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 1190EC46CA1 for ; Mon, 18 Sep 2023 12:01:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241688AbjIRMBK (ORCPT ); Mon, 18 Sep 2023 08:01:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34760 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241895AbjIRMA4 (ORCPT ); Mon, 18 Sep 2023 08:00:56 -0400 Received: from smtp-fw-80009.amazon.com (smtp-fw-80009.amazon.com [99.78.197.220]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B6D64DE; Mon, 18 Sep 2023 04:59:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.de; i=@amazon.de; q=dns/txt; s=amazon201209; t=1695038398; x=1726574398; h=message-id:date:mime-version:to:cc:references:from: in-reply-to:content-transfer-encoding:subject; bh=eG1C2BVfgTVepLC8sSyqp0SwuaWBXylv0y093IGXnjg=; b=TA/qFGuc7dCF5wMPiQGsqwunvKi3A24nQ3fGyvNir3hu4wsaIVDueQ6x NuRUPs6CCeNjHlEPLt6yg+4ZznhTJH1dGDWWv+onXMEzlXf0pxFiWFCdI xGVJq9vut3EUWz3Lvd5jv5hG5Ck1/haUpFnGM8xBJFBhSrJLtH6a/++V5 Y=; X-IronPort-AV: E=Sophos;i="6.02,156,1688428800"; d="scan'208";a="29601258" Subject: Re: [RFC] KVM: x86: Allow userspace exit on HLT and MWAIT, else yield on MWAIT Received: from pdx4-co-svc-p1-lb2-vlan2.amazon.com (HELO email-inbound-relay-pdx-2c-m6i4x-8c5b1df3.us-west-2.amazon.com) ([10.25.36.210]) by smtp-border-fw-80009.pdx80.corp.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Sep 2023 11:59:56 +0000 Received: from EX19MTAUWA002.ant.amazon.com (pdx1-ws-svc-p6-lb9-vlan2.pdx.amazon.com [10.236.137.194]) by email-inbound-relay-pdx-2c-m6i4x-8c5b1df3.us-west-2.amazon.com (Postfix) with ESMTPS id A557840D69; Mon, 18 Sep 2023 11:59:55 +0000 (UTC) Received: from EX19D020UWC004.ant.amazon.com (10.13.138.149) by EX19MTAUWA002.ant.amazon.com (10.250.64.202) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.37; Mon, 18 Sep 2023 11:59:55 +0000 Received: from [0.0.0.0] (10.253.83.51) by EX19D020UWC004.ant.amazon.com (10.13.138.149) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.37; Mon, 18 Sep 2023 