From: Paolo Bonzini <pbonzini@redhat.com>
To: Ben Gardon <bgardon@google.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Peter Xu <peterx@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Peter Shier <pshier@google.com>,
David Matlack <dmatlack@google.com>,
Mingwei Zhang <mizhang@google.com>,
Yulei Zhang <yulei.kernel@gmail.com>,
Wanpeng Li <kernellwp@gmail.com>,
Xiao Guangrong <xiaoguangrong.eric@gmail.com>,
Kai Huang <kai.huang@intel.com>,
Keqian Zhu <zhukeqian1@huawei.com>,
David Hildenbrand <david@redhat.com>
Subject: Re: [RFC 11/19] KVM: x86/mmu: Factor shadow_zero_check out of make_spte
Date: Wed, 10 Nov 2021 23:44:54 +0100 [thread overview]
Message-ID: <80407e4a-36e1-e606-ed9f-74429f850e77@redhat.com> (raw)
In-Reply-To: <20211110223010.1392399-12-bgardon@google.com>
On 11/10/21 23:30, Ben Gardon wrote:
> - WARN_ONCE(is_rsvd_spte(&vcpu->arch.mmu->shadow_zero_check, spte, level),
> + WARN_ONCE(is_rsvd_spte(shadow_zero_check, spte, level),
> "spte = 0x%llx, level = %d, rsvd bits = 0x%llx", spte, level,
> - get_rsvd_bits(&vcpu->arch.mmu->shadow_zero_check, spte, level));
> + get_rsvd_bits(shadow_zero_check, spte, level));
Hmm, there is a deeper issue here, in that when using EPT/NPT (on either
the legacy aka shadow or the TDP MMU) large parts of vcpu->arch.mmu are
really the same for all vCPUs. The only thing that varies is those
parts that actually depend on the guest's paging mode---the extended
role, the reserved bits, etc. Those are needed by the emulator, but
don't really belong in vcpu->arch.mmu when EPT/NPT is in use.
I wonder if there's room for splitting kvm_mmu in two parts, such as
kvm_mmu and kvm_guest_paging_context, and possibly change the walk_mmu
pointer into a pointer to kvm_guest_paging_context. This way the
EPT/NPT MMU (again either shadow or TDP) can be moved to kvm->arch. It
should simplify this series and also David's work on eager page splitting.
I'm not asking you to do this, of course, but perhaps I can trigger
Sean's itch to refactor stuff. :)
Paolo
next prev parent reply other threads:[~2021-11-10 22:45 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-10 22:29 [RFC 00/19] KVM: x86/mmu: Optimize disabling dirty logging Ben Gardon
2021-11-10 22:29 ` [RFC 01/19] KVM: x86/mmu: Fix TLB flush range when handling disconnected pt Ben Gardon
2021-11-11 17:44 ` David Matlack
2021-11-10 22:29 ` [RFC 02/19] KVM: x86/mmu: Batch TLB flushes for a single zap Ben Gardon
2021-11-11 18:06 ` David Matlack
2021-11-12 23:53 ` Sean Christopherson
2021-11-10 22:29 ` [RFC 03/19] KVM: x86/mmu: Factor flush and free up when zapping under MMU write lock Ben Gardon
2021-11-11 18:31 ` David Matlack
2021-11-10 22:29 ` [RFC 04/19] KVM: x86/mmu: Yield while processing disconnected_sps Ben Gardon
2021-11-11 18:50 ` David Matlack
2021-11-10 22:29 ` [RFC 05/19] KVM: x86/mmu: Remove redundant flushes when disabling dirty logging Ben Gardon
2021-11-11 18:55 ` David Matlack
2021-11-10 22:29 ` [RFC 06/19] KVM: x86/mmu: Introduce vcpu_make_spte Ben Gardon
2021-11-10 22:29 ` [RFC 07/19] KVM: x86/mmu: Factor wrprot for nested PML out of make_spte Ben Gardon
2021-11-18 2:12 ` Sean Christopherson
2021-11-18 17:43 ` Ben Gardon
2021-11-18 18:04 ` Paolo Bonzini
2021-11-10 22:29 ` [RFC 08/19] KVM: x86/mmu: Factor mt_mask " Ben Gardon
2021-11-10 22:30 ` [RFC 09/19] KVM: x86/mmu: Remove need for a vcpu from kvm_slot_page_track_is_active Ben Gardon
2021-11-10 22:30 ` [RFC 10/19] KVM: x86/mmu: Remove need for a vcpu from mmu_try_to_unsync_pages Ben Gardon
2021-11-10 22:30 ` [RFC 11/19] KVM: x86/mmu: Factor shadow_zero_check out of make_spte Ben Gardon
2021-11-10 22:44 ` Paolo Bonzini [this message]
2021-11-10 23:49 ` Ben Gardon
2021-11-11 1:18 ` Sean Christopherson
2021-11-11 1:44 ` Sean Christopherson
2021-11-11 7:06 ` Paolo Bonzini
2021-11-18 2:05 ` Sean Christopherson
2021-11-18 3:29 ` Sean Christopherson
2021-11-18 16:37 ` Sean Christopherson
2021-11-18 17:19 ` Paolo Bonzini
2021-11-18 18:02 ` Sean Christopherson
2021-11-18 18:07 ` Paolo Bonzini
2021-11-18 18:14 ` Sean Christopherson
2021-11-10 22:30 ` [RFC 12/19] KVM: x86/mmu: Replace vcpu argument with kvm pointer in make_spte Ben Gardon
2021-11-10 22:30 ` [RFC 13/19] KVM: x86/mmu: Factor out the meat of reset_tdp_shadow_zero_bits_mask Ben Gardon
2021-11-10 22:30 ` [RFC 14/19] KVM: x86/mmu: Propagate memslot const qualifier Ben Gardon
2021-11-10 22:30 ` [RFC 15/19] KVM: x86/MMU: Refactor vmx_get_mt_mask Ben Gardon
2021-11-10 22:30 ` [RFC 16/19] KVM: x86/mmu: Factor out part of vmx_get_mt_mask which does not depend on vcpu Ben Gardon
2021-11-10 22:30 ` [RFC 17/19] KVM: x86/mmu: Add try_get_mt_mask to x86_ops Ben Gardon
2021-11-10 22:30 ` [RFC 18/19] KVM: x86/mmu: Make kvm_is_mmio_pfn usable outside of spte.c Ben Gardon
2021-11-10 22:30 ` [RFC 19/19] KVM: x86/mmu: Promote pages in-place when disabling dirty logging Ben Gardon
2021-11-15 21:24 ` [RFC 00/19] KVM: x86/mmu: Optimize " Ben Gardon
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