[RFC PATCH v3 0/1] Sbsa-ref CXL Enablement

[RFC PATCH v3 0/1] Sbsa-ref CXL Enablement

[Yuquan Wang]

v2 -> v3:
- create a new host bridge type: TYPE_SBSA_CXL_HOST
- CXL exclusive ECAM, PIO, MMIO32 & MMIO64 space in sbsa-ref
- combine all cxl infrastructure creating into one function

v1 -> v2:
- provide CXL exclusive MMIO32 & MMIO64 space
- hard coded two cxl root ports

RFC because
- Many contents are ported from Jonathan' patch on qemu virt design

- Less experience and not particularly confident in sbsa-ref address space design
  so this might be stupidly broken in a way I've not considered.

Background
==========
Currently the base CXL support for arm platforms is only on Jonathan's patches[1]
which have not yet merged into upstream. SBSA-REF can be more like a real machine,
thus the support of cxl could be meaningful.

This series leverages Jonathan's patches[1] to design [SBSA_CXL_CHBCR] and
[SBSA_CXL_FIXED_WINDOW] spaces for sbsa-ref layout. 

Regard to the burden of edk2 firmware, I try to build a static CEDT table and add
acpi0016, acpi0017 and other cxl relevant contents into acpi tables[2][3]. Hence it
doesn't need to communicate cxl contents via DT to edk2. 

CXL HOST design
===============
In previous version, the pxb-cxl-host with any cxl root ports and cxl endpoint devices
would occupy the BDF number of the original pcie domain resulting in the max available
pcie devices on sbsa-ref would decrease, which seems to bring a series of trouble. 

In this version, to avoid that problems, the new host bridge type is defined
(TYPE_SBSA_CXL_HOST). Actually, this new device could be considered as a prototype of
an independent cxl host bridge which combines gpex features(mmio windows & irq) and
pxb-cxl features(CHBCR) at meanwhile. If this could be work, we can just remove the
prefix of 'SBSA' and introduce it as a general qemu object on other boards.

For [SBSA_CXL_CHBCR], since this creates a default cxl host bridge (0001:00)
with two cxl root ports on sbsa-ref, the new memory layout places 64K space for
one hard coded cxl host bridge register regions in the sbsa-ref memmap. (Meaning
for now only two cxl type3 devices could be added on the cxl host)

And the memory layout provides separate space windows for the cxl host bridge in the
sbsa-ref memmap:
- 64K  CXL Host Bridge Component Registers (CHBCR)
- 64K  CXL_PIO
- 128M CXL_MMIO
- 256M CXL_ECAM
- 4G   CXL_MMIO_HIGH

CXL FIXED WINDOW design
=======================
For [SBSA_CXL_FIXED_WINDOW], in order to provide CFMWs on sbsa-ref, this extends 1TB
space from the hole above RAM Memory [SBSA_MEM] for CXL Fixed Memory Window. 
- 1T   CXL_FIXED_WINDOW

0xA0000000000 is chosen as the base address of this space because of 3 reasons:
1) It is more suitable to choose a static address instead of that
implementation in virt, since a dynamic address space layout of
sbsa-ref is not appropriate for its original purpose as a reference
platform.

2) The Hotplug Memory address range should in the range of maximum
addressable range of sbsa-ref platform(0x10000000000-0x80ffffffffff).
It is satisfied the requirements of memory hotplug in linux kernel.

3) The start pfn of CFMW should exceed the reserved_pfn_range for
onlined numa node.

Usage of cxl on sbsa-ref
========================
With the 'create_cxl' and 'create_cxl_fixed_window', users don't need to input
'-device pxb-cxl' , '-device cxl-rp' and '-M cxl-fmw' parameters.

Thus, to run sbsa-ref with a cxl device could use:
qemu-system-aarch64 \
-object memory-backend-file,id=mem2,mem-path=/tmp/mem2,size=256M,share=true \
-device cxl-type3,bus=cxl.0,volatile-memdev=mem2,id=cxl-mem1 \

Incompatibility problem
=======================
Although the new cxl host bridge has been separated from the original pcie host, the
incompatibility problem of "-device qemu-xhci" is not resolved. Because the new device
to plug by qemu command would be enumerated at the largest domain(0001), for example,
if we add "-device qemu-xhci" to boot sbsa-ref with cxl, the lspci would show:

    root@ubuntu-jammy-arm64:~# lspci
    0000:00:00.0 Host bridge: Red Hat, Inc. QEMU PCIe Host bridge
    0000:00:01.0 Ethernet controller: Intel Corporation 82574L Gigabit Network Connection
    0000:00:02.0 Display controller: Device 1234:1111 (rev 02)
    0001:00:00.0 PCI bridge: Intel Corporation Device 7075
    0001:00:01.0 PCI bridge: Intel Corporation Device 7075
    0001:00:02.0 USB controller: Red Hat, Inc. QEMU XHCI Host Controller (rev 01)
    0001:01:00.0 CXL: Intel Corporation Device 0d93 (rev 01)

    root@ubuntu-jammy-arm64:~# lspci -tv
    -+-[0001:00]-+-00.0-[01]----00.0  Intel Corporation Device 0d93
    |           +-01.0-[02]--
    |           \-02.0  Red Hat, Inc. QEMU XHCI Host Controller
    \-[0000:00]-+-00.0  Red Hat, Inc. QEMU PCIe Host bridge
                +-01.0  Intel Corporation 82574L Gigabit Network Connection
                \-02.0  Device 1234:1111

Hence we should add "bus=pcie.0" when we want to plug some devices on the original
pcie bus, for example:
-device qemu-xhci,bus=pcie.0 \
or
-device nvme,serial=deadbeef,bus=pcie.0,drive=hdd \
-drive file=../disk/hdd.qcow2,format=qcow2,id=hdd,if=none \

So the result is:
    root@ubuntu-jammy-arm64:~# lspci
    0000:00:00.0 Host bridge: Red Hat, Inc. QEMU PCIe Host bridge
    0000:00:01.0 Ethernet controller: Intel Corporation 82574L Gigabit Network Connection
    0000:00:02.0 Display controller: Device 1234:1111 (rev 02)
    0000:00:03.0 USB controller: Red Hat, Inc. QEMU XHCI Host Controller (rev 01)
    0001:00:00.0 PCI bridge: Intel Corporation Device 7075
    0001:00:01.0 PCI bridge: Intel Corporation Device 7075
    0001:01:00.0 CXL: Intel Corporation Device 0d93 (rev 01)

    root@ubuntu-jammy-arm64:~# lspci -tv
    -+-[0001:00]-+-00.0-[01]----00.0  Intel Corporation Device 0d93
    |           \-01.0-[02]--
    \-[0000:00]-+-00.0  Red Hat, Inc. QEMU PCIe Host bridge
                +-01.0  Intel Corporation 82574L Gigabit Network Connection
                +-02.0  Device 1234:1111
                \-03.0  Red Hat, Inc. QEMU XHCI Host Controller

I am looking for suggestions on if there are better ways to do it.

This series patches are here to hopefully some comments to guide me!

