Received-SPF: pass (google.com: domain of linux-kernel+bounces-187881-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.48.161 as permitted sender) client-ip=147.75.48.161;
Message-ID: <3cadb384-3493-4f36-a0b9-a3dffbf9fa9f@oracle.com>
Date: Thu, 23 May 2024 20:30:44 +0200
User-Agent: Mozilla Thunderbird
Cc: alexandre.chartre@oracle.com, linux-kernel@vger.kernel.org,
        daniel.sneddon@linux.intel.com, pawan.kumar.gupta@linux.intel.com,
        tglx@linutronix.de, konrad.wilk@oracle.com, peterz@infradead.org,
        gregkh@linuxfoundation.org, seanjc@google.com,
        dave.hansen@linux.intel.com, nik.borisov@suse.com, kpsingh@kernel.org,
        longman@redhat.com, bp@alien8.de, pbonzini@redhat.com
Subject: Re: [PATCH] x86/bhi: BHI mitigation can trigger warning in #DB
 handler
Content-Language: en-US
To: Andrew Cooper <andrew.cooper3@citrix.com>,
        Dave Hansen <dave.hansen@intel.com>, x86@kernel.org,
        kvm@vger.kernel.org
References: <20240523123322.3326690-1-alexandre.chartre@oracle.com>
 <a04d82be-a0d6-4e53-b47c-dba8402199e7@intel.com>
 <1c69f62e-0dee-4caa-9cbe-f43d8efd597b@oracle.com>
 <93510641-9032-4612-9424-c048145e883e@intel.com>
 <5ed7d3c8-63c3-48f3-aaeb-a19514f4ef5e@oracle.com>
 <0fcbfcba-9fe2-414c-8424-347364fcbf35@citrix.com>
 <d9f5a2d4-9c73-45c5-9de9-12a4d1d9ee99@oracle.com>
From: Alexandre Chartre <alexandre.chartre@oracle.com>
Autocrypt: addr=alexandre.chartre@oracle.com; keydata=
 xsFNBGJDNGkBEACg7Xx1laJ1nI9Bp1l9KXjFNDAMy5gydTMpdiqPpPojJrit6FMbr6MziEMm
 T8U11oOmHlEqI24jtGLSzd74j+Y2qqREZb3GiaTlC1SiV9UfaO+Utrj6ik/DimGCPpPDjZUl
 X1cpveO2dtzoskTLS9Fg/40qlL2DMt1jNjDRLG3l6YK+6PA+T+1UttJoiuqUsWg3b3ckTGII
 y6yhhj2HvVaMPkjuadUTWPzS9q/YdVVtLnBdOk3ulnzSaUVQ2yo+OHaEOUFehuKb0VsP2z9c
 lnxSw1Gi1TOwATtoZLgyJs3cIk26WGegKcVdiMr0xUa615+OlEEKYacRk8RdVth8qK4ZOOTm
 PWAAFsNshPk9nDHJ3Ls0krdWllrGFZkV6ww6PVcUXW/APDsC4FiaT16LU8kz4Z1/pSgSsyxw
 bKlrCoyxtOfr/PFjmXhwGPGktzOq04p6GadljXLuq4KBzRqAynH0yd0kQMuPvQHie1yWVD0G
 /zS9z2tkARkR/UkO+HxfgA+HJapbYwhCmhtRdxMDFgk8rZNkaFZCj8eWRhCV8Bq7IW+1Mxrq
 a2q/tunQETek+lurM3/M6lljQs49V2cw7/yEYjbWfTMURBHXbUwJ/VkFoPT6Wr3DFiKUJ4Rq
