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Wysocki" , "Williams, Dan J" , "Moore, Robert" CC: "Wysocki, Rafael J" , Len Brown , Borislav Petkov , "Weiny, Ira" , James Morse , Myron Stowe , Andy Shevchenko , "linux-kernel@vger.kernel.org" , "linux-acpi@vger.kernel.org" , "linux-nvdimm@lists.01.org" Subject: RE: [RFT][PATCH v2 3/4] ACPICA: Preserve memory opregion mappings if supported by OS Thread-Topic: [RFT][PATCH v2 3/4] ACPICA: Preserve memory opregion mappings if supported by OS Thread-Index: AQHWSJ3r9KMXSpAH80ik4s+HK21kMKjrgw4Q Date: Fri, 26 Jun 2020 22:53:27 +0000 Message-ID: References: <158889473309.2292982.18007035454673387731.stgit@dwillia2-desk3.amr.corp.intel.com> <2713141.s8EVnczdoM@kreacher> <13749323.0m2ImmhSHx@kreacher> In-Reply-To: <13749323.0m2ImmhSHx@kreacher> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: dlp-version: 11.2.0.6 dlp-product: dlpe-windows dlp-reaction: no-action authentication-results: rjwysocki.net; dkim=none (message not signed) header.d=none;rjwysocki.net; dmarc=none action=none header.from=intel.com; x-originating-ip: [50.39.104.236] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 540bc442-6129-4e2b-6da8-08d81a23bd3e x-ms-traffictypediagnostic: MWHPR11MB1295: x-ld-processed: 46c98d88-e344-4ed4-8496-4ed7712e255d,ExtAddr,ExtFwd x-ms-exchange-transport-forked: True x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:10000; x-forefront-prvs: 0446F0FCE1 x-ms-exchange-senderadcheck: 1 x-microsoft-antispam: BCL:0; x-microsoft-antispam-message-info: 9BnIAXr1fynaDRsoaKVl1xRSdOoH/0pATGGThCWLAu0T/tSJzFxBFjJGbkNJxFkWp8ie0+d1fJzoq2mXUT3+dkpCSAy1miaX2O0dMGTt9TfBvIQImYAM61IyX2S6U1zbMU70uoThz7RHoQt+ybPWVyKAOYt+485UK9KiwR7aJtUWTiahL54T1Xb/gWWzX+6bp8+MEJ3Niff9LIUjQMKqA6hpPqECaRK2HIc6d5fUVjonvSnY+ZTisgf0VHNXK6asUrRqs5KRhWxMJrfCes1S8AQKdaUaugXIcrZE+W18+SGxelVnIkWwMlUWKSngyBkhBewHdHsp9YPkeVTy7eehHw== x-forefront-antispam-report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:MWHPR11MB1599.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFTY:;SFS:(4636009)(396003)(376002)(366004)(346002)(39860400002)(136003)(54906003)(66556008)(26005)(110136005)(66446008)(64756008)(76116006)(71200400001)(52536014)(33656002)(6636002)(66946007)(316002)(66476007)(186003)(7696005)(30864003)(8676002)(2906002)(6506007)(83380400001)(55016002)(86362001)(8936002)(7416002)(5660300002)(53546011)(478600001)(9686003)(4326008);DIR:OUT;SFP:1102; x-ms-exchange-antispam-messagedata: E3ijdBQ+CmQ9pHZWq8Tu6Rlt1p+lTyW6mGT1p3Z07O1S1+8Rb34sJG74PXlN5TgBvKPw0T0CHbWwT7NfIXKmdYKvNCHaU1m/QQtT+LnlN+g68b7VtxwgUTYmPWMq+kUUdWfG8UFjc8068dd0OLIUfYv4kPv4j1E5hmf9KaYUXPgdXIdaYZxd5SyelBC3royGyRBDPJH5HR3ywB7097bDa7CP7i4DXhVXwzIf2U04Khpd9P5COF8jc3SroHaxQq0d0G10D0D836kllsKwMqN2fKaanSCc/0GNSdlegUMwYVGivBO3dFPmacxDesHSK8msN22ENpVo/ueBf8gAxtrOcgAsic7cpmldUrdUkxMLPK9XBHqrEej35MOGYlD8ZOoE3TOzPaa6zDDA16Cub5Kxqt5SbDJhyqDA4AezLMzHi5KhIXAyGo4qtW0xSd0dFdRQvbY+9MaMgvV3FiGNPfjCZhh7ocBoy4ac5jIK07UCLkE= Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: MWHPR11MB1599.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 540bc442-6129-4e2b-6da8-08d81a23bd3e X-MS-Exchange-CrossTenant-originalarrivaltime: 26 Jun 2020 22:53:27.2618 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: DlZ9VCJerGmJEFIbItvoA0Rm4lWzDBJeBgaHs/NYF+oVR+3ESfY1hjz2O6iINEkXvo3aUo/3XTZxkihQsf3ZHQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR11MB1295 X-OriginatorOrg: intel.com Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org > -----Original Message----- > From: Rafael J. Wysocki > Sent: Monday, June 22, 2020 7:02 AM > To: Williams, Dan J ; Kaneda, Erik > > Cc: Wysocki, Rafael J ; Len Brown > ; Borislav Petkov ; Weiny, Ira > ; James Morse ; Myron > Stowe ; Andy Shevchenko > ; linux-kernel@vger.kernel.org; linux- > acpi@vger.kernel.org; linux-nvdimm@lists.01.org; Moore, Robert > > Subject: [RFT][PATCH v2 3/4] ACPICA: Preserve memory opregion mappings > if supported by OS >=20 > From: "Rafael J. Wysocki" >=20 > The ACPICA's strategy with respect to the handling of memory mappings > associated with memory operation regions is to avoid mapping the > entire region at once which may be problematic at least in