qemu-e2k/hw/cxl/cxl-host-stubs.c

/*
 * CXL host parameter parsing routine stubs
 *
 * Copyright (c) 2022 Huawei
 */
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "hw/cxl/cxl.h"

void cxl_fixed_memory_window_config(MachineState *ms,
                                    CXLFixedMemoryWindowOptions *object,
                                    Error **errp) {};

void cxl_fixed_memory_window_link_targets(Error **errp) {};

const MemoryRegionOps cfmws_ops;
hw/cxl/host: Add support for CXL Fixed Memory Windows. 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.cameron@huawei.com> Acked-by: Markus Armbruster <armbru@redhat.com> # QAPI Schema Message-Id: <20220429144110.25167-28-Jonathan.Cameron@huawei.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> 2022-04-29 16:40:52 +02:00			`/*`
			`* CXL host parameter parsing routine stubs`
			`*`
			`* Copyright (c) 2022 Huawei`
			`*/`
			`#include "qemu/osdep.h"`
			`#include "qapi/error.h"`
			`#include "hw/cxl/cxl.h"`

			`void cxl_fixed_memory_window_config(MachineState *ms,`
			`CXLFixedMemoryWindowOptions *object,`
			`Error **errp) {};`

			`void cxl_fixed_memory_window_link_targets(Error **errp) {};`
cxl/cxl-host: Add memops for CFMWS region. These memops perform interleave decoding, walking down the CXL topology from CFMWS described host interleave decoder via CXL host bridge HDM decoders, through the CXL root ports and finally call CXL type 3 specific read and write functions. Note that, whilst functional the current implementation does not support: * switches * multiple HDM decoders at a given level. * unaligned accesses across the interleave boundaries Signed-off-by: Jonathan Cameron <jonathan.cameron@huawei.com> Message-Id: <20220429144110.25167-34-Jonathan.Cameron@huawei.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> 2022-04-29 16:40:58 +02:00
			`const MemoryRegionOps cfmws_ops;`