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    SubjectRe: [PATCH 06/24] x86,kvm: Fix indirect calls in emulator
    On Tue, Jan 23, 2018 at 04:25:45PM +0100, Peter Zijlstra wrote:
    > Replace the indirect calls with CALL_NOSPEC.
    >
    > Cc: Paolo Bonzini <pbonzini@redhat.com>
    > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    > ---
    > arch/x86/kvm/emulate.c | 9 +++++----
    > 1 file changed, 5 insertions(+), 4 deletions(-)
    >
    > --- a/arch/x86/kvm/emulate.c
    > +++ b/arch/x86/kvm/emulate.c
    > @@ -25,6 +25,7 @@
    > #include <asm/kvm_emulate.h>
    > #include <linux/stringify.h>
    > #include <asm/debugreg.h>
    > +#include <asm/nospec-branch.h>
    >
    > #include "x86.h"
    > #include "tss.h"
    > @@ -1021,8 +1022,8 @@ static __always_inline u8 test_cc(unsign
    > void (*fop)(void) = (void *)em_setcc + 4 * (condition & 0xf);
    >
    > flags = (flags & EFLAGS_MASK) | X86_EFLAGS_IF;
    > - asm("push %[flags]; popf; call *%[fastop]"
    > - : "=a"(rc) : [fastop]"r"(fop), [flags]"r"(flags));
    > + asm("push %[flags]; popf; " CALL_NOSPEC
    > + : "=a"(rc) : [thunk_target]"r"(fop), [flags]"r"(flags));

    Oh, "thunk_target" is magical.

    --
    Regards/Gruss,
    Boris.

    Good mailing practices for 400: avoid top-posting and trim the reply.

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