principle > (for example, it may lead to conflicts with overlapping mappings > having different attributes created by drivers). It may also be > wasteful, because memory opregions on some systems take up vast > chunks of address space while the fields in those regions actually > accessed by AML are sparsely distributed. >=20 > For this reason, a one-page "window" is mapped for a given opregion > on the first memory access through it and if that "window" does not > cover an address range accessed through that opregion subsequently, > it is unmapped and a new "window" is mapped to replace it. Next, > if the new "window" is not sufficient to access memory through the > opregion in question in the future, it will be replaced with yet > another "window" and so on. That may lead to a suboptimal sequence > of memory mapping and unmapping operations, for example if two fields > in one opregion separated from each other by a sufficiently wide > chunk of unused address space are accessed in an alternating pattern. >=20 > The situation may still be suboptimal if the deferred unmapping > introduced previously is supported by the OS layer. For instance, > the alternating memory access pattern mentioned above may produce > a relatively long list of mappings to release with substantial > duplication among the entries in it, which could be avoided if > acpi_ex_system_memory_space_handler() did not release the mapping > used by it previously as soon as the current access was not covered > by it. >=20 > In order to improve that, modify acpi_ex_system_memory_space_handler() > to take advantage of the memory mappings reference counting at the OS > level if a suitable interface is provided. >=20 Hi, > Namely, if ACPI_USE_FAST_PATH_MAPPING is set, the OS is expected to > implement acpi_os_map_memory_fast_path() that will return NULL if > there is no mapping covering the given address range known to it. > If such a mapping is there, however, its reference counter will be > incremented and a pointer representing the requested virtual address > will be returned right away without any additional consequences. I do not fully understand why this is under a #ifdef. Is this to support op= erating systems that might not want to add support for this behavior? Also, instead of using the terminology fast_path, I think it would be easie= r to use terminology that describes the mechanism.. It might be easier for other Operating systems to understand something like= acpi_os_map_preserved_memory or acpi_os_map_sysmem_opregion_memory. Thanks, Erik >=20 > That allows acpi_ex_system_memory_space_handler() to acquire > additional references to all new memory mappings with the help > of acpi_os_map_memory_fast_path() so as to retain them until the > memory opregions associated with them go away. The function will > still use a new "window" mapping if the current one does not > cover the address range at hand, but it will avoid unmapping the > current one right away by adding it to a list of "known" mappings > associated with the given memory opregion which will be deleted at > the opregion deactivation time. The mappings in that list can be > used every time a "new window" is needed so as to avoid overhead > related to the mapping and unmapping of memory. >=20 > Signed-off-by: Rafael J. Wysocki > --- > drivers/acpi/acpica/acinterp.h | 4 + > drivers/acpi/acpica/evrgnini.c | 7 +- > drivers/acpi/acpica/exregion.c | 159 > ++++++++++++++++++++++++++++++++- > 3 files changed, 162 insertions(+), 8 deletions(-) >=20 > diff --git a/drivers/acpi/acpica/acinterp.h b/drivers/acpi/acpica/acinter= p.h > index 1f1026fb06e9..db9c279baa2e 100644 > --- a/drivers/acpi/acpica/acinterp.h > +++ b/drivers/acpi/acpica/acinterp.h > @@ -479,8 +479,12 @@ void acpi_ex_pci_cls_to_string(char *dest, u8 > class_code[3]); >=20 > u8 acpi_is_valid_space_id(u8 space_id); >=20 > +struct acpi_mem_space_context > *acpi_ex_alloc_mem_space_context(void); > + > void acpi_ex_unmap_region_memory(struct acpi_mem_space_context > *mem_info); >=20 > +void acpi_ex_unmap_all_region_mappings(struct > acpi_mem_space_context *mem_info); > + > /* > * exregion - default op_region handlers > */ > diff --git a/drivers/acpi/acpica/evrgnini.c b/drivers/acpi/acpica/evrgnin= i.c > index 9f33114a74ca..f6c5feea10bc 100644 > --- a/drivers/acpi/acpica/evrgnini.c > +++ b/drivers/acpi/acpica/evrgnini.c > @@ -46,10 +46,10 @@ acpi_ev_system_memory_region_setup(acpi_handle > handle, > local_region_context =3D > (struct acpi_mem_space_context > *)*region_context; >=20 > - /* Delete a cached mapping if present */ > + /* Delete memory mappings if present */ >=20 > if (local_region_context->mapped_length) { > - > acpi_ex_unmap_region_memory(local_region_context); > + > acpi_ex_unmap_all_region_mappings(local_region_context); > } > ACPI_FREE(local_region_context); > *region_context =3D NULL; > @@ -59,8 +59,7 @@ acpi_ev_system_memory_region_setup(acpi_handle > handle, >=20 > /* Create a new context */ >=20 > - local_region_context =3D > - ACPI_ALLOCATE_ZEROED(sizeof(struct > acpi_mem_space_context)); > + local_region_context =3D acpi_ex_alloc_mem_space_context(); > if (!(local_region_context)) { > return_ACPI_STATUS(AE_NO_MEMORY); > } > diff --git a/drivers/acpi/acpica/exregion.c b/drivers/acpi/acpica/exregio= n.c > index af777b7fccb0..9d97b6a67074 100644 > --- a/drivers/acpi/acpica/exregion.c > +++ b/drivers/acpi/acpica/exregion.c > @@ -14,6 +14,40 @@ > #define _COMPONENT ACPI_EXECUTER > ACPI_MODULE_NAME("exregion") >=20 > +struct acpi_mem_mapping { > + acpi_physical_address physical_address; > + u8 *logical_address; > + acpi_size length; > + struct acpi_mem_mapping *next_mm; > +}; > + > +struct acpi_mm_context { > + struct acpi_mem_space_context mem_info; > + struct acpi_mem_mapping *first_mm; > +}; > + > +/********************************************************* > ******************** > + * > + * FUNCTION: acpi_ex_alloc_mem_space_context > + * > + * PARAMETERS: None > + * > + * RETURN: Pointer to a new region context object. > + * > + * DESCRIPTION: Allocate memory for memory operation region > representation. > + * > + > ********************************************************** > ******************/ > +struct acpi_mem_space_context > *acpi_ex_alloc_mem_space_context(void) > +{ > + ACPI_FUNCTION_TRACE(acpi_ex_alloc_mem_space_context); > + > +#ifdef ACPI_USE_FAST_PATH_MAPPING > + return ACPI_ALLOCATE_ZEROED(sizeof(struct acpi_mm_context)); > +#else > + return ACPI_ALLOCATE_ZEROED(sizeof(struct > acpi_mem_space_context)); > +#endif > +} > + >=20 > /********************************************************** > ******************* > * > * FUNCTION: acpi_ex_unmap_region_memory > @@ -40,6 +74,44 @@ void acpi_ex_unmap_region_memory(struct > acpi_mem_space_context *mem_info) > return_VOID; > } >=20 > +/********************************************************* > ******************** > + * > + * FUNCTION: acpi_ex_unmap_all_region_mappings > + * > + * PARAMETERS: mem_info - Region specific context > + * > + * RETURN: None > + * > + * DESCRIPTION: Unmap all mappings associated with a memory operation > region. > + * > + > ********************************************************** > ******************/ > +void acpi_ex_unmap_all_region_mappings(struct > acpi_mem_space_context *mem_info) > +{ > +#ifdef ACPI_USE_FAST_PATH_MAPPING > + struct acpi_mm_context *mm_context =3D (struct acpi_mm_context > *)mem_info; > + struct acpi_mem_mapping *mm; > +#endif > + > + ACPI_FUNCTION_TRACE(acpi_ex_unmap_all_region_mappings); > + > + acpi_ex_unmap_region_memory(mem_info); > + > +#ifdef ACPI_USE_FAST_PATH_MAPPING > + while (mm_context->first_mm) { > + mm =3D mm_context->first_mm; > + mm_context->first_mm =3D mm->next_mm; > +#ifdef ACPI_USE_DEFERRED_UNMAPPING > + acpi_os_unmap_deferred(mm->logical_address, mm- > >length); > +#else > + acpi_os_unmap_memory(mm->logical_address, mm- > >length); > +#endif > + ACPI_FREE(mm); > + } > +#endif /* ACPI_USE_FAST_PATH_MAPPING */ > + > + return_VOID; > +} > + >=20 > /********************************************************** > ********************* > * > * FUNCTION: acpi_ex_system_memory_space_handler > @@ -70,6 +142,10 @@ acpi_ex_system_memory_space_handler(u32 > function, > u32 length; > acpi_size map_length; > acpi_size