From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 8F9603C1980; Thu, 15 Jan 2026 17:36:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768498594; cv=none; b=JI1rCo59hHUATpDu4oSYTtlXPO0LOacSASVdn4i6eoydyTZA5nAkURcjvQoszKj0n7JRw+CYPcedFwHAJeOAEYZovbjQxrFxcAARVuNhUSQZOKHjO2K50p+PngO7HkSfEEuP9jytLT13w/GynpF/djeigynXD1VMDmjuU9q1HBE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768498594; c=relaxed/simple; bh=U91Uws8IE9TO7DOz7vVEIfILKWXry6zRqIBHo0K4uv0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=La14AheSjN16p44QPKezPHfy1Sxc63m2YHuSyAe7WYsVtfC211XiLGX3vs9ahn9XpzFOrV3LepWp2AO72dvZDmDxH2HyWvNqDxhdb3QRS47ALgxGMXJIOJA94ptDezbC1WxVKkYnd0dhXckdeHJCbhvv28JgV7VXKaxF/MoIo2U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=fzWtFbBa; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="fzWtFbBa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1B27CC116D0; Thu, 15 Jan 2026 17:36:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1768498594; bh=U91Uws8IE9TO7DOz7vVEIfILKWXry6zRqIBHo0K4uv0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fzWtFbBaycFaNpDx6eKpkpnOw5aZvHvQfQG1pWUn/MjLkGHPEGUm7LeRFvZGeicfu wH0btAo0uBumDafCb1S3djXX5CzB2kNt++nj6rOrF6rcmOq5RbO5Ar5kmt5/KWSRmO YXo7d4xS64Ww4aGdzBAwd23b/OCEMsek7w1N3XdY= From: Greg Kroah-Hartman To: stable@vger.kernel.org, seanjc@google.com Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Rajani Kantha <681739313@139.com> Subject: [PATCH 5.15 485/554] KVM: x86: Acquire kvm->srcu when handling KVM_SET_VCPU_EVENTS Date: Thu, 15 Jan 2026 17:49:11 +0100 Message-ID: <20260115164303.867825622@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260115164246.225995385@linuxfoundation.org> References: <20260115164246.225995385@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sean Christopherson commit 4bcdd831d9d01e0fb64faea50732b59b2ee88da1 upstream. Grab kvm->srcu when processing KVM_SET_VCPU_EVENTS, as KVM will forcibly leave nested VMX/SVM if SMM mode is being toggled, and leaving nested VMX reads guest memory. Note, kvm_vcpu_ioctl_x86_set_vcpu_events() can also be called from KVM_RUN via sync_regs(), which already holds SRCU. I.e. trying to precisely use kvm_vcpu_srcu_read_lock() around the problematic SMM code would cause problems. Acquiring SRCU isn't all that expensive, so for simplicity, grab it unconditionally for KVM_SET_VCPU_EVENTS. ============================= WARNING: suspicious RCU usage 6.10.0-rc7-332d2c1d713e-next-vm #552 Not tainted ----------------------------- include/linux/kvm_host.h:1027 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by repro/1071: #0: ffff88811e424430 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0x7d/0x970 [kvm] stack backtrace: CPU: 15 PID: 1071 Comm: repro Not tainted 6.10.0-rc7-332d2c1d713e-next-vm #552 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 Call Trace: dump_stack_lvl+0x7f/0x90 lockdep_rcu_suspicious+0x13f/0x1a0 kvm_vcpu_gfn_to_memslot+0x168/0x190 [kvm] kvm_vcpu_read_guest+0x3e/0x90 [kvm] nested_vmx_load_msr+0x6b/0x1d0 [kvm_intel] load_vmcs12_host_state+0x432/0xb40 [kvm_intel] vmx_leave_nested+0x30/0x40 [kvm_intel] kvm_vcpu_ioctl_x86_set_vcpu_events+0x15d/0x2b0 [kvm] kvm_arch_vcpu_ioctl+0x1107/0x1750 [kvm] ? mark_held_locks+0x49/0x70 ? kvm_vcpu_ioctl+0x7d/0x970 [kvm] ? kvm_vcpu_ioctl+0x497/0x970 [kvm] kvm_vcpu_ioctl+0x497/0x970 [kvm] ? lock_acquire+0xba/0x2d0 ? find_held_lock+0x2b/0x80 ? do_user_addr_fault+0x40c/0x6f0 ? lock_release+0xb7/0x270 __x64_sys_ioctl+0x82/0xb0 do_syscall_64+0x6c/0x170 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x7ff11eb1b539 Fixes: f7e570780efc ("KVM: x86: Forcibly leave nested virt when SMM state is toggled") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20240723232055.3643811-1-seanjc@google.com Signed-off-by: Sean Christopherson [ Based on kernel 5.15 available functions, using srcu_read_lock/srcu_read_unlock instead of kvm_vcpu_srcu_read_lock/kvm_vcpu_srcu_read_unlock ] Signed-off-by: Rajani Kantha <681739313@139.com> Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/x86.c | 2 ++ 1 file changed, 2 insertions(+) --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -5294,7 +5294,9 @@ long kvm_arch_vcpu_ioctl(struct file *fi if (copy_from_user(&events, argp, sizeof(struct kvm_vcpu_events))) break; + vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu); r = kvm_vcpu_ioctl_x86_set_vcpu_events(vcpu, &events); + srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx); break; } case KVM_GET_DEBUGREGS: {