Re: [PATCH v2 08/14] x86/fault: Skip erratum #93 workaround on new CPUs

[Andy Lutomirski]

On Tue, Feb 9, 2021 at 6:33 PM Andy Lutomirski <luto@xxxxxxxxxx> wrote:
>
> Erratum #93 applies to the first generation of AMD K8 CPUs.  Skip the
> workaround on newer CPUs.

Whoops, this breaks the !CPU_SUP_AMD build.  It needs a fixup like this:

https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/commit/?h=x86/fault&id=06772a3b6918bf6d6d0778946149b7d56ae30d80

Boris, do you want a v3?

>
> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
> ---
>  arch/x86/mm/fault.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
> index cbb1a9754473..3fe2f4800b69 100644
> --- a/arch/x86/mm/fault.c
> +++ b/arch/x86/mm/fault.c
> @@ -442,9 +442,8 @@ static void dump_pagetable(unsigned long address)
>   */
>  static int is_errata93(struct pt_regs *regs, unsigned long address)
>  {
> -#if defined(CONFIG_X86_64) && defined(CONFIG_CPU_SUP_AMD)
> -       if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD
> -           || boot_cpu_data.x86 != 0xf)
> +#if defined(CONFIG_X86_64)
> +       if (!is_amd_k8_pre_npt())
>                 return 0;
>
>         if (user_mode(regs))
> --
> 2.29.2
>