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

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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: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-18-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
David Matlack 2022-01-19 23:07:38 +00:00 committed by Paolo Bonzini
parent cb00a70bd4
commit e0b728b1f1
2 changed files with 30 additions and 3 deletions
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23
arch/x86/kvm/mmu/mmutrace.h
View File

@ -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

10
arch/x86/kvm/mmu/tdp_mmu.c
View File

@ -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 @@ retry:
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 @@ retry:
if (sp)
tdp_mmu_free_sp(sp);
return ret;
}