[Xen-devel] Re: [PATCH 2/3] xen: add CPU microcode update driver

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

> +static enum ucode_state xen_request_microcode_user(int cpu,
> +                                                const void __user *buf, 
> size_t size)
> +{
> +     struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
> +     struct xen_microcode *uc;
> +     enum ucode_state ret;
> +     size_t unread;
> +
> +     if (cpu != 0) {
> +             /* No real firmware for non-zero cpus; just store a
> +                placeholder */
> +             size = 0;
> +     }
> +
> +     if (uci->mc != NULL) {
> +             vfree(uci->mc);
> +             uci->mc = NULL;
> +     }
> +
> +     ret = UCODE_ERROR;
> +     uc = vmalloc(sizeof(*uc) + size);
> +     if (uc == NULL)
> +             goto out;
> +
> +     uc->len = size;
> +
> +     ret = UCODE_NFOUND;
> +
> +     /* XXX This sporadically returns uncopied bytes, so we return
> +        EFAULT.  As far as I can see, the usermode code
           ^^^^^ UCODE_NFOUND.
> +        (microcode_ctl) isn't doing anything wrong... */

Is this still valid? Looking at AMD it checks for a magic key and the Intel
just copies without checks.

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