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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 8C9F4C433FF for ; Tue, 30 Jul 2019 14:02:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6C65420693 for ; Tue, 30 Jul 2019 14:02:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729627AbfG3OCN (ORCPT ); Tue, 30 Jul 2019 10:02:13 -0400 Received: from mail-wr1-f67.google.com ([209.85.221.67]:34276 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727787AbfG3OCN (ORCPT ); Tue, 30 Jul 2019 10:02:13 -0400 Received: by mail-wr1-f67.google.com with SMTP id 31so65951870wrm.1 for ; Tue, 30 Jul 2019 07:02:11 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:openpgp:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=9EuouZv6KkAfnXeYgN1dDIcC6u4TgIuceUgUlR6uEAU=; b=o24DdnahCk5rNUu6hAPBD6N/AzUSPSGgKfw9ekav/9534QWChmyfcxWRLi89WvNL6h dUjvYyOsiIV4sDQHCBLvuqNwPEEjMPwy9RzIec5ui7J2QuPEU1wepJ5GeEW/9SqUduVJ Nktj9IcvuXG89oKfpzbXQkpuN0og3vxYpBSkPgHymlNKAMqq+T5KaS4i0NrZ2OfSMftG RngeoRvV3q5yvJYcoWJlU6QOp14xOd06EAVXegDw3S/ErJOj6ax/wAY3D6KHdYKxsWlb Kk9naqbJT8HFeo+QOuOjMNrZ644o1pP+P4Rwv85iyJtUFC0Pcp2A5XJeut8PA9xneH8V h4gQ== X-Gm-Message-State: APjAAAXalIYfseV5zu6NRFzGovyX+sYGoYVpTT5m/bZBsvR9OlR970+j sv254bnsgOwDLJx5PS6dn865/8EelGk= X-Google-Smtp-Source: APXvYqz444q5M6LOXoHcyZ0+5NhLAV2GC/dilLeCMRigSflzkicbG33/VTK0UCpeR27ntA61CsOd8w== X-Received: by 2002:a5d:518d:: with SMTP id k13mr32991874wrv.40.1564495330668; Tue, 30 Jul 2019 07:02:10 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:29d3:6123:6d5f:2c04? ([2001:b07:6468:f312:29d3:6123:6d5f:2c04]) by smtp.gmail.com with ESMTPSA id j17sm107585902wrb.35.2019.07.30.07.02.09 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Tue, 30 Jul 2019 07:02:09 -0700 (PDT) Subject: Re: [RFC PATCH 00/16] KVM RISC-V Support To: Anup Patel Cc: Anup Patel , Palmer Dabbelt , Paul Walmsley , Radim K , Daniel Lezcano , Thomas Gleixner , Atish Patra , Alistair Francis , Damien Le Moal , Christoph Hellwig , "kvm@vger.kernel.org" , "linux-riscv@lists.infradead.org" , "linux-kernel@vger.kernel.org" References: <20190729115544.17895-1-anup.patel@wdc.com> <72e9f668-f496-3fca-a1a8-a3c3122a3fd9@redhat.com> <965cffdb-86e2-b422-9c23-345c7100fd88@redhat.com> From: Paolo Bonzini Openpgp: preference=signencrypt Message-ID: Date: Tue, 30 Jul 2019 16:02:08 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 30/07/19 15:50, Anup Patel wrote: >> BTW, since IPIs are handled in the SBI I wouldn't bother with in-kernel >> PLIC emulation unless you can demonstrate performance improvements (for >> example due to irqfd). In fact, it may be more interesting to add > > I thought VHOST requires irqfd and we would certainly endup providing > in-kernel PLIC emulation to support VHOST. vhost only needs an eventfd, userspace can poll the eventfd and inject the irq as usual with KVM_INTERRUPT. Of course that can be slower, but you can benchmark it and see if it's indeed a good reason for in-kernel PLIC. >> plumbing for userspace handling of selected SBI calls (in addition to >> get/putchar, sbi_system_reset and sbi_hart_down look like good >> candidates in SBI v0.2). > > The get/putchar SBI v0.1 calls won't be encouraged going forward because > we already have earlycon implmentation in-place and Guest kernel can directly > write to UART registers for earlyprints. > If we still wanted to implement get/putchar calls then we would need a RISC-V > specific exit reason in KVM. We have tried to avoid RISC-V specific IOCTLs > or exit reason in this series. Sounds good. Paolo >> >>> We were thinking to keep KVM RISC-V disabled by default (i.e. keep it >>> experimental) until we have validated it on some FPGA or real HW. For now, >>> users can explicitly enable it and play-around on QEMU emulation. I hope >>> this is fine with most people ? >> >> That's certainly okay with me. >> > > Thanks, > Anup > 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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 908B5C433FF for ; Tue, 30 Jul 2019 14:02:16 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 6683020693 for ; Tue, 30 Jul 2019 14:02:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="N38FCyx8" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6683020693 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-riscv-bounces+infradead-linux-riscv=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=41TfmMdlNl/JQiuDG9+MF178MDQz6LdGQFmJLHt+oIs=; b=N38FCyx8lQzmG1 