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Re: [PATCH v6 06/43] hw/cxl/device: Implement basic mailbox (8.2.8.4)
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From: |
Jonathan Cameron |
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Subject: |
Re: [PATCH v6 06/43] hw/cxl/device: Implement basic mailbox (8.2.8.4) |
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Date: |
Thu, 3 Mar 2022 16:31:28 +0000 |
On Tue, 01 Mar 2022 15:32:02 +0000
Alex Bennée <alex.bennee@linaro.org> wrote:
> Jonathan Cameron <Jonathan.Cameron@huawei.com> writes:
>
> > From: Ben Widawsky <ben.widawsky@intel.com>
> >
> > This is the beginning of implementing mailbox support for CXL 2.0
> > devices. The implementation recognizes when the doorbell is rung,
> > handles the command/payload, clears the doorbell while returning error
> > codes and data.
> >
> > Generally the mailbox mechanism is designed to permit communication
> > between the host OS and the firmware running on the device. For our
> > purposes, we emulate both the firmware, implemented primarily in
> > cxl-mailbox-utils.c, and the hardware.
> >
> > No commands are implemented yet.
> >
> > Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
> > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> > ---
> > hw/cxl/cxl-device-utils.c | 128 ++++++++++++++++++++++++++-
> > hw/cxl/cxl-mailbox-utils.c | 171 ++++++++++++++++++++++++++++++++++++
> > hw/cxl/meson.build | 1 +
> > include/hw/cxl/cxl.h | 3 +
> > include/hw/cxl/cxl_device.h | 19 +++-
> > 5 files changed, 320 insertions(+), 2 deletions(-)
> >
> > diff --git a/hw/cxl/cxl-device-utils.c b/hw/cxl/cxl-device-utils.c
> > index 0895b9d78b..39011468ef 100644
> > --- a/hw/cxl/cxl-device-utils.c
> > +++ b/hw/cxl/cxl-device-utils.c
> > @@ -44,6 +44,114 @@ static uint64_t dev_reg_read(void *opaque, hwaddr
> > offset, unsigned size)
> > return 0;
> > }
> >
> > +static uint64_t mailbox_reg_read(void *opaque, hwaddr offset, unsigned
> > size)
> > +{
> > + CXLDeviceState *cxl_dstate = opaque;
> > +
> > + switch (size) {
> > + case 1:
> > + return cxl_dstate->mbox_reg_state[offset];
> > + case 2:
> > + return cxl_dstate->mbox_reg_state16[offset / 2];
> > + case 4:
> > + return cxl_dstate->mbox_reg_state32[offset / 4];
> > + case 8:
> > + return cxl_dstate->mbox_reg_state64[offset / 8];
> > + default:
> > + g_assert_not_reached();
> > + }
> > +}
> > +
> > +static void mailbox_mem_writel(uint32_t *reg_state, hwaddr offset,
> > + uint64_t value)
> > +{
> > + switch (offset) {
> > + case A_CXL_DEV_MAILBOX_CTRL:
> > + /* fallthrough */
> > + case A_CXL_DEV_MAILBOX_CAP:
> > + /* RO register */
> > + break;
> > + default:
> > + qemu_log_mask(LOG_UNIMP,
> > + "%s Unexpected 32-bit access to 0x%" PRIx64 "
> > (WI)\n",
> > + __func__, offset);
> > + return;
> > + }
> > +
> > + reg_state[offset / 4] = value;
> > +}
> > +
> > +static void mailbox_mem_writeq(uint64_t *reg_state, hwaddr offset,
> > + uint64_t value)
> > +{
> > + switch (offset) {
> > + case A_CXL_DEV_MAILBOX_CMD:
> > + break;
> > + case A_CXL_DEV_BG_CMD_STS:
> > + /* BG not supported */
> > + /* fallthrough */
> > + case A_CXL_DEV_MAILBOX_STS:
> > + /* Read only register, will get updated by the state machine */
> > + return;
> > + default:
> > + qemu_log_mask(LOG_UNIMP,
> > + "%s Unexpected 64-bit access to 0x%" PRIx64 "
> > (WI)\n",
> > + __func__, offset);
> > + return;
> > + }
> > +
> > +
> > + reg_state[offset / 8] = value;
> > +}
> > +
> > +static void mailbox_reg_write(void *opaque, hwaddr offset, uint64_t value,
> > + unsigned size)
> > +{
> > + CXLDeviceState *cxl_dstate = opaque;
> > +
> > + if (offset >= A_CXL_DEV_CMD_PAYLOAD) {
> > + memcpy(cxl_dstate->mbox_reg_state + offset, &value, size);
> > + return;
> > + }
> > +
> > + /*
> > + * Lock is needed to prevent concurrent writes as well as to
> > + * prevent writes coming in while the firmware is processing.