 /y8sjkLSWKUcWcCAq5MGbMl+sqnlh5/XhLxsA44drqOZhfjFRQARAQABzTlBbGV4YW5kcmUg
 Q2hhcnRyZSAoT3JhY2xlKSA8YWxleGFuZHJlLmNoYXJ0cmVAb3JhY2xlLmNvbT7CwY4EEwEI
 ADgWIQRTYuq298qnHgO0VpNDF01Tug5U2AUCYkM0aQIbAwULCQgHAgYVCgkICwIEFgIDAQIe
 AQIXgAAKCRBDF01Tug5U2M0QD/9eqXBnu9oFqa5FpHC1ZwePN/1tfXzdW3L89cyS9jot79/j
 nwPK9slfRfhm93i0GR46iriSYJWEhCtMKi9ptFdVuDLCM3p4lRAeuaGT2H++lrayZCObmZxN
 UlVhZAK/rYic25fQYjxJD9T1E0pCqlVGDXr2yutaJJxml5/jL58LUlDcGfIeNpfNmrwOmtUi
 7Gkk+/NXU/yCY17vQgXXtfOATgusyjTFqHvdKgvYsJWfWZnDIkJslsGXjnC8PCqiLayCPHs+
 v+8RX5oawRuacXAcOM66MM3424SGK5shY4D0vgwTL8m0au5MVbkbkbg/aKDYLN33RNUdnTiz
 0eqIGxupzAIG9Tk46UnZ/4uDjdjmqJt1ol+1FvBlJCg+1iGGJ7cX5sWgx85BC63SpKBukaNu
 3BpQNPEJ4Kf+DIBvfq6Vf+GZcLT2YExXqDksh08eAIterYaVgO7vxq6eLOJjaQWZvZmR94br
 HIPjnpVT9whG1XHWNp2Cirh9PRKKYCn+otkuGiulXgRizRRq2z9WVVQddvCDBDpcBoSlj5n5
 97UG0bpLQ65yaNt5o30mqj4IgNWH4TO0VJlmNDFEW0EqCBqL1vZ2l97JktJosVQYCiW20/Iv
 GiRcr8RAIK8Yvs+pBjL6cL/l9dCpwfIphRI8KLhP8HsgaY2yIgLnGWFpseI3h87BTQRiQzRp
 ARAAxUJ7UpDLoKIVG0bF4BngeODzgcL4bsiuZO+TnZzDPna3/QV629cWcjVVjwOubh2xJZN2
 JfudWi2gz5rAVVxEW7iiQc3uvxRM9v+t3XmpfaUQSkFb7scSxn4eYB8mM0q0Vqbfek5h1VLx
 svbqutZV8ogeKfWJZgtbv8kjNMQ9rLhyZzFNioSrU3x9R8miZJXU6ZEqXzXPnYXMRuK0ISE9
 R7KMbgm4om+VL0DgGSxJDbPkG9pJJBe2CoKT/kIpb68yduc+J+SRQqDmBmk4CWzP2p7iVtNr
 xXin503e1IWjGS7iC/JpkVZew+3Wb5ktK1/SY0zwWhKS4Qge3S0iDBj5RPkpRu8u0fZsoATt
 DLRCTIRcOuUBmruwyR9FZnVXw68N3qJZsRqhp/q//enB1zHBsU1WQdyaavMKx6fi1DrF9KDp
 1qbOqYk2n1f8XLfnizuzY8YvWjcxnIH5NHYawjPAbA5l/8ZCYzX4yUvoBakYLWdmYsZyHKV7
 Y1cjJTMY2a/w1Y+twKbnArxxzNPY0rrwZPIOgej31IBo3JyA7fih1ZTuL7jdgFIGFxK3/mpn
 qwfZxrM76giRAoV+ueD/ioB5/HgqO1D09182sqTqKDnrkZlZK1knw2d/vMHSmUjbHXGykhN+
 j5XeOZ9IeBkA9A4Zw9H27QSoQK72Lw6mkGMEa4cAEQEAAcLBdgQYAQgAIBYhBFNi6rb3yqce
 A7RWk0MXTVO6DlTYBQJiQzRpAhsMAAoJEEMXTVO6DlTYaS0P/REYu5sVuY8+YmrS9PlLsLgQ
 U7hEnMt0MdeHhWYbqI5c2zhxgP0ZoJ7UkBjpK/zMAwpm+IonXM1W0xuD8ykiIZuV7OzEJeEm
 BXPc1hHV5+9DTIhYRt8KaOU6c4r0oIHkGbedkn9WSo631YluxEXPXdPp7olId5BOPwqkrz4r
 3vexwIAIVBpUNGb5DTvOYz1Tt42f7pmhCx2PPUBdKVLivwSdFGsxEtO5BaerDlitkKTpVlaK
 jnJ7uOvoYwVDYjKbrmNDYSckduJCBYBZzMvRW346i4b1sDMIAoZ0prKs2Sol7DyXGUoztGeO
 +64JguNXc9uBp3gkNfk1sfQpwKqUVLFt5r9mimNuj1L3Sw9DIRpEuEhXz3U3JkHvRHN5aM+J
