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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 C418ACA9EA0 for ; Tue, 22 Oct 2019 05:08:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 99FE02184C for ; Tue, 22 Oct 2019 05:08:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=brainfault-org.20150623.gappssmtp.com header.i=@brainfault-org.20150623.gappssmtp.com header.b="t5XI80Bi" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730997AbfJVFH6 (ORCPT ); Tue, 22 Oct 2019 01:07:58 -0400 Received: from mail-wm1-f68.google.com ([209.85.128.68]:37518 "EHLO mail-wm1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730601AbfJVFH5 (ORCPT ); Tue, 22 Oct 2019 01:07:57 -0400 Received: by mail-wm1-f68.google.com with SMTP id f22so14786241wmc.2 for ; Mon, 21 Oct 2019 22:07:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=brainfault-org.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=bTTMrmciHM4aiFMZR2LK71art6dDZteKsZ9m8QnTfYE=; b=t5XI80Bi4Lrln9mq+PcmKnh/yO/hMUHXGheJlgPjZHmjiOAKjNpjlwjXrH4e/9yOUp mR8jmhWjv/5OpGM8yjQhMT8lwxbmAwBue+sy9/eMu5EVFXjYnAzl3zU2VUOWqfu32NZM Z3zKuEf4f89oQkuqGUuY3+NKXqsGn82fXWfMpOdyot1HwqClZ0rZbi6horJoccoHlqBr kwilw8JQ+36mVE/vxn2gYkr710UiwpoIXu4c7yr5Z6txLx1fUYfbJjV7PbNxFvpZlrFo UqUOOHNXqgUT5BX0UdU1JbK4lADmJtAa4wyL7NBU3sCdNhXQnJrx368cQvjh4NYcUPA4 8zGQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=bTTMrmciHM4aiFMZR2LK71art6dDZteKsZ9m8QnTfYE=; b=kRabyR94Wqh7PVSzSYsuxV2y0hlIUegQZ9r3y2SyE2QmBgCiCiY/7lChf3B2NaKGgs Vs/npJhF6MtRhXUIJ+QoCG0/KB/JVGPvTO9apZQeLu/CmeQdGGYHQ5352xIIaNvv5y+l RmMyojDCD9ypHUC0jHCowWuq+l2PuC7bkXam5S9QTxgrSpKH5o6TnwZ5GrHPBCkKruZp Kanavk1k2RXstwzEn1YLojS9UniFvwRR9x4d16+BXiWHSaM7tjIp9X5Q9usYcLuGygsF 5G7GJr+L6RlOt2l/TH2Saxfwioc4EXSUChyK8cRtMwvSrOSvkocXH1MZHQhiF/Ejusu/ Nwlg== X-Gm-Message-State: APjAAAXMOaPoFQhjGycwlV0zmkjDSQXn3zxwUwgvGCXRzZ2LeumBR8HI LxLd/HrCJaCRuUt8Csp9M9ipQZfQ86I+uSXupD8XfQ== X-Google-Smtp-Source: APXvYqxl6FUWzhNJmV/twRIMg5J5dk1jL54DHL5eRqSLGaUjuAJZJFHphqKMrxpAOmdnSQ0pZAWlWkDR4Yx7NICACVk= X-Received: by 2002:a1c:9695:: with SMTP id y143mr1119738wmd.103.1571720874948; Mon, 21 Oct 2019 22:07:54 -0700 (PDT) MIME-Version: 1.0 References: <20191016160649.24622-1-anup.patel@wdc.com> <20191016160649.24622-21-anup.patel@wdc.com> <1d2e9514-235e-183e-b4fc-d3becc9ce471@redhat.com> In-Reply-To: <1d2e9514-235e-183e-b4fc-d3becc9ce471@redhat.com> From: Anup Patel Date: Tue, 22 Oct 2019 10:37:43 +0530 Message-ID: Subject: Re: [PATCH v9 20/22] RISC-V: KVM: Fix race-condition in kvm_riscv_vcpu_sync_interrupts() To: Paolo Bonzini Cc: Anup Patel , Palmer Dabbelt , Paul Walmsley , Radim K , Daniel Lezcano , Thomas Gleixner , Alexander Graf , Atish Patra , Alistair Francis , Damien Le Moal , Christoph Hellwig , "kvm@vger.kernel.org" , "linux-riscv@lists.infradead.org" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, Oct 21, 2019 at 10:57 PM Paolo Bonzini wrote: > > On 16/10/19 18:12, Anup Patel wrote: > > + /* Read current VSIP and VSIE CSRs */ > > + vsip = csr_read(CSR_VSIP); > > + csr->vsie = csr_read(CSR_VSIE); > > + > > + /* Sync-up VSIP.SSIP bit changes does by Guest */ > > + if ((csr->vsip ^ vsip) & (1UL << IRQ_S_SOFT)) { > > + if (!test_and_set_bit(IRQ_S_SOFT, &v->irqs_pending_mask)) { > > + if (vsip & (1UL << IRQ_S_SOFT)) > > + set_bit(IRQ_S_SOFT, &v->irqs_pending); > > + else > > + clear_bit(IRQ_S_SOFT, &v->irqs_pending); > > + } > > Looks good, but I wonder if this could just be "csr->vsip = > csr_read(CSR_VSIP)", which will be fixed up by flush_interrupts on the > next entry. It's not just "csr->vsip = csr_read(CSR_VSIP" because "irqs_pending" bitmap has to be in-sync with Guest updates to VSIP because WFI trap-n-emulate will check for pending interrupts which in-turn checks "irqs_pending" bitmap. Regards, Anup