From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9B417528423; Wed, 30 Sep 2026 17:39:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790789960; cv=none; b=V/w3pN79jP9ClIt0dkV4J8QtEZ4LPFf8U698JYgqllhC+ENdNAWhIBWUuHdwvanuSQAsHuvGFWGBqZmdxsN2r3FH0XXRAmGfv6pbRNBLhglyAui4yj5EwY/7r2ASArmWta5DBtTY+7Y1NJ7d91ZJwurrAY1OPmzvKVWQTUsXkY0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790789960; c=relaxed/simple; bh=HG3f559JaQsHAEaXs+wdI15vMhnw3CVQSj+KZ74UiH4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ClDhvgH4fti40L/1sF7Ksq457bqtCq1cpK42QG/RUEp7+2jrrR0l5AGZ6WRWoq/RU7wtOnwdJsqn262AIoiiU7Aez4LhuHj3ruzri36I+XnXlN6omszN/338Ek1DGUHfDVSIR4Oav6TMgZ86aXDTrfa2vS4GPcMG6jv7YT6n8aI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Wqc78erq; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Wqc78erq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A6CF01F000FF; Wed, 30 Sep 2026 17:39:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790789959; bh=4qlLuvrKpLrElhRChPaRJGrWochmIK5lu9J3RtCM+Dg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Wqc78erqeTL2WBUK4hRsj+TFJzGmGt3rJOvNNZ//aEtNVsAB5/0AkBKpqpiJyDe5j 0YIOtg1kiMYwZ981ZQpUKwO4kZ8LeUolLrhS2BhyWVWSkpP5r+x/Pok+wh0oroBFp+ G5du7vsNrsW7EnYsMj21Y4nKbo1UIMKFBkUkKfP8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Michael Roth , Sean Christopherson , Sasha Levin Subject: [PATCH 6.12 661/877] KVM: x86/mmu: Split kvm_mmu_zap_all_fast() into "front" and "back" halves Date: Wed, 30 Sep 2026 17:26:12 +0200 Message-ID: <20260930152428.927441146@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152414.738996857@linuxfoundation.org> References: <20260930152414.738996857@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sean Christopherson [ Upstream commit b27622c4eeb125814081baaefe9175191be5b94d ] Split kvm_mmu_zap_all_fast() into a "front half" and a "back half", where the front half is everything that runs with mmu_lock held for write, and the back half is the code that runs outside of mmu_lock. This will allow putting more code inside kvm_arch_flush_shadow_memslot()'s critical section without having to take mmu_lock twice in quick succession. No functional change intended. Cc: stable@vger.kernel.org # 6.12.x Reviewed-by: Michael Roth Link: https://patch.msgid.link/20260709204948.1988414-9-seanjc@google.com Signed-off-by: Sean Christopherson Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/mmu/mmu.c | 37 +++++++++++++++++++++++++------------ 1 file changed, 25 insertions(+), 12 deletions(-) --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -6489,20 +6489,11 @@ restart: kvm_mmu_commit_zap_page(kvm, &kvm->arch.zapped_obsolete_pages); } -/* - * Fast invalidate all shadow pages and use lock-break technique - * to zap obsolete pages. - * - * It's required when memslot is being deleted or VM is being - * destroyed, in these cases, we should ensure that KVM MMU does - * not use any resource of the being-deleted slot or all slots - * after calling the function. - */ -static void kvm_mmu_zap_all_fast(struct kvm *kvm) +static void __kvm_mmu_zap_all_fast_front_half(struct kvm *kvm) { lockdep_assert_held(&kvm->slots_lock); + lockdep_assert_held_write(&kvm->mmu_lock); - write_lock(&kvm->mmu_lock); trace_kvm_mmu_zap_all_fast(kvm); /* @@ -6534,8 +6525,12 @@ static void kvm_mmu_zap_all_fast(struct kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_FREE_OBSOLETE_ROOTS); kvm_zap_obsolete_pages(kvm); +} - write_unlock(&kvm->mmu_lock); +static void __kvm_mmu_zap_all_fast_back_half(struct kvm *kvm) +{ + lockdep_assert_held(&kvm->slots_lock); + lockdep_assert_not_held(&kvm->mmu_lock); /* * Zap the invalidated TDP MMU roots, all SPTEs must be dropped before @@ -6554,6 +6549,24 @@ static bool kvm_has_zapped_obsolete_page return unlikely(!list_empty_careful(&kvm->arch.zapped_obsolete_pages)); } +/* + * Fast invalidate all shadow pages and use lock-break technique + * to zap obsolete pages. + * + * It's required when memslot is being deleted or VM is being + * destroyed, in these cases, we should ensure that KVM MMU does + * not use any resource of the being-deleted slot or all slots + * after calling the function. + */ +static void kvm_mmu_zap_all_fast(struct kvm *kvm) +{ + write_lock(&kvm->mmu_lock); + __kvm_mmu_zap_all_fast_front_half(kvm); + write_unlock(&kvm->mmu_lock); + + __kvm_mmu_zap_all_fast_back_half(kvm); +} + int kvm_mmu_init_vm(struct kvm *kvm) { int r;