Simone
88a8b7eb27
v2 said firmware filters CF8/CFC config writes to this function and that
the registers are reachable only through ECAM. That was never tested; the
only evidence was the boot line "PCI: Using configuration type 1", which
names the accessor and says nothing about a write failing.
Measured on the board, driver unloaded:
# setpci -s 16:1e.5 9c.L=20085002 # read SPD 0x50 register 0x02
# setpci -s 16:1e.5 9c.L
20005002 # GO consumed by the engine
# setpci -s 16:1e.5 a8.L
0000500c # READ_DONE, no error
# setpci -s 16:1e.5 b4.L
0000000c # SPD byte 2, DDR4 type code
The command executes and returns correct data through the ordinary
accessors, and MSR_SMI_COUNT does not move across it. So the driver now
uses pci_read_config_dword() and pci_write_config_dword(), the submission
is a single patch again, and nothing in it touches the PCI core. The
cover letter retracts the claim explicitly rather than dropping it
quietly, because v2 was posted with it.
Correctness work in the same pass:
- the completion bits are latched, so a command word that never reaches
the register is indistinguishable from a completed transfer and the
caller gets the previous transaction's data. Read the command word
back and require it to be the one just written; the engine only ever
clears GO, which the measurement above shows directly;
- compare the command registers after every transfer against what the
driver left in them and fail with -EAGAIN on a mismatch. The original
iMC driver had this check and it is what makes an unarbitrated system
detectable instead of silently wrong;
- use the i2c core's suspended-adapter mechanism rather than a private
flag and -EHOSTDOWN;
- use devm_mutex_init(), drop the unnecessary pci_enable_device(), and
return -ENODEV rather than -EPERM from the default-off gate, which was
printing a driver-core error on every boot;
- mask GO when restoring a saved command word.
An earlier version of the latched-DONE check required the GO bit to be
seen set or the status word to change. That was wrong: repeated transfers
with the same outcome leave STATUS bit for bit identical, and GO is
consumed faster than a config read-back can observe it. It produced false
positives on 3 of 15 smoke-test items before being replaced.
Add Documentation/i2c/busses/i2c-imc-skylake.rst, which every other PC
SMBus driver has and which was asked for on the 2020 iMC thread, and the
tools/ scripts for the hardware measurements: probe-cf8-write.sh and
probe-cf8-transaction.sh produced the result above, dump-pcu-config.sh is
the search for a TSOD polling control, watch-engine.sh is the firmware
activity measurement.
Smoke test on the X299 system with the current module: 15 checks, 0
failures, dmesg clean.
254 lines
6.4 KiB
Bash
Executable File
254 lines
6.4 KiB
Bash
Executable File
#!/usr/bin/env bash
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# Read-only smoke test for i2c-imc-skylake.
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set -euo pipefail
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PASS=0
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FAIL=0
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CH0=""
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CH1=""
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CH0_ADDR=""
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CH1_ADDR=""
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if ((EUID == 0)); then
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SUDO=()
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else
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SUDO=(sudo -n)
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if ! "${SUDO[@]}" true 2>/dev/null; then
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echo "Run as root or configure non-interactive sudo." >&2
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exit 2
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fi
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fi
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MODULE_PATH=${MODULE_PATH:-$(modinfo -n i2c-imc-skylake)}
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if [[ ! -r "$MODULE_PATH" ]]; then
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echo "Module not found: $MODULE_PATH" >&2
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exit 2
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fi
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_ok()
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{
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echo "PASS: $*"
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((PASS++)) || true
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}
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_fail()
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{
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echo "FAIL: $*"
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((FAIL++)) || true
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}
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_module_loaded()
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{
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lsmod | awk '$1 == "i2c_imc_skylake" { found = 1 } END { exit !found }'
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}
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_bus()
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{
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local channel=$1
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i2cdetect -l 2>/dev/null | awk -v channel="$channel" '
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tolower($0) ~ /imc.*channel/ && $0 ~ "channel " channel {
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sub(/^i2c-/, "", $1)
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print $1
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exit
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}'
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}
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_find_pci_device()
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{
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local device path vendor
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for path in /sys/bus/pci/devices/*; do
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[[ -r "$path/vendor" && -r "$path/device" ]] || continue
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read -r vendor < "$path/vendor"
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read -r device < "$path/device"
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if [[ "$vendor" == "0x8086" && "$device" == "0x2085" ]]; then
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printf '%s\n' "$path"
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return 0
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fi
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done
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return 1
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}
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_refresh_buses()
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{
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CH0=$(_bus 0)
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CH1=$(_bus 1)
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}
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_scan_spd()
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{
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local bus=$1 result_var=$2
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local address address_hex device readable="" value
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local found=false
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echo "--- SPD scan bus $bus (read-only BYTE_DATA) ---"
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for address in {80..87}; do
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printf -v address_hex '0x%02x' "$address"
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printf -v device '%d-%04x' "$bus" "$address"
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if [[ -L "/sys/bus/i2c/devices/$device/driver" ]]; then
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echo " $address_hex present (bound to $(basename "$(readlink "/sys/bus/i2c/devices/$device/driver")"))"
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found=true
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continue
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fi
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if value=$("${SUDO[@]}" i2cget -y "$bus" "$address_hex" 0x00 2>/dev/null); then
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echo " $address_hex present (reg0=$value)"
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found=true
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readable=${readable:-$address_hex}
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fi
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done
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printf -v "$result_var" '%s' "$readable"
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$found
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}
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_word_test()
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{
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local bus=$1 address=$2
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local byte0 byte1 expected word
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if ! byte0=$("${SUDO[@]}" i2cget -y "$bus" "$address" 0x00 2>/dev/null) ||
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! byte1=$("${SUDO[@]}" i2cget -y "$bus" "$address" 0x01 2>/dev/null) ||
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! word=$("${SUDO[@]}" i2cget -y "$bus" "$address" 0x00 w 2>/dev/null); then
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return 1
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fi
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expected=$((byte0 | (byte1 << 8)))
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((word == expected))
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}
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_nack_test()
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{
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local bus=$1
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local trace
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command -v strace >/dev/null || return 1
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trace=$("${SUDO[@]}" strace -qq -f -e trace=ioctl \
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i2cget -y "$bus" 0x77 0x00 2>&1 || true)
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grep -q '= -1 ENXIO' <<< "$trace"
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}
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_stress_reader()
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{
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local bus=$1 address=$2
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local iteration
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for iteration in {1..100}; do
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"${SUDO[@]}" i2cget -y "$bus" "$address" 0x02 >/dev/null 2>&1 || return 1
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done
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}
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_load_unsafe()
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{
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"${SUDO[@]}" insmod "$MODULE_PATH" allow_unsafe_access=1
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}
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DMESG_START=$("${SUDO[@]}" dmesg | wc -l)
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"${SUDO[@]}" modprobe i2c-dev
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_module_loaded && "${SUDO[@]}" rmmod i2c-imc-skylake
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_load_unsafe
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echo "=== adapter discovery ==="
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_refresh_buses
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[[ -n "$CH0" ]] && _ok "ch0 adapter at i2c-$CH0" || _fail "ch0 adapter not found"
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[[ -n "$CH1" ]] && _ok "ch1 adapter at i2c-$CH1" || _fail "ch1 adapter not found"
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if [[ -n "$CH0" ]]; then
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_scan_spd "$CH0" CH0_ADDR && _ok "SPD device present on ch0" || _fail "no SPD device on ch0"
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fi
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if [[ -n "$CH1" ]]; then
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_scan_spd "$CH1" CH1_ADDR && _ok "SPD device present on ch1" || _fail "no SPD device on ch1"
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fi
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echo "=== transfer semantics ==="
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if [[ -n "$CH0_ADDR" ]]; then
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_word_test "$CH0" "$CH0_ADDR" && _ok "WORD_DATA byte order on ch0" || _fail "WORD_DATA test on ch0"
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fi
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if [[ -n "$CH1_ADDR" ]]; then
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_word_test "$CH1" "$CH1_ADDR" && _ok "WORD_DATA byte order on ch1" || _fail "WORD_DATA test on ch1"
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fi
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if [[ -n "$CH0" ]]; then
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_nack_test "$CH0" && _ok "absent-device ENXIO on ch0" || _fail "expected ENXIO at address 0x77 on ch0"
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fi
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if [[ -n "$CH1" ]]; then
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_nack_test "$CH1" && _ok "absent-device ENXIO on ch1" || _fail "expected ENXIO at address 0x77 on ch1"
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fi
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if [[ -n "$CH0_ADDR" && -n "$CH1_ADDR" ]]; then
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_stress_reader "$CH0" "$CH0_ADDR" &
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pid0=$!
