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Commit 210f4942 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
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Revert "KVM: MMU: collapse TLB flushes when zap all pages" 

Unwinding optimizations related to obsolete pages is a step towards
removing x86 KVM's fast invalidate mechanism, i.e. this is one part of
a revert all patches from the series that introduced the mechanism[1].

This reverts commit f34d251d.

[1] https://lkml.kernel.org/r/1369960590-14138-1-git-send-email-xiaoguangrong@linux.vnet.ibm.com



Cc: Xiao Guangrong <guangrong.xiao@gmail.com>
Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 52d5dedc

arch/x86/kvm/mmu.c

+3 −28
Original line number Diff line number Diff line
@@ -2211,14 +2211,6 @@ static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, 
static void kvm_mmu_commit_zap_page(struct kvm *kvm,

				    struct list_head *invalid_list);



/*

 * NOTE: we should pay more attention on the zapped-obsolete page

 * (is_obsolete_sp(sp) && sp->role.invalid) when you do hash list walk

 * since it has been deleted from active_mmu_pages but still can be found

 * at hast list.

 *

 * for_each_valid_sp() has skipped that kind of pages.

 */

#define for_each_valid_sp(_kvm, _sp, _gfn)				\

	hlist_for_each_entry(_sp,					\

	  &(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)], hash_link) \
@@ -5881,13 +5873,11 @@ static void kvm_zap_obsolete_pages(struct kvm *kvm) 
		if (sp->role.invalid)

			continue;



		/*

		 * Need not flush tlb since we only zap the sp with invalid

		 * generation number.

		 */

		if (batch >= BATCH_ZAP_PAGES &&

		      cond_resched_lock(&kvm->mmu_lock)) {

		      (need_resched() || spin_needbreak(&kvm->mmu_lock))) {

			batch = 0;

			kvm_mmu_commit_zap_page(kvm, &invalid_list);

			cond_resched_lock(&kvm->mmu_lock);

			goto restart;

		}
@@ -5898,10 +5888,6 @@ static void kvm_zap_obsolete_pages(struct kvm *kvm) 
			goto restart;

	}



	/*

	 * Should flush tlb before free page tables since lockless-walking

	 * may use the pages.

	 */

	kvm_mmu_commit_zap_page(kvm, &invalid_list);

}
@@ -5920,17 +5906,6 @@ void kvm_mmu_invalidate_zap_all_pages(struct kvm *kvm) 
	trace_kvm_mmu_invalidate_zap_all_pages(kvm);

	kvm->arch.mmu_valid_gen++;



	/*

	 * Notify all vcpus to reload its shadow page table

	 * and flush TLB. Then all vcpus will switch to new

	 * shadow page table with the new mmu_valid_gen.

	 *

	 * Note: we should do this under the protection of

	 * mmu-lock, otherwise, vcpu would purge shadow page

	 * but miss tlb flush.

	 */

	kvm_reload_remote_mmus(kvm);



	kvm_zap_obsolete_pages(kvm);

	spin_unlock(&kvm->mmu_lock);

}