Re: [PATCH 5.10 00/10] KVM CR0.WP series backport

On Mon, May 08, 2023, Mathias Krause wrote:

This is a backport of the CR0.WP KVM series[1] to Linux v5.10. It further extends the v5.15 backport by two patches, namely patch 5 (which is the prerequisite for Lai's patches) and patch 8 which was already part of the v5.15.27 stable update but didn't made it to v5.10.

I used 'ssdd 10 50000' from rt-tests[2] as a micro-benchmark, running on a grsecurity L1 VM. Below table shows the results (runtime in seconds, lower is better):

                      legacy     TDP    shadow
Linux v5.10.177       10.37s    88.7s    69.7s
+ patches              4.88s     4.92s   70.1s

TDP MMU is, as for v5.15, slower than shadow paging on a vanilla kernel. Fortunately it's disabled by default.

The KVM unit test suite showed no regressions.

Please consider applying.

NAK, same reasoning as the 5.15 backports.

https://lore.kernel.org/all/ZF1a8xIGLwcdJDVZ@google.com