Re: [PATCH] x86/amd_nb: Check for invalid SMN reads

From: Borislav Petkov
Date: Wed May 10 2023 - 07:36:08 EST

On Wed, Apr 05, 2023 at 03:10:09PM -0400, Yazen Ghannam wrote:
> What do you think?

Yes, please put that as a comment over __amd_smn_rw() as to why callers
should check the retval *and* make both the read and the write
__must_check and get rid of

if (err)
pr_warn("Error %s SMN address 0x%x.\n",
(write ? "writing to" : "reading from"), address);

which won't be seen in all cases. The __must_check will force the
callers to do the proper checking which is the only sane thing to do
with such a variety of bit behaviors.