From: David Matlack <dmatlack@google.com>
To: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Hou Wenlong <houwenlong93@linux.alibaba.com>,
Ben Gardon <bgardon@google.com>
Subject: Re: [PATCH 00/28] KVM: x86/mmu: Overhaul TDP MMU zapping and flushing
Date: Wed, 1 Dec 2021 09:53:52 -0800 [thread overview]
Message-ID: <CALzav=cRRW2ZdotseqV+eKcu2oxehkkzKjYYDc3PA=Lw16JrGQ@mail.gmail.com> (raw)
In-Reply-To: <20211120045046.3940942-1-seanjc@google.com>
On Fri, Nov 19, 2021 at 8:51 PM Sean Christopherson <seanjc@google.com> wrote:
>
> Overhaul TDP MMU's handling of zapping and TLB flushing to reduce the
> number of TLB flushes, and to clean up the zapping code. The final patch
> realizes the biggest change, which is to use RCU to defer any TLB flush
> due to zapping a SP to the caller. The largest cleanup is to separate the
> flows for zapping roots (zap _everything_), zapping leaf SPTEs (zap guest
> mappings for whatever reason), and zapping a specific SP (NX recovery).
> They're currently smushed into a single zap_gfn_range(), which was a good
> idea at the time, but became a mess when trying to handle the different
> rules, e.g. TLB flushes aren't needed when zapping a root because KVM can
> safely zap a root if and only if it's unreachable.
>
> For booting an 8 vCPU, remote_tlb_flush (requests) goes from roughly
> 180 (600) to 130 (215).
>
> Please don't apply patches 02 and 03, they've been posted elsehwere and by
> other people. I included them here because some of the patches have
> pseudo-dependencies on their changes. Patch 01 is also posted separately.
> I had a brain fart and sent it out realizing that doing so would lead to
> oddities.
What's the base commit for this series?
>
> Hou Wenlong (1):
> KVM: x86/mmu: Skip tlb flush if it has been done in zap_gfn_range()
>
> Sean Christopherson (27):
> KVM: x86/mmu: Use yield-safe TDP MMU root iter in MMU notifier
> unmapping
> KVM: x86/mmu: Remove spurious TLB flushes in TDP MMU zap collapsible
> path
> KVM: x86/mmu: Retry page fault if root is invalidated by memslot
> update
> KVM: x86/mmu: Check for present SPTE when clearing dirty bit in TDP
> MMU
> KVM: x86/mmu: Formalize TDP MMU's (unintended?) deferred TLB flush
> logic
> KVM: x86/mmu: Document that zapping invalidated roots doesn't need to
> flush
> KVM: x86/mmu: Drop unused @kvm param from kvm_tdp_mmu_get_root()
> KVM: x86/mmu: Require mmu_lock be held for write in unyielding root
> iter
> KVM: x86/mmu: Allow yielding when zapping GFNs for defunct TDP MMU
> root
> KVM: x86/mmu: Check for !leaf=>leaf, not PFN change, in TDP MMU SP
> removal
> KVM: x86/mmu: Batch TLB flushes from TDP MMU for MMU notifier
> change_spte
> KVM: x86/mmu: Drop RCU after processing each root in MMU notifier
> hooks
> KVM: x86/mmu: Add helpers to read/write TDP MMU SPTEs and document RCU
> KVM: x86/mmu: Take TDP MMU roots off list when invalidating all roots
> KVM: x86/mmu: WARN if old _or_ new SPTE is REMOVED in non-atomic path
> KVM: x86/mmu: Terminate yield-friendly walk if invalid root observed
> KVM: x86/mmu: Refactor low-level TDP MMU set SPTE helper to take raw
> vals
