Commit e0b728b1 authored by David Matlack's avatar David Matlack Committed by Paolo Bonzini
Browse files

KVM: x86/mmu: Add tracepoint for splitting huge pages 



Add a tracepoint that records whenever KVM eagerly splits a huge page
and the error status of the split to indicate if it succeeded or failed
and why.

Reviewed-by: default avatarPeter Xu <peterx@redhat.com>
Signed-off-by: default avatarDavid Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-18-dmatlack@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent cb00a70b

arch/x86/kvm/mmu/mmutrace.h

+23 −0
Original line number Diff line number Diff line
@@ -416,6 +416,29 @@ TRACE_EVENT( 
	)

);



TRACE_EVENT(

	kvm_mmu_split_huge_page,

	TP_PROTO(u64 gfn, u64 spte, int level, int errno),

	TP_ARGS(gfn, spte, level, errno),



	TP_STRUCT__entry(

		__field(u64, gfn)

		__field(u64, spte)

		__field(int, level)

		__field(int, errno)

	),



	TP_fast_assign(

		__entry->gfn = gfn;

		__entry->spte = spte;

		__entry->level = level;

		__entry->errno = errno;

	),



	TP_printk("gfn %llx spte %llx level %d errno %d",

		  __entry->gfn, __entry->spte, __entry->level, __entry->errno)

);



#endif /* _TRACE_KVMMMU_H */



#undef TRACE_INCLUDE_PATH

arch/x86/kvm/mmu/tdp_mmu.c

+7 −3
Original line number Diff line number Diff line
@@ -1347,7 +1347,7 @@ static int tdp_mmu_split_huge_page(struct kvm *kvm, struct tdp_iter *iter, 
	 */

	ret = tdp_mmu_link_sp(kvm, iter, sp, false, shared);

	if (ret)

		return ret;

		goto out;



	/*

	 * tdp_mmu_link_sp_atomic() will handle subtracting the huge page we
@@ -1356,7 +1356,9 @@ static int tdp_mmu_split_huge_page(struct kvm *kvm, struct tdp_iter *iter, 
	 */

	kvm_update_page_stats(kvm, level - 1, PT64_ENT_PER_PAGE);



	return 0;

out:

	trace_kvm_mmu_split_huge_page(iter->gfn, huge_spte, level, ret);

	return ret;

}



static int tdp_mmu_split_huge_pages_root(struct kvm *kvm,
@@ -1393,6 +1395,9 @@ static int tdp_mmu_split_huge_pages_root(struct kvm *kvm, 
			sp = tdp_mmu_alloc_sp_for_split(kvm, &iter, shared);

			if (!sp) {

				ret = -ENOMEM;

				trace_kvm_mmu_split_huge_page(iter.gfn,

							      iter.old_spte,

							      iter.level, ret);

				break;

			}
@@ -1416,7 +1421,6 @@ static int tdp_mmu_split_huge_pages_root(struct kvm *kvm, 
	if (sp)

		tdp_mmu_free_sp(sp);





	return ret;

}