Messages in this thread | | | Date | Mon, 27 Mar 2023 21:48:01 +0800 | Subject | Re: [PATCH v4 6/6] KVM: VMX: Make CR0.WP a guest owned bit | From | Xiaoyao Li <> |
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On 3/27/2023 4:37 PM, Mathias Krause wrote: > On 27.03.23 10:33, Xiaoyao Li wrote: >> On 3/22/2023 9:37 AM, Mathias Krause wrote: >>> Guests like grsecurity that make heavy use of CR0.WP to implement kernel >>> level W^X will suffer from the implied VMEXITs. >>> >>> With EPT there is no need to intercept a guest change of CR0.WP, so >>> simply make it a guest owned bit if we can do so. >> >> I'm interested in the performance gain. Do you have data like Patch 2? > > It's mentioned in the cover letter[1], quoted below:
Sorry I missed it. The data of not intercepting CR0.WP looks great as well.
> [1] > https://lore.kernel.org/kvm/20230322013731.102955-1-minipli@grsecurity.net/ > > : I used 'ssdd 10 50000' from rt-tests[5] as a micro-benchmark, running on a > : grsecurity L1 VM. Below table shows the results (runtime in seconds, lower > : is better): > : > : legacy TDP shadow > : kvm-x86/next@d8708b 8.43s 9.45s 70.3s > : + patches 1-3 5.39s 5.63s 70.2s > : + patches 4-6 3.51s 3.47s 67.8s > > > Thanks, > Mathias
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