Jonathan Cameron <jonathan.came...@huawei.com> writes:
> From: Jonathan Cameron <jonathan.came...@huawei.com>
>
> 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 <jonathan.came...@huawei.com>
[...]
> 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 */