11:59:52 +0000 Message-ID: Date: Mon, 18 Sep 2023 13:59:50 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Content-Language: en-GB To: David Woodhouse , , "Peter Zijlstra" CC: Sean Christopherson , Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , , "H. Peter Anvin" , , Nicolas Saenz Julienne , "Griffoul, Fred" References: <1b52b557beb6606007f7ec5672eab0adf1606a34.camel@infradead.org> <63b382bf-d1fb-464f-ab06-4185f796a85f@amazon.de> From: Alexander Graf In-Reply-To: X-Originating-IP: [10.253.83.51] X-ClientProxiedBy: EX19D046UWB001.ant.amazon.com (10.13.139.187) To EX19D020UWC004.ant.amazon.com (10.13.138.149) Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Transfer-Encoding: base64 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ck9uIDE4LjA5LjIzIDEzOjEwLCBEYXZpZCBXb29kaG91c2Ugd3JvdGU6Cj4gT24gTW9uLCAyMDIz LTA5LTE4IGF0IDExOjQxICswMjAwLCBBbGV4YW5kZXIgR3JhZiB3cm90ZToKPj4gSUlVQyB5b3Ug d2FudCB0byBkbyB3b3JrIGluIGEgdXNlciBzcGFjZSB2Q1BVIHRocmVhZCB3aGVuIHRoZSBndWVz dCB2Q1BVCj4+IGlzIGlkbGUuIEFzIHlvdSBwb2ludGVkIG91dCBhYm92ZSwgS1ZNIGNhbiBub3Qg YWN0dWFsbHkgZG8gbXVjaCBhYm91dAo+PiBNV0FJVDogSXQgYmFzaWNhbGx5IGJ1c3kgbG9vcHMg YW5kIGhvZ3MgdGhlIENQVS4KPiBXZWxsLi4gSSBzdXNwZWN0IHdoYXQgSSAqcmVhbGx5KiB3YW50 IGlzIGEgZGVjZW50IHdheSB0byBlbXVsYXRlIE1XQUlUCj4gcHJvcGVybHkgYW5kIGxldCBpdCBh Y3R1YWxseSBzbGVlcC4gT3IgZmFpbGluZyB0aGF0LCB0byBkZWNsYXJlIHRoYXQgd2UKPiBjYW4g YWN0dWFsbHkgY2hhbmdlIHRoZSBndWVzdC12aXNpYmxlIGV4cGVyaWVuY2Ugd2hlbiB0aG9zZSBn dWVzdHMgYXJlCj4gbWlncmF0ZWQgdG8gS1ZNLCBhbmQgdGFrZSBhd2F5IE1XQUlUIGNvbXBsZXRl bHkuCj4KPj4gVGhlIHR5cGljYWwgZmxvdyBJIHdvdWxkIGV4cGVjdCBmb3IgIndvcmsgaW4gYSB2 Q1BVIHRocmVhZCIgaXM6Cj4+Cj4+IDApIHZDUFUgcnVucy4gSExUL01XQUlUIGlzIGRpcmVjdGx5 IGV4cG9zZWQgdG8gZ3Vlc3QuCj4+IDEpIHZDUFUgZXhpdHMuIENyZWF0ZXMgZGVmZXJyZWQgd29y ay4gRW5hYmxlcyBITFQvTVdBSVQgdHJhcHBpbmcuCj4gVGhhdCBjYW4gaGFwcGVuLCBidXQgaXQg bWF5IGFsc28gYmUgYSBzZXBhcmF0ZSBJL08gdGhyZWFkIHdoaWNoCj4gcmVjZWl2ZXMgYW4gZXZl bnRmZCBub3RpZmljYXRpb24gYW5kIGZpbmRzIHRoYXQgdGhlcmUgaXMgbm93IHdvcmsgdG8gYmUK