From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0D6B3C5DF7D for ; Fri, 21 Aug 2026 16:18:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=WEF6doGMqjYIhz33csMFnuJ7kI3Ap/gnlovtm05IJSA=; b=klQXw/YLbc91hylM2BfnPi3Qq4 2b8hX4srVQv7u/lyLKD3amk5YklBfh01Klf/YdQyiwsIqzJMgTkvI3KihghjlpWeEZmUUQNmp1M/5 WSBPns4DCZ0gHmDrcKaE0Fmgaf0TcS6l8xoAD23zWSPNSOzDgCd6uxUrHHyROaHOEntV8oVn6x6ig 8n/hbZok6+ycc5vvML/Wq7cMF9pvyVXadTKA7I2k1KGoBm3H9pS47ixqsykglutENeVw0b8R7We+Q ePbsbIOPCCOMenbTigEY/L/6iy6lcwa8b7B7VBojw7is48kq65VHCO385wefxHdrXIW1lLEAxHgmQ 7BjUyF5g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wxRx2-0000000DmqX-0AUr; Fri, 21 Aug 2026 16:18:40 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wxRwx-0000000DmpL-2AwD for linux-arm-kernel@lists.infradead.org; Fri, 21 Aug 2026 16:18:38 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id F32DE43612; Fri, 21 Aug 2026 16:18:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D0DBD1F00A3D; Fri, 21 Aug 2026 16:18:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787329114; bh=WEF6doGMqjYIhz33csMFnuJ7kI3Ap/gnlovtm05IJSA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=GQC7wawvKnXLkRgv6ylwEUARIpLbVg4jxC3Y+2BhegpmppY9+fngslRaVBCkzevX8 3x1NZ0RzxZnlqycgjJlm4DAA0d+P7VTjxNUdVS5kLmxldK7TIwQFDyW3+YWiPDSvyO 9mOe0MicZ0PKIGxu7JbM6qnLTLMeTtI7+gi9ISTRWa/kVCroxT7xUt3bekvLiUgwpj RZ9ddTV1cQQqxlSf8qrhV+X04xwsUfBdSZCE3rELUwn4il431Bb5XRqfVvRS9uk7KR jVNMD/VVgmyA9nWVXveFAcYc+keHcd1SE+9xdefC9AdRam0jeIayqUDIc8BNqBckNR TUSfoxuIVO7Ew== Received: from sofa.misterjones.org ([185.219.108.64] helo=valley-girl.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1wxRwu-000000006fx-3yOk; Fri, 21 Aug 2026 16:18:33 +0000 From: Marc Zyngier To: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org Cc: Steffen Eiden , Joey Gouly , Suzuki K Poulose , Oliver Upton , Zenghui Yu , Fuad Tabba , ljs@kernel.org, Shen Yongchao , Karl Mehltretter , Wei-Lin Chang , stable@vger.kernel.org Subject: [PATCH v3 2/2] KVM: arm64: nv: Delay freeing of shadow S2 structures until VM destruction Date: Fri, 21 Aug 2026 17:18:29 +0100 Message-ID: <20260821161829.1032561-3-maz@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260821161829.1032561-1-maz@kernel.org> References: <20260821161829.1032561-1-maz@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, seiden@linux.ibm.com, joey.gouly@arm.com, suzuki.poulose@arm.com, oupton@kernel.org, yuzenghui@huawei.com, fuad.tabba@linux.dev, ljs@kernel.org, grayhat@foxmail.com, kmehltretter@gmail.com, weilin.chang@arm.com, stable@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org We free the shadow S2 structures from kvm_arch_flush_shadow_all(), which is a Bad Idea(tm). Freeing the page tables is fair game (this is what this callback is for), but freeing the container that could still be referenced by another part of the system is not great. Instead, grow separate destructors that gets called when we tear the VM down for good. From there, we can nuke both the individual MMUs as well as the global array that points to them, safe in the knowledge that the vcpus themselves have been destroyed already. Fixes: 4f128f8e1aaac ("KVM: arm64: nv: Support multiple nested Stage-2 mmu structures") Signed-off-by: Marc Zyngier Cc: stable@vger.kernel.org --- arch/arm64/include/asm/kvm_nested.h | 1 + arch/arm64/kvm/arm.c | 4 ++-- arch/arm64/kvm/nested.c | 15 ++++++++++----- 3 files changed, 13 insertions(+), 7 deletions(-) diff --git a/arch/arm64/include/asm/kvm_nested.h b/arch/arm64/include/asm/kvm_nested.h index 5b8edb2e8a87d..586026e859030 100644 --- a/arch/arm64/include/asm/kvm_nested.h +++ b/arch/arm64/include/asm/kvm_nested.h @@ -67,6 +67,7 @@ static inline u64 translate_ttbr0_el2_to_ttbr0_el1(u64 ttbr0) extern bool forward_smc_trap(struct kvm_vcpu *vcpu); extern bool forward_debug_exception(struct kvm_vcpu *vcpu); extern int kvm_init_nested(struct kvm *kvm); +extern void kvm_destroy_nested(struct kvm *kvm); extern int kvm_vcpu_init_nested(struct kvm_vcpu *vcpu); extern void kvm_init_nested_s2_mmu(struct kvm_s2_mmu *mmu); extern struct kvm_s2_mmu *lookup_s2_mmu(struct kvm_vcpu *vcpu); diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 7607173c1a40c..2b069c6440669 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -269,7 +269,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) err_uninit_mmu: kvm_uninit_stage2_mmu(kvm); - kvfree(kvm->arch.nested_mmus); + kvm_destroy_nested(kvm); err_free_cpumask: free_cpumask_var(kvm->arch.supported_cpus); err_unshare_kvm: @@ -327,7 +327,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm) kvm_unshare_hyp(kvm, kvm + 1); - kvfree(kvm->arch.nested_mmus); + kvm_destroy_nested(kvm); kvm_arm_teardown_hypercalls(kvm); } diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c index 05266f8b87304..00580ba6e8ba0 100644 --- a/arch/arm64/kvm/nested.c +++ b/arch/arm64/kvm/nested.c @@ -55,6 +55,15 @@ int kvm_init_nested(struct kvm *kvm) return kvm->arch.nested_mmus ? 0 : -ENOMEM; } +void kvm_destroy_nested(struct kvm *kvm) +{ + for (int i = 0; i < kvm->arch.nested_mmus_size; i+= S2_MMU_PER_VCPU) + kvfree(kvm->arch.nested_mmus[i]); + + kvm->arch.nested_mmus_size = 0; + kvfree(kvm->arch.nested_mmus); +} + static int init_nested_s2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu) { /* @@ -1310,16 +1319,12 @@ void kvm_nested_s2_flush(struct kvm *kvm) void kvm_arch_flush_shadow_all(struct kvm *kvm) { - for (int i = kvm->arch.nested_mmus_size - 1; i >= 0; i--) { + for (int i = 0; i < kvm->arch.nested_mmus_size; i++) { struct kvm_s2_mmu *mmu = kvm->arch.nested_mmus[i]; if (!WARN_ON(atomic_read(&mmu->refcnt))) kvm_free_stage2_pgd(mmu); - - if ((i % S2_MMU_PER_VCPU) == 0) - kvfree(mmu); } - kvm->arch.nested_mmus_size = 0; kvm_uninit_stage2_mmu(kvm); } -- 2.47.3