x86emul: fix FXRSTOR test for most AMD CPUs

AMD CPUs that we classify as X86_BUG_FPU_PTRS don't touch the selector/
offset portion of the save image during FXSAVE unless an unmasked
exception is pending. Hence the selector zapping done between the
initial FXSAVE and the emulated FXRSTOR needs to be mirrored onto the
second FXSAVE, output of which gets fed into memcmp() to compare with
the input image.

Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Tested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Release-acked-by: Paul Durrant <paul@xen.org>

diff --git a/tools/tests/x86_emulator/test_x86_emulator.c b/tools/tests/x86_emulator/test_x86_emulator.c
index e7de37eaef038d9375b1d6a36cc1a005d6ee128e..4b01fa8b8ddff009c4c9a4fe0a27f6faa85ffc3b 100644 (file)
--- a/tools/tests/x86_emulator/test_x86_emulator.c
+++ b/tools/tests/x86_emulator/test_x86_emulator.c
@@ -2577,6 +2577,7 @@ int main(int argc, char **argv)
         regs.ecx = (unsigned long)(res + 0x81);
         rc = x86_emulate(&ctxt, &emulops);
         asm volatile ( "fxsave %0" : "=m" (res[0x100]) :: "memory" );
+        zap_xfpsel(&res[0x100]);
         if ( (rc != X86EMUL_OKAY) ||
              memcmp(res + 0x100, res + 0x80, 0x200) ||
              (regs.eip != (unsigned long)&instr[4]) )