x86/fpu/xstate: Provide xstate_calculate_size()

Split out the size calculation from the paranoia check so it can be used
for recalculating buffer sizes when dynamically enabled features are
supported.

Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
[ tglx: Adopted to changed base code ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211021225527.10184-4-chang.seok.bae@intel.com

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index cbba381..310c420 100644 (file)
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -549,6 +549,33 @@ static bool __init check_xstate_against_struct(int nr)
        return true;
 }
 
+static unsigned int xstate_calculate_size(u64 xfeatures, bool compacted)
+{
+       unsigned int size = FXSAVE_SIZE + XSAVE_HDR_SIZE;
+       int i;
+
+       for_each_extended_xfeature(i, xfeatures) {
+               /* Align from the end of the previous feature */
+               if (xfeature_is_aligned(i))
+                       size = ALIGN(size, 64);
+               /*
+                * In compacted format the enabled features are packed,
+                * i.e. disabled features do not occupy space.
+                *
+                * In non-compacted format the offsets are fixed and
+                * disabled states still occupy space in the memory buffer.
+                */
+               if (!compacted)
+                       size = xfeature_uncompacted_offset(i);
+               /*
+                * Add the feature size even for non-compacted format
+                * to make the end result correct
+                */
+               size += xfeature_size(i);
+       }
+       return size;
+}
+
 /*
  * This essentially double-checks what the cpu told us about
  * how large the XSAVE buffer needs to be.  We are recalculating
@@ -575,25 +602,8 @@ static bool __init paranoid_xstate_size_valid(unsigned int kernel_size)
                        XSTATE_WARN_ON(1);
                        return false;
                }
-
-               /* Align from the end of the previous feature */
-               if (xfeature_is_aligned(i))
-                       size = ALIGN(size, 64);
-               /*
-                * In compacted format the enabled features are packed,
-                * i.e. disabled features do not occupy space.
-                *
-                * In non-compacted format the offsets are fixed and
-                * disabled states still occupy space in the memory buffer.
-                */
-               if (!compacted)
-                       size = xfeature_uncompacted_offset(i);
-               /*
-                * Add the feature size even for non-compacted format
-                * to make the end result correct
-                */
-               size += xfeature_size(i);
        }
+       size = xstate_calculate_size(fpu_kernel_cfg.max_features, compacted);
        XSTATE_WARN_ON(size != kernel_size);
        return size == kernel_size;
 }