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mx.microsoft.com 1; spf=pass smtp.mailfrom=citrix.com; dmarc=pass action=none header.from=citrix.com; dkim=pass header.d=citrix.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.onmicrosoft.com; s=selector2-citrix-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=hPP+gb/1JdksoVtDSzODY1lG/SGpk1N4fr0iVoKhuTo=; b=TiwIP6QkdAAKUi2tIr0Jmszukf0dzI7bEA+ZLzGP0OCdf++c1W7JwyY3EfKsHiR3HdvenXUbt/+4dfn6Pehe7kbdil/wgmwoSYkfMuY9DN/qPMPjQoTp9vpC8P/Rlc8koX0NwPyPyutY0PZpYm/pRrOAxtElEP46ztyJgf5L7YE= Date: Fri, 30 Apr 2021 16:37:54 +0200 From: Roger Pau =?utf-8?B?TW9ubsOp?= To: Jan Beulich CC: "xen-devel@lists.xenproject.org" , Andrew Cooper , George Dunlap , Ian Jackson , Julien Grall , Stefano Stabellini , Wei Liu , Daniel de Graaf , Paul Durrant , Tamas K Lengyel , Petre Pircalabu , Alexandru Isaila Subject: Re: [PATCH v2 09/12] x86: make mem-paging configuarable and default it to off for being unsupported Message-ID: References: <3cf73378-b9d6-0eca-12b6-0f628518bebf@suse.com> <26dae9ef-5fcb-f806-059d-7cdd2974ad40@suse.com> <143b84c7-84dd-6b36-997e-a38718651723@suse.com> Content-Type: text/plain; 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X-MS-Exchange-AntiSpam-MessageData: =?utf-8?B?SnBFakFpSDAvUm5TajRPZmdYOGdEcFNuVi9VTjRkMUVwcWdBRlpBSlhGcnE1?= =?utf-8?B?QWJVNUFCcndubjMwL0pJSWxKTi9NWlpYVFJaaktqeFNERTFLQ3pBMGlKUk9V?= =?utf-8?B?YnlrZnZjYy80ZEM0UThHWXd1a1l4ckN4VnJDaVlLMmZpTHhsbGJGQmMxVE9V?= =?utf-8?B?cjZWWUhVTFhZejlRU2srWW5ibWxaeGVEUWtISHNDT25TRmFyb3hTNzd1cG80?= =?utf-8?B?aVFCV3Jsb0VhUm54dkdjbFhUR0ZNNDk0TUNTanFVamlrTTdmNEtJRDJDMHNZ?= =?utf-8?B?enFwUTVlNTVjN3dVRHBOaWpTRkdiclI2VXoxekNRMHRYZCt0VUtNZHBXOUJO?= =?utf-8?B?aXVRdzM4eTRSOXoxT2pabW95bUdSQWRlSVRqYXBHY2M1TUlLZGwvWVh2ZTJG?= =?utf-8?B?dFY4UFFadzMzUWZYdkIrMi9Vd0JmTzRIcFltS1BlZ0sxZmNmSVF2c3I0TVNS?= =?utf-8?B?cHlkclVVYlVWa1hwU1dDRGlla1ZSRlhwbEo5YjZWSC85SkdPMklQc3BJWXVM?= =?utf-8?B?dzdGaVBMNW5BbTVlaXl4TjEzZnVDWG5YV3owN0F3S1dFbDZrSVFMNE1pdTdU?= =?utf-8?B?UWtqQ2FEQndMYWRnSXVMOERvZVQvSXVUNi9WSmIyZnh4VWdlVzB4L21EUlZL?= =?utf-8?B?dksvVjJMMUJ0Y2ZkN0I1RDlrdUhXd0lVa1dHcDhEQ2IwUERIdWFlSGF6MFJy?= =?utf-8?B?bmF2Z3plN2FyZk9CeFRPa1VrQ2M0ZkhBS01yRUlHMHhJb25kY21SckRGcG1h?= =?utf-8?B?MFphaFhueXRnT0RDS1JHQ1RyL1AyWnh4ZTRqS0J6REZiU0hsR0V3WnQ4RHV3?= =?utf-8?B?Vlc2M0k5ZzVmc09ybEpDRXBaZWdiekxoTlVlTURET2htNGxZSTkwQ3UvRFZJ?= =?utf-8?B?RUNFYW9kcW5Pa3hPbWNKREd3eXlQcHg4eTArZW5LNTRxR1grQlh5MFkydlEr?= =?utf-8?B?aHE4QW0rZWdXb1dSNXNvajlzNEsxbm03WmJRT204ZXd5ckplLzNKNVIwR3lH?= =?utf-8?B?aFlIeXllckNRR3ArNS9pWlpJdzlsYzZnU0J1dlV4YUJwckF4V1ExcCs0OHdy?= =?utf-8?B?QVBsTlJwS2E2ak51eWFzZi9Cano2NC9BcUMyOHRXcTBLTnZIYzBSTG1NN1Fn?= =?utf-8?B?MUcraGpHbzI0U00vaGEvTS9HTnpaaUpkM1p3MTE1Z3dsSjVXdXRTbUhuMFF2?= =?utf-8?B?Q05GbDNMK3BpMzVXMmpaUU1qS1J3ZTB6S2hvMHE3N0IySERNL1hIcWFvTzB6?= =?utf-8?B?Z3lCVlJ5WkRDbm1RaUVUV1B6bVV1NWZ2VWpPY0NmalEvdzM2WkpKNmJuSFVC?= =?utf-8?B?ZURoSWdrWU1zVGZ4WXZvL09GT2V0N1ZuckJubVdZNnBlRDBCTVFmUG9ZOVZi?= =?utf-8?B?dnZLc2p5L3p3cTl5dlVjZ281SWV0V1I5UHBuNEdjTTVBb1IyNUxwQ0dHSmtU?= =?utf-8?B?aVlwMlU2dFhaN005K01sZWUvdHcvS3BFRDBFNVJFSDZsbGNGZWFPRE9DdmNk?= =?utf-8?B?T2tHZjdqc2dXOW1wc2xlUktWS0ZBSzFjRjN4SmZrRVQ0cjA4ckh1ckpCc1FO?= =?utf-8?B?TCtHN0dwNFRjYjE2ZHNDbVVSQzhFbklkVnBraVhoa1dEdjNKSklIRm5haXRX?