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=-15.8 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 autolearn=ham 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 B1E93C433B4 for ; Thu, 22 Apr 2021 10:49:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6D18B60720 for ; Thu, 22 Apr 2021 10:49:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235917AbhDVKuM (ORCPT ); Thu, 22 Apr 2021 06:50:12 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:25799 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235455AbhDVKuJ (ORCPT ); Thu, 22 Apr 2021 06:50:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1619088574; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=cepH4DVmZgMHRHW+WV87UBOsh4wAs3M6NCnks6Bbd8Y=; b=I98JjUVOdepGVuTw5k2kwn+qPVr3FMwUfKpN7sa/uylvEkb4Qguhh0AcrwEkB25qrKCtqy 3jhzFWYhqvfAtY7G2OTleD2xYq5R3uErlTMNMuCRzzWNUKDL+DGH3y/z3+SaJ2tUzIL8Kc g1lMhrBf4XRZKDLwzhrbOcssTErDNQQ= Received: from mail-ej1-f72.google.com (mail-ej1-f72.google.com [209.85.218.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-493-2bJXaFlmMfWEVmlwf5-fnw-1; Thu, 22 Apr 2021 06:49:32 -0400 X-MC-Unique: 2bJXaFlmMfWEVmlwf5-fnw-1 Received: by mail-ej1-f72.google.com with SMTP id k5-20020a1709061c05b029037cb8a99e03so7010452ejg.16 for ; Thu, 22 Apr 2021 03:49:32 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version; bh=cepH4DVmZgMHRHW+WV87UBOsh4wAs3M6NCnks6Bbd8Y=; b=R0CLLCpquj0bc9q1YH5V0UOgpvaJANTLrsg4mbV97WiVX20DejcrJsvkIveD0W500O BDDhFVm+NlupFWnGZg4iFz4Hok6gRc2/i41VMmmyDhoJqZaQIimx72KAXd9t/oslPZg6 XqQP97zXKYdeU06LYcHTDsD08GD07+tNuLdjHY99DE9zS7OdN7qgwK2GHfi8r5ylJz3d ATpeqHQ0xleHuhfzf59eNVbzABCGRlr8Kf/T1zEFB0SW9+JkxNiKYU4YiI6cgbGlbqq9 idegs43RDFn5Og2uyDfl530cvdgwv9v6WarqnUEedgA5Xv+3FNBXCnuU4XYSTqiHTK7i RmBg== X-Gm-Message-State: AOAM5319RRyFhIxUBoGhqCe15Xjplff0jruOWk6fWy6cwgnQFymZ2hsH tX8R1ZG57+8MmQOloRsk6CT/ljjdvLzbgg/v9IT6tBSSLx7CJF7NIM/rBgAF6T4Q6ndnJC9wODu KRYXq1MXfGHr+ X-Received: by 2002:aa7:d9ce:: with SMTP id v14mr3085679eds.110.1619088571579; Thu, 22 Apr 2021 03:49:31 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzLGo5TNn7MXo/voi472GduRwPJLEiKPNQM3olHulqQpsFAmVYDu4AmUn1ZFcytO2+nkGT0YQ== X-Received: by 2002:aa7:d9ce:: with SMTP id v14mr3085671eds.110.1619088571445; Thu, 22 Apr 2021 03:49:31 -0700 (PDT) Received: from vitty.brq.redhat.com (g-server-2.ign.cz. [91.219.240.2]) by smtp.gmail.com with ESMTPSA id n13sm1598355ejx.27.2021.04.22.03.49.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Apr 2021 03:49:31 -0700 (PDT) From: Vitaly Kuznetsov To: Paolo Bonzini , Sean Christopherson Cc: Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Babu Moger , Joao Martins , David Woodhouse Subject: Re: [PATCH v2 7/9] KVM: x86/xen: Drop RAX[63:32] when processing hypercall In-Reply-To: <2ddcc979-519c-a38c-065f-a9036cc2b58e@redhat.com> References: <20210422022128.3464144-1-seanjc@google.com> <20210422022128.3464144-8-seanjc@google.com> <877dkuhcl7.fsf@vitty.brq.redhat.com> <2ddcc979-519c-a38c-065f-a9036cc2b58e@redhat.com> Date: Thu, 22 Apr 2021 12:49:30 +0200 Message-ID: <874kfyh9vp.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Paolo Bonzini writes: > On 22/04/21 11:51, Vitaly Kuznetsov wrote: >> Sean Christopherson writes: >> >>> Truncate RAX to 32 bits, i.e. consume EAX, when retrieving the hypecall >>> index for a Xen hypercall. Per Xen documentation[*], the index is EAX >>> when the vCPU is not in 64-bit mode. >>> >>> [*] http://xenbits.xenproject.org/docs/sphinx-unstable/guest-guide/x86/hypercall-abi.html >>> >>> Fixes: 23200b7a30de ("KVM: x86/xen: intercept xen hypercalls if enabled") >>> Cc: Joao Martins >>> Cc: David Woodhouse >>> Cc: stable@vger.kernel.org >>> Signed-off-by: Sean Christopherson >>> --- >>> arch/x86/kvm/xen.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c >>> index ae17250e1efe..7f27bb65a572 100644 >>> --- a/arch/x86/kvm/xen.c >>> +++ b/arch/x86/kvm/xen.c >>> @@ -673,7 +673,7 @@ int kvm_xen_hypercall(struct kvm_vcpu *vcpu) >>> bool longmode; >>> u64 input, params[6]; >>> >>> - input = (u64)kvm_register_read(vcpu, VCPU_REGS_RAX); >>> + input = (u64)kvm_register_readl(vcpu, VCPU_REGS_RAX); >>> >>> /* Hyper-V hypercalls get bit 31 set in EAX */ >>> if ((input & 0x80000000) && >> >> Reviewed-by: Vitaly Kuznetsov >> >> Alternatively, as a minor optimization, you could've used '!longmode' >> check below, something like: >> >> diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c >> index ae17250e1efe..7df1498d3a41 100644 >> --- a/arch/x86/kvm/xen.c >> +++ b/arch/x86/kvm/xen.c >> @@ -682,6 +682,7 @@ int kvm_xen_hypercall(struct kvm_vcpu *vcpu) >> >> longmode = is_64_bit_mode(vcpu); >> if (!longmode) { >> + input = (u32)input; >> params[0] = (u32)kvm_rbx_read(vcpu); >> params[1] = (u32)kvm_rcx_read(vcpu); >> params[2] = (u32)kvm_rdx_read(vcpu); >> > > You haven't seen patch 9 yet. :) > True; suggestion dismissed :-) -- Vitaly