Link:
[1]: https://lore.kernel.org/linux-cxl/20220616141950.23374-1-Jonathan.Cameron@huawei.com/
[2]: https://edk2.groups.io/g/devel/topic/rfc_edk2_patch_v3_0_1/109403423#
[3]: https://edk2.groups.io/g/devel/topic/rfc_patch_edk2_platforms_v3/109768222

Yuquan Wang (1):
  hw/arm/sbsa-ref: Support CXL Host Bridge & CFMW

 docs/system/arm/sbsa.rst  |   4 +
 hw/arm/sbsa-ref.c         | 139 ++++++++++++++++++++++++++++++-
 hw/cxl/cxl-host-stubs.c   |   2 +
 hw/cxl/cxl-host.c         | 169 +++++++++++++++++++++++++++++++++++++-
 include/hw/cxl/cxl.h      |  22 +++++
 include/hw/cxl/cxl_host.h |   5 ++
 6 files changed, 339 insertions(+), 2 deletions(-)

-- 
2.34.1

[RFC PATCH v3 1/1] hw/arm/sbsa-ref: Support CXL Host Bridge & CFMW

[Yuquan Wang]

This creates a specific cxl host bridge (0001:00) with two cxl
root ports on sbsa-ref. And the memory layout provides separate
space windows for the cxl host bridge in the sbsa-ref memmap:

- 64K  CXL Host Bridge Component Registers (CHBCR)
- 64K  CXL_PIO
- 128M CXL_MMIO
- 256M CXL_ECAM
- 4G   CXL_MMIO_HIGH

To provide CFMWs on sbsa-ref, this extends 1TB space from the
hole above RAM Memory [SBSA_MEM] for CXL Fixed Memory Window:

- 1T   CXL_FIXED_WINDOW

Signed-off-by: Yuquan Wang <wangyuquan1236@phytium.com.cn>
---
 docs/system/arm/sbsa.rst  |   4 +
 hw/arm/sbsa-ref.c         | 139 ++++++++++++++++++++++++++++++-
 hw/cxl/cxl-host-stubs.c   |   2 +
 hw/cxl/cxl-host.c         | 169 +++++++++++++++++++++++++++++++++++++-
 include/hw/cxl/cxl.h      |  22 +++++
 include/hw/cxl/cxl_host.h |   5 ++
 6 files changed, 339 insertions(+), 2 deletions(-)

diff --git a/docs/system/arm/sbsa.rst b/docs/system/arm/sbsa.rst
index 2bf3fc8d59..21b88e88e7 100644
--- a/docs/system/arm/sbsa.rst
+++ b/docs/system/arm/sbsa.rst
@@ -28,6 +28,7 @@ The ``sbsa-ref`` board supports:
   - E1000E ethernet card on PCIe bus
   - Bochs display adapter on PCIe bus
   - A generic SBSA watchdog device
+  - CXL host bridge and CXL fixed memory window
 
 
 Board to firmware interface
@@ -92,3 +93,6 @@ Platform version changes:
 
 0.4
   CPU topology information is present in devicetree.
+
+0.5
+  CXL host bridge and CXL fixed memory window are supported.
diff --git a/hw/arm/sbsa-ref.c b/hw/arm/sbsa-ref.c
index e3195d5449..78aef823a6 100644
--- a/hw/arm/sbsa-ref.c
+++ b/hw/arm/sbsa-ref.c
@@ -36,12 +36,18 @@
 #include "hw/arm/smmuv3.h"
 #include "hw/block/flash.h"
 #include "hw/boards.h"
+#include "hw/cxl/cxl.h"
+#include "hw/cxl/cxl_host.h"
 #include "hw/ide/ide-bus.h"
 #include "hw/ide/ahci-sysbus.h"
 #include "hw/intc/arm_gicv3_common.h"
 #include "hw/intc/arm_gicv3_its_common.h"
 #include "hw/loader.h"
+#include "hw/pci/pci_bridge.h"
+#include "hw/pci/pci_bus.h"
+#include "hw/pci/pcie_port.h"
 #include "hw/pci-host/gpex.h"
+#include "hw/pci-bridge/pci_expander_bridge.h"
 #include "hw/qdev-properties.h"
 #include "hw/usb.h"
 #include "hw/usb/xhci.h"
@@ -94,6 +100,13 @@ enum {
     SBSA_SECURE_MEM,
     SBSA_AHCI,
     SBSA_XHCI,
+    SBSA_CXL,
+    SBSA_CXL_CHBCR,
+    SBSA_CXL_MMIO,
+    SBSA_CXL_MMIO_HIGH,
+    SBSA_CXL_PIO,
+    SBSA_CXL_ECAM,
+    SBSA_CXL_FIXED_WINDOW,
 };
 
 struct SBSAMachineState {
@@ -105,6 +118,7 @@ struct SBSAMachineState {
     int psci_conduit;
     DeviceState *gic;
     PFlashCFI01 *flash[2];
+    CXLState cxl_devices_state;
 };
 
 #define TYPE_SBSA_MACHINE   MACHINE_TYPE_NAME("sbsa-ref")
@@ -132,6 +146,14 @@ static const MemMapEntry sbsa_ref_memmap[] = {
     /* Space here reserved for more SMMUs */
     [SBSA_AHCI] =               { 0x60100000, 0x00010000 },
     [SBSA_XHCI] =               { 0x60110000, 0x00010000 },
+    /* 64K CXL Host Bridge Registers space */
+    [SBSA_CXL_CHBCR] =          { 0x60120000, 0x00010000 },
+    /* 64K CXL PIO space */
+    [SBSA_CXL_PIO] =            { 0x60130000, 0x00010000 },
+    /* 128M CXL 32-bit MMIO space */
+    [SBSA_CXL_MMIO] =           { 0x60140000, 0x08000000 },
+    /* 256M CXL ECAM space */
+    [SBSA_CXL_ECAM] =           { 0x68140000, 0x10000000 },
     /* Space here reserved for other devices */
     [SBSA_PCIE_PIO] =           { 0x7fff0000, 0x00010000 },
     /* 32-bit address PCIE MMIO space */
@@ -141,6 +163,10 @@ static const MemMapEntry sbsa_ref_memmap[] = {
     /* ~1TB PCIE MMIO space (4GB to 1024GB boundary) */
     [SBSA_PCIE_MMIO_HIGH] =     { 0x100000000ULL, 0xFF00000000ULL },
     [SBSA_MEM] =                { 0x10000000000ULL, RAMLIMIT_BYTES },
+    /* 4G CXL 64-bit MMIO space */
+    [SBSA_CXL_MMIO_HIGH] =      { 0x90000000000ULL, 0x100000000ULL },
+    /* 1TB CXL FIXED WINDOW space */
+    [SBSA_CXL_FIXED_WINDOW] =   { 0xA0000000000ULL, 0x10000000000ULL },
 };
 
 static const int sbsa_ref_irqmap[] = {
@@ -154,6 +180,7 @@ static const int sbsa_ref_irqmap[] = {
     [SBSA_XHCI] = 11,
     [SBSA_SMMU] = 12, /* ... to 15 */
     [SBSA_GWDT_WS0] = 16,
+    [SBSA_CXL] = 17, /* ... to 20 */
 };
 
 static uint64_t sbsa_ref_cpu_mp_affinity(SBSAMachineState *sms, int idx)
@@ -216,7 +243,7 @@ static void create_fdt(SBSAMachineState *sms)
      *                        fw compatibility.
      */
     qemu_fdt_setprop_cell(fdt, "/", "machine-version-major", 0);
-    qemu_fdt_setprop_cell(fdt, "/", "machine-version-minor", 4);
+    qemu_fdt_setprop_cell(fdt, "/", "machine-version-minor", 5);
 
     if (ms->numa_state->have_numa_distance) {
         int size = nb_numa_nodes * nb_numa_nodes * 3 * sizeof(uint32_t);
@@ -629,6 +656,114 @@ static void create_smmu(const SBSAMachineState *sms, PCIBus *bus)
     }
 }
 