> > + * Until background commands or the second mailbox are implemented
> > + * memory access is synchronized at a higher level (per memory region).
> > + */
>
> What lock?
>
> That said you probably don't need one as all access to IO space should
> already be serialised by the BQL so even multiple vCPUs will serialise
> their access.
oops. I removed the lock for exactly this reason but failed to remove the
comment. Now gone ;)
> > +}
> > +
> > +static const MemoryRegionOps mailbox_ops = {
> > + .read = mailbox_reg_read,
> > + .write = mailbox_reg_write,
> > + .endianness = DEVICE_LITTLE_ENDIAN,
> > + .valid = {
> > + .min_access_size = 1,
> > + .max_access_size = 8,
> > + .unaligned = false,
> > + },
> > + .impl = {
> > + .min_access_size = 1,
> > + .max_access_size = 8,
> > + },
> > +};
> > +
> > static const MemoryRegionOps dev_ops = {
> > .read = dev_reg_read,
> > .write = NULL, /* status register is read only */
> > @@ -84,20 +192,33 @@ void cxl_device_register_block_init(Object *obj,
> > CXLDeviceState *cxl_dstate)
> > "cap-array", CXL_CAPS_SIZE);
> > memory_region_init_io(&cxl_dstate->device, obj, &dev_ops, cxl_dstate,
> > "device-status", CXL_DEVICE_REGISTERS_LENGTH);
> > + memory_region_init_io(&cxl_dstate->mailbox, obj, &mailbox_ops,
> > cxl_dstate,
> > + "mailbox", CXL_MAILBOX_REGISTERS_LENGTH);
> >
> > memory_region_add_subregion(&cxl_dstate->device_registers, 0,
> > &cxl_dstate->caps);
> > memory_region_add_subregion(&cxl_dstate->device_registers,
> > CXL_DEVICE_REGISTERS_OFFSET,
> > &cxl_dstate->device);
> > + memory_region_add_subregion(&cxl_dstate->device_registers,
> > + CXL_MAILBOX_REGISTERS_OFFSET,
> > + &cxl_dstate->mailbox);
> > }
> >
> > static void device_reg_init_common(CXLDeviceState *cxl_dstate) { }
> >
> > +static void mailbox_reg_init_common(CXLDeviceState *cxl_dstate)
> > +{
> > + /* 2048 payload size, with no interrupt or background support */
> > + ARRAY_FIELD_DP32(cxl_dstate->mbox_reg_state32, CXL_DEV_MAILBOX_CAP,
> > + PAYLOAD_SIZE, CXL_MAILBOX_PAYLOAD_SHIFT);
> > + cxl_dstate->payload_size = CXL_MAILBOX_MAX_PAYLOAD_SIZE;
> > +}
> > +
> > void cxl_device_register_init_common(CXLDeviceState *cxl_dstate)
> > {
> > uint64_t *cap_hdrs = cxl_dstate->caps_reg_state64;
> > - const int cap_count = 1;
> > + const int cap_count = 2;
> >
> > /* CXL Device Capabilities Array Register */
> > ARRAY_FIELD_DP64(cap_hdrs, CXL_DEV_CAP_ARRAY, CAP_ID, 0);
> > @@ -106,4 +227,9 @@ void cxl_device_register_init_common(CXLDeviceState
> > *cxl_dstate)
> >
> > cxl_device_cap_init(cxl_dstate, DEVICE, 1);
> > device_reg_init_common(cxl_dstate);
> > +
> > + cxl_device_cap_init(cxl_dstate, MAILBOX, 2);
> > + mailbox_reg_init_common(cxl_dstate);
> > +
> > + assert(cxl_initialize_mailbox(cxl_dstate) == 0);
> > }
> > diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
> > new file mode 100644
> > index 0000000000..d497ec50a6
> > --- /dev/null
> > +++ b/hw/cxl/cxl-mailbox-utils.c
> > @@ -0,0 +1,171 @@
> > +/*
> > + * CXL Utility library for mailbox interface
> > + *
> > + * Copyright(C) 2020 Intel Corporation.
