Re: [PATCH 12/27] x86/msr: Restrict MSR access when the kernel is locked down

From: David Howells
Date: Fri Oct 20 2017 - 16:48:24 EST


Alan Cox <gnomes@xxxxxxxxxxxxxxxxxxx> wrote:

> There are a load of standard tools that use this so I think you are going
> to need a whitelist. Can you at least log *which* MSR in the failing case
> so a whitelist can be built over time ?

Probably. Is it just the file position for msr_write()? Should the register
number increment with the copy loop?

What about for the X86_IOC_WRMSR_REGS ioctl? What's the reg number there?

And do you know where wrmsr_safe_regs() might be found? I can see things
using it and exporting it, but no implementation, so I'm guessing it's
macroised somewhere.

David