Message-ID: <f4aaf005-8b72-9b68-87bc-8019f0199f0d@oracle.com>
Date:   Thu, 18 Nov 2021 09:31:27 +0000
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.3.0
Subject: Re: [PATCH V5 46/50] x86/sev: Use C entry code
Content-Language: en-GB
To:     Lai Jiangshan <jiangshanlai@gmail.com>,
        linux-kernel@vger.kernel.org
Cc:     x86@kernel.org, Lai Jiangshan <laijs@linux.alibaba.com>,
        Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Juergen Gross <jgross@suse.com>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        Joerg Roedel <jroedel@suse.de>,
        Javier Martinez Canillas <javierm@redhat.com>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        Brijesh Singh <brijesh.singh@amd.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Tom Lendacky <thomas.lendacky@amd.com>
References: <20211110115736.3776-1-jiangshanlai@gmail.com>
 <20211110115736.3776-47-jiangshanlai@gmail.com>
From:   Liam Merwick <liam.merwick@oracle.com>
In-Reply-To: <20211110115736.3776-47-jiangshanlai@gmail.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?N1J2VUlRTkRxOUo1THlPVTFPT3N2cFd1U0UwSmtEZG9JRXQ4eUFlSU5tbkZL?=
 =?utf-8?B?ZW9hdXhKOFpvSkw3aHl6NDhTamZ4cHBTSXI4YmpXRjBKOXRMUG55Qm50MnN6?=
 =?utf-8?B?eXcrWStVb1lETzFHelBlKytGODNnNGhnQnBNc0tQLyswMDVzZlFrMG9kQ1pw?=
 =?utf-8?B?RlQ1ZWJxNzhlNHVVUUhnMmZ6TWpHQUtJU1ZEZFo2bTE4eS9MdSthWEdUOWVN?=
 =?utf-8?B?SjgzVWNkSFdwOFhaVlRBS0h1d3VwTzNYd0VWc0VGN2RaQmNPV1Q0T1lqYzlT?=
 =?utf-8?B?aS9pOGFKN1FzYWx3RXN0UzNoK1JKLzVGNkhWZmhVVUxEcDIwTDJSdXVkaHd4?=
 =?utf-8?B?b0crajR0TkVzSHhGOUVHQzdVeFZXWFU4NEpQYTRBNk9aSE9BaXdKVGFvMnRN?=
 =?utf-8?B?ZXVjWVFqYTluUGVwcS9yQ1BqcWRpMXdHOGQyeVFMZWd0cjdqY0xsWnI0bU4r?=
 =?utf-8?B?Tm1BdVVqTHVCbkxpZSt3OFIyUi85bU1mV2xwNDJBUDhBVmlXVU5JOTRPOUUy?=
 =?utf-8?B?VFVBUTMvdWp0MVRVRm83Qm1KdDg2dzNrZk1qSjYxNHlTZm93NjFnZmJqK2VX?=
 =?utf-8?B?NDJoeFRySThQR0NZSnhCSHNJOXBnTVRTdnpwS3lzUEhtS0pFanVFRERuWE1k?=
 =?utf-8?B?TjVZUWxneThNRTVmSmVLR1BtdURLN2RVc3hRM3JyTERTeTloTExGSm1SV2xP?=
 =?utf-8?B?WHM1NlBWMmhRQ0s0L3VscnY1SW9jOUJGSlQrUlQ1NjBrRWp6cWN2Y1ZLQ1VX?=
 =?utf-8?B?bkZwZThUZGFuWnhseFNaQmVpUVp5aGIxd2diS2lUK3Fld1Y3VzhFWW1Ecjkw?=
 =?utf-8?B?UWpscEoya0JkQVlEU09PcnpvZmttZVFxVVFVdnBCb3FiRWhzZXE5Y1N6UzBl?=
 =?utf-8?B?cnNGaXNhWnJpZVNBcjFqQ1FkK3R4djhWZTVzeE9rVktNQ2duZUJtcDZ3Q1Vo?=
 =?utf-8?B?cW9vWit1aTFzUXRNMGdxY2h5RWE1dWcyTGZNZUJLRldYaEVxZ2RNRDRZWkZW?=
 =?utf-8?B?ekJraTlFRWtDY1ZyOHZpZWxJZU10SW03K0RSSmRmRmYrSU9MY205VEpINXB6?=
 =?utf-8?B?cjBUM3FKS2phaDNiQmpBUklQWXJEeFF1Wm5tQSswZ3g4a2lLRnJDREVSZ2th?=
