lkml.org 
[lkml]   [2016]   [Feb]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2 3/3] paravirt: rename paravirt_enabled to paravirt_legacy
On Sat, Feb 06, 2016 at 12:05:32PM -0800, Andy Lutomirski wrote:
> int __init microcode_init(void)
> {
> [...]
> if (paravirt_enabled() || dis_ucode_ldr)
> return -EINVAL;
>
> This is also asking "are we the natively booted kernel?" This is
> plausibly useful for real. (Borislav, is this actually necessary?)

There was some breakage on 32-bit pvops with that.

> Seems to me there should be a function is_native_root_kernel() or
> similar. Obviously it could have false positives and code will have
> to deal with that. (This also could be entirely wrong. What code is
> responsible for CPU microcode updates on Xen? For all I know, dom0 is
> *supposed* to apply microcode updates, in which case that check really
> should be deleted.

So there are two aspects:

- the guest loading the microcode driver. Xen should behave like
qemu+kvm does: emulate the MSR accesses the microcode loader does.

- microcode application on Xen: we've had this before. The hypervisor
should do that (if it doesn't do so already).

So yes, that paravirt_enabled() thing should go away. Even more so if we
have CPUID leaf 0x4... reserved for hypervisors.

--
Regards/Gruss,
Boris.

ECO tip #101: Trim your mails when you reply.

\
 
 \ /
  Last update: 2016-02-06 23:21    [W:0.213 / U:2.744 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site