 ATLmm4lbF0kt2kd5FxvXPBskO2Ged3YY/PBT6LhhNettIRQLJkq5eHfQy0I1xtdlv2X+Yq8N
 9AWQ+rKrpeBaTypUnxZAgJ8memFoZd4i4pkXa0F2Q808bL7YrZa++cOg2+oEJhhHeZEctbPV
 rVx8JtRRUqZyoBcpZqpS+75ORI9N5OcbodxXr8AEdSXIpAdGwLamXR02HCuhqWAxk+tCv209
 ivTJtkxPvmmMNb1kilwYVd2j6pIdYIx8tvH0GPNwbno97BwpxTNkkVPoPEgeCHskYvjasM1e
 swLliy6PdpST
In-Reply-To: <d9f5a2d4-9c73-45c5-9de9-12a4d1d9ee99@oracle.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: 
	=?utf-8?B?ZjlabmdKZ21PQnNJbG8rNmR5a3ZwaERhSCtsQ0VodUI4ZW5kbVBZcGFlZ0s3?=
 =?utf-8?B?anVwMUtYczh2dDVzMWFENWdmMmNRNjJvMDBpSExhZXJDRTh1TS9pTkN1dTRx?=
 =?utf-8?B?ZWhFa0ZhdzV4ZnEyblhkWGhDamFJR3BhclFneVJKcjl4aGtyS0t0dkJYditw?=
 =?utf-8?B?SmpjSk5JaXcxaU9sWk5MakE0VHE5RkF1cnRraVJFMHQwVWZRTU84dGdadE03?=
 =?utf-8?B?Kzh0cWpPQ3NYU2M4djRRZlN3WXo2bHBPZ1FiSVczN000Zk04dEdid0pWaG9n?=
 =?utf-8?B?M0R6aUZvd016WmFETmxlZ3NLYVNGUEhsaThNbFBjNzZkbmFVSEpncG5uemxZ?=
 =?utf-8?B?ZHR2N2FKZjRaS1h4cGxWdEtZOGtoRVR5cktUZkdpR3ZVR3ZkY3k0dHFsb3NZ?=
 =?utf-8?B?dEE2MzdSblBvT2xYWjQ0RmJGSVBFZEVTdTdSNXJPcEVIL3NVME02ZHVTbWFQ?=
 =?utf-8?B?dzdGSFFDS0tsSE9Dam41ZFV5QXEzVkl1a1dvUElzZDhjT3JGTmVmZERRbVpz?=
 =?utf-8?B?RE1NeHZER1F2VFU4VmJGcExHdjdxT1NyNG43cmpWQThoc0tzYnpQdDVJTkQ1?=
 =?utf-8?B?bThGVi9ENXhCN0tjaU9wTHdLZ2Z1d0dBTVlNeGhzdUVIT25BMUZ0cUswdmFz?=
 =?utf-8?B?aEozQjNBRUc0b2luWFJobDFIRHlzL2FyN0hCZ29yVEpVL1RaUjFVYWhhNVRr?=
 =?utf-8?B?VU1UNnp2N1QyK1o4WmNIQ1lCSEpweU1uWXNYc010TlBya2xrUE8zbGM4KzQ3?=
 =?utf-8?B?RmMyKzZDMWRaNm5hVlhBd2VTcnU0NzFvLys3c3FCbnJXb2R2SURwY3VocWJq?=
 =?utf-8?B?QlZsNUtYZit6aTkycGl2ODg0cXVxNXdNNmowZ0xBbkRobjNJbzhCNXV0eVVZ?=
 =?utf-8?B?MnQ3eEs1MW43QVdFTWNTTEJKdmh2VHdtRUJsa0RQTW9EZzR6WXo4am1Ha1JD?=
 =?utf-8?B?YlFISnUyUE4rcDV3WnJDQzlvU0JySWxyRHZTMGpCTHA2OG52NDdaNVpvQVJa?=
 =?utf-8?B?dGd5SWRmcnVtY2owSitGdzBSQ2VRbmJTU0RXOHYwc2VwOGxiODJJMnYvYW5P?=
 =?utf-8?B?SE83MnhYc0p1TzdWelN0eFN4UVM1bEk1VlZxQi9iMXJORHFWN2JPUTJzOTRG?=
 =?utf-8?B?TUJLVmZZWUIwU09xMDkwSWVWaGxla2JFbWFqRkN5TllzSXRqUmhPWmx1TWJO?=
 =?utf-8?B?STlTNFordTZISUFieTU4N3VKRGRwcFlveVREVnYxNTN1VGlCc1pPemFmSExB?=
 =?utf-8?B?L0s1eDR1WUU1SUJ0ZkFoenFOZVhnaDQwSXUzUjRGdDFTMGRieDVzWU5oL3Nw?=
 =?utf-8?B?SzNwTTI3UmN3QU1UdlpSK1NUdU5kcGRoMG5UbU5DVjZDTy9FWFYvTUtDeHJx?=
