x86/fpu/xstate: Consolidate size calculations

Use the offset calculation to do the size calculation which avoids yet
another series of CPUID instructions for each invocation.

  [ Fix the FP/SSE only case which missed to take the xstate
    header into account, as
    Reported-by: kernel test robot <oliver.sang@intel.com> ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/87o81pgbp2.ffs@tglx

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 5ac934b..39e1c86 100644 (file)
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -385,25 +385,6 @@ static void __init setup_init_fpu_buf(void)
        fxsave(&init_fpstate.regs.fxsave);
 }
 
-static int xfeature_uncompacted_offset(int xfeature_nr)
-{
-       u32 eax, ebx, ecx, edx;
-
-       /*
-        * Only XSAVES supports supervisor states and it uses compacted
-        * format. Checking a supervisor state's uncompacted offset is
-        * an error.
-        */
-       if (XFEATURE_MASK_SUPERVISOR_ALL & BIT_ULL(xfeature_nr)) {
-               WARN_ONCE(1, "No fixed offset for xstate %d\n", xfeature_nr);
-               return -1;
-       }
-
-       CHECK_XFEATURE(xfeature_nr);
-       cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
-       return ebx;
-}
-
 int xfeature_size(int xfeature_nr)
 {
        u32 eax, ebx, ecx, edx;
@@ -581,29 +562,15 @@ static bool __init check_xstate_against_struct(int nr)
 
 static unsigned int xstate_calculate_size(u64 xfeatures, bool compacted)
 {
-       unsigned int size = FXSAVE_SIZE + XSAVE_HDR_SIZE;
-       int i;
+       unsigned int topmost = fls64(xfeatures) -  1;
+       unsigned int offset = xstate_offsets[topmost];
 
-       for_each_extended_xfeature(i, xfeatures) {
-               /* Align from the end of the previous feature */
-               if (xfeature_is_aligned64(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;
+       if (topmost <= XFEATURE_SSE)
+               return sizeof(struct xregs_state);
+
+       if (compacted)
+               offset = xfeature_get_offset(xfeatures, topmost);
+       return offset + xstate_sizes[topmost];
 }
 
 /*