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 A6797C433FF for ; Fri, 2 Aug 2019 09:03:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 87AA22173E for ; Fri, 2 Aug 2019 09:03:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404597AbfHBJDs (ORCPT ); Fri, 2 Aug 2019 05:03:48 -0400 Received: from mail-wr1-f68.google.com ([209.85.221.68]:44827 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732895AbfHBJDr (ORCPT ); Fri, 2 Aug 2019 05:03:47 -0400 Received: by mail-wr1-f68.google.com with SMTP id p17so76349774wrf.11 for ; Fri, 02 Aug 2019 02:03:46 -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=Bwx8/3+omec7zmijOtKif9DQxXapLJoupah+QfmoXjM=; b=N/AEu3hBPLdL4vg9tsSS6KikLBHJQE5kO6krW1gVc4kMOsZkFwErVX8M86CpocgWSx TBD+zEaz/w9+zmaj+jGmGMJc6yB90sQ96L6sFAmN32XmkrFAN/AZLmqCifZd9FjxyIAH j5Ogm/MeGKQCqmju/FARRtMRiOcABjXOzJ7oZtkYzoVp+YZzM4PMoCqYd6fG+RIQlT3N /3WiP8LoQct+bjvn+LKOwOH2EYTaL3pElAxwKV/3asgtTAXiElq5EsPZMw2KB08ORYW8 39CVXYp75VAeHI64/yTWUXMvu1N4Ez8v/D3+IPoZkDYpJ7AptQdXoA0wrUfT/06oJrAg gtiQ== X-Gm-Message-State: APjAAAVfOlhJlPGELxR29b+tjBhdwj1VgzCVf4ASne7tpgYrdnu8CJY2 JeIxSqH9XbBpzaP4XSe6xHnTTw== X-Google-Smtp-Source: APXvYqzL/HKYIOOtRRO6u1IKHQOTKAtJRMqcFBTlwICbd/6fS4zdHbTSm6by+RvwTllnE7+5D6q80Q== X-Received: by 2002:a5d:4e02:: with SMTP id p2mr36191018wrt.182.1564736625330; Fri, 02 Aug 2019 02:03:45 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:4013:e920:9388:c3ff? ([2001:b07:6468:f312:4013:e920:9388:c3ff]) by smtp.gmail.com with ESMTPSA id c30sm140911490wrb.15.2019.08.02.02.03.44 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Fri, 02 Aug 2019 02:03:44 -0700 (PDT) Subject: Re: [RFC PATCH v2 07/19] RISC-V: KVM: Implement KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls To: Anup Patel , Palmer Dabbelt , Paul Walmsley , Radim K Cc: Daniel Lezcano , Thomas Gleixner , Atish Patra , Alistair Francis , Damien Le Moal , Christoph Hellwig , Anup Patel , "kvm@vger.kernel.org" , "linux-riscv@lists.infradead.org" , "linux-kernel@vger.kernel.org" References: <20190802074620.115029-1-anup.patel@wdc.com> <20190802074620.115029-8-anup.patel@wdc.com> From: Paolo Bonzini Openpgp: preference=signencrypt Message-ID: <03f60f3a-bb50-9210-8352-da16cca322b9@redhat.com> Date: Fri, 2 Aug 2019 11:03:45 +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: <20190802074620.115029-8-anup.patel@wdc.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 02/08/19 09:47, Anup Patel wrote: > + if (reg_num == KVM_REG_RISCV_CSR_REG(sip)) > + kvm_riscv_vcpu_flush_interrupts(vcpu, false); Not updating the vsip CSR here can cause an interrupt to be lost, if the next call to kvm_riscv_vcpu_flush_interrupts finds a zero mask. You could add a new field vcpu->vsip_shadow that is updated every time CSR_VSIP is written (including kvm_arch_vcpu_load) with a function like void kvm_riscv_update_vsip(struct kvm_vcpu *vcpu) { if (vcpu->vsip_shadow != vcpu->arch.guest_csr.vsip) { csr_write(CSR_VSIP, vcpu->arch.guest_csr.vsip); vcpu->vsip_shadow = vcpu->arch.guest_csr.vsip; } } And just call this unconditionally from kvm_vcpu_ioctl_run. The cost is just a memory load per VS-mode entry, it should hardly be measurable. Paolo