• Dave Hansen's avatar
    x86/fpu: Do not BUG_ON() in early FPU code · ec3ed4a2
    Dave Hansen authored
    I don't think it is really possible to have a system where CPUID
    enumerates support for XSAVE but that it does not have FP/SSE
    (they are "legacy" features and always present).
    
    But, I did manage to hit this case in qemu when I enabled its
    somewhat shaky XSAVE support.  The bummer is that the FPU is set
    up before we parse the command-line or have *any* console support
    including earlyprintk.  That turned what should have been an easy
    thing to debug in to a bit more of an odyssey.
    
    So a BUG() here is worthless.  All it does it guarantee that
    if/when we hit this case we have an empty console.  So, remove
    the BUG() and try to limp along by disabling XSAVE and trying to
    continue.  Add a comment on why we are doing this, and also add
    a common "out_disable" path for leaving fpu__init_system_xstate().
    Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Dave Hansen <dave@sr71.net>
    Cc: Denys Vlasenko <dvlasenk@redhat.com>
    Cc: Fenghua Yu <fenghua.yu@intel.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Josh Poimboeuf <jpoimboe@redhat.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Oleg Nesterov <oleg@redhat.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Link: http://lkml.kernel.org/r/20160720194551.63BB2B58@viggo.jf.intel.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    ec3ed4a2
xstate.c 31.5 KB