Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Message-ID: <0fca8243-0106-8091-9635-53251c97149a@oracle.com>
Date:   Wed, 27 Oct 2021 09:17:12 -0400
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0)
 Gecko/20100101 Thunderbird/91.2.1
Subject: Re: [PATCH 0/6] xen/x86: PV boot speedup
Content-Language: en-US
To:     Jan Beulich <jbeulich@suse.com>, Juergen Gross <jgross@suse.com>
Cc:     Stefano Stabellini <sstabellini@kernel.org>,
        lkml <linux-kernel@vger.kernel.org>,
        "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
References: <022b1a5e-4121-6bae-f07c-4ad5eac12481@suse.com>
From:   Boris Ostrovsky <boris.ostrovsky@oracle.com>
In-Reply-To: <022b1a5e-4121-6bae-f07c-4ad5eac12481@suse.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?QUR3RjFYUE5wMlJuVnQrQW4xK1BKYzJQUEFNN3F0eVVkWWxkZ0lLYUorTEFx?=
 =?utf-8?B?ZXBRR0I1OUE2M0prY2Z0Nis4dGR2MG8zSTh1dnRBeE13bnYrWkNYNUVNeWJQ?=
 =?utf-8?B?WWZxYmhDdFY4MXViZm1UTkUyclhxK01QLzU5d1BRd3JhRzRCa21KaTFhNnk4?=
 =?utf-8?B?Z3cvVFJmNEZKZUhlL2kwZGo0NGYzS3dNL1cxTjJWNjIxVzRTaGVFM215akp6?=
 =?utf-8?B?MzU0ZllNaUorenVCN3pzeUx2a3VRMjlNSnlXM0ttSy94NHlmT0t0bUs1anlF?=
 =?utf-8?B?Y0VKNng3VHJMbDFScHB2UFFoY1RrZDZkNWNKRzVJTU9WSFFSLys3bHhmUmo1?=
 =?utf-8?B?UFk1anc5VExPUEN1L0paY1pvb2xNQ3V4TmZ2ZnNwa01JTnVpM2Q3bmU2V3Vu?=
 =?utf-8?B?WVZud3dnMndPbzVRWFZBM0padXE3b2xBU3FtTjdaQVN3dzNFWkhNU1c4MHRV?=
 =?utf-8?B?V2ZqZWNaWEI3VkRTbkZNLzg2SnQyYmpiUnc1WWhJTTRobHY5SjE3Q2xxVzNX?=
 =?utf-8?B?Z2FQU2VHU2tGOHpKNWRQUDdlb1ptcEpSS1YwcS9DTHhRR3hhNmFSUGRaZjYr?=
 =?utf-8?B?cFY1NmdXUzExang4OENhQWY0K0M0Tk9UL0MvaFNuTmY3Z2tieFc1a1BmMnZI?=
 =?utf-8?B?NnNuNkMzMmZrL3VHdXpIMjFqTmhYQzIwRTNQeEJQdW5WaFFqdWFYN0Z0R2Fr?=
 =?utf-8?B?SmR6RkxrZEtiOUZIN05oVVRDSUdZelJUMmJtNmFRMXlMTkdVQ3JvWThURDly?=
 =?utf-8?B?amRabmRhd3p4YXpxYXFaUmxlVDQ4OWdDNllWdm0rN1J2c09UbUt2Ny9OdjVU?=
 =?utf-8?B?S3BpcDR4MGRobjNiNXV5SUhTSkdLWVlpY2NERmw1WngvVE5uSVJEc3JOd1Zj?=
 =?utf-8?B?UXpCWU43bHcwNHFhRUpBSC94bUhLNXdjRC9mYWhyQWJyMVRjdEJmbG9aNjk5?=
 =?utf-8?B?bWwyNHB6OFFURS9lVHRINTVqZEJnZHMwZHFOOHhHc1FLME56Z3QwenhqTWFz?=
 =?utf-8?B?akZrLzh1aUQ5aG9JNm42Tm1ZUFhHREhDdWxlMmNtSjZSWElCZXVVWWlvYXBI?=
 =?utf-8?B?NW05c0RIdFZvZGE1NmVmRDBXUHlvVGFmTTVQclVwT2ROM1hiMjJEU2d1aXha?=
 =?utf-8?B?ZjBPQUphdGI2a2ZFZjJvVEYzZTNJQjJCZWluT1F5eVVudE1DRVoyVzByYmlU?=
 =?utf-8?B?RUlNcFVwQTV0QjZ2VnZ2WUtRc05MRnhMbEhDb2hMMTRlaGJYU0JJZEozZGdD?=
 =?utf-8?B?b3ZkcGxaRnptU2hJclkyOEYrRk0xQndLOFFZUlRpNFlIeG04a2J1MFdFYzdV?=
 =?utf-8?B?UTF6MnZ0UXBQV0hEcHZXSVA4dlZpa3JwdlZBQjB1OUIyRklMc2FFY0RNQU54?=
 =?utf-8?B?OFhxNWlvQTEvZjVmcCtOVG02SkhuLzgzK3ZMRzg0TFArYmNqWVJ5SFR2N0p6?=
 =?utf-8?B?OS9CUHJiMnlzdEJ3WThIRG13ekZjOUFGamlmUjRtV1pLNTJmbW1IUDE2ZlJi?=
 =?utf-8?B?akg2RUFWUTlhWm54UU0xWFlNdGx6TnN1WndGWTJoNnRMT2htdWRLMFFWT09s?=
 =?utf-8?B?b1hXeGluZmNWL1AxSk01QjZKUFdKSnlvR0F0M2x3U290dFhrZ3NmSGdKcDlT?=
