x86/fpu: Exclude MPX states from the initial fpu

MPX has been deprected in Linux Kernel and it is completely disabled in
VM-s (kvm).

Fixes #11687

Signed-off-by: Andrei Vagin <avagin@google.com>

Author: avagin

pkg/sentry/arch/fpu/fpu_amd64.s

@@ -22,11 +22,12 @@
 // FXSAVE/XSAVE area. (Intel SDM Vol. 1, Table 10-2 "Format of an FXSAVE Area")
 #define MXCSR_OFFSET	24
 
-// The value for XCR0 is defined to xsave/xrstor everything except for PKRU and
-// AMX regions.
+// The value for XCR0 is defined to xsave/xrstor everything except for MPX, PKRU
+// and AMX regions.
+// MPX has been deprecated.
 // TODO(gvisor.dev/issues/9896): Implement AMX support.
 // TODO(gvisor.dev/issues/10087): Implement PKRU support.
-#define XCR0_DISABLED_MASK ((1 << 9) | (1 << 17) | (1 << 18))
+#define XCR0_DISABLED_MASK ((1 << 3) | (1 << 4) | (1 << 9) | (1 << 17) | (1 << 18))
 #define XCR0_EAX (0xffffffff ^ XCR0_DISABLED_MASK)
 #define XCR0_EDX 0xffffffff