PiBkb25lLiBJZiB0aGF0IHdvcmsgY2FuIGJlIGZhaXJseSBtdWNoIGluc3RhbnRhbmVvdXMsIGl0 IGNhbiBiZSBkb25lCj4gaW1tZWRpYXRlbHkuIEVsc2UgaXQgZ2V0cyBkZWZlcnJlZCB0byB3aGF0 IHdlIExpbnV4IGhhY2tlcnMgbWlnaHQgdGhpbmsKPiBvZiBhcyBhIHdvcmtxdWV1ZS4KPgo+IElm IGFsbCB0aGUgdkNQVXMgYXJlIGluIEhMVCB3aGVuIHRoZSB3b3JrIHF1ZXVlIGJlY29tZXMgbm9u LWVtcHR5LCB3ZSdkCj4gbmVlZCB0byBwcm9kIHRoZW0gKmFsbCogdG8gY2hhbmdlIHRoZWlyIGV4 aXQtb24te0hMVCxNV0FJVH0gc3RhdHVzIHdoZW4KPiB3b3JrIGJlY29tZXMgYXZhaWxhYmxlLCBq dXN0IGluIGNhc2Ugb25lIG9mIHRoZW0gYmVjb21lcyBpZGxlIGFuZCBjYW4KPiBwcm9jZXNzIHRo ZSB3b3JrICJmb3IgZnJlZSIgdXNpbmcgaWRsZSBjeWNsZXMuCj4KPj4gMikgdkNQVSBydW5zIGFn YWluCj4+IDMpIHZDUFUgY2FsbHMgSExUL01XQUlULiBXZSBleGl0IHRvIHVzZXIgc3BhY2UgdG8g ZmluaXNoIHdvcmsgZnJvbSAxCj4+IDQpIHZDUFUgcnVucyBhZ2FpbiB3aXRob3V0IEhMVC9NV0FJ VCB0cmFwcGluZwo+Pgo+PiBUaGF0IG1lYW5zIG9uIHRvcCAob3IgaW5zdGVhZD8pIG9mIHRoZSBi aXRzIHlvdSBoYXZlIGJlbG93IHRoYXQgaW5kaWNhdGUKPj4gIlNob3VsZCBJIGV4aXQgdG8gdXNl ciBzcGFjZT8iLCB3aGF0IHlvdSByZWFsbHkgbmVlZCBhcmUgYml0cyB0aGF0IGRvCj4+IHdoYXQg ZW5hYmxlX2NhcChLVk1fQ0FQX1g4Nl9ESVNBQkxFX0VYSVRTKSBkb2VzIGluIGxpZ2h0LXdlaWdo dDogRGlzYWJsZQo+PiBITFQvTVdBSVQgdHJhcHBpbmcgdGVtcG9yYXJpbHkuCj4gSWYgSSBkbyBp dCB0aGF0IHdheSwgeWVzLiBBIGxpZ2h0d2VpZ2h0IHdheSB0byBlbmFibGUvZGlzYWJsZSB0aGUg ZXhpdHMKPiBldmVuIHRvIGtlcm5lbCB3b3VsZCBiZSBhIG5pY2UgdG8gaGF2ZS4gQnV0IGl0J3Mg YSB0cmFkZS1vZmYuIEZvciBITFQKPiB5b3UnZCBnZXQgbG93ZXIgbGF0ZW5jeSByZS1lbnRlcmlu ZyB0aGUgdkNQVSBhdCBhIGNvc3Qgb2YgbXVjaCBoaWdoZXIKPiBsYXRlbmN5IHByb2Nlc3Npbmcg d29yayBpZiB0aGUgdkNQVSB3YXMgKmFscmVhZHkqIGluIEhMVC4KPgo+IFdlIHByb2JhYmx5IHdv dWxkIHdhbnQgdG8gc3RvcCBidXJuaW5nIHBvd2VyIGluIHRoZSBNV0FJVCBsb29wIHRob3VnaCwK PiBhbmQgbGV0IHRoZSBwQ1BVIHNpdCBpbiB0aGUgZ3Vlc3QgaW4gTVdBSVQgaWYgdGhlcmUgcmVh bGx5IGlzIG5vdGhpbmcKPiBlbHNlIHRvIGRvLgo+Cj4gV2UncmUgZXhwZXJpbWVudGluZyB3aXRo IHZhcmlvdXMgcGVybXV0YXRpb25zLgo+Cj4+IEFsc28sIHBsZWFzZSBrZWVwIGluIG1pbmQgdGhh dCB5b3Ugc3RpbGwgd291bGQgbmVlZCBhIGZhbGxiYWNrIG1lY2hhbmlzbQo+PiB0byBydW4geW91 ciAiZGVmZXJyZWQgd29yayIgZXZlbiB3aGVuIHRoZSBndWVzdCBkb2VzIG5vdCBjYWxsIEhMVC9N