page_boundary_map_length; > +#ifdef ACPI_USE_FAST_PATH_MAPPING > + struct acpi_mm_context *mm_context =3D (struct acpi_mm_context > *)mem_info; > + struct acpi_mem_mapping *mm; > +#endif > #ifdef ACPI_MISALIGNMENT_NOT_SUPPORTED > u32 remainder; > #endif > @@ -128,7 +204,7 @@ acpi_ex_system_memory_space_handler(u32 > function, > mem_info->mapped_length))) { > /* > * The request cannot be resolved by the current memory > mapping; > - * Delete the existing mapping and create a new one. > + * Delete the current cached mapping and get a new one. > */ > if (mem_info->mapped_length) { >=20 > @@ -137,6 +213,36 @@ acpi_ex_system_memory_space_handler(u32 > function, > acpi_ex_unmap_region_memory(mem_info); > } >=20 > +#ifdef ACPI_USE_FAST_PATH_MAPPING > + /* > + * Look for an existing saved mapping matching the address > range > + * at hand. If found, make the OS layer bump up the > reference > + * counter of that mapping, cache it and carry out the access. > + */ > + for (mm =3D mm_context->first_mm; mm; mm =3D mm- > >next_mm) { > + if (address < mm->physical_address) > + continue; > + > + if ((u64)address + length > > + (u64)mm->physical_address + mm- > >length) > + continue; > + > + /* > + * When called on a known-existing memory mapping, > + * acpi_os_map_memory_fast_path() must return > the same > + * logical address as before or NULL. > + */ > + if (!acpi_os_map_memory_fast_path(mm- > >physical_address, > + mm->length)) > + continue; > + > + mem_info->mapped_logical_address =3D mm- > >logical_address; > + mem_info->mapped_physical_address =3D mm- > >physical_address; > + mem_info->mapped_length =3D mm->length; > + goto access; > + } > +#endif /* ACPI_USE_FAST_PATH_MAPPING */ > + > /* > * October 2009: Attempt to map from the requested > address to the > * end of the region. However, we will never map more than > one > @@ -168,9 +274,8 @@ acpi_ex_system_memory_space_handler(u32 > function, >=20 > /* Create a new mapping starting at the address given */ >=20 > - mem_info->mapped_logical_address =3D > - acpi_os_map_memory(address, map_length); > - if (!mem_info->mapped_logical_address) { > + logical_addr_ptr =3D acpi_os_map_memory(address, > map_length); > + if (!logical_addr_ptr) { > ACPI_ERROR((AE_INFO, > "Could not map memory at 0x%8.8X%8.8X, > size %u", > ACPI_FORMAT_UINT64(address), > @@ -181,10 +286,56 @@ acpi_ex_system_memory_space_handler(u32 > function, >=20 > /* Save the physical address and mapping size */ >=20 > + mem_info->mapped_logical_address =3D logical_addr_ptr; > mem_info->mapped_physical_address =3D address; > mem_info->mapped_length =3D map_length; > + > +#ifdef ACPI_USE_FAST_PATH_MAPPING > + /* > + * Create a new mm list entry to save the new mapping for > + * removal at the operation region deactivation time. > + */ > + mm =3D ACPI_ALLOCATE_ZEROED(sizeof(*mm)); > + if (!mm) { > + /* > + * No room to save the new mapping, but this is not > + * critical. Just log the error and carry out the > + * access as requested. > + */ > + ACPI_ERROR((AE_INFO, > + "Not enough memory to save memory > mapping at 0x%8.8X%8.8X, size %u", > + ACPI_FORMAT_UINT64(address), > + (u32)map_length)); > + goto access; > + } > + /* > + * Bump up the new mapping's reference counter in the OS > layer > + * to prevent it from getting dropped prematurely. > + */ > + if (!acpi_os_map_memory_fast_path(address, map_length)) > { > + /* > + * Something has gone wrong, but this is not critical. > + * Log the error, free the mm list entry that won't be > + * used and carry out the access as requested. > + */ > + ACPI_ERROR((AE_INFO, > + "Unable to save memory mapping at > 0x%8.8X%8.8X, size %u", > + ACPI_FORMAT_UINT64(address), > + (u32)map_length)); > + ACPI_FREE(mm); > + goto access; > + } > + mm->physical_address =3D address; > + mm->logical_address =3D logical_addr_ptr; > + mm->length =3D map_length; > + mm->next_mm =3D mm_context->first_mm; > + mm_context->first_mm =3D mm; > } >=20 > +access: > +#else /* !ACPI_USE_FAST_PATH_MAPPING */ > + } > +#endif /* !ACPI_USE_FAST_PATH_MAPPING */ > /* > * Generate a logical pointer corresponding to the address we want > to > * access > -- > 2.26.2 >=20 >=20 >=20