Re: [PATCHv6 06/30] x86/traps: Refactor exc_general_protection()

Thomas Gleixner
2022-03-17T00:22:03Z

On Wed, Mar 16 2022 at 05:08, Kirill A. Shutemov wrote:
> TDX brings a new exception -- Virtualization Exception (#VE). Handling
> of #VE structurally very similar to handling #GP.
>
> Extract two helpers from exc_general_protection() that can be reused for
> handling #VE.
>
> No functional changes.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>

Not that I care much, but this is the second instance of something I
suggested. We have tags for that...

> +static bool gp_try_fixup_and_notify(struct pt_regs *regs, int trapnr,
> + unsigned long error_code, const char *str)
> +{
> + int ret;

Adding this to make my suggestion compile is the easy way out, but...

> +
> + if (fixup_exception(regs, trapnr, error_code, 0))
> + return true;
> +
> + current->thread.error_code = error_code;
> + current->thread.trap_nr = trapnr;
> +
> + /*
> + * To be potentially processing a kprobe fault and to trust the result
> + * from kprobe_running(), we have to be non-preemptible.
> + */
> + if (!preemptible() && kprobe_running() &&
> + kprobe_fault_handler(regs, trapnr))
> + return true;
> +
> + ret = notify_die(DIE_GPF, str, regs, error_code, trapnr, SIGSEGV);
> + return ret == NOTIFY_STOP;

Why not doing the obvious:

return notify_die(DIE_GPF, str, regs, error_code, trapnr, SIGSEGV) == NOTIFY_STOP;

Hmm?

Thanks,

tglx