V0FJVCwKPj4gbGlrZSBhIHJlZ3VsYXIgdGltZXIgaW4geW91ciBtYWluIHRocmVhZC4KPiBZZWFo LiBJbiB0aGF0IGNhc2UgSSB0aGluayB0aGUgaWRlYWwgYW5zd2VyIGlzIHRoYXQgd2UgbGV0IHRo ZSBrZXJuZWwKPiBzY2hlZHVsZXIgc29ydCBpdCBvdXQuIEkgd2FzIHRoaW5raW5nIG9mIGEgbW9k ZWwgd2hlcmUgd2UgaGF2ZSBJL08gKG9yCj4gd29ya3F1ZXVlKSB0aHJlYWRzIGluICphZGRpdGlv biogdG8gdGhlIHVzZXJzcGFjZSBleGl0cyBvbiBpZGxlLiBUaGUKPiBzZXBhcmF0ZSB0aHJlYWRz IG93biB0aGUgd29yayAoYW5kIGEgbnVtYmVyIG9mIHRoZW0gYXJlIHdva2VuIGFjY29yZGluZwo+ IHRvIHRoZSBxdWV1ZSBkZXB0aCksIGFuZCBpZGxlIHZDUFVzICpvcHBvcnR1bmlzdGljYWxseSog cHJvY2VzcyB3b3JrCj4gaXRlbXMgb24gdG9wIG9mIHRoYXQuCj4KPiBUaGF0IGFwcHJvYWNoIGFs b25lIHdvdWxkIHdvcmsgZmluZSB3aXRoIHRoZSBleGlzdGluZyBITFQgc2NoZWR1bGluZzsKPiBp dCdzIGp1c3QgTVdBSVQgd2hpY2ggaXMgYSBwYWluIGJlY2F1c2UgeWllbGQoKSBkb2Vzbid0IHJl YWxseSBkbyBtdWNoCj4gKGJ1dCBhcyBub3RlZCwgaXQncyBiZXR0ZXIgdGhhbiAqbm90aGluZyop Lgo+Cj4+IE9uIHRvcCBvZiBhbGwgdGhpcywgSSdtIG5vdCBzdXJlIGl0J3MgbW9yZSBlZmZpY2ll bnQgdG8gZG8gdGhlIHRyYXAgdG8KPj4gdGhlIHZDUFUgdGhyZWFkIGNvbXBhcmVkIHRvIGp1c3Qg Y3JlYXRpbmcgYSBzZXBhcmF0ZSByZWFsIHRocmVhZC4gWW91cgo+PiBtYWluIHByb2JsZW0gaXMg dGhlIGVtdWxhdGFiaWxpdHkgb2YgTVdBSVQgYmVjYXVzZSB0aGF0IGxlYXZlcyAibm8gdGltZSIK Pj4gdG8gZG8gZGVmZXJyZWQgd29yay4gQnV0IHRoZW4gYWdhaW4sIGlmIHlvdXIgZGVmZXJyZWQg d29yayBpcyBzbyBjb21wbGV4Cj4+IHRoYXQgaXQgbmVlZHMgbW9yZSB0aGFuIGEgZmV3IG1zICh3 aGljaCB5b3UgY2FuIGFsd2F5cyBzdGVhbCBmcm9tIHRoZQo+PiB2Q1BVIHRocmVhZCwgZXNwZWNp YWxsIHdpdGggeWllbGQoKSksIHlvdSdsbCBuZWVkIHRvIHN0YXJ0IGltcGxlbWVudGluZwo+PiB0 aW1lIHNsaWNpbmcgb2YgdGhhdCB3b3JrIGluIHVzZXIgc3BhY2UgbmV4dCAtIGFuZCBiYXNpY2Fs bHkgcmVidWlsZAo+PiB5b3VyIG93biBzY2hlZHVsZXIgdGhlcmUuIFVnaC4KPj4KPj4gSU1ITyB0 aGUgcmVhbCBjb3JlIHZhbHVlIG9mIHRoaXMgaWRlYSB3b3VsZCBiZSBpbiBhIHZjcHVfcnVuIGJp dCB0aGF0IG9uCj4+IFZDUFVfUlVOIGNhbiB0b2dnbGUgYmV0d2VlbiBITFQvTVdBSVQgaW50ZXJj ZXB0IG9uIGFuZCBvZmYuIFRoZSBhY3R1YWwKPj4gdHJhcCB0byB1c2VyIHNwYWNlLCB5b3UncmUg bW9zdCBsaWtlbHkgYmV0dGVyIG9mZiB3aXRoIGEgc2VwYXJhdGUgdGhyZWFkLgo+IE5vLCB0aGF0 J3MgdmVyeSBtdWNoIG5vdCB0aGUgcG9pbnQuIFRoZSBwcm9ibGVtIGlzIHRoYXQgeWllbGQoKSBk