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References: <20220318150635.24600-1-Jonathan.Cameron@huawei.com> <20220318150635.24600-28-Jonathan.Cameron@huawei.com> Date: Mon, 28 Mar 2022 14:50:23 +0200 In-Reply-To: <20220318150635.24600-28-Jonathan.Cameron@huawei.com> (Jonathan Cameron's message of "Fri, 18 Mar 2022 15:06:16 +0000") Message-ID: <87lewu8cmo.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.11.54.2 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Ben Widawsky , "Michael S . Tsirkin" , Mark Cave-Ayland , David Hildenbrand , Chris Browy , linuxarm@huawei.com, linux-cxl@vger.kernel.org, qemu-devel@nongnu.org, Shreyas Shah , Peter Xu , Saransh Gupta1 , Shameerali Kolothum Thodi , Paolo Bonzini , Marcel Apfelbaum , Igor Mammedov , Samarth Saxena , Alex =?utf-8?Q?Benn?= =?utf-8?Q?=C3=A9e?= , Dan Williams , Philippe =?utf-8?Q?Mathieu-Daud?= =?utf-8?Q?=C3=A9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Jonathan Cameron writes: > From: Jonathan Cameron > > The concept of these is introduced in [1] in terms of the > description the CEDT ACPI table. The principal is more general. > Unlike once traffic hits the CXL root bridges, the host system > memory address routing is implementation defined and effectively > static once observable by standard / generic system software. > Each CXL Fixed Memory Windows (CFMW) is a region of PA space > which has fixed system dependent routing configured so that > accesses can be routed to the CXL devices below a set of target > root bridges. The accesses may be interleaved across multiple > root bridges. > > For QEMU we could have fully specified these regions in terms > of a base PA + size, but as the absolute address does not matter > it is simpler to let individual platforms place the memory regions. > > ExampleS: > -cxl-fixed-memory-window targets.0=cxl.0,size=128G > -cxl-fixed-memory-window targets.0=cxl.1,size=128G > -cxl-fixed-memory-window targets.0=cxl0,targets.1=cxl.1,size=256G,interleave-granularity=2k > > Specifies > * 2x 128G regions not interleaved across root bridges, one for each of > the root bridges with ids cxl.0 and cxl.1 > * 256G region interleaved across root bridges with ids cxl.0 and cxl.1 > with a 2k interleave granularity. > > When system software enumerates the devices below a given root bridge > it can then decide which CFMW to use. If non interleave is desired > (or possible) it can use the appropriate CFMW for the root bridge in > question. If there are suitable devices to interleave across the > two root bridges then it may use the 3rd CFMS. > > A number of other designs were considered but the following constraints > made it hard to adapt existing QEMU approaches to this particular problem. > 1) The size must be known before a specific architecture / board brings > up it's PA memory map. We need to set up an appropriate region. > 2) Using links to the host bridges provides a clean command line interface > but these links cannot be established until command line devices have > been added. > > Hence the two step process used here of first establishing the size, > interleave-ways and granularity + caching the ids of the host bridges > and then, once available finding the actual host bridges so they can > be used later to support interleave decoding. > > [1] CXL 2.0 ECN: CEDT CFMWS & QTG DSM (computeexpresslink.org / specifications) > > Signed-off-by: Jonathan Cameron [...] > diff --git a/qapi/machine.json b/qapi/machine.json > index 42fc68403d..e4e64096ca 100644 > --- a/qapi/machine.json > +++ b/qapi/machine.json > @@ -504,6 +504,24 @@ > 'dst': 'uint16', > 'val': 'uint8' }} > > +## > +# @CXLFixedMemoryWindowOptions: > +# > +# Create a CXL Fixed Memory Window (for OptsVisitor) Please drop "(for OptsVisitor)". It's no longer true. Aside: I'd ask to drop it even if it was true, because it's about an implementation detail. Such details don't belong in doc comments, which become QMP *user* documentation. I know we have the same parenthesis elsewhere. It should be dropped there as well, but that's not this series' problem. > +# > +# @size: Size in bytes of the Fixed Memory Window I'm not a native speaker, but "Size of the fixed memory window in bytes" sounds better to me. Are arbitrary sizes accepted? > +# @interleave-granularity: Number of contiguous bytes for which > +# accesses will go to a given interleave target. > +# @targets: Target root bridge IDs What kind of IDs are these? Hmm, the CLI help text below suggest qdev IDs (the ones in -device id=...). Correct? > +# > +# Since 6.3 7.1 most likely. > +## > +{ 'struct': 'CXLFixedMemoryWindowOptions', > + 'data': { > + 'size': 'size', > + '*interleave-granularity': 'size', > + 'targets': ['str'] }} > + > ## > # @X86CPURegister32: > # > diff --git a/qemu-options.hx b/qemu-options.hx > index 58f2f76775..764f57606d 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -467,6 +467,44 @@ SRST > -numa hmat-cache,node-id=1,size=10K,level=1,associativity=direct,policy=write-back,line=8 > ERST > > +DEF("cxl-fixed-memory-window", HAS_ARG, QEMU_OPTION_cxl_fixed_memory_window, > + "-cxl-fixed-memory-window targets.0=firsttarget,targets.1=secondtarget,size=size[,interleave-granularity=granularity]\n", > + QEMU_ARCH_ALL) > +SRST > +``-cxl-fixed-memory-window targets.0=firsttarget,targets.1=secondtarget,size=size[,interleave-granularity=granularity]`` > + Define a CXL Fixed Memory Window (CFMW). > + > + Described in the CXL 2.0 ECN: CEDT CFMWS & QTG _DSM. > + > + They are regions of Host Physical Addresses (HPA) on a system which > + may be interleaved across one or more CXL host bridges. The system > + software will assign particular devices into these windows and > + configure the downstream Host-managed Device Memory (HDM) decoders > + in root ports, switch ports and devices appropriately to meet the > + interleave requirements before enabling the memory devices. > + > + ``targets.X=firsttarget`` provides the mapping to CXL host bridges > + which may be identified by the id provied in the -device entry. > + Multiple entries are needed to specify all the targets when > + the fixed memory window represents interleaved memory. X is the > + target index from 0. > + > + ``size=size`` sets the size of the CFMW. This must be a multiple of > + 256MiB. The region will be aligned to 256MiB but the location is > + platform and configuration dependent. > + > + ``interleave-granularity=granularity`` sets the granularity of > + interleave. Default 256KiB. Only 256KiB, 512KiB, 1024KiB, 2048KiB > + 4096KiB, 8192KiB and 16384KiB granularities supported. > + > + Example: > + > + :: > + > + -cxl-fixed-memory-window -targets.0=cxl.0,-targets.1=cxl.1,size=128G,interleave-granularity=512k > + > +ERST > + > DEF("add-fd", HAS_ARG, QEMU_OPTION_add_fd, > "-add-fd fd=fd,set=set[,opaque=opaque]\n" > " Add 'fd' to fd 'set'\n", QEMU_ARCH_ALL) > diff --git a/softmmu/vl.c b/softmmu/vl.c > index 0b81f61535..dab1eb3380 100644 > --- a/softmmu/vl.c > +++ b/softmmu/vl.c > @@ -92,6 +92,7 @@ > #include "qemu/config-file.h" > #include "qemu/qemu-options.h" > #include "qemu/main-loop.h" > +#include "hw/cxl/cxl.h" > #ifdef CONFIG_VIRTFS > #include "fsdev/qemu-fsdev.h" > #endif > @@ -117,6 +118,7 @@ > #include "qapi/qapi-events-run-state.h" > #include "qapi/qapi-visit-block-core.h" > #include "qapi/qapi-visit-compat.h" > +#include "qapi/qapi-visit-machine.h" > #include "qapi/qapi-visit-ui.h" > #include "qapi/qapi-commands-block-core.h" > #include "qapi/qapi-commands-migration.h" > @@ -140,6 +142,11 @@ typedef struct BlockdevOptionsQueueEntry { > > typedef QSIMPLEQ_HEAD(, BlockdevOptionsQueueEntry) BlockdevOptionsQueue; > > +typedef struct CXLFMWOptionQueueEntry { > + CXLFixedMemoryWindowOptions *opts; > + QSIMPLEQ_ENTRY(CXLFMWOptionQueueEntry) entry; > +} CXLFMWOptionQueueEntry; > + > typedef struct ObjectOption { > ObjectOptions *opts; > QTAILQ_ENTRY(ObjectOption) next; > @@ -166,6 +173,8 @@ static int snapshot; > static bool preconfig_requested; > static QemuPluginList plugin_list = QTAILQ_HEAD_INITIALIZER(plugin_list); > static BlockdevOptionsQueue bdo_queue = QSIMPLEQ_HEAD_INITIALIZER(bdo_queue); > +static QSIMPLEQ_HEAD(, CXLFMWOptionQueueEntry) CXLFMW_opts = > + QSIMPLEQ_HEAD_INITIALIZER(CXLFMW_opts); > static bool nographic = false; > static int mem_prealloc; /* force preallocation of physical target memory */ > static ram_addr_t ram_size; > @@ -1149,6 +1158,23 @@ static void parse_display(const char *p) > } > } > > +static void parse_cxl_fixed_memory_window(const char *optarg) > +{ > + CXLFMWOptionQueueEntry *cfmws_entry; > + Visitor *v; > + > + v = qobject_input_visitor_new_str(optarg, "cxl-fixed-memory-window", > + &error_fatal); > + cfmws_entry = g_new(CXLFMWOptionQueueEntry, 1); > + visit_type_CXLFixedMemoryWindowOptions(v, NULL, &cfmws_entry->opts, > + &error_fatal); > + if (!cfmws_entry->opts) { > + exit(1); > + } > + visit_free(v); If you loc_save() here like we do for QEMU_OPTION_blockdev, and ... > + QSIMPLEQ_INSERT_TAIL(&CXLFMW_opts, cfmws_entry, entry); > +} > + > static inline bool nonempty_str(const char *str) > { > return str && *str; > @@ -2020,6 +2046,19 @@ static void qemu_create_late_backends(void) > qemu_semihosting_console_init(); > } > > +static void cxl_set_opts(void) > +{ > + while (!QSIMPLEQ_EMPTY(&CXLFMW_opts)) { > + CXLFMWOptionQueueEntry *cfmws_entry = QSIMPLEQ_FIRST(&CXLFMW_opts); > + > + QSIMPLEQ_REMOVE_HEAD(&CXLFMW_opts, entry); ... loc_pop() here, like we do in configure_blockdev(), then the error messages from cxl_fixed_memory_window_options_set() will point to the offending option, which is nice. Give it a try, please. > + cxl_fixed_memory_window_options_set(current_machine, cfmws_entry->opts, Line is a bit long. Name the function cxl_fixed_memory_window_config()? > + &error_fatal); > + qapi_free_CXLFixedMemoryWindowOptions(cfmws_entry->opts); > + g_free(cfmws_entry); > + } > +} > + > static bool have_custom_ram_size(void) > { > QemuOpts *opts = qemu_find_opts_singleton("memory"); > @@ -2745,6 +2784,7 @@ void qmp_x_exit_preconfig(Error **errp) > > qemu_init_board(); > qemu_create_cli_devices(); > + cxl_fixed_memory_window_link_targets(errp); > qemu_machine_creation_done(); > > if (loadvm) { > @@ -2925,6 +2965,9 @@ void qemu_init(int argc, char **argv, char **envp) > exit(1); > } > break; > + case QEMU_OPTION_cxl_fixed_memory_window: > + parse_cxl_fixed_memory_window(optarg); > + break; > case QEMU_OPTION_display: > parse_display(optarg); > break; > @@ -3762,6 +3805,7 @@ void qemu_init(int argc, char **argv, char **envp) > > qemu_resolve_machine_memdev(); > parse_numa_opts(current_machine); > + cxl_set_opts(); > > if (vmstate_dump_file) { > /* dump and exit */