From: Xiaoyao Li <xiaoyao.li@intel.com>
To: Mathias Krause <minipli@grsecurity.net>, kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org,
Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH v4 6/6] KVM: VMX: Make CR0.WP a guest owned bit
Date: Mon, 27 Mar 2023 21:48:01 +0800 [thread overview]
Message-ID: <9b81cfa8-1e36-cbed-3399-c178f7388067@intel.com> (raw)
In-Reply-To: <814c8975-17ad-f1bb-3b26-2175d79a1153@grsecurity.net>
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
next prev parent reply other threads:[~2023-03-27 13:49 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-22 1:37 [PATCH v4 0/6] KVM: MMU: performance tweaks for heavy CR0.WP users Mathias Krause
2023-03-22 1:37 ` [PATCH v4 1/6] KVM: x86/mmu: Avoid indirect call for get_cr3 Mathias Krause
2023-03-22 1:37 ` [PATCH v4 2/6] KVM: x86: Do not unload MMU roots when only toggling CR0.WP with TDP enabled Mathias Krause
2023-05-07 7:32 ` Robert Hoo
2023-05-08 9:30 ` Mathias Krause
2023-05-09 1:04 ` Robert Hoo
2023-03-22 1:37 ` [PATCH v4 3/6] KVM: x86: Ignore CR0.WP toggles in non-paging mode Mathias Krause
2023-03-22 1:37 ` [PATCH v4 4/6] KVM: x86: Make use of kvm_read_cr*_bits() when testing bits Mathias Krause
2023-03-22 1:37 ` [PATCH v4 5/6] KVM: x86/mmu: Fix comment typo Mathias Krause
2023-03-22 1:37 ` [PATCH v4 6/6] KVM: VMX: Make CR0.WP a guest owned bit Mathias Krause
2023-03-27 8:33 ` Xiaoyao Li
2023-03-27 8:37 ` Mathias Krause
2023-03-27 13:48 ` Xiaoyao Li [this message]
2023-03-30 8:45 ` Mathias Krause
2023-03-30 17:12 ` Sean Christopherson
2023-03-30 20:15 ` Mathias Krause
2023-03-30 20:30 ` Mathias Krause
2023-03-30 20:36 ` Sean Christopherson
2023-03-30 20:33 ` Sean Christopherson
2023-03-30 20:55 ` Mathias Krause
2023-03-31 14:18 ` Mathias Krause
2023-03-22 7:41 ` [PATCH v4 0/6] KVM: MMU: performance tweaks for heavy CR0.WP users Mathias Krause
2023-03-23 22:50 ` Sean Christopherson
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