Merge branch 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 cpu handling changes from Ingo Molnar:
 "Bigger changes:

   - Intel CPU hardware-enablement: new vector instructions support
     (AVX-512), by Fenghua Yu.

   - Support the clflushopt instruction and use it in appropriate
     places.  clflushopt is similar to clflush but with more relaxed
     ordering, by Ross Zwisler.

   - MSR accessor cleanups, by Borislav Petkov.

   - 'forcepae' boot flag for those who have way too much time to spend
     on way too old Pentium-M systems and want to live way too
     dangerously, by Chris Bainbridge"

* 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86, cpu: Add forcepae parameter for booting PAE kernels on PAE-disabled Pentium M
  Rename TAINT_UNSAFE_SMP to TAINT_CPU_OUT_OF_SPEC
  x86, intel: Make MSR_IA32_MISC_ENABLE bit constants systematic
  x86, Intel: Convert to the new bit access MSR accessors
  x86, AMD: Convert to the new bit access MSR accessors
  x86: Add another set of MSR accessor functions
  x86: Use clflushopt in drm_clflush_virt_range
  x86: Use clflushopt in drm_clflush_page
  x86: Use clflushopt in clflush_cache_range
  x86: Add support for the clflushopt instruction
  x86, AVX-512: Enable AVX-512 States Context Switch
  x86, AVX-512: AVX-512 Feature Detection

1 files changed, 8 insertions, 2 deletions

diff --git a/drivers/gpu/drm/drm_cache.c b/drivers/gpu/drm/drm_cache.c
index bb8f58012189..534cb89b160d 100644
--- a/drivers/gpu/drm/drm_cache.c
+++ b/drivers/gpu/drm/drm_cache.c
@@ -32,6 +32,12 @@
 #include <drm/drmP.h>
 
 #if defined(CONFIG_X86)
+
+/*
+ * clflushopt is an unordered instruction which needs fencing with mfence or
+ * sfence to avoid ordering issues.  For drm_clflush_page this fencing happens
+ * in the caller.
+ */
 static void
 drm_clflush_page(struct page *page)
 {
@@ -44,7 +50,7 @@ drm_clflush_page(struct page *page)
 
         page_virtual = kmap_atomic(page);
         for (i = 0; i < PAGE_SIZE; i += size)
-                clflush(page_virtual + i);
+                clflushopt(page_virtual + i);
         kunmap_atomic(page_virtual);
 }
 
@@ -133,7 +139,7 @@ drm_clflush_virt_range(char *addr, unsigned long length)
                 mb();
                 for (; addr < end; addr += boot_cpu_data.x86_clflush_size)
                         clflush(addr);
-                clflush(end - 1);
+                clflushopt(end - 1);
                 mb();
                 return;
         }