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* [RFC PATCH 00/25] Introduce CXL 2.0 Emulation
@ 2020-11-11  5:46 Ben Widawsky
  2020-11-11  5:47 ` [RFC PATCH 01/25] Temp: Add the PCI_EXT_ID_DVSEC definition to the qemu pci_regs.h copy Ben Widawsky
                   ` (26 more replies)
  0 siblings, 27 replies; 67+ messages in thread
From: Ben Widawsky @ 2020-11-11  5:46 UTC (permalink / raw)
  To: qemu-devel; +Cc: Vishal Verma, Dan Williams, Ben Widawsky

Introduce emulation of Compute Express Link 2.0, which was released
today at https://www.computeexpresslink.org/.

I've pushed a branch here: https://gitlab.com/bwidawsk/qemu/-/tree/cxl-2.0

The emulation has been critical to get the Linux enabling started
(https://lore.kernel.org/linux-cxl/), it would be an ideal place to land
regression tests for different topology handling, and there may be applications
for this emulation as a way for a guest to manipulate its address space relative
to different performance memories. I am new to QEMU development, so please
forgive and point me in the right direction if I severely misinterpreted where a
piece of infrastructure belongs.

Three of the five CXL component types are emulated with some level of functionality:
host bridge, root port, and memory device. Upstream ports and downstream ports
aren't implemented (the two components needed to make up a switch).

CXL 2.0 is built on top of PCIe (see spec for details). As a result, much of the
implementation utilizes existing PCI paradigms. To implement the host bridge,
I've chosen to use PXB (PCI Expander Bridge). It seemed to be the most natural
fit even though it doesn't directly map to how hardware will work. For
persistent capacity of the memory device, I utilized the memory subsystem
(hw/mem).

We have 3 reasons why this work is valuable:
1. OS driver development and testing
2. OS driver regression testing
3. Possible guest support for HDMs

As mentioned above there are three benefits to carrying this enabling in
upstream QEMU:

1. Linux driver feature development benefits from emulation both due to
a lack of initial hardware availability, but also, as is seen with
NVDIMM/PMEM emulation, there is value in being able to share
topologies with system-software developers even after hardware is
available.

2. The Linux kernel's unit test suite for NVDIMM/PMEM ended up injecting fake
resources via custom modules (nfit_test). In retrospect a QEMU emulation of
nfit_test capabilities would have made the test environment more portable, and
allowed for easier community contributions of example configurations.

3. This is still being fleshed out, but in short it provides a standardized
mechanism for the guest to provide feedback to the host about size and placement
needs of the memory. After the host gives the guest a physical window mapping to
the CXL device, the emulated HDM decoders allow the guest a way to tell the host
how much it wants and where. There are likely simpler ways to do this, but
they'd require inventing a new interface and you'd need to have diverging driver
code in the guest programming of the HDM decoder vs. the host. Since we've
already done this work, why not use it?

There is quite a long list of work to do for full spec compliance, but I don't
believe that any of it precludes merging. Off the top of my head:
- Main host bridge support (WIP)
- Interleaving
- Better Tests
- Huge swaths of firmware functionality
- Hot plug support
- Emulating volatile capacity

The flow of the patches in general is to define all the data structures and
registers associated with the various components in a top down manner. Host
bridge, component, ports, devices. Then, the actual implementation is done in
the same order.

The summary is:
1-8: Put infrastructure in place for emulation of the components.
9-11: Create the concept of a CXL bus and plumb into PXB
12-16: Implement host bridges
17: Implement a root port
18: Implement a memory device
19: Implement HDM decoders
20-24: ACPI bits
25: Start working on enabling the main host bridge

