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=-13.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 D28ACC433DB for ; Tue, 16 Mar 2021 18:10:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 91BFB65108 for ; Tue, 16 Mar 2021 18:10:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239932AbhCPSJv (ORCPT ); Tue, 16 Mar 2021 14:09:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43174 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239906AbhCPSIl (ORCPT ); Tue, 16 Mar 2021 14:08:41 -0400 Received: from mail-pj1-x1035.google.com (mail-pj1-x1035.google.com [IPv6:2607:f8b0:4864:20::1035]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B100EC061756 for ; Tue, 16 Mar 2021 11:08:41 -0700 (PDT) Received: by mail-pj1-x1035.google.com with SMTP id j6-20020a17090adc86b02900cbfe6f2c96so1873937pjv.1 for ; Tue, 16 Mar 2021 11:08:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=tZy3IUpWZ7t7bh+2zyTwr3sKql3tBpCeQ+1BYTDB4w4=; b=NC/9oMaY8Rm9otFHqcm+jKoqM1GFXaA57RIG4D7TGgW0Ynol3+8lZ1Cz/YPTNl4cn3 dR/GEOex4IJjjQRY3RNtZvhvCphxtHn7mf6HKKUmRNbkc6fUYrpiIhbpet4PaMVEzO0D uXcU+BxuI6FL+rQmCSAuks1hs726ONtkvPWmNdHJTTa3xlO+tvERAh0m8t/e+/AZE5xU Keq53AMaBAqnmLJGDMVWRTfBApKjjLuBtFjTxEJhjC9Njqw7fKZV0d4lnxr0juNjWQW4 UlNX1J56TTSeoS2PLI/sv7TpdmRtNm/SOFdqPVY6o67cnU6F1ycD+5R8nADZHeUY7S3C kLCw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=tZy3IUpWZ7t7bh+2zyTwr3sKql3tBpCeQ+1BYTDB4w4=; b=kUPSSl8zsCw4izHneUEjkEo1xVE8p/f4cSINvc40oyrtRTCn5y5FZuWznYkVy2jQNL vHNVql5tHgGL/96wivEsRSsrgNj3D/IFExz41hNBEEGSlq01j3nTfsMovmyn0zsuay+X IUDSWrDDMYCH2uAZr6wnfheIBz3XKts/bvGrkwMFaap/wFpEfLtEclP+1n+iqvi8vWEu +3ET5s+pGCUMzefvM+7jq6TWrF9WQhuk2kHOsCO3YKlupONSiAbTnnzgSBzJ7GrwZPP/ ircOsz/EGg52EaUHvA/R6Ithd8TDfvL6359cN6gr7BmCxT83b3Xma7nAvBjHTMYP4o1P 8iNg== X-Gm-Message-State: AOAM532yxZxVMSY8XKkJydXqr0KMj4+v3mKPvz3KKcGlmz3MYbcy8pQH dnRv4LLvI/OTqrY4YbGIHwVp7w== X-Google-Smtp-Source: ABdhPJzp/t6b5YlCZLrR8WKN0/mxohDZtV728KX/QgOYC7i3LcivZg84bV6/Bihm8sRwIDS6odBvAA== X-Received: by 2002:a17:903:18a:b029:e6:7fc1:1c2a with SMTP id z10-20020a170903018ab02900e67fc11c2amr705916plg.5.1615918121046; Tue, 16 Mar 2021 11:08:41 -0700 (PDT) Received: from google.com ([2620:15c:f:10:e113:95c2:2d1:e304]) by smtp.gmail.com with ESMTPSA id 205sm12606570pfc.201.2021.03.16.11.08.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 16 Mar 2021 11:08:40 -0700 (PDT) Date: Tue, 16 Mar 2021 11:08:34 -0700 From: Sean Christopherson To: Paolo Bonzini Cc: Nathan Tempelman , Thomas Lendacky , x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Steve Rutherford , David Rientjes , Brijesh Singh , Ashish Kalra Subject: Re: [RFC] KVM: x86: Support KVM VMs sharing SEV context Message-ID: References: <20210224085915.28751-1-natet@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, Mar 16, 2021, Paolo Bonzini wrote: > On 16/03/21 18:52, Sean Christopherson wrote: > > > I don't > > > know that holding the fd instead of the kvm makes that much better though, > > > are there advantages to that I'm not seeing? > > If there's no kvm pointer, it's much more difficult for someone to do the wrong > > thing, and any such shenanigans stick out like a sore thumb in patches, which > > makes reviewing future changes easier. > > On the other hand holding the fd open complicates the code, reference > counting rules are already hard enough. How so? KVM already has to do "fget(source_kvm)", can't we just hold onto to that instead of doing an additional kvm_get_kvm()?