Jonathan Cameron via <qemu-devel@nongnu.org> 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=cxl.0,size=128G
> -cxl-fixed-memory-window targets=cxl.1,size=128G
> -cxl-fixed-memory-window
> targets=cxl0,targets=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/hw/cxl/cxl-host.c b/hw/cxl/cxl-host.c
> new file mode 100644
> index 0000000000..9f303e6d8e
> --- /dev/null
> +++ b/hw/cxl/cxl-host.c
[...]
> +QemuOptsList qemu_cxl_fixed_window_opts = {
> + .name = "cxl-fixed-memory-window",
> + .implied_opt_name = "type",
> + .head = QTAILQ_HEAD_INITIALIZER(qemu_cxl_fixed_window_opts.head),
> + .desc = { { 0 } }
> +};
> +
[...]
> +static int parse_cxl_fixed_memory_window(void *opaque, QemuOpts *opts,
> + Error **errp)
> +{
> + CXLFixedMemoryWindowOptions *object = NULL;
> + MachineState *ms = MACHINE(opaque);
> + Error *err = NULL;
> + Visitor *v = opts_visitor_new(opts);
> +
> + visit_type_CXLFixedMemoryWindowOptions(v, NULL, &object, errp);
> + visit_free(v);
> + if (!object) {
> + return -1;
> + }
> +
> + set_cxl_fixed_memory_window_options(ms, object, &err);
> +
> + qapi_free_CXLFixedMemoryWindowOptions(object);
> + if (err) {
> + error_propagate(errp, err);
> + return -1;
> + }
> +
> + return 0;
> +}
> +
> +void parse_cxl_fixed_memory_window_opts(MachineState *ms)
> +{
> + qemu_opts_foreach(qemu_find_opts("cxl-fixed-memory-window"),
> + parse_cxl_fixed_memory_window, ms, &error_fatal);
> +}
[...]
> diff --git a/qapi/machine.json b/qapi/machine.json
> index 42fc68403d..0998a9128d 100644
> --- a/qapi/machine.json
> +++ b/qapi/machine.json
> @@ -504,6 +504,21 @@
> 'dst': 'uint16',
> 'val': 'uint8' }}
>
> +##
> +# @CXLFixedMemoryWindowOptions:
> +#
> +# Create a CXL Fixed Memory Window (for OptsVisitor)
> +#
> +# @targets: Target root bridge IDs
Missing: @size, @targets.
> +#
> +# Since X.X //fixme
Well, "fix me, please".
> +##
> +{ 'struct': 'CXLFixedMemoryWindowOptions',
> + 'data': {
> + 'size': 'size',
> + '*interleave-granularity': 'size',
> + 'targets': ['str'] }}
> +
> ##
> # @X86CPURegister32:
> #
[...]
> diff --git a/qemu-options.hx b/qemu-options.hx
> index ba3ae6a42a..b4d2cc6f48 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -467,6 +467,43 @@ 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=firsttarget,targets=secondtarget,size=size[,interleave-granularity=granularity]\n",
> + QEMU_ARCH_ALL)
> +SRST
> +``-cxl-fixed-memory-window
> targets=firsttarget,targets=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=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.
> +
> + ``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=cxl.0,-targets=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 5e1b35ba48..f83f158fff 100644
> --- a/softmmu/vl.c
> +++ b/softmmu/vl.c
> @@ -91,6 +91,7 @@
> #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
> @@ -2744,6 +2745,7 @@ 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) {
> @@ -2805,6 +2807,7 @@ void qemu_init(int argc, char **argv, char **envp)
> qemu_add_opts(&qemu_msg_opts);
> qemu_add_opts(&qemu_name_opts);
> qemu_add_opts(&qemu_numa_opts);
> + qemu_add_opts(&qemu_cxl_fixed_window_opts);
> qemu_add_opts(&qemu_icount_opts);
> qemu_add_opts(&qemu_semihosting_config_opts);
> qemu_add_opts(&qemu_fw_cfg_opts);
> @@ -2927,6 +2930,13 @@ void qemu_init(int argc, char **argv, char **envp)
> exit(1);
> }
> break;
> + case QEMU_OPTION_cxl_fixed_memory_window:
> + opts =
> qemu_opts_parse_noisily(qemu_find_opts("cxl-fixed-memory-window"),
> + optarg, true);
> + if (!opts) {
> + exit(1);
> + }
> + break;
> case QEMU_OPTION_display:
> parse_display(optarg);
> break;
> @@ -3764,6 +3774,7 @@ void qemu_init(int argc, char **argv, char **envp)
>
> qemu_resolve_machine_memdev();
> parse_numa_opts(current_machine);
> + parse_cxl_fixed_memory_window_opts(current_machine);
>
> if (vmstate_dump_file) {
> /* dump and exit */
Have you considered using qobject_input_visitor_new_str() instead of
QemuOpts?