Ben Widawsky (23):
  hw/pci/cxl: Add a CXL component type (interface)
  hw/cxl/component: Introduce CXL components (8.1.x, 8.2.5)
  hw/cxl/device: Introduce a CXL device (8.2.8)
  hw/cxl/device: Implement the CAP array (8.2.8.1-2)
  hw/cxl/device: Add device status (8.2.8.3)
  hw/cxl/device: Implement basic mailbox (8.2.8.4)
  hw/cxl/device: Add memory devices (8.2.8.5)
  hw/pxb: Use a type for realizing expanders
  hw/pci/cxl: Create a CXL bus type
  hw/pxb: Allow creation of a CXL PXB (host bridge)
  acpi/pci: Consolidate host bridge setup
  hw/pci: Plumb _UID through host bridges
  hw/cxl/component: Implement host bridge MMIO (8.2.5, table 142)
  acpi/pxb/cxl: Reserve host bridge MMIO
  hw/pxb/cxl: Add "windows" for host bridges
  hw/cxl/rp: Add a root port
  hw/cxl/device: Add a memory device (8.2.8.5)
  hw/cxl/device: Implement MMIO HDM decoding (8.2.5.12)
  acpi/cxl: Add _OSC implementation (9.14.2)
  acpi/cxl: Create the CEDT (9.14.1)
  Temp: acpi/cxl: Add ACPI0017 (CEDT awareness)
  WIP: i386/cxl: Initialize a host bridge
  qtest/cxl: Add very basic sanity tests

Jonathan Cameron (1):
  Temp: Add the PCI_EXT_ID_DVSEC definition to the qemu pci_regs.h copy.

Vishal Verma (1):
  acpi/cxl: Introduce a compat-driver UUID for CXL _OSC

 MAINTAINERS                               |   6 +
 hw/Kconfig                                |   1 +
 hw/acpi/Kconfig                           |   5 +
 hw/acpi/cxl.c                             | 198 +++++++++++++
 hw/acpi/meson.build                       |   1 +
 hw/arm/virt.c                             |   1 +
 hw/core/machine.c                         |  26 ++
 hw/core/numa.c                            |   3 +
 hw/cxl/Kconfig                            |   3 +
 hw/cxl/cxl-component-utils.c              | 192 +++++++++++++
 hw/cxl/cxl-device-utils.c                 | 293 +++++++++++++++++++
 hw/cxl/cxl-mailbox-utils.c                | 139 +++++++++
 hw/cxl/meson.build                        |   5 +
 hw/i386/acpi-build.c                      |  87 +++++-
 hw/i386/microvm.c                         |   1 +
 hw/i386/pc.c                              |   2 +
 hw/mem/Kconfig                            |   5 +
 hw/mem/cxl_type3.c                        | 334 ++++++++++++++++++++++
 hw/mem/meson.build                        |   1 +
 hw/meson.build                            |   1 +
 hw/pci-bridge/Kconfig                     |   5 +
 hw/pci-bridge/cxl_root_port.c             | 231 +++++++++++++++
 hw/pci-bridge/meson.build                 |   1 +
 hw/pci-bridge/pci_expander_bridge.c       | 209 +++++++++++++-
 hw/pci-bridge/pcie_root_port.c            |   6 +-
 hw/pci/pci.c                              |  32 ++-
 hw/pci/pcie.c                             |  30 ++
 hw/ppc/spapr.c                            |   2 +
 include/hw/acpi/cxl.h                     |  27 ++
 include/hw/boards.h                       |   2 +
 include/hw/cxl/cxl.h                      |  30 ++
 include/hw/cxl/cxl_component.h            | 181 ++++++++++++
 include/hw/cxl/cxl_device.h               | 199 +++++++++++++
 include/hw/cxl/cxl_pci.h                  | 155 ++++++++++
 include/hw/pci/pci.h                      |  15 +
 include/hw/pci/pci_bridge.h               |  25 ++
 include/hw/pci/pci_bus.h                  |   8 +
 include/hw/pci/pci_ids.h                  |   1 +
 include/standard-headers/linux/pci_regs.h |   1 +
 monitor/hmp-cmds.c                        |  15 +
 qapi/machine.json                         |   1 +
 tests/qtest/cxl-test.c                    |  93 ++++++
 tests/qtest/meson.build                   |   4 +
 43 files changed, 2547 insertions(+), 30 deletions(-)
 create mode 100644 hw/acpi/cxl.c
 create mode 100644 hw/cxl/Kconfig
 create mode 100644 hw/cxl/cxl-component-utils.c
 create mode 100644 hw/cxl/cxl-device-utils.c
 create mode 100644 hw/cxl/cxl-mailbox-utils.c
 create mode 100644 hw/cxl/meson.build
 create mode 100644 hw/mem/cxl_type3.c
 create mode 100644 hw/pci-bridge/cxl_root_port.c
 create mode 100644 include/hw/acpi/cxl.h
 create mode 100644 include/hw/cxl/cxl.h
 create mode 100644 include/hw/cxl/cxl_component.h
 create mode 100644 include/hw/cxl/cxl_device.h
 create mode 100644 include/hw/cxl/cxl_pci.h
 create mode 100644 tests/qtest/cxl-test.c

