From e0b728b1f1a951e0d23eef08cfa920a8104e39db Mon Sep 17 00:00:00 2001 From: David Matlack Date: Wed, 19 Jan 2022 23:07:38 +0000 Subject: [PATCH] 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: Peter Xu Signed-off-by: David Matlack Message-Id: <20220119230739.2234394-18-dmatlack@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/mmutrace.h | 23 +++++++++++++++++++++++ arch/x86/kvm/mmu/tdp_mmu.c | 10 +++++++--- 2 files changed, 30 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/mmu/mmutrace.h b/arch/x86/kvm/mmu/mmutrace.h index de5e8e4..12247b96 100644 --- a/arch/x86/kvm/mmu/mmutrace.h +++ b/arch/x86/kvm/mmu/mmutrace.h @@ -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 diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index dae2ceb..8def8f8 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -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; } -- 2.7.4