b2Vzbid0Cj4gd29yayB3ZWxsIGVub3VnaCDigJQgYW5kIGlzbid0IGRlc2lnbmVkIG9yIGd1YXJh bnRlZWQgdG8gZG8gYW55dGhpbmcgaW4KPiBwYXJ0aWN1bGFyIGZvciBtb3N0IGNhc2VzLiBJdCdz IGJldHRlciB0aGFuICpub3RoaW5nKiBidXQgd2Ugd2FudCB0aGUKPiBvcHBvcnR1bml0eSB0byBk byB0aGUgYWN0dWFsIHdvcmsgcmlnaHQgdGhlcmUgaW4gdGhlICpsb29wKiBvZiB0aGUKPiBndWVz dCBib3VuY2luZyB0aHJvdWdoIE1XQUlULgoKClRoZSBwcm9ibGVtIHdpdGggTVdBSVQgaXMgdGhh dCB5b3UgZG9uJ3QgcmVhbGx5IGtub3cgd2hlbiBpdCdzIGRvbmUuCgpZb3UgY291bGQgZmluZCBv dXQgYnkgbWFraW5nIE1PTklUT1InZWQgcGFnZXMoISkgcmVhZC1vbmx5IHNvIHlvdSBjYW4gCndh a2UgdXAgYW55IHRhcmdldCB2Q1BVIHRoYXQncyBpbiBNV0FJVCwgYnV0IHRoYXQncyBjb25zaWRl cmFibHkgCmV4cGVuc2l2ZSBpZiB5b3Ugd2FudCB0byBkbyBpdCB3ZWxsLgoKWW91IGNvdWxkIGFs c28gYnVybiBvbmUgVk0vc3lzdGVtIHdpZGUgQ1BVIHRoYXQgZG9lcyBub3RoaW5nIGJ1dCB3YWl0 cyAKZm9yIGNoYW5nZXMgaW4gYW55IE1PTklUT1InZWQgY2FjaGUgbGluZS4gRG9hYmxlIHdpdGgg bGVzcyBwb3dlciAKY29uc3VtcHRpb24gaWYgeW91IHVzZSBUU1ggSSBndWVzcy4gQnV0IHByb2Jh Ymx5IG5vdCB3aGF0IHlvdSB3YW50IGVpdGhlci4KCkFub3RoZXIgYWx0ZXJuYXRpdmUgd291bGQg YmUgdG8gbWFrZSBndWVzdHMgUFYgYXdhcmUsIHNvIHRoZXkgdW5kZXJzdGFuZCAKeW91IGRvbid0 IGFjdHVhbGx5IGRvIE1XQUlUIGFuZCBnaXZlIHlvdSBhIGh5cGVyY2FsbCBldmVyeSB0aW1lIHRo ZXkgCm1vZGlmeSB3aGF0ZXZlciBhbnlvbmUgd291bGQgd2FudCB0byBtb25pdG9yIChzdWNoIGFz IAp0aHJlYWRfaW5mby0+ZmxhZ3MpLiBCdXQgdGhhdCByZXF1aXJlcyBuZXcgZ3Vlc3Qga2VybmVs cy4gSSBkb24ndCB0aGluayAKeW91IHdhbnQgdG8gd2FpdCBmb3IgdGhhdCA6KS4KClNvIGluIGEg bnV0c2hlbGwsIGVtdWxhdGluZyBNV0FJVCBwcm9wZXJseSBpcyBqdXN0IHN1cGVyIGRpZmZpY3Vs dC4gSWYgCnlvdSBoYXZlIGV2ZW4gdGhlIHJlbW90ZXN0IGNoYW5jZSB0byBnZXQgYXdheSB3aXRo IGRvaW5nIEhMVCBpbnN0ZWFkLCAKSSdkIHRha2UgdGhhdC4gSW4gdGhhdCBtb2RlbCwgYW4gSS9P IHRocmVhZCB0aGF0IHNjaGVkdWxlcyBvdmVyIGlkbGUgCnRocmVhZHMgYmVjb21lcyBuYXR1cmFs LgoKCkFsZXgKCgoKCgpBbWF6b24gRGV2ZWxvcG1lbnQgQ2VudGVyIEdlcm1hbnkgR21iSApLcmF1 c2Vuc3RyLiAzOAoxMDExNyBCZXJsaW4KR2VzY2hhZWZ0c2Z1ZWhydW5nOiBDaHJpc3RpYW4gU2No bGFlZ2VyLCBKb25hdGhhbiBXZWlzcwpFaW5nZXRyYWdlbiBhbSBBbXRzZ2VyaWNodCBDaGFybG90 dGVuYnVyZyB1bnRlciBIUkIgMTQ5MTczIEIKU2l0ejogQmVybGluClVzdC1JRDogREUgMjg5IDIz NyA4NzkKCgo=