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Commit b3ae2096 authored by Takuya Yoshikawa's avatar Takuya Yoshikawa Committed by Marcelo Tosatti
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KVM: Introduce kvm_unmap_hva_range() for kvm_mmu_notifier_invalidate_range_start() 



When we tested KVM under memory pressure, with THP enabled on the host,
we noticed that MMU notifier took a long time to invalidate huge pages.

Since the invalidation was done with mmu_lock held, it not only wasted
the CPU but also made the host harder to respond.

This patch mitigates this by using kvm_handle_hva_range().

Signed-off-by: default avatarTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Cc: Alexander Graf <agraf@suse.de>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 84504ef3

arch/powerpc/include/asm/kvm_host.h

+2 −0
Original line number Diff line number Diff line
@@ -52,6 +52,8 @@ 


struct kvm;

extern int kvm_unmap_hva(struct kvm *kvm, unsigned long hva);

extern int kvm_unmap_hva_range(struct kvm *kvm,

			       unsigned long start, unsigned long end);

extern int kvm_age_hva(struct kvm *kvm, unsigned long hva);

extern int kvm_test_age_hva(struct kvm *kvm, unsigned long hva);

extern void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte);

arch/powerpc/kvm/book3s_64_mmu_hv.c

+7 −0
Original line number Diff line number Diff line
@@ -870,6 +870,13 @@ int kvm_unmap_hva(struct kvm *kvm, unsigned long hva) 
	return 0;

}



int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end)

{

	if (kvm->arch.using_mmu_notifiers)

		kvm_handle_hva_range(kvm, start, end, kvm_unmap_rmapp);

	return 0;

}



static int kvm_age_rmapp(struct kvm *kvm, unsigned long *rmapp,

			 unsigned long gfn)

{

arch/x86/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -944,6 +944,7 @@ extern bool kvm_rebooting; 


#define KVM_ARCH_WANT_MMU_NOTIFIER

int kvm_unmap_hva(struct kvm *kvm, unsigned long hva);

int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end);

int kvm_age_hva(struct kvm *kvm, unsigned long hva);

int kvm_test_age_hva(struct kvm *kvm, unsigned long hva);

void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte);

arch/x86/kvm/mmu.c

+5 −0
Original line number Diff line number Diff line
@@ -1324,6 +1324,11 @@ int kvm_unmap_hva(struct kvm *kvm, unsigned long hva) 
	return kvm_handle_hva(kvm, hva, 0, kvm_unmap_rmapp);

}



int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end)

{

	return kvm_handle_hva_range(kvm, start, end, 0, kvm_unmap_rmapp);

}



void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte)

{

	kvm_handle_hva(kvm, hva, (unsigned long)&pte, kvm_set_pte_rmapp);

virt/kvm/kvm_main.c

+1 −2
Original line number Diff line number Diff line
@@ -332,8 +332,7 @@ static void kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn, 
	 * count is also read inside the mmu_lock critical section.

	 */

	kvm->mmu_notifier_count++;

	for (; start < end; start += PAGE_SIZE)

		need_tlb_flush |= kvm_unmap_hva(kvm, start);

	need_tlb_flush = kvm_unmap_hva_range(kvm, start, end);

	need_tlb_flush |= kvm->tlbs_dirty;

	/* we've to flush the tlb before the pages can be freed */

	if (need_tlb_flush)