On Tue, Apr 20, 2021 at 04:20:11AM -0700, Guenter Roeck wrote:
> Commit 60268b0e8258 ("hwmon: (amd_energy) modify the visibility of
> the counters") restricted visibility of AMD energy counters to work
> around a side-channel attack using energy data to determine which
> instructions are executed. The attack is described in 'PLATYPUS:
> Software-based Power Side-Channel Attacks on x86'. It relies on quick
> and accurate energy readings.
>
> This change made the counters provided by the amd_energy driver
> effectively unusable for non-provileged users. However, unprivileged
> read access is the whole point of hardware monitoring attributes.
>
> An attempt to remedy the situation by limiting and randomizing access
> to chip registers was rejected by AMD. Since the driver is for all
> practical purposes unusable, remove it.
>
> Cc: Naveen Krishna Chatradhi <nchatrad@xxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
> Note:
> This submission supersedes the set of patches which was
> limiting and randomizing RAPL register access.
Sad, maybe AMD will fix their hardware someday :(
Acked-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