+static void create_cxl_fixed_window(SBSAMachineState *sms,
+                               MemoryRegion *mem, SbsaCXLHost *host)
+{
+    PCIBus *cxlbus = PCI_HOST_BRIDGE(host)->bus;
+    char *cxl_host = object_get_canonical_path(OBJECT(cxlbus));
+    hwaddr base = sbsa_ref_memmap[SBSA_CXL_FIXED_WINDOW].base;
+    GList *it;
+    strList host_target = { NULL, cxl_host };
+    CXLFixedMemoryWindowOptions sbsa_ref_cfmwoptions = {
+        .size = 1 * TiB,
+        .has_interleave_granularity = false,
+        .targets = &host_target,
+    };
+    CXLFixedWindow *fw;
+
+    cxl_fixed_memory_window_config(&sms->cxl_devices_state,
+                               &sbsa_ref_cfmwoptions, &error_fatal);
+
+    it = sms->cxl_devices_state.fixed_windows;
+    fw = it->data;
+    fw->base = base;
+    fw->sbsa_target = host;
+
+    memory_region_init_io(&fw->mr, OBJECT(sms), &cfmws_ops, fw,
+                            "cxl-fixed-memory-region", fw->size);
+
+    memory_region_add_subregion(mem, fw->base, &fw->mr);
+}
+
+static void create_cxl(SBSAMachineState *sms)
+{
+    hwaddr base_ecam = sbsa_ref_memmap[SBSA_CXL_ECAM].base;
+    hwaddr size_ecam = sbsa_ref_memmap[SBSA_CXL_ECAM].size;
+    hwaddr base_mmio = sbsa_ref_memmap[SBSA_CXL_MMIO].base;
+    hwaddr size_mmio = sbsa_ref_memmap[SBSA_CXL_MMIO].size;
+    hwaddr base_mmio_high = sbsa_ref_memmap[SBSA_CXL_MMIO_HIGH].base;
+    hwaddr size_mmio_high = sbsa_ref_memmap[SBSA_CXL_MMIO_HIGH].size;
+    hwaddr base_pio = sbsa_ref_memmap[SBSA_CXL_PIO].base;
+    int irq = sbsa_ref_irqmap[SBSA_CXL];
+    MemoryRegion *mmio_alias, *mmio_alias_high, *mmio_reg;
+    MemoryRegion *ecam_alias, *ecam_reg;
+    MemoryRegion *sysmem = get_system_memory();
+    MemoryRegion *chbcr = &sms->cxl_devices_state.host_mr;
+    DeviceState *dev;
+    SbsaCXLHost *host;
+    PCIHostState *cxl;
+    PCIDevice *cxlrp;
+    PCIEPort *p;
+    PCIESlot *s;
+    int i;
+
+    dev = qdev_new(TYPE_SBSA_CXL_HOST);
+    sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
+    sms->cxl_devices_state.is_enabled = true;
+
+    /* Map CXL ECAM space */
+    ecam_alias = g_new0(MemoryRegion, 1);
+    ecam_reg = sysbus_mmio_get_region(SYS_BUS_DEVICE(dev), 1);
+    memory_region_init_alias(ecam_alias, OBJECT(dev), "cxl-ecam",
+                             ecam_reg, 0, size_ecam);
+    memory_region_add_subregion(get_system_memory(), base_ecam, ecam_alias);
+
+    /* Map CXL MMIO space */
+    mmio_alias = g_new0(MemoryRegion, 1);
+    mmio_reg = sysbus_mmio_get_region(SYS_BUS_DEVICE(dev), 2);
+    memory_region_init_alias(mmio_alias, OBJECT(dev), "cxl-mmio",
+                             mmio_reg, base_mmio, size_mmio);
+    memory_region_add_subregion(get_system_memory(), base_mmio, mmio_alias);
+
+    /* Map CXL MMIO_HIGH space */
+    mmio_alias_high = g_new0(MemoryRegion, 1);
+    memory_region_init_alias(mmio_alias_high, OBJECT(dev), "cxl-mmio-high",
+                             mmio_reg, base_mmio_high, size_mmio_high);
+    memory_region_add_subregion(get_system_memory(), base_mmio_high,
+                                mmio_alias_high);
+
+    /* Map CXL IO port space */
+    sysbus_mmio_map(SYS_BUS_DEVICE(dev), 3, base_pio);
+
+    for (i = 0; i < SBSA_CXL_NUM_IRQS; i++) {
+        sysbus_connect_irq(SYS_BUS_DEVICE(dev), i,
+                           qdev_get_gpio_in(sms->gic, irq + i));
+        sbsa_cxl_set_irq_num(SBSA_CXL_HOST(dev), i, irq + i);
+    }
+
+    /* Map CXL CHBCR space */
+    memory_region_init(chbcr, OBJECT(sms), "cxl_host_reg",
+                       sbsa_ref_memmap[SBSA_CXL_CHBCR].size);
+    memory_region_add_subregion(sysmem, sbsa_ref_memmap[SBSA_CXL_CHBCR].base, chbcr);
+
+    cxl = PCI_HOST_BRIDGE(dev);
+
+    /* Connect two cxl root ports */
+    for (i = 0; i < 2; i++) {
+        cxlrp = pci_new(-1, "cxl-rp");
+        p = PCIE_PORT(cxlrp);
+        s = PCIE_SLOT(cxlrp);
+        p->port = i;
+        s->slot = i;
+        pci_realize_and_unref(cxlrp, cxl->bus, &error_fatal);
+    }
+
+    host = SBSA_CXL_HOST(dev);
+    sbsa_cxl_hook_up_registers(&sms->cxl_devices_state, host, &error_fatal);
+
+    create_cxl_fixed_window(sms, sysmem, host);
+}
+
 static void create_pcie(SBSAMachineState *sms)
 {
     hwaddr base_ecam = sbsa_ref_memmap[SBSA_PCIE_ECAM].base;
@@ -821,6 +956,8 @@ static void sbsa_ref_init(MachineState *machine)
 
     create_pcie(sms);
 
+    create_cxl(sms);
+
     create_secure_ec(secure_sysmem);
 
     sms->bootinfo.ram_size = machine->ram_size;
diff --git a/hw/cxl/cxl-host-stubs.c b/hw/cxl/cxl-host-stubs.c
index cae4afcdde..aea94933ba 100644
--- a/hw/cxl/cxl-host-stubs.c
+++ b/hw/cxl/cxl-host-stubs.c
@@ -11,5 +11,7 @@
 void cxl_fmws_link_targets(CXLState *stat, Error **errp) {};
 void cxl_machine_init(Object *obj, CXLState *state) {};
 void cxl_hook_up_pxb_registers(PCIBus *bus, CXLState *state, Error **errp) {};
+void cxl_fixed_memory_window_config(CXLState *cxl_state,
+                        CXLFixedMemoryWindowOptions *object, Error **errp) {};
 
 const MemoryRegionOps cfmws_ops;
diff --git a/hw/cxl/cxl-host.c b/hw/cxl/cxl-host.c
index e9f2543c43..7e9d82819a 100644
--- a/hw/cxl/cxl-host.c
+++ b/hw/cxl/cxl-host.c
@@ -16,13 +16,14 @@
 #include "qapi/qapi-visit-machine.h"
 #include "hw/cxl/cxl.h"
 #include "hw/cxl/cxl_host.h"
+#include "hw/irq.h"
 #include "hw/pci/pci_bus.h"
 #include "hw/pci/pci_bridge.h"
 #include "hw/pci/pci_host.h"
 #include "hw/pci/pcie_port.h"
 #include "hw/pci-bridge/pci_expander_bridge.h"
 