> > + *
> > + * This work is licensed under the terms of the GNU GPL, version 2. See the
> > + * COPYING file in the top-level directory.
> > + */
> > +
> > +#include "qemu/osdep.h"
> > +#include "hw/cxl/cxl.h"
> > +#include "hw/pci/pci.h"
> > +#include "qemu/log.h"
> > +#include "qemu/uuid.h"
> > +
> > +/*
> > + * How to add a new command, example. The command set FOO, with cmd BAR.
> > + * 1. Add the command set and cmd to the enum.
> > + * FOO = 0x7f,
> > + * #define BAR 0
> > + * 2. Implement the handler
> > + * static ret_code cmd_foo_bar(struct cxl_cmd *cmd,
> > + * CXLDeviceState *cxl_dstate, uint16_t
> > *len)
> > + * 3. Add the command to the cxl_cmd_set[][]
> > + * [FOO][BAR] = { "FOO_BAR", cmd_foo_bar, x, y },
> > + * 4. Implement your handler
> > + * define_mailbox_handler(FOO_BAR) { ... return CXL_MBOX_SUCCESS; }
> > + *
> > + *
> > + * Writing the handler:
> > + * The handler will provide the &struct cxl_cmd, the &CXLDeviceState,
> > and the
> > + * in/out length of the payload. The handler is responsible for
> > consuming the
> > + * payload from cmd->payload and operating upon it as necessary. It
> > must then
> > + * fill the output data into cmd->payload (overwriting what was there),
> > + * setting the length, and returning a valid return code.
> > + *
> > + * XXX: The handler need not worry about endianess. The payload is read
> > out of
> > + * a register interface that already deals with it.
> > + */
> > +
> > +/* 8.2.8.4.5.1 Command Return Codes */
> > +typedef enum {
> > + CXL_MBOX_SUCCESS = 0x0,
> > + CXL_MBOX_BG_STARTED = 0x1,
> > + CXL_MBOX_INVALID_INPUT = 0x2,
> > + CXL_MBOX_UNSUPPORTED = 0x3,
> > + CXL_MBOX_INTERNAL_ERROR = 0x4,
> > + CXL_MBOX_RETRY_REQUIRED = 0x5,
> > + CXL_MBOX_BUSY = 0x6,
> > + CXL_MBOX_MEDIA_DISABLED = 0x7,
> > + CXL_MBOX_FW_XFER_IN_PROGRESS = 0x8,
> > + CXL_MBOX_FW_XFER_OUT_OF_ORDER = 0x9,
> > + CXL_MBOX_FW_AUTH_FAILED = 0xa,
> > + CXL_MBOX_FW_INVALID_SLOT = 0xb,
> > + CXL_MBOX_FW_ROLLEDBACK = 0xc,
> > + CXL_MBOX_FW_REST_REQD = 0xd,
> > + CXL_MBOX_INVALID_HANDLE = 0xe,
> > + CXL_MBOX_INVALID_PA = 0xf,
> > + CXL_MBOX_INJECT_POISON_LIMIT = 0x10,
> > + CXL_MBOX_PERMANENT_MEDIA_FAILURE = 0x11,
> > + CXL_MBOX_ABORTED = 0x12,
> > + CXL_MBOX_INVALID_SECURITY_STATE = 0x13,
> > + CXL_MBOX_INCORRECT_PASSPHRASE = 0x14,
> > + CXL_MBOX_UNSUPPORTED_MAILBOX = 0x15,
> > + CXL_MBOX_INVALID_PAYLOAD_LENGTH = 0x16,
> > + CXL_MBOX_MAX = 0x17
> > +} ret_code;
> > +
> > +struct cxl_cmd;
> > +typedef ret_code (*opcode_handler)(struct cxl_cmd *cmd,
> > + CXLDeviceState *cxl_dstate, uint16_t
> > *len);
> > +struct cxl_cmd {
> > + const char *name;
> > + opcode_handler handler;