= =?utf-8?B?dEJVSHc0dEp5a09xRjloblIyUmdKclV2clF3Ty9URWxvUUFQVy9yUEgveGZF?= =?utf-8?B?eSs3NXk1U2c5a1hyTmJpczQxZnNOTk9ZMklEQmwvWHU1c01ITGhvL1VvWFl0?= =?utf-8?Q?b+s1+xya2/3XcagfnvEhO/0qizV2iZi5koio7bd?= X-MS-Exchange-CrossTenant-Network-Message-Id: fb4740d7-19d2-4278-ba62-08d90be58d95 X-MS-Exchange-CrossTenant-AuthSource: DS7PR03MB5608.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Apr 2021 14:38:00.3319 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 335836de-42ef-43a2-b145-348c2ee9ca5b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: +xIH/qs9SeLZBmT9AA9CJXtH0osl25k/gmmVTjjb3Cbkf8VJ7BpPhDIu6KMSs6Y3vNiNRWBuDRWNb07nXbiLvg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR03MB4476 X-OriginatorOrg: citrix.com On Fri, Apr 30, 2021 at 04:16:24PM +0200, Jan Beulich wrote: > On 30.04.2021 11:55, Roger Pau Monné wrote: > > On Mon, Apr 12, 2021 at 04:12:41PM +0200, Jan Beulich wrote: > >> --- a/xen/arch/x86/x86_64/compat/mm.c > >> +++ b/xen/arch/x86/x86_64/compat/mm.c > >> @@ -155,8 +155,10 @@ int compat_arch_memory_op(unsigned long > >> case XENMEM_get_sharing_shared_pages: > >> return mem_sharing_get_nr_shared_mfns(); > >> > >> +#ifdef CONFIG_MEM_PAGING > >> case XENMEM_paging_op: > >> return mem_paging_memop(guest_handle_cast(arg, xen_mem_paging_op_t)); > >> +#endif > >> > >> #ifdef CONFIG_MEM_SHARING > >> case XENMEM_sharing_op: > >> --- a/xen/arch/x86/x86_64/mm.c > >> +++ b/xen/arch/x86/x86_64/mm.c > >> @@ -994,8 +994,10 @@ long subarch_memory_op(unsigned long cmd > >> case XENMEM_get_sharing_shared_pages: > >> return mem_sharing_get_nr_shared_mfns(); > >> > >> +#ifdef CONFIG_MEM_PAGING > >> case XENMEM_paging_op: > >> return mem_paging_memop(guest_handle_cast(arg, xen_mem_paging_op_t)); > >> +#endif > > > > I would create a dummy handler when !CONFIG_MEM_PAGING in > > asm-x86/mem_paging.h. > > I was simply following the neighboring mem-sharing approach, > which you've stripped here, but which is still visible in the > xen/arch/x86/x86_64/compat/mm.c change above. I think the two > are helpful to be similar in such aspects. > > >> --- a/xen/include/asm-x86/p2m.h > >> +++ b/xen/include/asm-x86/p2m.h > >> @@ -136,11 +136,16 @@ typedef unsigned int p2m_query_t; > >> #define P2M_PAGEABLE_TYPES (p2m_to_mask(p2m_ram_rw) \ > >> | p2m_to_mask(p2m_ram_logdirty) ) > >> > >> +#ifdef CONFIG_MEM_PAGING > >> #define P2M_PAGING_TYPES (p2m_to_mask(p2m_ram_paging_out) \ > >> | p2m_to_mask(p2m_ram_paged) \ > >> | p2m_to_mask(p2m_ram_paging_in)) > >> > >> #define P2M_PAGED_TYPES (p2m_to_mask(p2m_ram_paged)) > >> +#else > >> +#define P2M_PAGING_TYPES 0 > >> +#define P2M_PAGED_TYPES 0 > >> +#endif > > > > Since you don't guard the p2m related paged types in p2m_type_t is it > > worth having diverging P2M_{PAGING/PAGED}_TYPES? > > > > I guess it might be required in order to force the compiler to DCE > > without having to add yet more CONFIG_MEM_PAGING guards? > > Indeed, this is the reason. > > > I don't really have a strong opinion on whether the code should be > > removed, IMO it's best to start by making it off by default at build > > time and remove it in a later release? > > Matches my way of thinking. I also wouldn't want to be the one to > delete code completely out of the blue. Acked-by: Roger Pau Monné Thanks.