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 11EBFE7E65A for ; Tue, 26 Sep 2023 17:31:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233879AbjIZRcD (ORCPT ); Tue, 26 Sep 2023 13:32:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48116 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231659AbjIZRcC (ORCPT ); Tue, 26 Sep 2023 13:32:02 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 866CC10A for ; Tue, 26 Sep 2023 10:31:54 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id 3f1490d57ef6-d866d13c637so10657472276.3 for ; Tue, 26 Sep 2023 10:31:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1695749513; x=1696354313; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=XkOwjfTSaHY+m/Zl9b5fE1gcn9HuUtefVhZTX1+CRKM=; b=SmGBrNauuLEYP0AaOKRObj3Gcuwo3oeyPPyVYuvynGxEsRrIgk03qWG5oRBWYalrsS yBYVOrE+SR09JPwHikw4R/tPPh65SXs2qQd8+85sJMsMJMJucIU8dV9KnM40/i4aDB7q 4W+REDDFRLUsfOG4spcKjMvqfNaEEqd7Y6e5kYT7bi0f84Mexg+aHQraehsN6kT0SqiB +UpW1wL6QuKaOURdeZPc7ZxEiHw1eCVmQO0Qj4nSsmLSuiu6l7MGWh4z4qZSQnUnzfTX CR/UUH4hyYEIUG+m2PI6hST8d3TWnD/Nr0WEcbmz2OJLFhAzaC8Jn+h4TyOebijBEJ2i 4l6w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1695749513; x=1696354313; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=XkOwjfTSaHY+m/Zl9b5fE1gcn9HuUtefVhZTX1+CRKM=; b=pMsrWtIy5MQiSytXGGcnMQPHuubS9UH3LhCSTq2AXb86wcS/Re8YWdwuJltQ5DoC2D gAAFXkkS6EBz2gWxb8AMubzALxkq38R809AcouVOypCqzLlLtJXRUf6MBdklYFR8SLVK Rr6GHBjUzBfOT18JqNE+Wu2CET6Hi5iYv6OvtdQdqQRCxF2hY7AhpS0q/plfn+5u60uE EOg49WFiYS1fPoxOZ1o7OoNDKMhZBir9HGCJquuTMG/OPONlcbhILuzTAwa1aiRZXt8o T9F3vETDLeiVpMgDn9xjNPe9SyNNK4TdXEZyA2iRV41960sMBFvcRLOW2sZqv87o7Fiu gVrA== X-Gm-Message-State: AOJu0YyhZhG1br1op/Q3e2JnYB2tO+6v3xSS5qpK0ZVszrkQDVjOKZJv 01wbCEMN3HtcosQzvyK7jDO/l6DAhWE= X-Google-Smtp-Source: AGHT+IExq3tjwerjS6HeYq1RGLysSQci3pAH4clVrhj0LxExcmC9lW1kAbBZp0UEI75+zMH0OFY5ZyUXqVo= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a25:ec0c:0:b0:d7e:b82a:ef68 with SMTP id j12-20020a25ec0c000000b00d7eb82aef68mr112052ybh.3.1695749513702; Tue, 26 Sep 2023 10:31:53 -0700 (PDT) Date: Tue, 26 Sep 2023 10:31:51 -0700 In-Reply-To: Mime-Version: 1.0 References: <20230914010003.358162-1-tstachecki@bloomberg.net> <93592292-ab7e-71ac-dd72-74cc76e97c74@oracle.com> Message-ID: Subject: Re: [PATCH] x86/kvm: Account for fpstate->user_xfeatures changes From: Sean Christopherson To: Tyler Stachecki Cc: Leonardo Bras , Dongli Zhang , kvm@vger.kernel.org, pbonzini@redhat.com, dgilbert@redhat.com, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, bp@alien8.de, Tyler Stachecki , stable@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Tue, Sep 26, 2023, Sean Christopherson wrote: > Masking fpstate->user_xfeatures is buggy for another reason: it's destructive if > userspace calls KVM_SET_CPUID multiple times. No real world userspace actually > calls KVM_SET_CPUID to "expand" features, but it's technically possible and KVM > is supposed to allow it. This particular bit is wrong, KVM overwrites user_xfeatures, it doesn't AND it. I misremembered the code.