> KVM: x86/mmu: Zap only the target TDP MMU shadow page in NX recovery
> KVM: x86/mmu: Use common TDP MMU zap helper for MMU notifier unmap
> hook
> KVM: x86/mmu: Add TDP MMU helper to zap a root
> KVM: x86/mmu: Skip remote TLB flush when zapping all of TDP MMU
> KVM: x86/mmu: Use "zap root" path for "slow" zap of all TDP MMU SPTEs
> KVM: x86/mmu: Add dedicated helper to zap TDP MMU root shadow page
> KVM: x86/mmu: Require mmu_lock be held for write to zap TDP MMU range
> KVM: x86/mmu: Zap only TDP MMU leafs in kvm_zap_gfn_range()
> KVM: x86/mmu: Do remote TLB flush before dropping RCU in TDP MMU
> resched
> KVM: x86/mmu: Defer TLB flush to caller when freeing TDP MMU shadow
> pages
>
> arch/x86/kvm/mmu/mmu.c | 74 +++--
> arch/x86/kvm/mmu/mmu_internal.h | 7 +-
> arch/x86/kvm/mmu/paging_tmpl.h | 3 +-
> arch/x86/kvm/mmu/tdp_iter.c | 6 +-
> arch/x86/kvm/mmu/tdp_iter.h | 15 +-
> arch/x86/kvm/mmu/tdp_mmu.c | 526 +++++++++++++++++++-------------
> arch/x86/kvm/mmu/tdp_mmu.h | 48 +--
> 7 files changed, 406 insertions(+), 273 deletions(-)
>
> --
> 2.34.0.rc2.393.gf8c9666880-goog
>
next prev parent reply other threads:[~2021-12-01 17:54 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-20 4:50 [PATCH 00/28] KVM: x86/mmu: Overhaul TDP MMU zapping and flushing Sean Christopherson
2021-11-20 4:50 ` [PATCH 01/28] KVM: x86/mmu: Use yield-safe TDP MMU root iter in MMU notifier unmapping Sean Christopherson
2021-11-22 19:48 ` Ben Gardon
2021-11-30 8:03 ` Paolo Bonzini
2021-11-20 4:50 ` [PATCH 02/28] KVM: x86/mmu: Skip tlb flush if it has been done in zap_gfn_range() Sean Christopherson
2021-11-20 4:50 ` [PATCH 03/28] KVM: x86/mmu: Remove spurious TLB flushes in TDP MMU zap collapsible path Sean Christopherson
2021-11-20 4:50 ` [PATCH 04/28] KVM: x86/mmu: Retry page fault if root is invalidated by memslot update Sean Christopherson
2021-11-22 19:54 ` Ben Gardon
2021-12-01 20:49 ` Paolo Bonzini
2021-12-08 19:17 ` Sean Christopherson
2021-11-20 4:50 ` [PATCH 05/28] KVM: x86/mmu: Check for present SPTE when clearing dirty bit in TDP MMU Sean Christopherson
2021-11-22 19:57 ` Ben Gardon
2021-11-20 4:50 ` [PATCH 06/28] KVM: x86/mmu: Formalize TDP MMU's (unintended?) deferred TLB flush logic Sean Christopherson
2021-11-20 4:50 ` [PATCH 07/28] KVM: x86/mmu: Document that zapping invalidated roots doesn't need to flush Sean Christopherson
2021-11-20 4:50 ` [PATCH 08/28] KVM: x86/mmu: Drop unused @kvm param from kvm_tdp_mmu_get_root() Sean Christopherson
2021-11-22 20:02 ` Ben Gardon
2021-11-20 4:50 ` [PATCH 09/28] KVM: x86/mmu: Require mmu_lock be held for write in unyielding root iter Sean Christopherson
2021-11-22 20:10 ` Ben Gardon
2021-11-22 20:19 ` Sean Christopherson
2021-11-20 4:50 ` [PATCH 10/28] KVM: x86/mmu: Allow yielding when zapping GFNs for defunct TDP MMU root Sean Christopherson
2021-11-22 21:30 ` Ben Gardon
2021-11-22 22:40 ` Sean Christopherson
2021-11-22 23:03 ` Ben Gardon
2021-12-14 23:45 ` Sean Christopherson
2021-12-14 23:52 ` Sean Christopherson
2021-11-20 4:50 ` [PATCH 11/28] KVM: x86/mmu: Check for !leaf=>leaf, not PFN change, in TDP MMU SP removal Sean Christopherson
