From: Sean Christopherson <seanjc@google.com>
To: Yan Zhao <yan.y.zhao@intel.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
pbonzini@redhat.com, chao.gao@intel.com, kai.huang@intel.com,
robert.hoo.linux@gmail.com, yuan.yao@linux.intel.com
Subject: Re: [PATCH v4 11/12] KVM: x86/mmu: split a single gfn zap range when guest MTRRs are honored
Date: Fri, 25 Aug 2023 16:15:41 -0700 [thread overview]
Message-ID: <ZOk2HWEubJIRo1HN@google.com> (raw)
In-Reply-To: <20230714065602.20805-1-yan.y.zhao@intel.com>
On Fri, Jul 14, 2023, Yan Zhao wrote:
> Split a single gfn zap range (specifially range [0, ~0UL)) to smaller
> ranges according to current memslot layout when guest MTRRs are honored.
>
> Though vCPUs have been serialized to perform kvm_zap_gfn_range() for MTRRs
> updates and CR0.CD toggles, contention caused rescheduling cost is still
> huge when there're concurrent page fault holding mmu_lock for read.
Unless the pre-check doesn't work for some reason, I definitely want to avoid
this patch. This is a lot of complexity that, IIUC, is just working around a
problem elsewhere in KVM.
> Split a single huge zap range according to the actual memslot layout can
> reduce unnecessary transversal and yielding cost in tdp mmu.
> Also, it can increase the chances for larger ranges to find existing ranges
> to zap in zap list.
>
> Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
> ---
next prev parent reply other threads:[~2023-08-25 23:16 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-14 6:46 [PATCH v4 00/12] KVM: x86/mmu: refine memtype related mmu zap Yan Zhao
2023-07-14 6:50 ` [PATCH v4 01/12] KVM: x86/mmu: helpers to return if KVM honors guest MTRRs Yan Zhao
2023-10-07 7:00 ` Like Xu
2023-10-09 19:52 ` Sean Christopherson
2023-10-09 21:27 ` Sean Christopherson
2023-10-09 21:36 ` Sean Christopherson
2023-10-10 3:46 ` Yan Zhao
2023-10-11 0:08 ` Sean Christopherson
2023-10-11 1:47 ` Yan Zhao
2023-07-14 6:50 ` [PATCH v4 02/12] KVM: x86/mmu: Use KVM honors guest MTRRs helper in kvm_tdp_page_fault() Yan Zhao
2023-07-14 6:51 ` [PATCH v4 03/12] KVM: x86/mmu: Use KVM honors guest MTRRs helper when CR0.CD toggles Yan Zhao
2023-07-14 6:51 ` [PATCH v4 04/12] KVM: x86/mmu: Use KVM honors guest MTRRs helper when update mtrr Yan Zhao
2023-07-14 6:52 ` [PATCH v4 05/12] KVM: x86/mmu: zap KVM TDP when noncoherent DMA assignment starts/stops Yan Zhao
2023-07-14 6:52 ` [PATCH v4 06/12] KVM: x86/mmu: move TDP zaps from guest MTRRs update to CR0.CD toggling Yan Zhao
2023-07-14 6:53 ` [PATCH v4 07/12] KVM: VMX: drop IPAT in memtype when CD=1 for KVM_X86_QUIRK_CD_NW_CLEARED Yan Zhao
2023-08-25 21:43 ` Sean Christopherson
2023-09-04 7:41 ` Yan Zhao
2023-07-14 6:53 ` [PATCH v4 08/12] KVM: x86: centralize code to get CD=1 memtype when guest MTRRs are honored Yan Zhao
2023-08-25 21:46 ` Sean Christopherson
2023-09-04 7:46 ` Yan Zhao
2023-07-14 6:54 ` [PATCH v4 09/12] KVM: x86/mmu: serialize vCPUs to zap gfn " Yan Zhao
2023-08-25 22:47 ` Sean Christopherson
2023-09-04 8:24 ` Yan Zhao
2023-07-14 6:55 ` [PATCH v4 10/12] KVM: x86/mmu: fine-grained gfn zap " Yan Zhao
2023-08-25 23:13 ` Sean Christopherson
2023-09-04 8:37 ` Yan Zhao
2023-07-14 6:56 ` [PATCH v4 11/12] KVM: x86/mmu: split a single gfn zap range " Yan Zhao
2023-08-25 23:15 ` Sean Christopherson [this message]
2023-09-04 8:39 ` Yan Zhao
2023-07-14 6:56 ` [PATCH v4 12/12] KVM: x86/mmu: convert kvm_zap_gfn_range() to use shared mmu_lock in TDP MMU Yan Zhao
2023-08-25 21:34 ` Sean Christopherson
2023-09-04 7:31 ` Yan Zhao
2023-09-05 22:31 ` Sean Christopherson
2023-09-06 0:50 ` Yan Zhao
2023-08-25 23:17 ` [PATCH v4 00/12] KVM: x86/mmu: refine memtype related mmu zap Sean Christopherson
2023-09-04 8:48 ` Yan Zhao
2023-10-05 1:29 ` Sean Christopherson
2023-10-05 2:19 ` Huang, Kai
2023-10-05 2:28 ` Sean Christopherson
2023-10-06 0:50 ` Sean Christopherson
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