From a3febd57c5ccbf8a8d9ee0dc3c49f0f8fdbab8fc Mon Sep 17 00:00:00 2001
From: Thomas Hellstrom <thellstrom@vmware.com>
Date: Wed, 4 Dec 2019 11:42:15 +0100
Subject: drm/vmwgfx: Use VM_PFNMAP instead of VM_MIXEDMAP when possible
Git-commit: b20414252068263c736d008e536658f9ce13d74a
Patch-mainline: v5.6-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
For shared, and read-only private mappings of graphics memory, use
VM_PFNMAP instead of VM_MIXEDMAP. This means less accounting overhead
when inserting and removing page-table entries. TTM doesn't do this
by default, since there was a performance problem with book-keeping of
write-combined mappings. Since vmwgfx solely uses cached mappings, that's
not a problem and now that the TTM vm has largely been turned into
helpers, we can use VM_PFNMAP on a per-driver basis
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
index ce288756531b..aa7e50f63b94 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
@@ -45,6 +45,10 @@ int vmw_mmap(struct file *filp, struct vm_area_struct *vma)
vma->vm_ops = &vmw_vm_ops;
+ /* Use VM_PFNMAP rather than VM_MIXEDMAP if not a COW mapping */
+ if ((vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) != VM_MAYWRITE)
+ vma->vm_flags = (vma->vm_flags & ~VM_MIXEDMAP) | VM_PFNMAP;
+
return 0;
}
--
2.28.0