2021-11-20 4:50 ` [PATCH 12/28] KVM: x86/mmu: Batch TLB flushes from TDP MMU for MMU notifier change_spte Sean Christopherson
2021-11-22 21:45 ` Ben Gardon
2021-11-20 4:50 ` [PATCH 13/28] KVM: x86/mmu: Drop RCU after processing each root in MMU notifier hooks Sean Christopherson
2021-11-22 21:47 ` Ben Gardon
2021-11-20 4:50 ` [PATCH 14/28] KVM: x86/mmu: Add helpers to read/write TDP MMU SPTEs and document RCU Sean Christopherson
2021-11-22 21:55 ` Ben Gardon
2021-11-20 4:50 ` [PATCH 15/28] KVM: x86/mmu: Take TDP MMU roots off list when invalidating all roots Sean Christopherson
2021-11-22 22:20 ` Ben Gardon
2021-11-22 23:08 ` Sean Christopherson
2021-11-23 0:03 ` Ben Gardon
2021-12-14 23:34 ` Sean Christopherson
2021-11-20 4:50 ` [PATCH 16/28] KVM: x86/mmu: WARN if old _or_ new SPTE is REMOVED in non-atomic path Sean Christopherson
2021-11-22 21:57 ` Ben Gardon
2021-11-20 4:50 ` [PATCH 17/28] KVM: x86/mmu: Terminate yield-friendly walk if invalid root observed Sean Christopherson
2021-11-22 22:25 ` Ben Gardon
2021-11-20 4:50 ` [PATCH 18/28] KVM: x86/mmu: Refactor low-level TDP MMU set SPTE helper to take raw vals Sean Christopherson
2021-11-22 22:29 ` Ben Gardon
2021-11-20 4:50 ` [PATCH 19/28] KVM: x86/mmu: Zap only the target TDP MMU shadow page in NX recovery Sean Christopherson
2021-11-22 22:43 ` Ben Gardon
2021-11-23 1:16 ` Sean Christopherson
2021-11-23 19:35 ` Ben Gardon
2021-11-20 4:50 ` [PATCH 20/28] KVM: x86/mmu: Use common TDP MMU zap helper for MMU notifier unmap hook Sean Christopherson
2021-11-22 22:49 ` Ben Gardon
2021-11-20 4:50 ` [PATCH 21/28] KVM: x86/mmu: Add TDP MMU helper to zap a root Sean Christopherson
2021-11-22 22:54 ` Ben Gardon
2021-11-22 23:15 ` Sean Christopherson
2021-11-22 23:38 ` Ben Gardon
2021-11-20 4:50 ` [PATCH 22/28] KVM: x86/mmu: Skip remote TLB flush when zapping all of TDP MMU Sean Christopherson
2021-11-22 23:00 ` Ben Gardon
2021-11-20 4:50 ` [PATCH 23/28] KVM: x86/mmu: Use "zap root" path for "slow" zap of all TDP MMU SPTEs Sean Christopherson
2021-11-20 4:50 ` [PATCH 24/28] KVM: x86/mmu: Add dedicated helper to zap TDP MMU root shadow page Sean Christopherson
2021-11-23 1:04 ` Ben Gardon
2021-11-20 4:50 ` [PATCH 25/28] KVM: x86/mmu: Require mmu_lock be held for write to zap TDP MMU range Sean Christopherson
2021-11-23 19:58 ` Ben Gardon
2021-11-20 4:50 ` [PATCH 26/28] KVM: x86/mmu: Zap only TDP MMU leafs in kvm_zap_gfn_range() Sean Christopherson
2021-11-23 19:58 ` Ben Gardon
2021-11-20 4:50 ` [PATCH 27/28] KVM: x86/mmu: Do remote TLB flush before dropping RCU in TDP MMU resched Sean Christopherson
2021-11-23 19:58 ` Ben Gardon
2021-11-24 18:42 ` Sean Christopherson
2021-11-30 11:29 ` Paolo Bonzini
2021-11-30 15:45 ` Sean Christopherson
2021-11-30 16:16 ` Paolo Bonzini
2021-11-20 4:50 ` [PATCH 28/28] KVM: x86/mmu: Defer TLB flush to caller when freeing TDP MMU shadow pages Sean Christopherson
2021-11-23 20:12 ` Ben Gardon
2021-12-01 17:53 ` David Matlack [this message]
2021-12-02 2:03 ` [PATCH 00/28] KVM: x86/mmu: Overhaul TDP MMU zapping and flushing Sean Christopherson
2021-12-03 0:16 ` David Matlack
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