freebsd stable - Jul 2018 - Ryzen issues on FreeBSD ? (with sort of workaround)

On Thu, Jul 05, 2018 at 11:43:29AM +0100, Pete French
wrote:
> > It does not make any sense to even try to access the chicken bits
> > MSRs when running under virtualization.  It is the duty of the
> > hypervisor to configure hardware. 
> 
> I would tend to agree with you :-) I was kind of surprised to read that
they
> are actually saved and restored as part of a VM context switch in fact.
Why do you state that they are saved/restored ?  What is the evidence ?
> 
> > I updated the patch.
> 
> Thanks I shall try this now on my workstation and the Epyc virtual machine
On VM the patch should be NOP, testing it is a waste of time IMO.

On 05/07/2018 11:47, Konstantin Belousov wrote:
> Why do you state that they are saved/restored ?  What is the evidence ?

https://software.intel.com/en-us/blogs/2009/06/25/virtualization-and-performance-understanding-vm-exits

specificly...

3) "Save MSRs in the VM-exit MSR-store area."

and

5) "Load MSRs from the VM-exit MSR-load area."

but maybe thats not actyually true, I assumed it was given its an Intel 
document, but admittedly its not an actual specification.

> On VM the patch should be NOP, testing it is a waste of time IMO.

OK, will ignore that then. I am running the new patch on my workstation 
now - I still need the old patch for the other files, yes ?

-pete.