> > + ssize_t in;
> > + uint16_t effect; /* Reported in CEL */
> > + uint8_t *payload;
> > +};
> > +
> > +#define DEFINE_MAILBOX_HANDLER_ZEROED(name, size) \
> > + uint16_t __zero##name = size; \
> > + static ret_code cmd_##name(struct cxl_cmd *cmd, \
> > + CXLDeviceState *cxl_dstate, uint16_t *len) \
> > + { \
> > + *len = __zero##name; \
> > + memset(cmd->payload, 0, *len); \
> > + return CXL_MBOX_SUCCESS; \
> > + }
> > +#define DEFINE_MAILBOX_HANDLER_NOP(name) \
> > + static ret_code cmd_##name(struct cxl_cmd *cmd, \
> > + CXLDeviceState *cxl_dstate, uint16_t *len) \
> > + { \
> > + return CXL_MBOX_SUCCESS; \
> > + }
> > +
> > +static QemuUUID cel_uuid;
> > +
> > +static struct cxl_cmd cxl_cmd_set[256][256] = {};
> > +
> > +void cxl_process_mailbox(CXLDeviceState *cxl_dstate)
> > +{
> > + uint16_t ret = CXL_MBOX_SUCCESS;
> > + struct cxl_cmd *cxl_cmd;
> > + uint64_t status_reg;
> > + opcode_handler h;
> > +
> > + /*
> > + * current state of mailbox interface
> > + * mbox_cap_reg = cxl_dstate->reg_state32[R_CXL_DEV_MAILBOX_CAP];
> > + * mbox_ctrl_reg = cxl_dstate->reg_state32[R_CXL_DEV_MAILBOX_CTRL];
> > + * status_reg = *(uint64_t
> > *)&cxl_dstate->reg_state[A_CXL_DEV_MAILBOX_STS];
> > + */
> > + uint64_t command_reg =
> > cxl_dstate->mbox_reg_state64[R_CXL_DEV_MAILBOX_CMD];
> > +
> > + uint8_t set = FIELD_EX64(command_reg, CXL_DEV_MAILBOX_CMD,
> > COMMAND_SET);
> > + uint8_t cmd = FIELD_EX64(command_reg, CXL_DEV_MAILBOX_CMD, COMMAND);
> > + uint16_t len = FIELD_EX64(command_reg, CXL_DEV_MAILBOX_CMD, LENGTH);
> > + cxl_cmd = &cxl_cmd_set[set][cmd];
> > + h = cxl_cmd->handler;
> > + if (!h) {
> > + qemu_log_mask(LOG_UNIMP, "Command %04xh not implemented\n",
> > + set << 8 | cmd);
>
> is ret of CXL_MBOX_SUCCESS still ok for an unimplemented command?
Good spot. CXL_MBOX_UNSUPPORTED is a more useful response.
>
> > + goto handled;
> > + }
> > +
> > + if (len != cxl_cmd->in) {
> > + ret = CXL_MBOX_INVALID_PAYLOAD_LENGTH;
> > + }
> > +
> > + cxl_cmd->payload = cxl_dstate->mbox_reg_state + A_CXL_DEV_CMD_PAYLOAD;
> > + ret = (*h)(cxl_cmd, cxl_dstate, &len);
> > + assert(len <= cxl_dstate->payload_size);
> > +
>
> Not super keen on the goto, it seems to me the you could trivially
> re-arrange this to avoid it as it is not a super deep implementation.
>
> if (h) {
> if (len == cxl_cmd->in) {
> /* do the thing */
> } else {
> ret = CXL_MBOX_INVALID_PAYLOAD_LENGTH;
> } else {
> qemu_log_mask(LOG_UNIMP, "Command %04xh not implemented\n",
> set << 8 | cmd);
> }
Indeed much cleaner.
..
>
> Otherwise:
>
> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
>
Everything else changed as suggested.
Thanks,
Jonathan