 =?utf-8?B?aENsWXlWOFBlVDRNOXZOYWZGZ1dRKzBWeENEcnJtSDN0L2xWOXlIMXkyZEVY?=
 =?utf-8?B?RGVJUDRRTmcwTXlya2xpSXFFUk1aK2lkMnN1REl5RDBjMnk5aDNxRkdPM0ts?=
 =?utf-8?B?eGRVTmJrWTdKRUZjVGVlSlJBNzZlTGhkOVlGOWNxY1V2SW55eXpSMStmZllm?=
 =?utf-8?B?VWRGbFprdTVTQWtGTERKZ3pwU1diaXJ5dWM2NEo3S1BybUw2L2UyTnZjSzVL?=
 =?utf-8?B?ZnZPZ0M3bmZoWVJ2UFNLY0pjWTBONmZXZWQzS0MycFNQZkYzbndqTDREbSsz?=
 =?utf-8?B?aG1KUzFxRTlxRnRocU92NFdQYWZ4ZUhVVTFFUHRiZlJ1M2prYUM3YU1RN3My?=
 =?utf-8?B?QUhTbFFBRXJQZkd2VTlJSW84T3NZeWxsV2dmVlRpbG9OVnI4cUpoT1pYSm13?=
 =?utf-8?B?SU1rOUplSW9kem5kWEE1dDlqZUtVRnhrN0ZrTDRPbElmRWx3S1B3VjdIbTUx?=
 =?utf-8?B?SzVVS2dVZ1FOMVNxdnpMUmVkSzJLMGZuVFNndE4zUjZRTis0Ull1cDBPTm1Q?=
 =?utf-8?B?VnJpbFczclhzY3ZqckJNRUUzbHFObEJ6MnZJVXNnS1ZBY01TRGJvaDF4ZkJ1?=
 =?utf-8?B?eVN2ZSs5NHQ0M1V4UnFMNENCWHR1ZG1LZWdncmFEcEZuMlBXRkxrVWx4REJl?=
 =?utf-8?B?NkFVOGZFbkFOWDZQYXVaSUQyL3ZOWCtnTHBGS2htSG03emJxUWN5aXN2NW1C?=
 =?utf-8?B?TEw3MUlZTG4zRkZSdEtqWUI2aThNZ1ZlUGdoVE5OL2ZVZk1GREZDcXJET1BD?=
 =?utf-8?B?TFlab09WdWNlK1Y3WldYZm80NHRyKzUzdjdPbWdPM21hMGMwMzlZMGtiV1Va?=
 =?utf-8?B?ZnZrVTRRYWg5cHlQNHFmQlFqQkNMUE12MC9jRGNnZDhVK1BuZ2VaVmErdGtp?=
 =?utf-8?B?ZFdNTk12VDNCanV1emdLS1VmU2ppYkI0dmlMYlNWdTNpYXJsWjVhc29KSXRi?=
 =?utf-8?B?NzVIVCtQaHdXMkpJU284c2NHdWhMUmhlM3N0Zkd1M2ZMdW9jd2dqQ3UwUHZB?=
 =?utf-8?Q?MKMvkV0i4Gbnt6GjVlko/nc=3D?=
X-OriginatorOrg: oracle.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 8f49be4d-e808-4b04-7a22-08d9aa763607
X-MS-Exchange-CrossTenant-AuthSource: BN0PR10MB5030.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Nov 2021 09:31:34.1537
 (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: bwYjmzQDdUotd7eCS9mH3PCly2Qb6eL4i2pirSo6w4+k58zqH15a/1FAPBwwOSalbWhRTgYg3gV+rpwJyNKtJg==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN6PR10MB1538
X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10171 signatures=668683
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 suspectscore=0 mlxscore=0
 phishscore=0 bulkscore=0 mlxlogscore=999 adultscore=0 malwarescore=0
 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000
 definitions=main-2111180055
X-Proofpoint-ORIG-GUID: 5xdFjFryiOvb-gkdkQupKRITdCJ7Tf2g
X-Proofpoint-GUID: 5xdFjFryiOvb-gkdkQupKRITdCJ7Tf2g
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 10/11/2021 11:57, Lai Jiangshan wrote:
> From: Lai Jiangshan <laijs@linux.alibaba.com>
> 
> Use DEFINE_IDTENTRY_IST_ETNRY_ERRORCODE to emit C entry function and
> use the function directly in entry_64.S.
