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Re: [PATCH v4 04/42] hw/cxl/device: Introduce a CXL device (8.2.8)
From: |
Alex Bennée |
Subject: |
Re: [PATCH v4 04/42] hw/cxl/device: Introduce a CXL device (8.2.8) |
Date: |
Wed, 26 Jan 2022 18:07:40 +0000 |
User-agent: |
mu4e 1.7.6; emacs 28.0.91 |
Jonathan Cameron <Jonathan.Cameron@huawei.com> writes:
> From: Ben Widawsky <ben.widawsky@intel.com>
>
> A CXL device is a type of CXL component. Conceptually, a CXL device
> would be a leaf node in a CXL topology. From an emulation perspective,
> CXL devices are the most complex and so the actual implementation is
> reserved for discrete commits.
>
> This new device type is specifically catered towards the eventual
> implementation of a Type3 CXL.mem device, 8.2.8.5 in the CXL 2.0
> specification.
>
> Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> ---
> include/hw/cxl/cxl.h | 1 +
> include/hw/cxl/cxl_device.h | 157 ++++++++++++++++++++++++++++++++++++
> 2 files changed, 158 insertions(+)
>
> diff --git a/include/hw/cxl/cxl.h b/include/hw/cxl/cxl.h
> index 8c738c7a2b..b9d1ac3fad 100644
> --- a/include/hw/cxl/cxl.h
> +++ b/include/hw/cxl/cxl.h
> @@ -12,5 +12,6 @@
>
> #include "cxl_pci.h"
> #include "cxl_component.h"
> +#include "cxl_device.h"
>
> #endif
> diff --git a/include/hw/cxl/cxl_device.h b/include/hw/cxl/cxl_device.h
> new file mode 100644
> index 0000000000..3b6ed745f0
> --- /dev/null
> +++ b/include/hw/cxl/cxl_device.h
> @@ -0,0 +1,157 @@
> +/*
> + * QEMU CXL Devices
> + *
> + * Copyright (c) 2020 Intel
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2. See the
> + * COPYING file in the top-level directory.
> + */
> +
> +#ifndef CXL_DEVICE_H
> +#define CXL_DEVICE_H
> +
> +#include "hw/register.h"
> +
> +/*
> + * The following is how a CXL device's MMIO space is laid out. The only
> + * requirement from the spec is that the capabilities array and the
> capability
> + * headers start at offset 0 and are contiguously packed. The headers
> themselves
> + * provide offsets to the register fields. For this emulation, registers will
> + * start at offset 0x80 (m == 0x80). No secondary mailbox is implemented
> which
> + * means that n = m + sizeof(mailbox registers) + sizeof(device registers).
> + *
> + * This is roughly described in 8.2.8 Figure 138 of the CXL 2.0 spec.
> + *
> + * +---------------------------------+
> + * | |
> + * | Memory Device Registers |
> + * | |
> + * n + PAYLOAD_SIZE_MAX -----------------------------------
> + * ^ | |
> + * | | |
> + * | | |
> + * | | |
> + * | | |
> + * | | Mailbox Payload |
> + * | | |
> + * | | |
> + * | | |
> + * | -----------------------------------
> + * | | Mailbox Registers |
> + * | | |
> + * n -----------------------------------
> + * ^ | |
> + * | | Device Registers |
> + * | | |
> + * m ---------------------------------->
> + * ^ | Memory Device Capability Header|
> + * | -----------------------------------
> + * | | Mailbox Capability Header |
> + * | -------------- --------------------
> + * | | Device Capability Header |
> + * | -----------------------------------
> + * | | |
> + * | | |
> + * | | Device Cap Array[0..n] |
> + * | | |
> + * | | |
> + * | |
> + * 0 +---------------------------------+
> + *
> + */
Excellent diagram ;-)
> +
> +#define CXL_DEVICE_CAP_HDR1_OFFSET 0x10 /* Figure 138 */
> +#define CXL_DEVICE_CAP_REG_SIZE 0x10 /* 8.2.8.2 */
> +#define CXL_DEVICE_CAPS_MAX 4 /* 8.2.8.2.1 + 8.2.8.5 */
> +
> +#define CXL_DEVICE_REGISTERS_OFFSET 0x80 /* Read comment above */
> +#define CXL_DEVICE_REGISTERS_LENGTH 0x8 /* 8.2.8.3.1 */
> +
> +#define CXL_MAILBOX_REGISTERS_OFFSET \
> + (CXL_DEVICE_REGISTERS_OFFSET + CXL_DEVICE_REGISTERS_LENGTH)
> +#define CXL_MAILBOX_REGISTERS_SIZE 0x20 /* 8.2.8.4, Figure 139 */
> +#define CXL_MAILBOX_PAYLOAD_SHIFT 11
> +#define CXL_MAILBOX_MAX_PAYLOAD_SIZE (1 << CXL_MAILBOX_PAYLOAD_SHIFT)
> +#define CXL_MAILBOX_REGISTERS_LENGTH \
> + (CXL_MAILBOX_REGISTERS_SIZE + CXL_MAILBOX_MAX_PAYLOAD_SIZE)
> +
> +typedef struct cxl_device_state {
> + MemoryRegion device_registers;
> +
> + /* mmio for device capabilities array - 8.2.8.2 */
> + MemoryRegion caps;
> +
> + /* mmio for the device status registers 8.2.8.3 */
> + MemoryRegion device;
> +
> + /* mmio for the mailbox registers 8.2.8.4 */
> + MemoryRegion mailbox;
> +
> + /* memory region for persistent memory, HDM */
> + uint64_t pmem_size;
> +} CXLDeviceState;
> +
> +/* Initialize the register block for a device */
> +void cxl_device_register_block_init(Object *obj, CXLDeviceState *dev);
> +
> +/* Set up default values for the register block */
> +void cxl_device_register_init_common(CXLDeviceState *dev);
> +
> +/* CXL 2.0 - 8.2.8.1 */
> +REG32(CXL_DEV_CAP_ARRAY, 0) /* 48b!?!?! */
What does this comment mean? A 48 bit register stuffed in a 32 bit one?
