Re: [PATCH] kdump, vmcoreinfo: Export sme_me_mask value to vmcoreinfo
Date: Fri Oct 26 2018 - 23:04:18 EST
å 2018å10æ27æ 06:25, Borislav Petkov åé:
> On Fri, Oct 26, 2018 at 06:24:40PM +0200, Petr Tesarik wrote:
>> But we need the MSR value from the panic kernel environment, not while
>> the production kernel is still running, right?
> Actually, we need only the encryption bit number (and it should be 0
> otherwise to denote SME wasn't enabled).
Thanks for your comment.
For this patch, it really needs only the encryption bit number.
For the AMD machine with SME feature, the OS or HV sets bit 47 of a
physical address to 1 in the page table entry to indicate the page
should be encrypted.
> I guess something like
> which gets written by the kexec-ed kernel.
>> If so, then this reminds me that I have wanted for a long time to store
>> more of the hardware state in a vmcore NOTE after a kernel crash ...
>> control registers, MSRs and whatnot. Of course, this would be a
>> long-term project, but I wonder what other people think about it in
> I guess that sounds like a good idea - the more relevant hw info for
> debugging, the better. Determining the important MSRs to save would need
> a bit of a pondering over though. For example, some MSRs are per-core,
> some per-socket, etc...