> 

A drive-by comment as I was looking for SEV commits...

Typo in definition names, ETNRY -> ENTRY, (which impacts most patches 
between 38-48) would likely cause confusion in the future.

Regards,
Liam


> Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
> ---
>   arch/x86/entry/entry_64.S       | 22 +---------------------
>   arch/x86/include/asm/idtentry.h |  1 +
>   arch/x86/kernel/Makefile        |  1 +
>   3 files changed, 3 insertions(+), 21 deletions(-)
> 
> diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
> index 944cf85e67da..dfef02696319 100644
> --- a/arch/x86/entry/entry_64.S
> +++ b/arch/x86/entry/entry_64.S
> @@ -527,28 +527,8 @@ SYM_CODE_START(\asmsym)
>   
>   	UNWIND_HINT_REGS
>   
> -	/*
> -	 * paranoid_entry returns SWAPGS flag for paranoid_exit in EBX.
> -	 * EBX == 0 -> SWAPGS, EBX == 1 -> no SWAPGS
> -	 */
> -	call	paranoid_entry
> -
> -	UNWIND_HINT_REGS
> -
> -	/* Update pt_regs */
> -	movq	ORIG_RAX(%rsp), %rsi	/* get error code into 2nd argument*/
> -	movq	$-1, ORIG_RAX(%rsp)	/* no syscall to restart */
> -
>   	movq	%rsp, %rdi		/* pt_regs pointer */
> -
> -	call	kernel_\cfunc
> -
> -	/*
> -	 * No need to switch back to the IST stack. The current stack is either
> -	 * identical to the stack in the IRET frame or the VC fall-back stack,
> -	 * so it is definitely mapped even with PTI enabled.
> -	 */
> -	call	paranoid_exit
> +	call	ist_kernel_\cfunc
>   	jmp	restore_regs_and_return_to_kernel
>   
>   	/* Switch to the regular task stack */
> diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
> index 931b689f464c..84ce63f03c7f 100644
> --- a/arch/x86/include/asm/idtentry.h
> +++ b/arch/x86/include/asm/idtentry.h
> @@ -426,6 +426,7 @@ __visible __entry_text void ist_##func(struct pt_regs *regs)		\
>    * Maps to DEFINE_IDTENTRY_RAW_ERRORCODE
>    */
>   #define DEFINE_IDTENTRY_VC_KERNEL(func)				\
> +	DEFINE_IDTENTRY_IST_ETNRY_ERRORCODE(kernel_##func)	\
>   	DEFINE_IDTENTRY_RAW_ERRORCODE(kernel_##func)
>   
>   /**
> diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
> index 28815c2e6cb2..9535d03aaa61 100644
> --- a/arch/x86/kernel/Makefile
> +++ b/arch/x86/kernel/Makefile
> @@ -52,6 +52,7 @@ CFLAGS_head$(BITS).o	+= -fno-stack-protector
>   CFLAGS_cc_platform.o	+= -fno-stack-protector
>   CFLAGS_traps.o		+= -fno-stack-protector
>   CFLAGS_nmi.o		+= -fno-stack-protector
> +CFLAGS_sev.o		+= -fno-stack-protector
>   
>   CFLAGS_irq.o := -I $(srctree)/$(src)/../include/asm/trace
>   
>