viza2LwxW5bqO26hquh1D2aWLwI0MSqkMO2LNGFbAZ7Rub49jUukaTcBkEy6DKwasP5nS8cXh36f+ WXGjVzLUMw+3n7xAmR7FFZA5d/pbKgAQvsVvByAl5D60uhdzkpecczw11QSjYzcpEiuhmoAnpj20j Ja/x3R1NMhMcbj01vvpfTEd9IzRAzIT4RUZRw9Zj2WigmlfhF73xQO6NRt0iHsssJYlSJXBhc7LXj Y490wrUuEyG6RWY5D7GT1l8UR3KaPW+SJfkb7i1AD7WPikycOrInW0Y9acoo/02HqWRfbqdlNEoEX FK2YWpvE1/VDW3i6u2pQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hsShj-0003GJ-6D; Tue, 30 Jul 2019 14:02:15 +0000 Received: from mail-wr1-f66.google.com ([209.85.221.66]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1hsShg-0003Fn-4P for linux-riscv@lists.infradead.org; Tue, 30 Jul 2019 14:02:13 +0000 Received: by mail-wr1-f66.google.com with SMTP id n9so66021063wru.0 for ; Tue, 30 Jul 2019 07:02:11 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:openpgp:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=9EuouZv6KkAfnXeYgN1dDIcC6u4TgIuceUgUlR6uEAU=; b=ZPh5HOjuTPo+NKEJkJrkrETvuAlMAx6RTTFBgZx0MRk8kej5ndfeJd9Jvs0TohVjEL D52z9HLWyzNmMKMF1lNx/8JUsRCP9E0oGnFc2E6OPpcBSTXsxJvmSds0ciV7iKxTe1T+ gP+wxr6d/PCT4wyLcCYAW7HM7CEIXrD6/LiUbmloDFIch9k1itEeIBfME2fU+cd2sqlF h7U6mizbXPlkNIfaxqYhrLDOi1x9MCo0qTHnkX6R6Wzz7ZmpdIm3+zJuVjBkMZMRuIjA 15Rnnch7BeUXWEfFvp6TAzfxFnN6q2Goqb84r1boiZi3IIvTRSulMq+KekzpDZeGr7tl QVog== X-Gm-Message-State: APjAAAVmW7fVEe9Hm6YtmMK5XkRmbL3Pw/nE/hW5PLes6ZhAbRnNwe1m LwWswPTYS6PpIua7uTO/0/cN6A== X-Google-Smtp-Source: APXvYqz444q5M6LOXoHcyZ0+5NhLAV2GC/dilLeCMRigSflzkicbG33/VTK0UCpeR27ntA61CsOd8w== X-Received: by 2002:a5d:518d:: with SMTP id k13mr32991874wrv.40.1564495330668; Tue, 30 Jul 2019 07:02:10 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:29d3:6123:6d5f:2c04? ([2001:b07:6468:f312:29d3:6123:6d5f:2c04]) by smtp.gmail.com with ESMTPSA id j17sm107585902wrb.35.2019.07.30.07.02.09 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Tue, 30 Jul 2019 07:02:09 -0700 (PDT) Subject: Re: [RFC PATCH 00/16] KVM RISC-V Support To: Anup Patel References: <20190729115544.17895-1-anup.patel@wdc.com> <72e9f668-f496-3fca-a1a8-a3c3122a3fd9@redhat.com> <965cffdb-86e2-b422-9c23-345c7100fd88@redhat.com> From: Paolo Bonzini Openpgp: preference=signencrypt Message-ID: Date: Tue, 30 Jul 2019 16:02:08 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190730_070212_177113_3EA1D81C X-CRM114-Status: GOOD ( 15.05 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Damien Le Moal , Palmer Dabbelt , Daniel Lezcano , "kvm@vger.kernel.org" , Radim K , Anup Patel , "linux-kernel@vger.kernel.org" , Christoph Hellwig , Atish Patra , Alistair Francis , Paul Walmsley , Thomas Gleixner , "linux-riscv@lists.infradead.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+infradead-linux-riscv=archiver.kernel.org@lists.infradead.org On 30/07/19 15:50, Anup Patel wrote: >> BTW, since IPIs are handled in the SBI I wouldn't bother with in-kernel >> PLIC emulation unless you can demonstrate performance improvements (for >> example due to irqfd). In fact, it may be more interesting to add > > I thought VHOST requires irqfd and we would certainly endup providing > in-kernel PLIC emulation to support VHOST. vhost only needs an eventfd, userspace can poll the eventfd and inject the irq as usual with KVM_INTERRUPT. Of course that can be slower, but you can benchmark it and see if it's indeed a good reason for in-kernel PLIC. >> plumbing for userspace handling of selected SBI calls (in addition to >> get/putchar, sbi_system_reset and sbi_hart_down look like good >> candidates in SBI v0.2). > > The get/putchar SBI v0.1 calls won't be encouraged going forward because > we already have earlycon implmentation in-place and Guest kernel can directly > write to UART registers for earlyprints. > If we still wanted to implement get/putchar calls then we would need a RISC-V > specific exit reason in KVM. We have tried to avoid RISC-V specific IOCTLs > or exit reason in this series. Sounds good. Paolo >> >>> We were thinking to keep KVM RISC-V disabled by default (i.e. keep it >>> experimental) until we have validated it on some FPGA or real HW. For now, >>> users can explicitly enable it and play-around on QEMU emulation. I hope >>> this is fine with most people ? >> >> That's certainly okay with me. >> > > Thanks, > Anup > _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv