[PATCH] hw/cxl: Support aborting background commands

Davidlohr Bueso
2024-08-13T22:29:41Z

As of 3.1 spec, background commands can be canceled with a new
abort command. Implement the support, which is advertised in
the CEL. No ad-hoc context undoing is necessary as all the
command logic of the running bg command is done upon completion.
Arbitrarily, the on-going background cmd will not be aborted if
already at least 85% done;

A mutex is introduced to stabilize mbox request cancel command vs
the timer callback being fired scenarios (as well as reading the
mbox registers). While some operations under critical regions
may be unnecessary (irq notifying, cmd callbacks), this is not
a path where performance is important, so simplicity is preferred.

Tested-by: Ajay Joshi <ajay.opensrc@micron.com>
Reviewed-by: Ajay Joshi <ajay.opensrc@micron.com>
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
---

Changes based on the following thread:
https://lore.kernel.org/linux-cxl/20240729102010.20996-1-ajay.opensrc@micron.com

- Added a mutex (and expanded CCI to have a destroy counterpart).
An 'initialized' flag is added for correctly handling the reset()
case.
- Added the case where cancel is not done.
- Picked up Ajay's tags but it would be good to re-review/test if
possible.

hw/cxl/cxl-device-utils.c | 5 ++-
hw/cxl/cxl-mailbox-utils.c | 63 +++++++++++++++++++++++++++++++++---
hw/mem/cxl_type3.c | 8 ++++-
include/hw/cxl/cxl_device.h | 4 +++
include/hw/cxl/cxl_mailbox.h | 1 +
5 files changed, 74 insertions(+), 7 deletions(-)

diff --git a/hw/cxl/cxl-device-utils.c b/hw/cxl/cxl-device-utils.c
index 035d034f6dd8..1a9779ed8201 100644
--- a/hw/cxl/cxl-device-utils.c
+++ b/hw/cxl/cxl-device-utils.c
@@ -95,11 +95,14 @@ static uint64_t mailbox_reg_read(void *opaque, hwaddr offset, unsigned size)
}
if (offset == A_CXL_DEV_MAILBOX_STS) {
uint64_t status_reg = cxl_dstate->mbox_reg_state64[offset / size];
- if (cci->bg.complete_pct) {
+
+ qemu_mutex_lock(&cci->bg.lock);
+ if (cci->bg.complete_pct == 100 || cci->bg.aborted) {
status_reg = FIELD_DP64(status_reg, CXL_DEV_MAILBOX_STS, BG_OP,
0);
cxl_dstate->mbox_reg_state64[offset / size] = status_reg;
}
+ qemu_mutex_unlock(&cci->bg.lock);
}
return cxl_dstate->mbox_reg_state64[offset / size];
default:
diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
index b752920ec88a..ff12dfc3dcc4 100644
--- a/hw/cxl/cxl-mailbox-utils.c
+++ b/hw/cxl/cxl-mailbox-utils.c
@@ -56,6 +56,7 @@ enum {
INFOSTAT = 0x00,
#define IS_IDENTIFY 0x1
#define BACKGROUND_OPERATION_STATUS 0x2
+ #define BACKGROUND_OPERATION_ABORT 0x5
EVENTS = 0x01,
#define GET_RECORDS 0x0
#define CLEAR_RECORDS 0x1
@@ -624,6 +625,38 @@ static CXLRetCode cmd_infostat_bg_op_sts(const struct cxl_cmd *cmd,
return CXL_MBOX_SUCCESS;
}

+/* CXL r3.1 Section 8.2.9.1.5: Request Abort Background Operation (Opcode 0005h) */
+static CXLRetCode cmd_infostat_bg_op_abort(const struct cxl_cmd *cmd,
+ uint8_t *payload_in,
+ size_t len_in,
+ uint8_t *payload_out,
+ size_t *len_out,
+ CXLCCI *cci)
+{
+ int bg_set = cci->bg.opcode >> 8;
+ int bg_cmd = cci->bg.opcode & 0xff;
+ const struct cxl_cmd *bg_c = &cci->cxl_cmd_set[bg_set][bg_cmd];
+
+ if (!(bg_c->effect & CXL_MBOX_BACKGROUND_OPERATION_ABORT)) {
+ return CXL_MBOX_REQUEST_ABORT_NOTSUP;
+ }
+
+ qemu_mutex_lock(&cci->bg.lock);
+ if (cci->bg.runtime) {
+ /* operation is near complete, let it finish */
+ if (cci->bg.complete_pct < 85) {
+ timer_del(cci->bg.timer);
+ cci->bg.ret_code = CXL_MBOX_ABORTED;
+ cci->bg.starttime = 0;
+ cci->bg.runtime = 0;
+ cci->bg.aborted = true;
+ }
+ }
+ qemu_mutex_unlock(&cci->bg.lock);
+
+ return CXL_MBOX_SUCCESS;
+}
+
#define CXL_FW_SLOTS 2
#define CXL_FW_SIZE 0x02000000 /* 32 mb */

@@ -2665,6 +2698,8 @@ static CXLRetCode cmd_dcd_release_dyn_cap(const struct cxl_cmd *cmd,
}

static const struct cxl_cmd cxl_cmd_set[256][256] = {
+ [INFOSTAT][BACKGROUND_OPERATION_ABORT] = { "BACKGROUND_OPERATION_ABORT",
+ cmd_infostat_bg_op_abort, 0, 0 },
[EVENTS][GET_RECORDS] = { "EVENTS_GET_RECORDS",
cmd_events_get_records, 1, 0 },
[EVENTS][CLEAR_RECORDS] = { "EVENTS_CLEAR_RECORDS",
@@ -2708,7 +2743,8 @@ static const struct cxl_cmd cxl_cmd_set[256][256] = {
[SANITIZE][OVERWRITE] = { "SANITIZE_OVERWRITE", cmd_sanitize_overwrite, 0,
(CXL_MBOX_IMMEDIATE_DATA_CHANGE |
CXL_MBOX_SECURITY_STATE_CHANGE |
- CXL_MBOX_BACKGROUND_OPERATION)},
+ CXL_MBOX_BACKGROUND_OPERATION |
+ CXL_MBOX_BACKGROUND_OPERATION_ABORT)},
[PERSISTENT_MEM][GET_SECURITY_STATE] = { "GET_SECURITY_STATE",
cmd_get_security_state, 0, 0 },
[MEDIA_AND_POISON][GET_POISON_LIST] = { "MEDIA_AND_POISON_GET_POISON_LIST",
@@ -2721,7 +2757,8 @@ static const struct cxl_cmd cxl_cmd_set[256][256] = {
"MEDIA_AND_POISON_GET_SCAN_MEDIA_CAPABILITIES",
cmd_media_get_scan_media_capabilities, 16, 0 },
[MEDIA_AND_POISON][SCAN_MEDIA] = { "MEDIA_AND_POISON_SCAN_MEDIA",
- cmd_media_scan_media, 17, CXL_MBOX_BACKGROUND_OPERATION },
+ cmd_media_scan_media, 17,
+ (CXL_MBOX_BACKGROUND_OPERATION | CXL_MBOX_BACKGROUND_OPERATION_ABORT)},
[MEDIA_AND_POISON][GET_SCAN_MEDIA_RESULTS] = {
"MEDIA_AND_POISON_GET_SCAN_MEDIA_RESULTS",
cmd_media_get_scan_media_results, 0, 0 },
@@ -2745,6 +2782,8 @@ static const struct cxl_cmd cxl_cmd_set_sw[256][256] = {
[INFOSTAT][IS_IDENTIFY] = { "IDENTIFY", cmd_infostat_identify, 0, 0 },
[INFOSTAT][BACKGROUND_OPERATION_STATUS] = { "BACKGROUND_OPERATION_STATUS",
cmd_infostat_bg_op_sts, 0, 0 },
+ [INFOSTAT][BACKGROUND_OPERATION_ABORT] = { "BACKGROUND_OPERATION_ABORT",
+ cmd_infostat_bg_op_abort, 0, 0 },
[TIMESTAMP][GET] = { "TIMESTAMP_GET", cmd_timestamp_get, 0, 0 },
[TIMESTAMP][SET] = { "TIMESTAMP_SET", cmd_timestamp_set, 8,
CXL_MBOX_IMMEDIATE_POLICY_CHANGE },
@@ -2831,6 +2870,7 @@ int cxl_process_cci_message(CXLCCI *cci, uint8_t set, uint8_t cmd,
cci->bg.opcode = (set << 8) | cmd;

cci->bg.complete_pct = 0;
+ cci->bg.aborted = false;
cci->bg.ret_code = 0;

now = qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL);
@@ -2844,10 +2884,12 @@ int cxl_process_cci_message(CXLCCI *cci, uint8_t set, uint8_t cmd,
static void bg_timercb(void *opaque)
{
CXLCCI *cci = opaque;
- uint64_t now = qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL);
- uint64_t total_time = cci->bg.starttime + cci->bg.runtime;
+ uint64_t now, total_time;
+
+ qemu_mutex_lock(&cci->bg.lock);

- assert(cci->bg.runtime > 0);
+ now = qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL);
+ total_time = cci->bg.starttime + cci->bg.runtime;

if (now >= total_time) { /* we are done */
uint16_t ret = CXL_MBOX_SUCCESS;
@@ -2899,6 +2941,8 @@ static void bg_timercb(void *opaque)
msi_notify(pdev, cxl_dstate->mbox_msi_n);
}
}
+
+ qemu_mutex_unlock(&cci->bg.lock);
}

static void cxl_rebuild_cel(CXLCCI *cci)
@@ -2927,12 +2971,21 @@ void cxl_init_cci(CXLCCI *cci, size_t payload_max)
cci->bg.complete_pct = 0;
cci->bg.starttime = 0;
cci->bg.runtime = 0;
+ cci->bg.aborted = false;
cci->bg.timer = timer_new_ms(QEMU_CLOCK_VIRTUAL,
bg_timercb, cci);
+ qemu_mutex_init(&cci->bg.lock);

memset(&cci->fw, 0, sizeof(cci->fw));
cci->fw.active_slot = 1;
cci->fw.slot[cci->fw.active_slot - 1] = true;
+ cci->initialized = true;
+}
+
+void cxl_destroy_cci(CXLCCI *cci)
+{
+ qemu_mutex_destroy(&cci->bg.lock);
+ cci->initialized = false;
}

static void cxl_copy_cci_commands(CXLCCI *cci, const struct cxl_cmd (*cxl_cmds)[256])
diff --git a/hw/mem/cxl_type3.c b/hw/mem/cxl_type3.c
index 4114163324bd..f04aa58ea85d 100644
--- a/hw/mem/cxl_type3.c
+++ b/hw/mem/cxl_type3.c
@@ -961,6 +961,7 @@ static void ct3_exit(PCIDevice *pci_dev)
pcie_aer_exit(pci_dev);
cxl_doe_cdat_release(cxl_cstate);
g_free(regs->special_ops);
+ cxl_destroy_cci(&ct3d->cci);
if (ct3d->dc.host_dc) {
cxl_destroy_dc_regions(ct3d);
address_space_destroy(&ct3d->dc.host_dc_as);
@@ -1209,12 +1210,17 @@ static void ct3d_reset(DeviceState *dev)
* Bring up an endpoint to target with MCTP over VDM.
* This device is emulating an MLD with single LD for now.
*/
+ if (ct3d->vdm_fm_owned_ld_mctp_cci.initialized) {
+ cxl_destroy_cci(&ct3d->vdm_fm_owned_ld_mctp_cci);
+ }
cxl_initialize_t3_fm_owned_ld_mctpcci(&ct3d->vdm_fm_owned_ld_mctp_cci,
DEVICE(ct3d), DEVICE(ct3d),
512); /* Max payload made up */
+ if (ct3d->ld0_cci.initialized) {
+ cxl_destroy_cci(&ct3d->ld0_cci);
+ }
cxl_initialize_t3_ld_cci(&ct3d->ld0_cci, DEVICE(ct3d), DEVICE(ct3d),
512); /* Max payload made up */
-
}

static Property ct3_props[] = {
diff --git a/include/hw/cxl/cxl_device.h b/include/hw/cxl/cxl_device.h
index e14e56ae4bc2..c0e8d40053db 100644
--- a/include/hw/cxl/cxl_device.h
+++ b/include/hw/cxl/cxl_device.h
@@ -176,10 +176,12 @@ typedef struct CXLCCI {
uint16_t opcode;
uint16_t complete_pct;
uint16_t ret_code; /* Current value of retcode */
+ bool aborted;
uint64_t starttime;
/* set by each bg cmd, cleared by the bg_timer when complete */
uint64_t runtime;
QEMUTimer *timer;
+ QemuMutex lock; /* serializes mbox abort vs timer cb */
} bg;

/* firmware update */
@@ -201,6 +203,7 @@ typedef struct CXLCCI {
DeviceState *d;
/* Pointer to the device hosting the protocol conversion */
DeviceState *intf;
+ bool initialized;
} CXLCCI;

typedef struct cxl_device_state {
@@ -316,6 +319,7 @@ void cxl_initialize_mailbox_t3(CXLCCI *cci, DeviceState *d, size_t payload_max);
void cxl_initialize_mailbox_swcci(CXLCCI *cci, DeviceState *intf,
DeviceState *d, size_t payload_max);
void cxl_init_cci(CXLCCI *cci, size_t payload_max);
+void cxl_destroy_cci(CXLCCI *cci);
void cxl_add_cci_commands(CXLCCI *cci, const struct cxl_cmd (*cxl_cmd_set)[256],
size_t payload_max);
int cxl_process_cci_message(CXLCCI *cci, uint8_t set, uint8_t cmd,
diff --git a/include/hw/cxl/cxl_mailbox.h b/include/hw/cxl/cxl_mailbox.h
index beb048052e1b..9008402d1c46 100644
--- a/include/hw/cxl/cxl_mailbox.h
+++ b/include/hw/cxl/cxl_mailbox.h
@@ -14,5 +14,6 @@
#define CXL_MBOX_IMMEDIATE_LOG_CHANGE (1 << 4)
#define CXL_MBOX_SECURITY_STATE_CHANGE (1 << 5)
#define CXL_MBOX_BACKGROUND_OPERATION (1 << 6)
+#define CXL_MBOX_BACKGROUND_OPERATION_ABORT (1 << 7)

#endif
--
2.45.2