Doesn't seem right.
> + FIELD(CXL_DEV_CAP_ARRAY, CAP_ID, 0, 16)
> + FIELD(CXL_DEV_CAP_ARRAY, CAP_VERSION, 16, 8)
> +REG32(CXL_DEV_CAP_ARRAY2, 4) /* We're going to pretend it's 64b */
> + FIELD(CXL_DEV_CAP_ARRAY2, CAP_COUNT, 0, 16)
I'm confused why you don't treat it as a single register it is in the
spec.
> +
> +/*
> + * Helper macro to initialize capability headers for CXL devices.
> + *
> + * In the 8.2.8.2, this is listed as a 128b register, but in 8.2.8, it says:
> + * > No registers defined in Section 8.2.8 are larger than 64-bits wide so
> that
> + * > is the maximum access size allowed for these registers. If this rule is
> not
> + * > followed, the behavior is undefined
> + *
> + * Here we've chosen to make it 4 dwords. The spec allows any pow2 multiple
> + * access to be used for a register (2 qwords, 8 words, 128 bytes).
> + */
> +#define CXL_DEVICE_CAPABILITY_HEADER_REGISTER(n, offset) \
> + REG32(CXL_DEV_##n##_CAP_HDR0, offset) \
> + FIELD(CXL_DEV_##n##_CAP_HDR0, CAP_ID, 0, 16) \
> + FIELD(CXL_DEV_##n##_CAP_HDR0, CAP_VERSION, 16, 8) \
> + REG32(CXL_DEV_##n##_CAP_HDR1, offset + 4) \
> + FIELD(CXL_DEV_##n##_CAP_HDR1, CAP_OFFSET, 0, 32) \
> + REG32(CXL_DEV_##n##_CAP_HDR2, offset + 8) \
> + FIELD(CXL_DEV_##n##_CAP_HDR2, CAP_LENGTH, 0, 32)
> +
> +CXL_DEVICE_CAPABILITY_HEADER_REGISTER(DEVICE, CXL_DEVICE_CAP_HDR1_OFFSET)
> +CXL_DEVICE_CAPABILITY_HEADER_REGISTER(MAILBOX, CXL_DEVICE_CAP_HDR1_OFFSET + \
> + CXL_DEVICE_CAP_REG_SIZE)
> +
> +REG32(CXL_DEV_MAILBOX_CAP, 0)
> + FIELD(CXL_DEV_MAILBOX_CAP, PAYLOAD_SIZE, 0, 5)
> + FIELD(CXL_DEV_MAILBOX_CAP, INT_CAP, 5, 1)
> + FIELD(CXL_DEV_MAILBOX_CAP, BG_INT_CAP, 6, 1)
> + FIELD(CXL_DEV_MAILBOX_CAP, MSI_N, 7, 4)
> +
> +REG32(CXL_DEV_MAILBOX_CTRL, 4)
> + FIELD(CXL_DEV_MAILBOX_CTRL, DOORBELL, 0, 1)
> + FIELD(CXL_DEV_MAILBOX_CTRL, INT_EN, 1, 1)
> + FIELD(CXL_DEV_MAILBOX_CTRL, BG_INT_EN, 2, 1)
> +
> +/* XXX: actually a 64b register */
> +REG32(CXL_DEV_MAILBOX_STS, 0x10)
> + FIELD(CXL_DEV_MAILBOX_STS, BG_OP, 0, 1)
> + FIELD(CXL_DEV_MAILBOX_STS, ERRNO, 32, 16)
> + FIELD(CXL_DEV_MAILBOX_STS, VENDOR_ERRNO, 48, 16)
> +
> +/* XXX: actually a 64b register */
> +REG32(CXL_DEV_BG_CMD_STS, 0x18)
> + FIELD(CXL_DEV_BG_CMD_STS, BG, 0, 16)
> + FIELD(CXL_DEV_BG_CMD_STS, DONE, 16, 7)
> + FIELD(CXL_DEV_BG_CMD_STS, ERRNO, 32, 16)
> + FIELD(CXL_DEV_BG_CMD_STS, VENDOR_ERRNO, 48, 16)
Again is there a reason not to use REG64? I can see the need to split
128 bit registers but not 64 bit ones.
> +
> +REG32(CXL_DEV_CMD_PAYLOAD, 0x20)
> +
> +#endif
Otherwise:
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
--
Alex Bennée
[PATCH v4 06/42] hw/cxl/device: Implement basic mailbox (8.2.8.4), Jonathan Cameron, 2022/01/24
[PATCH v4 08/42] hw/cxl/device: Add cheap EVENTS implementation (8.2.9.1), Jonathan Cameron, 2022/01/24