 =?utf-8?B?WU13WlYvbWJrVVZadDBqY3NnQzRpU0xkald2bmQzaHovMXV0QjdQMnRRQUpY?=
 =?utf-8?B?cU1pWmdvWEdZc1FqSjVkNU9uRDFiZ3lsSm1wWTVjRlBDS0NvL1JaTWlOak9Z?=
 =?utf-8?B?Ry81OFRtQW1ZSzhhaWVPNERkN3B0T0lCeUl4bWJJVnN3REpMLzlaSkxzbkhq?=
 =?utf-8?B?QTBxSjMzdW9rWlFadVJPTXI3Y1M5c0UyWUNFWjJhaGlrcVBaWkVYOHRPR2E0?=
 =?utf-8?B?TjVyWEJGdGl5WWovNEsrM0RHRVVnNEtsNTBVNCtQK2czbnU0M3ArVHZubjFE?=
 =?utf-8?B?RzhqNHZxcDNJbnRtNTJKQmsvdFpybVNUNWovQWloR2pRL2dRUDlseGg3RG10?=
 =?utf-8?B?bTNmVVBFa3BjaDlJZHpmYWtDVEQ2ei9EQmFnM0xiWUJYQURRb0UzbDV6dDFY?=
 =?utf-8?B?RTJjVUNGaEo5ZllnVEtZRGZ4ZEJiSzZuRGVJd3NVUWpVWlJwOC92OXBnVnJo?=
 =?utf-8?B?dUt3T0d1bTN1eWY3U3RkN1dOODh6OUFZcmpabEwxRFRRd21BZUNkdnZ3NklR?=
 =?utf-8?B?cTY4bWh1eUsxU2ZmYWVJOTM0OXRHa1duc1pNaUh3ZGdPT0ljd1dYMUpaRWJ5?=
 =?utf-8?B?eVlTQnE1NXhTN0EyOTFzVW9SMXErVUdVOTYrTkxLS1kyNXRLUzloTW9VdmJM?=
 =?utf-8?B?VjI2bFgzM3lDcWxZTXZLL3cwMWV2NllLSHRNTXAxMm1vaUthMm05SDBDZks2?=
 =?utf-8?B?WXA4VHQ3YmZyUU5paE1DYU5sQTFtRlAwck5zclRacERkS0JOcG1CQjZjMFA2?=
 =?utf-8?B?L3c9PQ==?=
X-MS-Exchange-AntiSpam-ExternalHop-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-ExternalHop-MessageData-0: 
	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
X-OriginatorOrg: oracle.com
X-MS-Exchange-CrossTenant-Network-Message-Id: e450b140-34e7-4642-643f-08dc7b567892
X-MS-Exchange-CrossTenant-AuthSource: SN4PR10MB5622.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 May 2024 18:30:50.1941
 (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: n5goMUVm8z/5sM7INTUiA+G2ERjyw0VM0ZyBLK6bA1tHDuY76h37MAOfyqMdc3aZjlKNsg/o0wdBiI0LBIUaGBuyEnYQ2w/+GYNICZnYHdc=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN0PR10MB5063
X-Proofpoint-Virus-Version: vendor=baseguard
 engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.650,FMLib:17.12.28.16
 definitions=2024-05-23_11,2024-05-23_01,2024-05-17_01
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 mlxscore=0 mlxlogscore=999
 phishscore=0 bulkscore=0 suspectscore=0 malwarescore=0 spamscore=0
 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2405010000
 definitions=main-2405230129
X-Proofpoint-ORIG-GUID: LzEmcPLsYm8XILRAThA6G4VE4E9HLm-y
X-Proofpoint-GUID: LzEmcPLsYm8XILRAThA6G4VE4E9HLm-y


