On Tue, Jan 23, 2018 at 04:25:45PM +0100, Peter Zijlstra wrote:
> Replace the indirect calls with CALL_NOSPEC.
>
> Cc: Paolo Bonzini <pbonz...@redhat.com>
> Signed-off-by: Peter Zijlstra (Intel) <pet...@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.
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