-static void cxl_fixed_memory_window_config(CXLState *cxl_state,
+void cxl_fixed_memory_window_config(CXLState *cxl_state,
                                            CXLFixedMemoryWindowOptions *object,
                                            Error **errp)
 {
@@ -166,6 +167,17 @@ static PCIDevice *cxl_cfmws_find_device(CXLFixedWindow *fw, hwaddr addr)
     /* Address is relative to memory region. Convert to HPA */
     addr += fw->base;
 
+    if (fw->sbsa_target) {
+        hb = PCI_HOST_BRIDGE(fw->sbsa_target);
+        SbsaCXLHost *host = fw->sbsa_target;
+
+        hb_cstate = &host->cxl_cstate;
+        cache_mem = hb_cstate->crb.cache_mem_registers;
+        target_found = cxl_hdm_find_target(cache_mem, addr, &target);
+        rp = pcie_find_port_by_pn(hb->bus, target);
+        goto done;
+    }
+
     rb_index = (addr / cxl_decode_ig(fw->enc_int_gran)) % fw->num_targets;
     hb = PCI_HOST_BRIDGE(fw->target_hbs[rb_index]->cxl_host_bridge);
     if (!hb || !hb->bus || !pci_bus_is_cxl(hb->bus)) {
@@ -196,6 +208,7 @@ static PCIDevice *cxl_cfmws_find_device(CXLFixedWindow *fw, hwaddr addr)
         }
     }
 
+done:
     d = pci_bridge_get_sec_bus(PCI_BRIDGE(rp))->devices[0];
     if (!d) {
         return NULL;
@@ -372,3 +385,157 @@ void cxl_hook_up_pxb_registers(PCIBus *bus, CXLState *state, Error **errp)
         }
     }
 }
+
+/****************************************************************************
+ * Sbsa CXL host
+ */
+
+static void sbsa_cxl_set_irq(void *opaque, int irq_num, int level)
+{
+    SbsaCXLHost *host = opaque;
+
+    qemu_set_irq(host->irq[irq_num], level);
+}
+
+int sbsa_cxl_set_irq_num(SbsaCXLHost *host, int index, int gsi)
+{
+    if (index >= SBSA_CXL_NUM_IRQS) {
+        return -EINVAL;
+    }
+
+    host->irq_num[index] = gsi;
+    return 0;
+}
+
+static PCIINTxRoute sbsa_cxl_route_intx_pin_to_irq(void *opaque, int pin)
+{
+    PCIINTxRoute route;
+    SbsaCXLHost *host = opaque;
+    int gsi = host->irq_num[pin];
+
+    route.irq = gsi;
+    if (gsi < 0) {
+        route.mode = PCI_INTX_DISABLED;
+    } else {
+        route.mode = PCI_INTX_ENABLED;
+    }
+
+    return route;
+}
+
+static const char *sbsa_host_root_bus_path(PCIHostState *host_bridge,
+                                          PCIBus *rootbus)
+{
+    return "0001:00";
+}
+
+void sbsa_cxl_hook_up_registers(CXLState *cxl_state, SbsaCXLHost *host, Error **errp)
+{
+    CXLComponentState *cxl_cstate = &host->cxl_cstate;
+    struct MemoryRegion *mr = &cxl_cstate->crb.component_registers;
+    hwaddr offset;
+
+    offset = memory_region_size(mr) * cxl_state->next_mr_idx;
+    if (offset > memory_region_size(&cxl_state->host_mr)) {
+        error_setg(errp, "Insufficient space for sbsa cxl host register space");
+        return;
+    }
+
+    memory_region_add_subregion(&cxl_state->host_mr, offset, mr);
+    cxl_state->next_mr_idx++;
+}
+
+static void sbsa_cxl_host_reset(SbsaCXLHost *host)
+{
+    CXLComponentState *cxl_cstate = &host->cxl_cstate;
+    uint32_t *reg_state = cxl_cstate->crb.cache_mem_registers;
+    uint32_t *write_msk = cxl_cstate->crb.cache_mem_regs_write_mask;
+
+    cxl_component_register_init_common(reg_state, write_msk, CXL2_RC);
+
+    ARRAY_FIELD_DP32(reg_state, CXL_HDM_DECODER_CAPABILITY, TARGET_COUNT,
+                         8);
+}
+
+static void sbsa_cxl_realize(DeviceState *dev, Error **errp)
+{
+    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
+    SbsaCXLHost *host = SBSA_CXL_HOST(dev);
+    CXLComponentState *cxl_cstate = &host->cxl_cstate;
+    struct MemoryRegion *mr = &cxl_cstate->crb.component_registers;
+    PCIBus *cxlbus;
+    PCIHostState *pci = PCI_HOST_BRIDGE(dev);
+    PCIExpressHost *pex = PCIE_HOST_BRIDGE(dev);
+    int i;
+
+    /* CHBCR MMIO init */
+    sbsa_cxl_host_reset(host);
+    cxl_component_register_block_init(OBJECT(dev), cxl_cstate,
+                                      TYPE_SBSA_CXL_HOST);
+    sysbus_init_mmio(sbd, mr);
+
+    /* PCIe Host MMIO init */
+    pcie_host_mmcfg_init(pex, PCIE_MMCFG_SIZE_MAX);
+    sysbus_init_mmio(sbd, &pex->mmio);
+
+    memory_region_init(&host->io_mmio, OBJECT(host), "cxl_host_mmio", UINT64_MAX);
+    memory_region_init(&host->io_ioport, OBJECT(host), "cxl_host_ioport", 64 * 1024);
+
+    memory_region_init_io(&host->io_mmio_window, OBJECT(host),
+                              &unassigned_io_ops, OBJECT(host),
+                              "cxl_host_mmio_window", UINT64_MAX);
+    memory_region_init_io(&host->io_ioport_window, OBJECT(host),
+                              &unassigned_io_ops, OBJECT(host),
+                              "cxl_host_ioport_window", 64 * 1024);
+
+    memory_region_add_subregion(&host->io_mmio_window, 0, &host->io_mmio);
+    memory_region_add_subregion(&host->io_ioport_window, 0, &host->io_ioport);
+    sysbus_init_mmio(sbd, &host->io_mmio_window);
+    sysbus_init_mmio(sbd, &host->io_ioport_window);
+
+    sysbus_init_mmio(sbd, &host->io_mmio);
+    sysbus_init_mmio(sbd, &host->io_ioport);
+
+    for (i = 0; i < SBSA_CXL_NUM_IRQS; i++) {
+        sysbus_init_irq(sbd, &host->irq[i]);
+        host->irq_num[i] = -1;
+    }
+
+    pci->bus = pci_register_root_bus(dev, "cxlhost.0", sbsa_cxl_set_irq,
+                                     pci_swizzle_map_irq_fn, host, &host->io_mmio,
+                                     &host->io_ioport, 0, 4, TYPE_CXL_BUS);
+    cxlbus = pci->bus;
+    cxlbus->flags |= PCI_BUS_CXL;
+
+    pci_bus_set_route_irq_fn(pci->bus, sbsa_cxl_route_intx_pin_to_irq);
+}
+
+static void sbsa_cxl_host_class_init(ObjectClass *class, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(class);
+    PCIHostBridgeClass *hc = PCI_HOST_BRIDGE_CLASS(class);
+
+    hc->root_bus_path = sbsa_host_root_bus_path;
+    dc->realize = sbsa_cxl_realize;
+    dc->desc = "Sbsa CXL Host Bridge";
+    set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
+    dc->fw_name = "cxl";
+
+}
+
+/*
+ *  SBSA CXL HOST
+ */
+static const TypeInfo sbsa_cxl_host_info = {
+    .name          = TYPE_SBSA_CXL_HOST,
+    .parent        = TYPE_PCIE_HOST_BRIDGE,
+    .instance_size = sizeof(SbsaCXLHost),
+    .class_init    = sbsa_cxl_host_class_init,
+};
+
+static void cxl_host_register(void)
+{
+    type_register_static(&sbsa_cxl_host_info);
+}
+
+type_init(cxl_host_register)
diff --git a/include/hw/cxl/cxl.h b/include/hw/cxl/cxl.h
index 75e47b6864..5ae9957c69 100644
--- a/include/hw/cxl/cxl.h
+++ b/include/hw/cxl/cxl.h
@@ -17,6 +17,7 @@
 #include "cxl_pci.h"
 #include "cxl_component.h"
 #include "cxl_device.h"
+#include "hw/pci/pcie_host.h"
 