-- 
2.29.2



^ permalink raw reply	[flat|nested] 67+ messages in thread
* Re: [RFC PATCH 00/25] Introduce CXL 2.0 Emulation
@ 2020-12-04  5:08 Chris Browy
  2020-12-04  5:55   ` Dan Williams
  0 siblings, 1 reply; 67+ messages in thread
From: Chris Browy @ 2020-12-04  5:08 UTC (permalink / raw)
  To: ben.widawsky; +Cc: vishal.l.verma, dan.j.williams, qemu-devel

[-- Attachment #1: Type: text/plain, Size: 5474 bytes --]

Hi Ben,

Trying to bring up the environment using the latest developments as follows:

1. Linux kernel baseline version is cloned using
     git clone git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
   Using master branch.  Merged the 9 CXL linux kernel patches manually and built kernel

2. QEMU baseline version is cloned using
     git clone https://gitlab.com/bwidawsk/qemu.git <https://gitlab.com/bwidawsk/qemu.git>

3. UEFI baseline is cloned using
     git clone https://github.com/tianocore/edk2.git <https://github.com/tianocore/edk2.git>
   Using master and built

4. Now can run qemu as follows:
     The qcow2 we use is based on Ubuntu 20.10 with updated with kernel from 1) above

     QEMU command:

     sudo qemu-system-x86_64 -nic \
     user,hostfwd=tcp::2222-:22,hostfwd=tcp::1234-:1234 -machine \
     type=pc-q35-4.0,hmat=on,accel=kvm -enable-kvm -cpu host -smp \
     6,cores=6,threads=1,sockets=1 -m 8G -boot order=d -k 'en-us' -vga virtio \
     -drive file=/home/chris/Downloads/AQCXL/ubuntu_20.qcow,format=qcow2 -drive \
     if=pflash,format=raw,readonly,file=/home/chris/OVMF_CODE.fd \
     -drive if=pflash,format=raw,file=/home/chris/OVMF_VARS.fd \
     -object memory-backend-file,id=cxl-mem1,share,mem-path=/tmp/cxl-test/cxl,size=512M \
     -device pxb-cxl,id=cxl.0,bus=pcie.0,bus_nr=52,uid=0,len-window-base=1,\
     window-base[0]=0x4c0000000,memdev[0]=cxl-mem1 \
     -device cxl-rp,id=rp0,bus=cxl.0,addr=0.0,chassis=0,slot=0  \
     -device cxl-type3,bus=rp0,memdev=cxl-mem1,id=cxl-pmem0,size=256M  2>&1 | tee -a \
     /home/chris/Downloads/AQCXL/log/qemu.log

   The qemu options are derived from looking at the tests/qtests/cxl-test.c
   along with the -hmat=on which seemed to make sense.

   The system boots and lspci -vvv shows the CXL device is enumerated.  But
   no DOE capability register for CDAT access though (see below).  Otherwise the
   DVSEC registers are present.

   acpidump indicates the CXL0 and CXLM devices but no SRAT or HMAT tables are
   in the dump which is curious.


35:00.0 Memory controller [0502]: Intel Corporation Device 0d93 (rev 01) (prog-if 10)
    Subsystem: Red Hat, Inc. Device 1100
    Physical Slot: 0
    Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
    Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
    Latency: 0
    Region 0: Memory at c0a00000 (64-bit, non-prefetchable) [size=64K]
    Region 2: Memory at c0a10000 (64-bit, non-prefetchable) [size=4K]
    Capabilities: [80] Express (v2) Endpoint, MSI 00
        DevCap: MaxPayload 128 bytes, PhantFunc 0, Latency L0s <64ns, L1 <1us
            ExtTag- AttnBtn- AttnInd- PwrInd- RBE+ FLReset- SlotPowerLimit 0.000W
        DevCtl: CorrErr- NonFatalErr- FatalErr- UnsupReq-
            RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
            MaxPayload 128 bytes, MaxReadReq 128 bytes
        DevSta: CorrErr- NonFatalErr- FatalErr- UnsupReq- AuxPwr- TransPend-
        LnkCap: Port #0, Speed 2.5GT/s, Width x1, ASPM L0s, Exit Latency L0s <64ns
            ClockPM- Surprise- LLActRep- BwNot- ASPMOptComp-
        LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
            ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
        LnkSta: Speed 2.5GT/s (ok), Width x1 (ok)
            TrErr- Train- SlotClk- DLActive+ BWMgmt- ABWMgmt-
        DevCap2: Completion Timeout: Not Supported, TimeoutDis-, NROPrPrP-, LTR-
             10BitTagComp-, 10BitTagReq-, OBFF Not Supported, ExtFmt+, EETLPPrefix+, MaxEETLPPrefixes 4
               EmergencyPowerReduction Not Supported, EmergencyPowerReductionInit-
             FRS-, TPHComp-, ExtTPHComp-
             AtomicOpsCap: 32bit- 64bit- 128bitCAS-
        DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-, LTR-, OBFF Disabled
             AtomicOpsCtl: ReqEn-
        LnkCtl2: Target Link Speed: 2.5GT/s, EnterCompliance- SpeedDis-
             Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
             Compliance De-emphasis: -6dB
        LnkSta2: Current De-emphasis Level: -6dB, EqualizationComplete-, EqualizationPhase1-
             EqualizationPhase2-, EqualizationPhase3-, LinkEqualizationRequest-
    Capabilities: [100 v1] Designated Vendor-Specific <?>
    Capabilities: [138 v1] Designated Vendor-Specific <?>
    Kernel driver in use: cxl_mem

Questions/Comments:
-------------------
1. Linux
  a. Is there a gitlab for the linux kernel patches for CXL?  This would
     facilitate review and code modifications.

2. UEFI (edk2 from tianocore)
  a. seems to only support CXL 1.1 which means only method #1 (Device
     option ROM) of Coherent Device Attribute Table_1.02 spec
     for CDAT handling is possible now.

     Does device option ROM need to be added to QEMU CXL setup?

     Can we add a CXL 1.1 emulated device?

  b. lspci doesn’t show the existence of the DOE extended capability register
     in the CXL CT3D (needed to support method #2).  Are there more patches?

3. Do you have example user programs to share or better yet the CXL 2.0
   Sec 14.3.6.1 Application Layer/ Transaction layer test for CXL.mem?

4. What are the userspace system APIs for targeting CXL HDM address domain?
   Usually you can mmap a SPA if you know how to look it up.


Best Regards,
Chris Browy


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^ permalink raw reply	[flat|nested] 67+ messages in thread

end of thread, other threads:[~2020-12-04 14:28 UTC | newest]

