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 X-Spam-Level: X-Spam-Status: No, score=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 10E6CC47080 for ; Mon, 31 May 2021 16:51:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E858C6101C for ; Mon, 31 May 2021 16:51:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233805AbhEaQwt (ORCPT ); Mon, 31 May 2021 12:52:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:51350 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234453AbhEaO7o (ORCPT ); Mon, 31 May 2021 10:59:44 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 321E361413; Mon, 31 May 2021 14:01:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1622469701; bh=HIihrXyinQlGhsl/lM+nxWJxwIl1GrGyXLWn1KBymE4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Su9enMj84LaVGT/2Nsr7DcrwVPa9iqj+3NkJtE9ZKFl9MxGraFpxT+WJXR1iiKAuW e/x2NFuOdZojK1SDi8La+T7UZJmA3mkbi3pdiUmUdwgFNwlvcWs4z8lQH3VeVGT+2j zzYuSZyANVz8zroVxKQqohWRT+H42UOosrAqbnQc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vitaly Kuznetsov , Wanpeng Li , Sean Christopherson , Paolo Bonzini , Sasha Levin Subject: [PATCH 5.12 287/296] KVM: X86: hyper-v: Task srcu lock when accessing kvm_memslots() Date: Mon, 31 May 2021 15:15:42 +0200 Message-Id: <20210531130713.363862598@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210531130703.762129381@linuxfoundation.org> References: <20210531130703.762129381@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Wanpeng Li [ Upstream commit da6d63a0062a3ee721b84123b83ec093f25759b0 ] WARNING: suspicious RCU usage 5.13.0-rc1 #4 Not tainted ----------------------------- ./include/linux/kvm_host.h:710 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by hyperv_clock/8318: #0: ffffb6b8cb05a7d8 (&hv->hv_lock){+.+.}-{3:3}, at: kvm_hv_invalidate_tsc_page+0x3e/0xa0 [kvm] stack backtrace: CPU: 3 PID: 8318 Comm: hyperv_clock Not tainted 5.13.0-rc1 #4 Call Trace: dump_stack+0x87/0xb7 lockdep_rcu_suspicious+0xce/0xf0 kvm_write_guest_page+0x1c1/0x1d0 [kvm] kvm_write_guest+0x50/0x90 [kvm] kvm_hv_invalidate_tsc_page+0x79/0xa0 [kvm] kvm_gen_update_masterclock+0x1d/0x110 [kvm] kvm_arch_vm_ioctl+0x2a7/0xc50 [kvm] kvm_vm_ioctl+0x123/0x11d0 [kvm] __x64_sys_ioctl+0x3ed/0x9d0 do_syscall_64+0x3d/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae kvm_memslots() will be called by kvm_write_guest(), so we should take the srcu lock. Fixes: e880c6ea5 (KVM: x86: hyper-v: Prevent using not-yet-updated TSC page by secondary CPUs) Reviewed-by: Vitaly Kuznetsov Signed-off-by: Wanpeng Li Message-Id: <1621339235-11131-4-git-send-email-wanpengli@tencent.com> Reviewed-by: Sean Christopherson Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin --- arch/x86/kvm/hyperv.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index f98370a39936..f00830e5202f 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -1172,6 +1172,7 @@ void kvm_hv_invalidate_tsc_page(struct kvm *kvm) { struct kvm_hv *hv = to_kvm_hv(kvm); u64 gfn; + int idx; if (hv->hv_tsc_page_status == HV_TSC_PAGE_BROKEN || hv->hv_tsc_page_status == HV_TSC_PAGE_UNSET || @@ -1190,9 +1191,16 @@ void kvm_hv_invalidate_tsc_page(struct kvm *kvm) gfn = hv->hv_tsc_page >> HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT; hv->tsc_ref.tsc_sequence = 0; + + /* + * Take the srcu lock as memslots will be accessed to check the gfn + * cache generation against the memslots generation. + */ + idx = srcu_read_lock(&kvm->srcu); if (kvm_write_guest(kvm, gfn_to_gpa(gfn), &hv->tsc_ref, sizeof(hv->tsc_ref.tsc_sequence))) hv->hv_tsc_page_status = HV_TSC_PAGE_BROKEN; + srcu_read_unlock(&kvm->srcu, idx); out_unlock: mutex_unlock(&hv->hv_lock); -- 2.30.2