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[156.151.31.86]) by mx.google.com with ESMTPS id bf1si176325plb.49.2019.05.14.00.58.02 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 14 May 2019 00:58:03 -0700 (PDT) Received-SPF: pass (google.com: domain of liran.alon@oracle.com designates 156.151.31.86 as permitted sender) client-ip=156.151.31.86; Authentication-Results: mx.google.com; dkim=pass header.i=@oracle.com header.s=corp-2018-07-02 header.b=Cxu0Rbtn; spf=pass (google.com: domain of liran.alon@oracle.com designates 156.151.31.86 as permitted sender) smtp.mailfrom=liran.alon@oracle.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=oracle.com Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x4E7rWLj013371; Tue, 14 May 2019 07:57:44 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=content-type : mime-version : subject : from : in-reply-to : date : cc : content-transfer-encoding : message-id : references : to; s=corp-2018-07-02; bh=Hm9Tm5LOAz3Yewu8iIsMrN/PygszNEAXdNiSHUZXasc=; b=Cxu0RbtnDfFw0XdHX1a2nnhh6Murm5HeXI3uwUQKENUOiWgCk+Uad2iC/dmeOx92QJ4c ArOiWnnJX0B4nK1vHuAdNSDrIwvsD3/DLRNjc+AfrPwlVG7eY1cpq+mQpPHLqKkSXGZM s3Zzb+PcTUXnnJoR0u5Vu0UtNpHoH2qD/++5S7CaEEHgYj+WZhVYhg7kpQ5gqvdiE6l6 XxxsU8vhbvd8ChVXIr9Z9SYgOwqyAb6FiFlf+ykIotOkitY7klVomllhLJliLaJ/O8Ws 0PBgos6GaN0Wt4URNQU2Md4SGAZ5MlFC+MM9fI6bw4HS4Mi0ylZzQx9Igug9XTnyytC3 7g== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by userp2130.oracle.com with ESMTP id 2sdnttm1k1-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 14 May 2019 07:57:44 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x4E7vHQ8144326; Tue, 14 May 2019 07:57:43 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserp3030.oracle.com with ESMTP id 2sdmeax9ua-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 14 May 2019 07:57:43 +0000 Received: from abhmp0001.oracle.com (abhmp0001.oracle.com [141.146.116.7]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x4E7vZFf007379; Tue, 14 May 2019 07:57:37 GMT Received: from [10.0.5.57] (/213.57.127.10) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 14 May 2019 07:57:35 +0000 Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 11.1 \(3445.4.7\)) Subject: Re: [RFC KVM 00/27] KVM Address Space Isolation From: Liran Alon In-Reply-To: <20190514072941.GG2589@hirez.programming.kicks-ass.net> Date: Tue, 14 May 2019 10:57:29 +0300 Cc: Andy Lutomirski , Alexandre Chartre , Paolo Bonzini , Radim Krcmar , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Dave Hansen , kvm list , X86 ML , Linux-MM , LKML , Konrad Rzeszutek Wilk , jan.setjeeilers@oracle.com, Jonathan Adams Content-Transfer-Encoding: quoted-printable Message-Id: References: <1557758315-12667-1-git-send-email-alexandre.chartre@oracle.com> <20190514072941.GG2589@hirez.programming.kicks-ass.net> To: Peter Zijlstra X-Mailer: Apple Mail (2.3445.4.7) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9256 signatures=668686 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1905140058 X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9256 signatures=668686 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1905140058 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > On 14 May 2019, at 10:29, Peter Zijlstra wrote: >=20 >=20 > (please, wrap our emails at 78 chars) >=20 > On Tue, May 14, 2019 at 12:08:23AM +0300, Liran Alon wrote: >=20 >> 3) =46rom (2), we should have theoretically deduced that for every >> #VMExit, there is a need to kick the sibling hyperthread also outside >> of guest until the #VMExit is completed. >=20 > That's not in fact quite true; all you have to do is send the IPI. > Having one sibling IPI the other sibling carries enough guarantees = that > the receiving sibling will not execute any further guest instructions. >=20 > That is, you don't have to wait on the VMExit to complete; you can = just > IPI and get on with things. Now, this is still expensive, But it is > heaps better than doing a full sync up between siblings. >=20 I agree. I didn=E2=80=99t say you need to do full sync. You just need to IPI the = sibling hyperthreads before switching to the full kernel address space. But you need to make sure these sibling hyperthreads don=E2=80=99t get = back into the guest until all hyperthreads are running with KVM isolated address = space. It is still very expensive if done for every #VMExit. Which as I = explained, can be avoided in case we use the KVM isolated address space technique. -Liran