From patchwork Tue Dec 3 11:47:58 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Huacai Chen X-Patchwork-Id: 13892265 Received: from mail.loongson.cn (mail.loongson.cn [114.242.206.163]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 66F901E411C; Tue, 3 Dec 2024 11:48:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=114.242.206.163 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733226504; cv=none; b=F5RVyajkqkPq2fdro8r4VtDVIHvX9zeT1YVfMSXO7LtrnovRW06iPIYEzhjCKUcllRIHxkZOWQhhPvdehTODTNQOIrEv9et9frW2P8f8Qgw6Ga2xZVJ7Ay8QIix3ghVgSV1Dve0WUAoxtoA0HMRlgplUXRxV5Aefkf5PB+kWhjI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733226504; c=relaxed/simple; bh=TqawTQjbMSMJ23s8nCMeSH4mAdv9G2HhO1QDLyCtIGU=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=aamaKt+tLc7Fadp2t26ofNDVLkv/n4ButyWt2razMley8KjFGpKsmgs8sO7xJMfJrQMyZIGanXzEY9XnNkXGEhUWhtwVUFYUPAQQspCinlnuAXCT61dbjcadY4SK/gZajUu8sovgESgxp0RhRLn5bKMZ5Bl78QWnkg8tYleV/P0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=loongson.cn; spf=pass smtp.mailfrom=loongson.cn; arc=none smtp.client-ip=114.242.206.163 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=loongson.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=loongson.cn Received: from loongson.cn (unknown [223.64.68.38]) by gateway (Coremail) with SMTP id _____8CxSOH+705n2rJPAA--.23423S3; Tue, 03 Dec 2024 19:48:14 +0800 (CST) Received: from localhost.localdomain (unknown [223.64.68.38]) by front1 (Coremail) with SMTP id qMiowMAxmsH3705ne9JzAA--.9972S2; Tue, 03 Dec 2024 19:48:14 +0800 (CST) From: Huacai Chen To: Paolo Bonzini , Huacai Chen , Tianrui Zhao , Bibo Mao Cc: kvm@vger.kernel.org, loongarch@lists.linux.dev, linux-kernel@vger.kernel.org, Xuerui Wang , Jiaxun Yang , Huacai Chen , stable@vger.kernel.org Subject: [PATCH V2 1/2] LoongArch: KVM: Protect kvm_check_requests() with SRCU Date: Tue, 3 Dec 2024 19:47:58 +0800 Message-ID: <20241203114759.419261-1-chenhuacai@loongson.cn> X-Mailer: git-send-email 2.43.5 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID: qMiowMAxmsH3705ne9JzAA--.9972S2 X-CM-SenderInfo: hfkh0x5xdftxo6or00hjvr0hdfq/ X-Coremail-Antispam: 1Uk129KBj93XoWxZF4UXF1DXFyrWry7tr13GFX_yoW5WF1xpr 9xAr4xGr48Xry7Aw1UAF1DAr1UX3yDAF1xJry8Jr18Ar1UZr1DJFyUJrW8Jry5G34rAF17 Jr1Utr15tr1UJwcCm3ZEXasCq-sJn29KB7ZKAUJUUUUr529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUU9Fb4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r1Y6r17M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_JFI_Gr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Jr0_Gr1l84ACjcxK6I8E87Iv67AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVCY1x0267AK xVW8Jr0_Cr1UM2kKe7AKxVWUXVWUAwAS0I0E0xvYzxvE52x082IY62kv0487Mc804VCY07 AIYIkI8VC2zVCFFI0UMc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWU XVWUAwAv7VC2z280aVAFwI0_Gr0_Cr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcxkI7V AKI48JMxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMxCIbckI1I0E14v2 6r1Y6r17MI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17 CEb7AF67AKxVWUtVW8ZwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF 0xvE2Ix0cI8IcVCY1x0267AKxVWUJVW8JwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIx AIcVC2z280aVAFwI0_Gr0_Cr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2 KfnxnUUI43ZEXa7IU8CksDUUUUU== When we enable lockdep we get such a warning: ============================= WARNING: suspicious RCU usage 6.12.0-rc7+ #1891 Tainted: G W ----------------------------- include/linux/kvm_host.h:1043 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by qemu-system-loo/948: #0: 90000001184a00a8 (&vcpu->mutex){+.+.}-{4:4}, at: kvm_vcpu_ioctl+0xf4/0xe20 [kvm] stack backtrace: CPU: 0 UID: 0 PID: 948 Comm: qemu-system-loo Tainted: G W 6.12.0-rc7+ #1891 Tainted: [W]=WARN Hardware name: Loongson Loongson-3A5000-7A1000-1w-CRB/Loongson-LS3A5000-7A1000-1w-CRB, BIOS vUDK2018-LoongArch-V2.0.0-prebeta9 10/21/2022 Stack : 0000000000000089 9000000005a0db9c 90000000071519c8 900000012c578000 900000012c57b920 0000000000000000 900000012c57b928 9000000007e53788 900000000815bcc8 900000000815bcc0 900000012c57b790 0000000000000001 0000000000000001 4b031894b9d6b725 0000000004dec000 90000001003299c0 0000000000000414 0000000000000001 000000000000002d 0000000000000003 0000000000000030 00000000000003b4 0000000004dec000 90000001184a0000 900000000806d000 9000000007e53788 00000000000000b4 0000000000000004 0000000000000004 0000000000000000 0000000000000000 9000000107baf600 9000000008916000 9000000007e53788 9000000005924778 0000000010000044 00000000000000b0 0000000000000004 0000000000000000 0000000000071c1d ... Call Trace: [<9000000005924778>] show_stack+0x38/0x180 [<90000000071519c4>] dump_stack_lvl+0x94/0xe4 [<90000000059eb754>] lockdep_rcu_suspicious+0x194/0x240 [] kvm_gfn_to_hva_cache_init+0xfc/0x120 [kvm] [] kvm_pre_enter_guest+0x3a4/0x520 [kvm] [] kvm_handle_exit+0x23c/0x480 [kvm] Fix it by protecting kvm_check_requests() with SRCU. Cc: stable@vger.kernel.org Signed-off-by: Huacai Chen --- arch/loongarch/kvm/vcpu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c index cab1818be68d..d18a4a270415 100644 --- a/arch/loongarch/kvm/vcpu.c +++ b/arch/loongarch/kvm/vcpu.c @@ -240,7 +240,7 @@ static void kvm_late_check_requests(struct kvm_vcpu *vcpu) */ static int kvm_enter_guest_check(struct kvm_vcpu *vcpu) { - int ret; + int idx, ret; /* * Check conditions before entering the guest @@ -249,7 +249,9 @@ static int kvm_enter_guest_check(struct kvm_vcpu *vcpu) if (ret < 0) return ret; + idx = srcu_read_lock(&vcpu->kvm->srcu); ret = kvm_check_requests(vcpu); + srcu_read_unlock(&vcpu->kvm->srcu, idx); return ret; }