Thread overview: 67+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-11-11  5:46 [RFC PATCH 00/25] Introduce CXL 2.0 Emulation Ben Widawsky
2020-11-11  5:47 ` [RFC PATCH 01/25] Temp: Add the PCI_EXT_ID_DVSEC definition to the qemu pci_regs.h copy Ben Widawsky
2020-11-11  5:47 ` [RFC PATCH 02/25] hw/pci/cxl: Add a CXL component type (interface) Ben Widawsky
2020-11-11  5:47 ` [RFC PATCH 03/25] hw/cxl/component: Introduce CXL components (8.1.x, 8.2.5) Ben Widawsky
2020-11-16 12:03   ` Jonathan Cameron
2020-11-16 19:19     ` Ben Widawsky
2020-11-17 12:29       ` Jonathan Cameron
2020-11-24 23:09         ` Ben Widawsky
2020-11-11  5:47 ` [RFC PATCH 04/25] hw/cxl/device: Introduce a CXL device (8.2.8) Ben Widawsky
2020-11-16 13:07   ` Jonathan Cameron
2020-11-16 21:11     ` Ben Widawsky
2020-11-17 14:21       ` Jonathan Cameron
2020-11-11  5:47 ` [RFC PATCH 05/25] hw/cxl/device: Implement the CAP array (8.2.8.1-2) Ben Widawsky
2020-11-16 13:11   ` Jonathan Cameron
2020-11-16 18:08     ` Ben Widawsky
2020-11-11  5:47 ` [RFC PATCH 06/25] hw/cxl/device: Add device status (8.2.8.3) Ben Widawsky
2020-11-16 13:16   ` Jonathan Cameron
2020-11-16 21:18     ` Ben Widawsky
2020-11-17 14:24       ` Jonathan Cameron
2020-11-11  5:47 ` [RFC PATCH 07/25] hw/cxl/device: Implement basic mailbox (8.2.8.4) Ben Widawsky
2020-11-16 13:46   ` Jonathan Cameron
2020-11-16 21:42     ` Ben Widawsky
2020-11-11  5:47 ` [RFC PATCH 08/25] hw/cxl/device: Add memory devices (8.2.8.5) Ben Widawsky
2020-11-16 16:37   ` Jonathan Cameron
2020-11-16 21:45     ` Ben Widawsky
2020-11-17 14:31       ` Jonathan Cameron
2020-11-11  5:47 ` [RFC PATCH 09/25] hw/pxb: Use a type for realizing expanders Ben Widawsky
2020-11-11  5:47 ` [RFC PATCH 10/25] hw/pci/cxl: Create a CXL bus type Ben Widawsky
2020-11-11  5:47 ` [RFC PATCH 11/25] hw/pxb: Allow creation of a CXL PXB (host bridge) Ben Widawsky
2020-11-16 16:44   ` Jonathan Cameron
2020-11-16 22:01     ` Ben Widawsky
2020-11-17 14:33       ` Jonathan Cameron
2020-11-11  5:47 ` [RFC PATCH 12/25] acpi/pci: Consolidate host bridge setup Ben Widawsky
2020-11-12 17:46   ` Ben Widawsky
2020-11-16 16:45   ` Jonathan Cameron
2020-11-11  5:47 ` [RFC PATCH 13/25] hw/pci: Plumb _UID through host bridges Ben Widawsky
2020-11-11  5:47 ` [RFC PATCH 14/25] hw/cxl/component: Implement host bridge MMIO (8.2.5, table 142) Ben Widawsky
2020-11-11  5:47 ` [RFC PATCH 15/25] acpi/pxb/cxl: Reserve host bridge MMIO Ben Widawsky
2020-11-16 16:54   ` Jonathan Cameron
2020-11-11  5:47 ` [RFC PATCH 16/25] hw/pxb/cxl: Add "windows" for host bridges Ben Widawsky
2020-11-13  0:49   ` Ben Widawsky
2020-11-23 19:12     ` Philippe Mathieu-Daudé
2020-11-11  5:47 ` [RFC PATCH 17/25] hw/cxl/rp: Add a root port Ben Widawsky
2020-11-11  5:47 ` [RFC PATCH 18/25] hw/cxl/device: Add a memory device (8.2.8.5) Ben Widawsky
2020-11-12 18:37   ` Eric Blake
2020-11-13  7:47     ` Markus Armbruster
2020-11-25 16:53       ` Ben Widawsky
2020-11-26  6:36         ` Markus Armbruster
2020-11-30 17:07           ` Ben Widawsky
2020-12-01 17:06             ` Markus Armbruster
2020-11-11  5:47 ` [RFC PATCH 19/25] hw/cxl/device: Implement MMIO HDM decoding (8.2.5.12) Ben Widawsky
2020-11-11  5:47 ` [RFC PATCH 20/25] acpi/cxl: Add _OSC implementation (9.14.2) Ben Widawsky
2020-11-11  5:47 ` [RFC PATCH 21/25] acpi/cxl: Introduce a compat-driver UUID for CXL _OSC Ben Widawsky
2020-11-11  5:47 ` [RFC PATCH 22/25] acpi/cxl: Create the CEDT (9.14.1) Ben Widawsky
2020-11-16 17:15   ` Jonathan Cameron
2020-11-16 22:05     ` Ben Widawsky
2020-11-11  5:47 ` [RFC PATCH 23/25] Temp: acpi/cxl: Add ACPI0017 (CEDT awareness) Ben Widawsky
2020-11-11  5:47 ` [RFC PATCH 24/25] WIP: i386/cxl: Initialize a host bridge Ben Widawsky
2020-11-11  5:47 ` [RFC PATCH 25/25] qtest/cxl: Add very basic sanity tests Ben Widawsky
2020-11-16 17:21 ` [RFC PATCH 00/25] Introduce CXL 2.0 Emulation Jonathan Cameron
2020-11-16 18:06   ` Ben Widawsky
2020-11-17 14:09     ` Jonathan Cameron
2020-11-25 18:29       ` Ben Widawsky
2020-12-04 14:27 ` Daniel P. Berrangé
2020-12-04  5:08 Chris Browy
2020-12-04  5:55 ` Dan Williams
2020-12-04  5:55   ` Dan Williams

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