linux-kernel - [PATCH] Revert "KVM: x86/mmu: Zap only the relevant pages when removing a memslot"

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Date:   Thu, 15 Aug 2019 09:46:09 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     stable@...r.kernel.org,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: [PATCH] Revert "KVM: x86/mmu: Zap only the relevant pages when removing a memslot"

This reverts commit 4e103134b862314dc2f2f18f2fb0ab972adc3f5f.
Alex Williamson reported regressions with device assignment with
this patch.  Even though the bug is probably elsewhere and still
latent, this is needed to fix the regression.

Fixes: 4e103134b862 ("KVM: x86/mmu: Zap only the relevant pages when removing a memslot", 2019-02-05)
Reported-by: Alex Willamson <alex.williamson@...hat.com>
Cc: stable@...r.kernel.org
Cc: Sean Christopherson <sean.j.christopherson@...el.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/mmu.c | 33 +--------------------------------
 1 file changed, 1 insertion(+), 32 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 8190a195623a..d14656c5407b 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -5656,38 +5656,7 @@ static void kvm_mmu_invalidate_zap_pages_in_memslot(struct kvm *kvm,
 			struct kvm_memory_slot *slot,
 			struct kvm_page_track_notifier_node *node)
 {
-	struct kvm_mmu_page *sp;
-	LIST_HEAD(invalid_list);
-	unsigned long i;
-	bool flush;
-	gfn_t gfn;
-
-	spin_lock(&kvm->mmu_lock);
-
-	if (list_empty(&kvm->arch.active_mmu_pages))
-		goto out_unlock;
-
-	flush = slot_handle_all_level(kvm, slot, kvm_zap_rmapp, false);
-
-	for (i = 0; i < slot->npages; i++) {
-		gfn = slot->base_gfn + i;
-
-		for_each_valid_sp(kvm, sp, gfn) {
-			if (sp->gfn != gfn)
-				continue;
-
-			kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list);
-		}
-		if (need_resched() || spin_needbreak(&kvm->mmu_lock)) {
-			kvm_mmu_remote_flush_or_zap(kvm, &invalid_list, flush);
-			flush = false;
-			cond_resched_lock(&kvm->mmu_lock);
-		}
-	}
-	kvm_mmu_remote_flush_or_zap(kvm, &invalid_list, flush);
-
-out_unlock:
-	spin_unlock(&kvm->mmu_lock);
+	kvm_mmu_invalidate_zap_all_pages(kvm);
 }
 
 void kvm_mmu_init_vm(struct kvm *kvm)
-- 
1.8.3.1