linux-kernel - Re: [PATCH] thermal: intel: Don't set HFI status bit to 1

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Message-ID: <CAHk-=wi-bq6-d=aoVRDWpLxU-2c2vjkU3OTv37hcK5q781aK+w@mail.gmail.com>
Date:   Tue, 13 Dec 2022 19:16:30 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Cc:     rafael@...nel.org, daniel.lezcano@...aro.org, rui.zhang@...el.com,
        amitk@...nel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] thermal: intel: Don't set HFI status bit to 1

On Tue, Dec 13, 2022 at 6:07 PM Srinivas Pandruvada
<srinivas.pandruvada@...ux.intel.com> wrote:
>
> When CPU doesn't support HFI (Hardware Feedback Interface), don't include
> BIT 26 in the mask to prevent clearing. otherwise this results in:
>     unchecked MSR access error: WRMSR to 0x1b1
>       (tried to write 0x0000000004000aa8)
>       at rIP: 0xffffffff8b8559fe (throttle_active_work+0xbe/0x1b0)
>
> Reported-by: Linus Torvalds <torvalds@...ux-foundation.org>
> Fixes: 6fe1e64b6026 ("thermal: intel: Prevent accidental clearing of HFI status")
> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>

You can add my tested-by as well, it seems to fix the issue.

Of course, it could be that I just didn't happen to trigger the
throttling in my test just now, so that testing is pretty limited, but
at least from a very quick check it seems good.

                 Linus