diff options
| author | Sean Christopherson <seanjc@google.com> | 2025-03-14 19:34:48 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2025-04-04 07:07:40 -0400 |
| commit | 81d480fdf8b7d9b13fe87e1f0516f89794708094 (patch) | |
| tree | dc764547bbd6d5dfbc2177c1c61cd7ea785058e4 /arch | |
| parent | 0297cdc12a87629ad904ac8c0630f7702f9a2d48 (diff) | |
KVM: x86/mmu: Wrap sanity check on number of TDP MMU pages with KVM_PROVE_MMU
Wrap the TDP MMU page counter in CONFIG_KVM_PROVE_MMU so that the sanity
check is omitted from production builds, and more importantly to remove
the atomic accesses to account pages. A one-off memory leak in production
is relatively uninteresting, and a WARN_ON won't help mitigate a systemic
issue; it's as much about helping triage memory leaks as it is about
detecting them in the first place, and doesn't magically stop the leaks.
I.e. production environments will be quite sad if a severe KVM bug escapes,
regardless of whether or not KVM WARNs.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20250315023448.2358456-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 7 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu/tdp_mmu.c | 8 |
2 files changed, 13 insertions, 2 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index a884ab544335..3bdae454a959 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1472,8 +1472,13 @@ struct kvm_arch { struct once nx_once; #ifdef CONFIG_X86_64 - /* The number of TDP MMU pages across all roots. */ +#ifdef CONFIG_KVM_PROVE_MMU + /* + * The number of TDP MMU pages across all roots. Used only to sanity + * check that KVM isn't leaking TDP MMU pages. + */ atomic64_t tdp_mmu_pages; +#endif /* * List of struct kvm_mmu_pages being used as roots. diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 7cc0564f5f97..21a3b8166242 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -40,7 +40,9 @@ void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm) kvm_tdp_mmu_invalidate_roots(kvm, KVM_VALID_ROOTS); kvm_tdp_mmu_zap_invalidated_roots(kvm, false); - WARN_ON(atomic64_read(&kvm->arch.tdp_mmu_pages)); +#ifdef CONFIG_KVM_PROVE_MMU + KVM_MMU_WARN_ON(atomic64_read(&kvm->arch.tdp_mmu_pages)); +#endif WARN_ON(!list_empty(&kvm->arch.tdp_mmu_roots)); /* @@ -325,13 +327,17 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, static void tdp_account_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) { kvm_account_pgtable_pages((void *)sp->spt, +1); +#ifdef CONFIG_KVM_PROVE_MMU atomic64_inc(&kvm->arch.tdp_mmu_pages); +#endif } static void tdp_unaccount_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) { kvm_account_pgtable_pages((void *)sp->spt, -1); +#ifdef CONFIG_KVM_PROVE_MMU atomic64_dec(&kvm->arch.tdp_mmu_pages); +#endif } /** |