Re: [RFC PATCH] x86/cpu: Fix MSR value truncation issue

From: Borislav Petkov
Date: Fri Oct 30 2015 - 15:33:12 EST

On Fri, Oct 30, 2015 at 12:26:42PM -0700, Andy Lutomirski wrote:
> Want to add that to the patch or make it another patch?

Yeah, I'll make another one as it is going to document why we're
explicitly ANDing with 0xffffffffull.

> Fair enough. I suppose that this thing is a handful of separate
> fields as opposed to being just a number.

You mean MSR_STAR?

Just the two upper 16-bit values. The lower 32-bit are reserved on Intel
while on AMD they're "32-bit SYSCALL Target EIP", meaning that you can
use SYSCALL on 32-bit too.


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