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From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.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: [PATCH 12/28] KVM: x86/mmu: Batch TLB flushes from TDP MMU for MMU notifier change_spte
Date: Sat, 20 Nov 2021 04:50:30 +0000	[thread overview]
Message-ID: <20211120045046.3940942-13-seanjc@google.com> (raw)
In-Reply-To: <20211120045046.3940942-1-seanjc@google.com>

Batch TLB flushes (with other MMUs) when handling ->change_spte()
notifications in the TDP MMU.  The MMU notifier path in question doesn't
allow yielding and correcty flushes before dropping mmu_lock.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/mmu/tdp_mmu.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 8e446ef03022..06b500fab248 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1182,13 +1182,12 @@ static bool set_spte_gfn(struct kvm *kvm, struct tdp_iter *iter,
  */
 bool kvm_tdp_mmu_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
 {
-	bool flush = kvm_tdp_mmu_handle_gfn(kvm, range, set_spte_gfn);
-
-	/* FIXME: return 'flush' instead of flushing here. */
-	if (flush)
-		kvm_flush_remote_tlbs_with_address(kvm, range->start, 1);
-
-	return false;
+	/*
+	 * No need to handle the remote TLB flush under RCU protection, the
+	 * target SPTE _must_ be a leaf SPTE, i.e. cannot result in freeing a
+	 * shadow page.  See the WARN on pfn_changed in __handle_changed_spte().
+	 */
+	return kvm_tdp_mmu_handle_gfn(kvm, range, set_spte_gfn);
 }
 
 /*
-- 
2.34.0.rc2.393.gf8c9666880-goog


  parent reply	other threads:[~2021-11-20  4:52 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 ` Sean Christopherson [this message]
2021-11-22 21:45   ` [PATCH 12/28] KVM: x86/mmu: Batch TLB flushes from TDP MMU for MMU notifier change_spte 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 ` [PATCH 00/28] KVM: x86/mmu: Overhaul TDP MMU zapping and flushing David Matlack
2021-12-02  2:03   ` Sean Christopherson
2021-12-03  0:16     ` David Matlack

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