 =?utf-8?B?bC9mQWRNRXA0MGMvM3ozSUVvSjRaRDB6Ukl0U2xSVnBNaksvbkowZ2lNUWdy?=
 =?utf-8?B?UGtTK3lUK2NqeUprak1CNzhFbitzbW03Wk9RUEVnWFB3b3lSNytPTW1QWnEw?=
 =?utf-8?B?ZzJyR3Erd2ZJVE5jcmlVSDdKTmxtRWlFTUVNemFQWXZueXZhM2M0VGFLYU9x?=
 =?utf-8?B?d01uY0kwU0xuYWZ2czQ2Z21EQlBXNWlPY2pBQjVZY2JzTHlGSFowZm5peHJS?=
 =?utf-8?B?ekpPRjgvVDJ4MkNUQ2Q5NXVSR2pwdEJsdUxkWG0rWEpPUmN0ZWdtY2ZCa3BJ?=
 =?utf-8?B?c2lWTWpkaWVrRDBrNHZUUFNSM1h2MGhURnRvZDNvQXJpOWthZWhTRVllTnkr?=
 =?utf-8?B?TmRVS0I2TXo1MG1IeVUyZ2t0VHBtS3JJcjk3aUhoVit3YmZCSDM4Nm9FckZ6?=
 =?utf-8?B?cTBZdjJZK083WDVabUpkdFZVbDRVRnA5OFBQeUcxYk04ZmcvN0c5U2RtL2c1?=
 =?utf-8?B?TVN2QTBSR0pOK1c2OHJqZ0k3TENxaFpUWTJIcE5VeFcrbTczQ05TN3c5NjBV?=
 =?utf-8?B?MVd6NFlGRlM4R3pTUVMwSFd2NjhEU1B1WnliVDFhMmp2UGZ3R1pnSUhDUEs4?=
 =?utf-8?B?UWtrNU45cUpDUWFkdFJ4Z2FVQ3pnPT0=?=
X-OriginatorOrg: oracle.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 14717415-b223-4b82-e8ec-08d9994c1980
X-MS-Exchange-CrossTenant-AuthSource: BLAPR10MB5009.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 27 Oct 2021 13:17:17.6448
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: z0AiZT1boac9VOL6ePHA2yblIgl5mnOb2RGYuvajIYvMnAC/6FFRPw2fc72VzW8aQB5x9urApDq4AANJJaDTv0WDvhzKNrIKkDNtJNLRcH8=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR10MB4029
X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10149 signatures=668683
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 phishscore=0 malwarescore=0
 adultscore=0 suspectscore=0 bulkscore=0 mlxscore=0 spamscore=0
 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1
 engine=8.12.0-2110150000 definitions=main-2110270081
X-Proofpoint-ORIG-GUID: SthDEoaTXnYSC6InyF03KM7WKXPFgABg
X-Proofpoint-GUID: SthDEoaTXnYSC6InyF03KM7WKXPFgABg
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org


On 9/30/21 8:33 AM, Jan Beulich wrote:
> The observed (by the human eye) performance difference of early boot
> between native and PV-on-Xen was just too large to not look into. As
> it turns out, gaining performance back wasn't all that difficult.
>
> While the series (re)introduces a small number of PTWR emulations on
> the boot path (from phys_pte_init()), there has been a much larger
> number of them post-boot. Hence I think if this was of concern, the
> post-boot instances would want eliminating first.
>
> Some of the later changes aren'r directly related to the main goal of
> the series; these address aspects noticed while doing the investigation.
>
> 1: streamline set_pte_mfn()
> 2: restore (fix) xen_set_pte_init() behavior
> 3: adjust xen_set_fixmap()
> 4: adjust handling of the L3 user vsyscall special page table
> 5: there's no highmem anymore in PV mode
> 6: restrict PV Dom0 identity mapping


Applied to for-linus-5.16


-boris