 #define CXL_CACHE_LINE_SIZE 64
 #define CXL_COMPONENT_REG_BAR_IDX 0
@@ -24,12 +25,33 @@
 
 #define CXL_WINDOW_MAX 10
 
+#define TYPE_SBSA_CXL_HOST "sbsa-cxl-host"
+OBJECT_DECLARE_SIMPLE_TYPE(SbsaCXLHost, SBSA_CXL_HOST)
+
+#define SBSA_CXL_NUM_IRQS 4
+
 typedef struct PXBCXLDev PXBCXLDev;
 
+struct SbsaCXLHost {
+    PCIExpressHost parent_obj;
+
+    CXLComponentState cxl_cstate;
+    bool passthrough;
+    int rp_count;
+
+    MemoryRegion io_ioport;
+    MemoryRegion io_mmio;
+    MemoryRegion io_ioport_window;
+    MemoryRegion io_mmio_window;
+    qemu_irq irq[SBSA_CXL_NUM_IRQS];
+    int irq_num[SBSA_CXL_NUM_IRQS];
+};
+
 typedef struct CXLFixedWindow {
     uint64_t size;
     char **targets;
     PXBCXLDev *target_hbs[16];
+    SbsaCXLHost *sbsa_target;
     uint8_t num_targets;
     uint8_t enc_int_ways;
     uint8_t enc_int_gran;
diff --git a/include/hw/cxl/cxl_host.h b/include/hw/cxl/cxl_host.h
index c9bc9c7c50..ae3ba436cc 100644
--- a/include/hw/cxl/cxl_host.h
+++ b/include/hw/cxl/cxl_host.h
@@ -16,6 +16,11 @@
 void cxl_machine_init(Object *obj, CXLState *state);
 void cxl_fmws_link_targets(CXLState *stat, Error **errp);
 void cxl_hook_up_pxb_registers(PCIBus *bus, CXLState *state, Error **errp);
+void cxl_fixed_memory_window_config(CXLState *cxl_state,
+                        CXLFixedMemoryWindowOptions *object, Error **errp);
+
+int sbsa_cxl_set_irq_num(SbsaCXLHost *host, int index, int gsi);
+void sbsa_cxl_hook_up_registers(CXLState *cxl_state, SbsaCXLHost *host, Error **errp);
 
 extern const MemoryRegionOps cfmws_ops;
 
-- 
2.34.1

Re: [RFC PATCH v3 1/1] hw/arm/sbsa-ref: Support CXL Host Bridge & CFMW

[Jonathan Cameron]

On Mon, 25 Nov 2024 17:37:09 +0800
Yuquan Wang <wangyuquan1236@phytium.com.cn> wrote:

> This creates a specific cxl host bridge (0001:00) with two cxl
> root ports on sbsa-ref. And the memory layout provides separate
> space windows for the cxl host bridge in the sbsa-ref memmap:
> 
> - 64K  CXL Host Bridge Component Registers (CHBCR)
> - 64K  CXL_PIO
> - 128M CXL_MMIO
> - 256M CXL_ECAM
> - 4G   CXL_MMIO_HIGH
> 
> To provide CFMWs on sbsa-ref, this extends 1TB space from the
> hole above RAM Memory [SBSA_MEM] for CXL Fixed Memory Window:
> 
> - 1T   CXL_FIXED_WINDOW
> 
> Signed-off-by: Yuquan Wang <wangyuquan1236@phytium.com.cn>
Hi.

I'm surprised this wasn't more complex.

Main feedback is that this new host bridge is not SBSA specific
so name it more generally. I'll try and find some time to see if I can
also spin one up with arm-virt as for my usecases that is more useful
as a modeling platform than SBSA ref.

Various other minor comments inline.
+CC Michael Tsirkin as this is effectively a new PCI host bridge.

Jonathan

> ---
>  docs/system/arm/sbsa.rst  |   4 +
>  hw/arm/sbsa-ref.c         | 139 ++++++++++++++++++++++++++++++-
>  hw/cxl/cxl-host-stubs.c   |   2 +
>  hw/cxl/cxl-host.c         | 169 +++++++++++++++++++++++++++++++++++++-
>  include/hw/cxl/cxl.h      |  22 +++++
>  include/hw/cxl/cxl_host.h |   5 ++
>  6 files changed, 339 insertions(+), 2 deletions(-)
> 
> diff --git a/docs/system/arm/sbsa.rst b/docs/system/arm/sbsa.rst
> index 2bf3fc8d59..21b88e88e7 100644
> --- a/docs/system/arm/sbsa.rst
> +++ b/docs/system/arm/sbsa.rst
> @@ -28,6 +28,7 @@ The ``sbsa-ref`` board supports:
>    - E1000E ethernet card on PCIe bus
>    - Bochs display adapter on PCIe bus
>    - A generic SBSA watchdog device
> +  - CXL host bridge and CXL fixed memory window
>  
>  
>  Board to firmware interface
> @@ -92,3 +93,6 @@ Platform version changes:
>  
>  0.4
>    CPU topology information is present in devicetree.
> +
> +0.5
> +  CXL host bridge and CXL fixed memory window are supported.
> diff --git a/hw/arm/sbsa-ref.c b/hw/arm/sbsa-ref.c
> index e3195d5449..78aef823a6 100644
> --- a/hw/arm/sbsa-ref.c
> +++ b/hw/arm/sbsa-ref.c
> @@ -36,12 +36,18 @@
>  #include "hw/arm/smmuv3.h"
>  #include "hw/block/flash.h"
>  #include "hw/boards.h"
> +#include "hw/cxl/cxl.h"
> +#include "hw/cxl/cxl_host.h"
>  #include "hw/ide/ide-bus.h"
>  #include "hw/ide/ahci-sysbus.h"
>  #include "hw/intc/arm_gicv3_common.h"
>  #include "hw/intc/arm_gicv3_its_common.h"
>  #include "hw/loader.h"
> +#include "hw/pci/pci_bridge.h"
> +#include "hw/pci/pci_bus.h"
> +#include "hw/pci/pcie_port.h"
Surprised if you need all of these.