On 5/23/24 20:27, Alexandre Chartre wrote:
> 
> 
> On 5/23/24 19:53, Andrew Cooper wrote:
>> On 23/05/2024 6:03 pm, Alexandre Chartre wrote:
>>>
>>> On 5/23/24 17:36, Dave Hansen wrote:
>>>> On 5/23/24 07:52, Alexandre Chartre wrote:
>>>>>> Should we wrap up this gem and put it with the other entry selftests?
>>>>>
>>>>> It looks like tools/testing/selftests/x86/single_step_syscall.c tests
>>>>> sysenter with TF set but it doesn't check if the kernel issues any
>>>>> warning.
>>>>
>>>> Does it actually trip the warning though? I'm a bit surprised that
>>>> nobody reported it if so.
>>>
>>> single_step_syscall does trigger the warning:
>>>
>>> $ ./single_step_syscall
>>> [RUN]    Set TF and check nop
>>> [OK]    Survived with TF set and 26 traps
>>> [RUN]    Set TF and check syscall-less opportunistic sysret
>>> [OK]    Survived with TF set and 30 traps
>>> [RUN]    Set TF and check a fast syscall
>>> [OK]    Survived with TF set and 40 traps
>>> [RUN]    Fast syscall with TF cleared
>>> [OK]    Nothing unexpected happened
>>> [RUN]    Set TF and check SYSENTER
>>>      Got SIGSEGV with RIP=ed7fe579, TF=256
>>> [RUN]    Fast syscall with TF cleared
>>> [OK]    Nothing unexpected happened
>>
>> :-/
>>
>> What about the exit code?
>>
>> I find the absence of a [FAIL] concerning...
>>
> 
> $ ./single_step_syscall
> [RUN]    Set TF and check nop
> [OK]    Survived with TF set and 26 traps
> [RUN]    Set TF and check syscall-less opportunistic sysret
> [OK]    Survived with TF set and 30 traps
> [RUN]    Set TF and check a fast syscall
> [OK]    Survived with TF set and 40 traps
> [RUN]    Fast syscall with TF cleared
> [OK]    Nothing unexpected happened
> [RUN]    Set TF and check SYSENTER
>      Got SIGSEGV with RIP=bb44b579, TF=256
> [RUN]    Fast syscall with TF cleared
> [OK]    Nothing unexpected happened
> 
> $ echo $?
> 0
> 
> The program runs as expected (but it doesn't expect much than a SIGSEGV).
> It triggers a warning from the kernel but it doesn't check if a warning
> was produced.
> 

Actually it checks that TF isn't cleared after the sysenter, but that's all.

alex.