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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C2AD2ECAA25 for ; Thu, 25 Aug 2022 16:20:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243014AbiHYQUI (ORCPT ); Thu, 25 Aug 2022 12:20:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40024 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243023AbiHYQUD (ORCPT ); Thu, 25 Aug 2022 12:20:03 -0400 Received: from mail-pg1-x52f.google.com (mail-pg1-x52f.google.com [IPv6:2607:f8b0:4864:20::52f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3CD1DBCBF for ; Thu, 25 Aug 2022 09:20:01 -0700 (PDT) Received: by mail-pg1-x52f.google.com with SMTP id q63so4080864pga.9 for ; Thu, 25 Aug 2022 09:20:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc; bh=WAj0AHoiwnkmFJmmfno3NergegJGg1EwrtdnvbOAI9o=; b=a5lj54YXr+P5Qzt2j9UpZH3fRt8z3UbyRuIuMJCb8+0NjkeROBRHnn/SsP6sy3BW86 CR+5GOL6/1GL0MBSUdpOQec4+jDUd6UBi1wH/VIHfGhGsl5/EVmEStjzf3a5W6dS/kr5 P+2mKmMPBtgQc2aX4x+DQz1GoMkA1/eJkGsnURjxGdPdxY9eVo6loMDIXiPu3+Q7loLM oovo7rYFIyhFK4YE7SVemYrKViXvSSgZUAV6PkVBQja59EvX4lKjNSTVdj/LJe0lQPhD 5zmb288RbHTZvpuiBNK4OJJ2+cYailmAl8XSF+goSukeFWn2PwxU/mYfc+wTcI01NlW0 EVHw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc; bh=WAj0AHoiwnkmFJmmfno3NergegJGg1EwrtdnvbOAI9o=; b=KToi+CK0iBrLyNtOtVVKBVk6/nNq6v+bqIXoWYkm3qHJOa8k7yrbxPqJ8XIEFsTGkk tae18BTCkHH24OuUGSMD9uFE7hDuEroX0lxm7jpD5xbdUgpN3pTFUHP71Byt5tkITIAw oj6X86/aalf6DUIhi1l9ombUv9IcvMgeuwHoqQbJvQL7OyYzYbDc6dOaVkgUSy6Fg/ml WkzcPLAFlqOrTvYs/6tqkQL50ZYmyuCvfgiAGnNZ3m3B9vli4zxR3QHU+KqeuZBsj8Fo dvJZQhbOgnHklSNq2iDKtK0ZGkwDEQIyRKn9pIYeuyFCtUJEtUk0TnMR+a/akMAOR2sQ Qpwg== X-Gm-Message-State: ACgBeo3jN4/mnLe9IbacmxPYxerZ3bdhFiZno6KVerC/0pzDpqvGIy/Q nuOETvBVjjfw8iUq/jR1wPu9Cw== X-Google-Smtp-Source: AA6agR63kTdxJt3IwFH3SprzjdLCpiJhtIgy3SaxUDsr7aKI7q57qkSrsP8Tke9HSTXe5G5SJzo4BQ== X-Received: by 2002:a63:1725:0:b0:42b:4300:358 with SMTP id x37-20020a631725000000b0042b43000358mr3915004pgl.536.1661444400571; Thu, 25 Aug 2022 09:20:00 -0700 (PDT) Received: from google.com (7.104.168.34.bc.googleusercontent.com. [34.168.104.7]) by smtp.gmail.com with ESMTPSA id d62-20020a623641000000b0052d2cd99490sm15388101pfa.5.2022.08.25.09.19.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 25 Aug 2022 09:20:00 -0700 (PDT) Date: Thu, 25 Aug 2022 16:19:56 +0000 From: Sean Christopherson To: "Chang S. Bae" Cc: kvm@vger.kernel.org, pbonzini@redhat.com, linux-kernel@vger.kernel.org, yang.zhong@intel.com Subject: Re: [RFC PATCH 1/2] KVM: x86: Add a new system attribute for dynamic XSTATE component Message-ID: References: <20220823231402.7839-1-chang.seok.bae@intel.com> <20220823231402.7839-2-chang.seok.bae@intel.com> <08e59f2d-24cb-dca8-b1b8-9e80f8a85398@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <08e59f2d-24cb-dca8-b1b8-9e80f8a85398@intel.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, Aug 24, 2022, Chang S. Bae wrote: > On 8/24/2022 2:42 PM, Sean Christopherson wrote: > Maybe this is a policy decision. I don't think that > ARCH_REQ_XCOMP_GUEST_PERM goes away with this. Userspace may still use the > arch_prctl() set. But then it makes more sense and consistent to use > ARCH_GET_XCOMP_SUPP in first place, instead of KVM_X86_XCOMP_GUEST_SUPP, no? KVM_X86_XCOMP_GUEST_SUPP is needed so that userspace understands what _KVM_ supports. > > If QEMU wants to assert that it didn't misconfigure itself, it can assert on the > > config in any number of ways, e.g. assert that ARCH_GET_XCOMP_GUEST_PERM is a > > subset of KVM_X86_XCOMP_GUEST_SUPP at the end of kvm_request_xsave_components(). > > Yes, but I guess the new attribute can make it simple. Adding new uAPI and new exports to eliminate one line of userspace code is not a good tradeoff. Am I missing something? This really seems like solution looking for a problem.