>  #include "hw/pci-host/gpex.h"
> +#include "hw/pci-bridge/pci_expander_bridge.h"
Don't think you need this any more.
>  #include "hw/qdev-properties.h"
>  #include "hw/usb.h"
>  #include "hw/usb/xhci.h"
> @@ -94,6 +100,13 @@ enum {
>      SBSA_SECURE_MEM,
>      SBSA_AHCI,
>      SBSA_XHCI,
> +    SBSA_CXL,
> +    SBSA_CXL_CHBCR,
> +    SBSA_CXL_MMIO,
> +    SBSA_CXL_MMIO_HIGH,
> +    SBSA_CXL_PIO,
> +    SBSA_CXL_ECAM,
> +    SBSA_CXL_FIXED_WINDOW,
>  };
>  
>  struct SBSAMachineState {
> @@ -105,6 +118,7 @@ struct SBSAMachineState {
>      int psci_conduit;
>      DeviceState *gic;
>      PFlashCFI01 *flash[2];
> +    CXLState cxl_devices_state;
>  };
>  
>  #define TYPE_SBSA_MACHINE   MACHINE_TYPE_NAME("sbsa-ref")
> @@ -132,6 +146,14 @@ static const MemMapEntry sbsa_ref_memmap[] = {
>      /* Space here reserved for more SMMUs */
>      [SBSA_AHCI] =               { 0x60100000, 0x00010000 },
>      [SBSA_XHCI] =               { 0x60110000, 0x00010000 },
> +    /* 64K CXL Host Bridge Registers space */
> +    [SBSA_CXL_CHBCR] =          { 0x60120000, 0x00010000 },
> +    /* 64K CXL PIO space */
> +    [SBSA_CXL_PIO] =            { 0x60130000, 0x00010000 },
> +    /* 128M CXL 32-bit MMIO space */
> +    [SBSA_CXL_MMIO] =           { 0x60140000, 0x08000000 },
> +    /* 256M CXL ECAM space */
> +    [SBSA_CXL_ECAM] =           { 0x68140000, 0x10000000 },

I'd be tempted to align these at least somewhat - so leave gaps.

>      /* Space here reserved for other devices */
>      [SBSA_PCIE_PIO] =           { 0x7fff0000, 0x00010000 },
>      /* 32-bit address PCIE MMIO space */
> @@ -141,6 +163,10 @@ static const MemMapEntry sbsa_ref_memmap[] = {
>      /* ~1TB PCIE MMIO space (4GB to 1024GB boundary) */
>      [SBSA_PCIE_MMIO_HIGH] =     { 0x100000000ULL, 0xFF00000000ULL },
>      [SBSA_MEM] =                { 0x10000000000ULL, RAMLIMIT_BYTES },
> +    /* 4G CXL 64-bit MMIO space */
> +    [SBSA_CXL_MMIO_HIGH] =      { 0x90000000000ULL, 0x100000000ULL },
> +    /* 1TB CXL FIXED WINDOW space */
> +    [SBSA_CXL_FIXED_WINDOW] =   { 0xA0000000000ULL, 0x10000000000ULL },
>  };
>  
>  static const int sbsa_ref_irqmap[] = {
> @@ -154,6 +180,7 @@ static const int sbsa_ref_irqmap[] = {
>      [SBSA_XHCI] = 11,
>      [SBSA_SMMU] = 12, /* ... to 15 */
>      [SBSA_GWDT_WS0] = 16,
> +    [SBSA_CXL] = 17, /* ... to 20 */
>  };
>  
>  static uint64_t sbsa_ref_cpu_mp_affinity(SBSAMachineState *sms, int idx)
> @@ -216,7 +243,7 @@ static void create_fdt(SBSAMachineState *sms)
>       *                        fw compatibility.
>       */
>      qemu_fdt_setprop_cell(fdt, "/", "machine-version-major", 0);
> -    qemu_fdt_setprop_cell(fdt, "/", "machine-version-minor", 4);
> +    qemu_fdt_setprop_cell(fdt, "/", "machine-version-minor", 5);
>  
>      if (ms->numa_state->have_numa_distance) {
>          int size = nb_numa_nodes * nb_numa_nodes * 3 * sizeof(uint32_t);
> @@ -629,6 +656,114 @@ static void create_smmu(const SBSAMachineState *sms, PCIBus *bus)
>      }
>  }
>  
> +static void create_cxl_fixed_window(SBSAMachineState *sms,
> +                               MemoryRegion *mem, SbsaCXLHost *host)
> +{
> +    PCIBus *cxlbus = PCI_HOST_BRIDGE(host)->bus;
> +    char *cxl_host = object_get_canonical_path(OBJECT(cxlbus));
> +    hwaddr base = sbsa_ref_memmap[SBSA_CXL_FIXED_WINDOW].base;
> +    GList *it;
> +    strList host_target = { NULL, cxl_host };
> +    CXLFixedMemoryWindowOptions sbsa_ref_cfmwoptions = {
> +        .size = 1 * TiB,
> +        .has_interleave_granularity = false,
> +        .targets = &host_target,
> +    };
> +    CXLFixedWindow *fw;
> +
> +    cxl_fixed_memory_window_config(&sms->cxl_devices_state,
> +                               &sbsa_ref_cfmwoptions, &error_fatal);
> +
> +    it = sms->cxl_devices_state.fixed_windows;
> +    fw = it->data;
> +    fw->base = base;
> +    fw->sbsa_target = host;
> +
> +    memory_region_init_io(&fw->mr, OBJECT(sms), &cfmws_ops, fw,
> +                            "cxl-fixed-memory-region", fw->size);
> +
> +    memory_region_add_subregion(mem, fw->base, &fw->mr);
> +}
> +
> +static void create_cxl(SBSAMachineState *sms)
> +{
> +    hwaddr base_ecam = sbsa_ref_memmap[SBSA_CXL_ECAM].base;
> +    hwaddr size_ecam = sbsa_ref_memmap[SBSA_CXL_ECAM].size;
> +    hwaddr base_mmio = sbsa_ref_memmap[SBSA_CXL_MMIO].base;
> +    hwaddr size_mmio = sbsa_ref_memmap[SBSA_CXL_MMIO].size;
> +    hwaddr base_mmio_high = sbsa_ref_memmap[SBSA_CXL_MMIO_HIGH].base;
> +    hwaddr size_mmio_high = sbsa_ref_memmap[SBSA_CXL_MMIO_HIGH].size;

For most of these I'd just use the values inline.  That will be easier
to read than having to check where the value in the local variable came from.