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_stress_reader "$CH1" "$CH1_ADDR" &
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pid1=$!
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stress_ok=true
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wait "$pid0" || stress_ok=false
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wait "$pid1" || stress_ok=false
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$stress_ok && _ok "concurrent 100-read stress on both channels" || _fail "concurrent read stress"
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fi
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echo "=== safe default and targeted udev event ==="
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PCI_DEVICE=$(_find_pci_device) || {
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_fail "PCI device 8086:2085 not found"
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PCI_DEVICE=""
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}
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if [[ -n "$PCI_DEVICE" ]]; then
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"${SUDO[@]}" rmmod i2c-imc-skylake
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"${SUDO[@]}" insmod "$MODULE_PATH"
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_refresh_buses
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if [[ -z "$CH0" && -z "$CH1" ]]; then
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_ok "default-off gate rejected bind without opt-in"
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else
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_fail "driver bound without allow_unsafe_access=1"
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fi
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_module_loaded && "${SUDO[@]}" rmmod i2c-imc-skylake
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if "${SUDO[@]}" udevadm trigger --action=add "$PCI_DEVICE" &&
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"${SUDO[@]}" udevadm settle --timeout=5; then
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_ok "targeted PCI udev event completed"
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else
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_fail "targeted PCI udev event failed"
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fi
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_module_loaded && "${SUDO[@]}" rmmod i2c-imc-skylake
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_load_unsafe
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fi
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echo "=== load/unload x20 ==="
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for iteration in {1..20}; do
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"${SUDO[@]}" rmmod i2c-imc-skylake
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_load_unsafe
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echo " cycle $iteration OK"
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done
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_ok "20 load/unload cycles completed"
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echo "=== kernel messages produced by this test ==="
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NEW_DMESG=$("${SUDO[@]}" dmesg | tail -n "+$((DMESG_START + 1))")
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RELEVANT_DMESG=$(grep -Ei 'i2c-imc-skylake [0-9a-f]{4}:|BUG:|WARNING:|Oops:|KASAN:|lockdep' <<< "$NEW_DMESG" || true)
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printf '%s\n' "$RELEVANT_DMESG"
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if grep -Eiq 'BUG:|WARNING:|Oops:|KASAN:|lockdep' <<< "$NEW_DMESG"; then
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_fail "kernel warning/oops detected"
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else
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_ok "no kernel warning/oops detected"
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fi
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# The driver compares the command registers before and after every transfer.
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# A hit here means firmware, a BMC or CLTT is driving the same engine, which
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# invalidates every other result in this run.
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if grep -q 'another master is using the engine' <<< "$NEW_DMESG"; then
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_fail "foreign master detected on the engine; do not use this system"
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else
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_ok "no foreign master detected during the test"
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fi
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# Likewise for a command that never reached the register: that path exists
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# because the done bits are latched and a stale DONE must not be mistaken for
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# a fresh completion.
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if grep -q 'did not reach the register' <<< "$NEW_DMESG"; then
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_fail "a command never reached the register; config access is unreliable"
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else
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_ok "every command reached the register"
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fi
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echo "=== result: $PASS passed, $FAIL failed ==="
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((FAIL == 0))
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