nvgpu: Fix big_pages logic in nvgpu_vm_init

Fix the way big_pages is handled in nvgpu_vm_init(). Prior to this
patch big_pages could wind up being true even if disable_bigpages is
set in the mm struct. Clearly this is wrong.

The logic is now simplified a little bit and makes it so that if the
disable_bigpages field is set then the resulting VM created by
nvgpu_vm_init() has only one user area (no need for a second LP user
area) and the big_pages field for the VM is set to false.

JIRA NVGPU-12
JIRA NVGPU-30

Change-Id: If5dc7fcf3fa4e070f87295406f0afe414269b702
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: http://git-master/r/1493318
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: svccoveritychecker <svccoveritychecker@nvidia.com>
Reviewed-by: Aingara Paramakuru <aparamakuru@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 13 insertions, 6 deletions

diff --git a/drivers/gpu/nvgpu/common/mm/vm.c b/drivers/gpu/nvgpu/common/mm/vm.c
index 904284ec..b957e755 100644
--- a/drivers/gpu/nvgpu/common/mm/vm.c
+++ b/drivers/gpu/nvgpu/common/mm/vm.c
@@ -279,7 +279,6 @@ int nvgpu_init_vm(struct mm_gk20a *mm,
 
         vm->va_start  = low_hole;
         vm->va_limit  = aperture_size;
-        vm->big_pages = big_pages;
 
         vm->big_page_size     = vm->gmmu_page_sizes[gmmu_page_size_big];
         vm->userspace_managed = userspace_managed;
@@ -292,7 +291,13 @@ int nvgpu_init_vm(struct mm_gk20a *mm,
 
         /* Setup vma limits. */
         if (kernel_reserved + low_hole < aperture_size) {
-                if (nvgpu_is_enabled(g, NVGPU_MM_UNIFY_ADDRESS_SPACES)) {
+                /*
+                 * If big_pages are disabled for this VM then it only makes
+                 * sense to make one VM, same as if the unified address flag
+                 * is set.
+                 */
+                if (!big_pages ||
+                    nvgpu_is_enabled(g, NVGPU_MM_UNIFY_ADDRESS_SPACES)) {
                         user_vma_start = low_hole;
                         user_vma_limit = vm->va_limit - kernel_reserved;
                         user_lp_vma_start = user_vma_limit;
@@ -346,11 +351,13 @@ int nvgpu_init_vm(struct mm_gk20a *mm,
          * space is used then check the user_lp vma instead of the user vma.
          */
         if (nvgpu_is_enabled(g, NVGPU_MM_UNIFY_ADDRESS_SPACES))
-                vm->big_pages = nvgpu_big_pages_possible(vm, user_vma_start,
-                                         user_vma_limit - user_vma_start);
+                vm->big_pages = big_pages &&
+                        nvgpu_big_pages_possible(vm, user_vma_start,
+                                        user_vma_limit - user_vma_start);
         else
-                vm->big_pages = nvgpu_big_pages_possible(vm, user_lp_vma_start,
-                                         user_lp_vma_limit - user_lp_vma_start);
+                vm->big_pages = big_pages &&
+                        nvgpu_big_pages_possible(vm, user_lp_vma_start,
+                                        user_lp_vma_limit - user_lp_vma_start);
 
         /*
          * User VMA.