> +    hwaddr base_pio = sbsa_ref_memmap[SBSA_CXL_PIO].base;
> +    int irq = sbsa_ref_irqmap[SBSA_CXL];
> +    MemoryRegion *mmio_alias, *mmio_alias_high, *mmio_reg;
> +    MemoryRegion *ecam_alias, *ecam_reg;
> +    MemoryRegion *sysmem = get_system_memory();
> +    MemoryRegion *chbcr = &sms->cxl_devices_state.host_mr;
> +    DeviceState *dev;
> +    SbsaCXLHost *host;
> +    PCIHostState *cxl;
> +    PCIDevice *cxlrp;
> +    PCIEPort *p;
> +    PCIESlot *s;
> +    int i;
> +
> +    dev = qdev_new(TYPE_SBSA_CXL_HOST);
> +    sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
> +    sms->cxl_devices_state.is_enabled = true;
> +
> +    /* Map CXL ECAM space */
> +    ecam_alias = g_new0(MemoryRegion, 1);
> +    ecam_reg = sysbus_mmio_get_region(SYS_BUS_DEVICE(dev), 1);
> +    memory_region_init_alias(ecam_alias, OBJECT(dev), "cxl-ecam",
> +                             ecam_reg, 0, size_ecam);
> +    memory_region_add_subregion(get_system_memory(), base_ecam, ecam_alias);
> +
> +    /* Map CXL MMIO space */
> +    mmio_alias = g_new0(MemoryRegion, 1);
> +    mmio_reg = sysbus_mmio_get_region(SYS_BUS_DEVICE(dev), 2);
> +    memory_region_init_alias(mmio_alias, OBJECT(dev), "cxl-mmio",
> +                             mmio_reg, base_mmio, size_mmio);
> +    memory_region_add_subregion(get_system_memory(), base_mmio, mmio_alias);
> +
> +    /* Map CXL MMIO_HIGH space */
> +    mmio_alias_high = g_new0(MemoryRegion, 1);
> +    memory_region_init_alias(mmio_alias_high, OBJECT(dev), "cxl-mmio-high",
> +                             mmio_reg, base_mmio_high, size_mmio_high);
> +    memory_region_add_subregion(get_system_memory(), base_mmio_high,
> +                                mmio_alias_high);
> +
> +    /* Map CXL IO port space */
> +    sysbus_mmio_map(SYS_BUS_DEVICE(dev), 3, base_pio);
> +
> +    for (i = 0; i < SBSA_CXL_NUM_IRQS; i++) {
> +        sysbus_connect_irq(SYS_BUS_DEVICE(dev), i,
> +                           qdev_get_gpio_in(sms->gic, irq + i));
> +        sbsa_cxl_set_irq_num(SBSA_CXL_HOST(dev), i, irq + i);
> +    }
> +
> +    /* Map CXL CHBCR space */
> +    memory_region_init(chbcr, OBJECT(sms), "cxl_host_reg",
> +                       sbsa_ref_memmap[SBSA_CXL_CHBCR].size);
> +    memory_region_add_subregion(sysmem, sbsa_ref_memmap[SBSA_CXL_CHBCR].base, chbcr);
> +
> +    cxl = PCI_HOST_BRIDGE(dev);
> +
> +    /* Connect two cxl root ports */
> +    for (i = 0; i < 2; i++) {
> +        cxlrp = pci_new(-1, "cxl-rp");
> +        p = PCIE_PORT(cxlrp);
> +        s = PCIE_SLOT(cxlrp);
> +        p->port = i;
> +        s->slot = i;
> +        pci_realize_and_unref(cxlrp, cxl->bus, &error_fatal);
> +    }
> +
> +    host = SBSA_CXL_HOST(dev);
> +    sbsa_cxl_hook_up_registers(&sms->cxl_devices_state, host, &error_fatal);
> +
> +    create_cxl_fixed_window(sms, sysmem, host);
> +}
> +
>  static void create_pcie(SBSAMachineState *sms)
>  {
>      hwaddr base_ecam = sbsa_ref_memmap[SBSA_PCIE_ECAM].base;
> @@ -821,6 +956,8 @@ static void sbsa_ref_init(MachineState *machine)
>  
>      create_pcie(sms);
>  
> +    create_cxl(sms);
> +
>      create_secure_ec(secure_sysmem);
>  
>      sms->bootinfo.ram_size = machine->ram_size;
> diff --git a/hw/cxl/cxl-host-stubs.c b/hw/cxl/cxl-host-stubs.c
> index cae4afcdde..aea94933ba 100644
> --- a/hw/cxl/cxl-host-stubs.c
> +++ b/hw/cxl/cxl-host-stubs.c
> @@ -11,5 +11,7 @@
>  void cxl_fmws_link_targets(CXLState *stat, Error **errp) {};
>  void cxl_machine_init(Object *obj, CXLState *state) {};
>  void cxl_hook_up_pxb_registers(PCIBus *bus, CXLState *state, Error **errp) {};
> +void cxl_fixed_memory_window_config(CXLState *cxl_state,
> +                        CXLFixedMemoryWindowOptions *object, Error **errp) {};
>  
>  const MemoryRegionOps cfmws_ops;
> diff --git a/hw/cxl/cxl-host.c b/hw/cxl/cxl-host.c
> index e9f2543c43..7e9d82819a 100644
> --- a/hw/cxl/cxl-host.c
> +++ b/hw/cxl/cxl-host.c
> @@ -16,13 +16,14 @@
>  #include "qapi/qapi-visit-machine.h"
>  #include "hw/cxl/cxl.h"
>  #include "hw/cxl/cxl_host.h"
> +#include "hw/irq.h"
>  #include "hw/pci/pci_bus.h"
>  #include "hw/pci/pci_bridge.h"
>  #include "hw/pci/pci_host.h"
>  #include "hw/pci/pcie_port.h"
>  #include "hw/pci-bridge/pci_expander_bridge.h"
>  
> -static void cxl_fixed_memory_window_config(CXLState *cxl_state,
> +void cxl_fixed_memory_window_config(CXLState *cxl_state,
>                                             CXLFixedMemoryWindowOptions *object,
>                                             Error **errp)
>  {
> @@ -166,6 +167,17 @@ static PCIDevice *cxl_cfmws_find_device(CXLFixedWindow *fw, hwaddr addr)
>      /* Address is relative to memory region. Convert to HPA */
>      addr += fw->base;
>  
> +    if (fw->sbsa_target) {

This should be established by parameters parsed that are not specific to sbsa.
I'd like to see the thing created as a normal device then just hooked up here
if its found.

> +        hb = PCI_HOST_BRIDGE(fw->sbsa_target);
> +        SbsaCXLHost *host = fw->sbsa_target;
> +
> +        hb_cstate = &host->cxl_cstate;
> +        cache_mem = hb_cstate->crb.cache_mem_registers;
> +        target_found = cxl_hdm_find_target(cache_mem, addr, &target);
> +        rp = pcie_find_port_by_pn(hb->bus, target);
> +        goto done;

Probably makes sense to use an else and deal with a mix of cxl host (your sbsa
one that needs renaming) and pxb.

> +    }
> +
>      rb_index = (addr / cxl_decode_ig(fw->enc_int_gran)) % fw->num_targets;
>      hb = PCI_HOST_BRIDGE(fw->target_hbs[rb_index]->cxl_host_bridge);
>      if (!hb || !hb->bus || !pci_bus_is_cxl(hb->bus)) {
> @@ -196,6 +208,7 @@ static PCIDevice *cxl_cfmws_find_device(CXLFixedWindow *fw, hwaddr addr)
>          }
>      }
>  
> +done:
>      d = pci_bridge_get_sec_bus(PCI_BRIDGE(rp))->devices[0];
>      if (!d) {
>          return NULL;
> @@ -372,3 +385,157 @@ void cxl_hook_up_pxb_registers(PCIBus *bus, CXLState *state, Error **errp)
>          }
>      }
>  }
> +
> +/****************************************************************************
> + * Sbsa CXL host
Naming makes all this obvious, I'd not have a the comment as it's just an
opportunity for problems later.

May make sense to split up cxl-host now we have multiple host bridges.

> + */
> +
> +static void sbsa_cxl_set_irq(void *opaque, int irq_num, int level)
> +{
> +    SbsaCXLHost *host = opaque;
> +
> +    qemu_set_irq(host->irq[irq_num], level);
> +}
> +
> +int sbsa_cxl_set_irq_num(SbsaCXLHost *host, int index, int gsi)
> +{
> +    if (index >= SBSA_CXL_NUM_IRQS) {
> +        return -EINVAL;
> +    }
> +
> +    host->irq_num[index] = gsi;
> +    return 0;
> +}

> +
> +static const char *sbsa_host_root_bus_path(PCIHostState *host_bridge,
> +                                          PCIBus *rootbus)
> +{
> +    return "0001:00";

