From: Jan Beulich Date: Mon, 6 Jul 2020 15:14:24 +0000 (+0200) Subject: x86emul: fix FXRSTOR test for most AMD CPUs X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=f97f99c8d88ebc108f6adc3ba74e87d53ba57c70;p=people%2Fsstabellini%2Fxen-unstable.git%2F.git 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 Signed-off-by: Jan Beulich Acked-by: Andrew Cooper Tested-by: Andrew Cooper Release-acked-by: Paul Durrant --- diff --git a/tools/tests/x86_emulator/test_x86_emulator.c b/tools/tests/x86_emulator/test_x86_emulator.c index e7de37eaef..4b01fa8b8d 100644 --- 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]) )