Re: [PATCH v2 6/6] x86/speculation: Use IBRS if available before calling into firmware

Ingo Molnar
2018-02-11T11:46:49Z

* David Woodhouse <dwmw@amazon.co.uk> wrote:

> Retpoline means the kernel is safe because it has no indirect branches.
> But firmware isn't, so use IBRS for firmware calls if it's available.

Ok, this approach looks good to me in principle, but:

> --- a/arch/x86/include/asm/apm.h
> +++ b/arch/x86/include/asm/apm.h
> @@ -7,6 +7,8 @@
> #ifndef _ASM_X86_MACH_DEFAULT_APM_H
> #define _ASM_X86_MACH_DEFAULT_APM_H
>
> +#include <asm/spec_ctrl.h>

I cannot see this header file upstream anywhere, nor in any other patch in my mbox
- is there some dependency that has to be applied first?

Thanks,

Ingo