> +}
> +static void sbsa_cxl_host_reset(SbsaCXLHost *host)
> +{
> +    CXLComponentState *cxl_cstate = &host->cxl_cstate;
> +    uint32_t *reg_state = cxl_cstate->crb.cache_mem_registers;
> +    uint32_t *write_msk = cxl_cstate->crb.cache_mem_regs_write_mask;
> +
> +    cxl_component_register_init_common(reg_state, write_msk, CXL2_RC);
> +
> +    ARRAY_FIELD_DP32(reg_state, CXL_HDM_DECODER_CAPABILITY, TARGET_COUNT,
> +                         8);
Fix alignment.
> +}
> +
> +static void sbsa_cxl_realize(DeviceState *dev, Error **errp)
> +{
> +    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
> +    SbsaCXLHost *host = SBSA_CXL_HOST(dev);
> +    CXLComponentState *cxl_cstate = &host->cxl_cstate;
> +    struct MemoryRegion *mr = &cxl_cstate->crb.component_registers;
> +    PCIBus *cxlbus;
> +    PCIHostState *pci = PCI_HOST_BRIDGE(dev);
> +    PCIExpressHost *pex = PCIE_HOST_BRIDGE(dev);
> +    int i;
> +
> +    /* CHBCR MMIO init */
> +    sbsa_cxl_host_reset(host);
> +    cxl_component_register_block_init(OBJECT(dev), cxl_cstate,
> +                                      TYPE_SBSA_CXL_HOST);
> +    sysbus_init_mmio(sbd, mr);
> +
> +    /* PCIe Host MMIO init */
> +    pcie_host_mmcfg_init(pex, PCIE_MMCFG_SIZE_MAX);
> +    sysbus_init_mmio(sbd, &pex->mmio);
> +
> +    memory_region_init(&host->io_mmio, OBJECT(host), "cxl_host_mmio", UINT64_MAX);
> +    memory_region_init(&host->io_ioport, OBJECT(host), "cxl_host_ioport", 64 * 1024);

Why that size?  Add a comment.

> +
> +    memory_region_init_io(&host->io_mmio_window, OBJECT(host),
> +                              &unassigned_io_ops, OBJECT(host),
> +                              "cxl_host_mmio_window", UINT64_MAX);
> +    memory_region_init_io(&host->io_ioport_window, OBJECT(host),
> +                              &unassigned_io_ops, OBJECT(host),
> +                              "cxl_host_ioport_window", 64 * 1024);
> +
> +    memory_region_add_subregion(&host->io_mmio_window, 0, &host->io_mmio);
> +    memory_region_add_subregion(&host->io_ioport_window, 0, &host->io_ioport);
> +    sysbus_init_mmio(sbd, &host->io_mmio_window);
> +    sysbus_init_mmio(sbd, &host->io_ioport_window);
> +
> +    sysbus_init_mmio(sbd, &host->io_mmio);
> +    sysbus_init_mmio(sbd, &host->io_ioport);
> +
> +    for (i = 0; i < SBSA_CXL_NUM_IRQS; i++) {
> +        sysbus_init_irq(sbd, &host->irq[i]);
> +        host->irq_num[i] = -1;
> +    }
> +
> +    pci->bus = pci_register_root_bus(dev, "cxlhost.0", sbsa_cxl_set_irq,
> +                                     pci_swizzle_map_irq_fn, host, &host->io_mmio,
> +                                     &host->io_ioport, 0, 4, TYPE_CXL_BUS);
> +    cxlbus = pci->bus;
> +    cxlbus->flags |= PCI_BUS_CXL;
> +
> +    pci_bus_set_route_irq_fn(pci->bus, sbsa_cxl_route_intx_pin_to_irq);
> +}
> +
> +static void sbsa_cxl_host_class_init(ObjectClass *class, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(class);
> +    PCIHostBridgeClass *hc = PCI_HOST_BRIDGE_CLASS(class);
> +
> +    hc->root_bus_path = sbsa_host_root_bus_path;
> +    dc->realize = sbsa_cxl_realize;
> +    dc->desc = "Sbsa CXL Host Bridge";
> +    set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
> +    dc->fw_name = "cxl";
> +
No blank line here.

> +}
> +
> +/*
> + *  SBSA CXL HOST

Obvious enough that Id' drop the comment. Naming should tell
us everything we need here.

> + */
> +static const TypeInfo sbsa_cxl_host_info = {
> +    .name          = TYPE_SBSA_CXL_HOST,
> +    .parent        = TYPE_PCIE_HOST_BRIDGE,
> +    .instance_size = sizeof(SbsaCXLHost),
> +    .class_init    = sbsa_cxl_host_class_init,
> +};

> diff --git a/include/hw/cxl/cxl.h b/include/hw/cxl/cxl.h
> index 75e47b6864..5ae9957c69 100644
> --- a/include/hw/cxl/cxl.h
> +++ b/include/hw/cxl/cxl.h
> @@ -17,6 +17,7 @@
>  #include "cxl_pci.h"
>  #include "cxl_component.h"
>  #include "cxl_device.h"
> +#include "hw/pci/pcie_host.h"
>  
>  #define CXL_CACHE_LINE_SIZE 64
>  #define CXL_COMPONENT_REG_BAR_IDX 0
> @@ -24,12 +25,33 @@
>  
>  #define CXL_WINDOW_MAX 10
>  
> +#define TYPE_SBSA_CXL_HOST "sbsa-cxl-host"
> +OBJECT_DECLARE_SIMPLE_TYPE(SbsaCXLHost, SBSA_CXL_HOST)
> +
> +#define SBSA_CXL_NUM_IRQS 4
> +
>  typedef struct PXBCXLDev PXBCXLDev;
>  
> +struct SbsaCXLHost {

This is not Sbsa specific that I can see - I'm certainly going to
play around with it on virt (as generally SBSA-ref is no use for testing CXL
because of it's relatively fixed configuration - it serves a different
purpose!)  It might be more generally useful. So just go with CXLHostBridge

> +    PCIExpressHost parent_obj;
> +
> +    CXLComponentState cxl_cstate;
> +    bool passthrough;

Not used.

> +    int rp_count;

Not used.

> +
> +    MemoryRegion io_ioport;
> +    MemoryRegion io_mmio;
> +    MemoryRegion io_ioport_window;
> +    MemoryRegion io_mmio_window;
> +    qemu_irq irq[SBSA_CXL_NUM_IRQS];
> +    int irq_num[SBSA_CXL_NUM_IRQS];
> +};
> +
>  typedef struct CXLFixedWindow {
>      uint64_t size;
>      char **targets;
>      PXBCXLDev *target_hbs[16];
> +    SbsaCXLHost *sbsa_target;

We probably want to allow for several even if sbsa is
only using one for now.   I'd copy PXBCXLDev and just make
it [16];

>      uint8_t num_targets;
>      uint8_t enc_int_ways;
>      uint8_t enc_int_gran;
> diff --git a/include/hw/cxl/cxl_host.h b/include/hw/cxl/cxl_host.h
> index c9bc9c7c50..ae3ba436cc 100644
> --- a/include/hw/cxl/cxl_host.h
> +++ b/include/hw/cxl/cxl_host.h
> @@ -16,6 +16,11 @@
>  void cxl_machine_init(Object *obj, CXLState *state);
>  void cxl_fmws_link_targets(CXLState *stat, Error **errp);
>  void cxl_hook_up_pxb_registers(PCIBus *bus, CXLState *state, Error **errp);
> +void cxl_fixed_memory_window_config(CXLState *cxl_state,
> +                        CXLFixedMemoryWindowOptions *object, Error **errp);
> +
> +int sbsa_cxl_set_irq_num(SbsaCXLHost *host, int index, int gsi);
> +void sbsa_cxl_hook_up_registers(CXLState *cxl_state, SbsaCXLHost *host, Error **errp);

As above, this is not an SBSA thing, you are just using it for sbsa, so
drop that form all the naming and refer to CXLHostBridge or similar.

>  
>  extern const MemoryRegionOps cfmws_ops;
>