| Message ID | 20240912141931.2447826-1-oocheret@cisco.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] iTCO_wdt: mask NMI_NOW bit for update_no_reboot_bit() call | expand |
On 9/12/24 07:19, Oleksandr Ocheretnyi wrote: > Commit da23b6faa8bf ("watchdog: iTCO: Add support for Cannon Lake > PCH iTCO") does not mask NMI_NOW bit during TCO1_CNT register's > value comparison for update_no_reboot_bit() call causing following > failure: > > ... > iTCO_vendor_support: vendor-support=0 > iTCO_wdt iTCO_wdt: unable to reset NO_REBOOT flag, device > disabled by hardware/BIOS > ... > > and this can lead to unexpected NMIs later during regular > crashkernel's workflow because of watchdog probe call failures. > > This change masks NMI_NOW bit for TCO1_CNT register values to > avoid unexpected NMI_NOW bit inversions. > > Fixes: da23b6faa8bf ("watchdog: iTCO: Add support for Cannon Lake PCH iTCO") > Signed-off-by: Oleksandr Ocheretnyi <oocheret@cisco.com> > --- Oh, and change log goes here. Guenter
Hi Oleksandr, kernel test robot noticed the following build warnings: [auto build test WARNING on westeri-thunderbolt/next] [also build test WARNING on linus/master v6.11-rc7 next-20240912] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch#_base_tree_information] url: https://github.com/intel-lab-lkp/linux/commits/Oleksandr-Ocheretnyi/iTCO_wdt-mask-NMI_NOW-bit-for-update_no_reboot_bit-call/20240912-222231 base: https://git.kernel.org/pub/scm/linux/kernel/git/westeri/thunderbolt.git next patch link: https://lore.kernel.org/r/20240912141931.2447826-1-oocheret%40cisco.com patch subject: [PATCH v2] iTCO_wdt: mask NMI_NOW bit for update_no_reboot_bit() call config: i386-buildonly-randconfig-001-20240913 (https://download.01.org/0day-ci/archive/20240913/202409131548.X0MGdN1r-lkp@intel.com/config) compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff) reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240913/202409131548.X0MGdN1r-lkp@intel.com/reproduce) If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot <lkp@intel.com> | Closes: https://lore.kernel.org/oe-kbuild-all/202409131548.X0MGdN1r-lkp@intel.com/ All warnings (new ones prefixed by >>): >> drivers/watchdog/iTCO_wdt.c:226:27: warning: implicit conversion from 'unsigned long' to 'u16' (aka 'unsigned short') changes value from 4294967039 to 65279 [-Wconstant-conversion] 226 | u16 val, newval, mask = (~NMI_NOW); | ~~~~ ^~~~~~~~ 1 warning generated. vim +226 drivers/watchdog/iTCO_wdt.c 222 223 static int update_no_reboot_bit_cnt(void *priv, bool set) 224 { 225 struct iTCO_wdt_private *p = priv; > 226 u16 val, newval, mask = (~NMI_NOW); 227 228 /* writing back 1b1 to NMI_NOW of TCO1_CNT register 229 * causes NMI_NOW bit inversion what consequently does 230 * not allow to perform the register's value comparison 231 * properly. 232 * 233 * NMI_NOW bit masking for TCO1_CNT register values 234 * helps to avoid possible NMI_NOW bit inversions on 235 * following write operation. 236 */ 237 val = inw(TCO1_CNT(p)) & mask; 238 if (set) 239 val |= BIT(0); 240 else 241 val &= ~BIT(0); 242 outw(val, TCO1_CNT(p)); 243 newval = inw(TCO1_CNT(p)) & mask; 244 245 /* make sure the update is successful */ 246 return val != newval ? -EIO : 0; 247 } 248
diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c index 264857d314da..46c09359588f 100644 --- a/drivers/watchdog/iTCO_wdt.c +++ b/drivers/watchdog/iTCO_wdt.c @@ -82,6 +82,12 @@ #define TCO2_CNT(p) (TCOBASE(p) + 0x0a) /* TCO2 Control Register */ #define TCOv2_TMR(p) (TCOBASE(p) + 0x12) /* TCOv2 Timer Initial Value*/ +/* NMI_NOW is bit 8 of TCO1_CNT register + * Read/Write + * This bit is implemented as RW but has no effect on HW. + */ +#define NMI_NOW BIT(8) + /* internal variables */ struct iTCO_wdt_private { struct watchdog_device wddev; @@ -217,15 +223,24 @@ static int update_no_reboot_bit_mem(void *priv, bool set) static int update_no_reboot_bit_cnt(void *priv, bool set) { struct iTCO_wdt_private *p = priv; - u16 val, newval; - - val = inw(TCO1_CNT(p)); + u16 val, newval, mask = (~NMI_NOW); + + /* writing back 1b1 to NMI_NOW of TCO1_CNT register + * causes NMI_NOW bit inversion what consequently does + * not allow to perform the register's value comparison + * properly. + * + * NMI_NOW bit masking for TCO1_CNT register values + * helps to avoid possible NMI_NOW bit inversions on + * following write operation. + */ + val = inw(TCO1_CNT(p)) & mask; if (set) val |= BIT(0); else val &= ~BIT(0); outw(val, TCO1_CNT(p)); - newval = inw(TCO1_CNT(p)); + newval = inw(TCO1_CNT(p)) & mask; /* make sure the update is successful */ return val != newval ? -EIO : 0;
Commit da23b6faa8bf ("watchdog: iTCO: Add support for Cannon Lake PCH iTCO") does not mask NMI_NOW bit during TCO1_CNT register's value comparison for update_no_reboot_bit() call causing following failure: ... iTCO_vendor_support: vendor-support=0 iTCO_wdt iTCO_wdt: unable to reset NO_REBOOT flag, device disabled by hardware/BIOS ... and this can lead to unexpected NMIs later during regular crashkernel's workflow because of watchdog probe call failures. This change masks NMI_NOW bit for TCO1_CNT register values to avoid unexpected NMI_NOW bit inversions. Fixes: da23b6faa8bf ("watchdog: iTCO: Add support for Cannon Lake PCH iTCO") Signed-off-by: Oleksandr Ocheretnyi <oocheret@cisco.com> --- drivers/watchdog/iTCO_wdt.c | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-)