Re: [Intel-wired-lan] [PATCH iwl v3] ice: acquire NVM lock around each flash read

[Marcin Szycik <marcin.szycik@linux.intel.com>]

On 31/07/2026 13:10, Robert Malz via Intel-wired-lan wrote:
> FW caps the NVM read lock at a maximum of 3000ms regardless of the timeout
> requested via ice_acquire_nvm(). ice_read_flat_nvm() splits a read into
> multiple ice_aq_read_nvm() commands, one per 4KB sector, all issued under a
> single lock taken by the caller. Reading a large region can exceed 3000ms,
> so FW reclaims the lock mid-read and the remaining commands might fail.
> 
> Move the lock acquire/release into ice_read_flat_nvm() so it brackets each
> individual ice_aq_read_nvm() command, ensuring the lock is never held
> across more than one FW read.
> 
> ice_release_nvm() issues its own AQ command and overwrites
> hw->adminq.sq_last_status, which some callers inspect after a failed read.
> Add an optional read_aq_err output parameter to ice_read_flat_nvm() to
> capture the failing read's AQ error before the release; callers that need
> it (ice_discover_flash_size() and the ethtool/devlink log paths) use it
> instead of sq_last_status, others pass NULL.
> 
> Callers that previously took the lock around ice_read_flat_nvm(),
> ice_read_sr_word() or ice_read_flash_module() now call them without it.
> The now-redundant per-block locking in ice_devlink_nvm_snapshot() is
> dropped.
> 
> Fixes: e94509906d6b ("ice: create function to read a section of the NVM and Shadow RAM")
> Signed-off-by: Robert Malz <robert.malz@canonical.com>
> ---
> v3:
> - Log the failure via ice_debug() when ice_acquire_nvm() fails inside
>   ice_read_flat_nvm(), rather than silently aborting the read.
> v2:
> - Replace the save/restore of sq_last_status across ice_release_nvm(),
>   which could race with a concurrent AdminQ command, with a new optional
>   read_aq_err output parameter.
> - Add missing "Return:" kdoc to ice_read_sr_word().
> ---
>  .../net/ethernet/intel/ice/devlink/devlink.c  | 32 ++------
>  drivers/net/ethernet/intel/ice/ice_ethtool.c  | 16 +---
>  drivers/net/ethernet/intel/ice/ice_nvm.c      | 79 +++++++++++--------
>  drivers/net/ethernet/intel/ice/ice_nvm.h      |  2 +-
>  4 files changed, 59 insertions(+), 70 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/ice/devlink/devlink.c b/drivers/net/ethernet/intel/ice/devlink/devlink.c
> index 22b7d8e6bd9e..5a1ab9654fb8 100644
> --- a/drivers/net/ethernet/intel/ice/devlink/devlink.c
> +++ b/drivers/net/ethernet/intel/ice/devlink/devlink.c
> @@ -1856,6 +1856,7 @@ static int ice_devlink_nvm_snapshot(struct devlink *devlink,
>  {
>  	struct ice_pf *pf = devlink_priv(devlink);
>  	struct device *dev = ice_pf_to_dev(pf);
> +	enum libie_aq_err read_aq_err = LIBIE_AQ_RC_OK;

RCT
Also scope can be reduced.

>  	struct ice_hw *hw = &pf->hw;
>  	bool read_shadow_ram;
>  	u8 *nvm_data, *tmp, i;
> @@ -1891,26 +1892,16 @@ static int ice_devlink_nvm_snapshot(struct devlink *devlink,
>  	for (i = 0; i < num_blks; i++) {
>  		u32 read_sz = min_t(u32, ICE_DEVLINK_READ_BLK_SIZE, left);
>  
> -		status = ice_acquire_nvm(hw, ICE_RES_READ);
> -		if (status) {
> -			dev_dbg(dev, "ice_acquire_nvm failed, err %d aq_err %d\n",
> -				status, hw->adminq.sq_last_status);
> -			NL_SET_ERR_MSG_MOD(extack, "Failed to acquire NVM semaphore");
> -			vfree(nvm_data);
> -			return -EIO;
> -		}
> -
>  		status = ice_read_flat_nvm(hw, i * ICE_DEVLINK_READ_BLK_SIZE,
> -					   &read_sz, tmp, read_shadow_ram);
> +					   &read_sz, tmp, read_shadow_ram,
> +					   &read_aq_err);
>  		if (status) {
>  			dev_dbg(dev, "ice_read_flat_nvm failed after reading %u bytes, err %d aq_err %d\n",
> -				read_sz, status, hw->adminq.sq_last_status);
> +				read_sz, status, read_aq_err);
>  			NL_SET_ERR_MSG_MOD(extack, "Failed to read NVM contents");
> -			ice_release_nvm(hw);
>  			vfree(nvm_data);
>  			return -EIO;
>  		}
> -		ice_release_nvm(hw);
>  
>  		tmp += read_sz;
>  		left -= read_sz;
> @@ -1945,6 +1936,7 @@ static int ice_devlink_nvm_read(struct devlink *devlink,
>  {
>  	struct ice_pf *pf = devlink_priv(devlink);
>  	struct device *dev = ice_pf_to_dev(pf);
> +	enum libie_aq_err read_aq_err = LIBIE_AQ_RC_OK;

RCT

>  	struct ice_hw *hw = &pf->hw;
>  	bool read_shadow_ram;
>  	u64 nvm_size;

...

>  /**
> - * ice_read_sr_word - Reads Shadow RAM word and acquire NVM if necessary
> + * ice_read_sr_word - Reads Shadow RAM word
>   * @hw: pointer to the HW structure
>   * @offset: offset of the Shadow RAM word to read (0x000000 - 0x001FFF)
>   * @data: word read from the Shadow RAM
>   *
> - * Reads one 16 bit word from the Shadow RAM using the ice_read_sr_word_aq.
> + * Reads one 16 bit word from the Shadow RAM using ice_read_sr_word_aq.
> + *
> + * The NVM lock is acquired and released internally by ice_read_flat_nvm()
> + * around the FW read, so this function must be called without the lock held.
> + *
> + * Return: zero on success, or a negative error code on failure.
>   */
>  int ice_read_sr_word(struct ice_hw *hw, u16 offset, u16 *data)
>  {
> -	int status;
> -
> -	status = ice_acquire_nvm(hw, ICE_RES_READ);
> -	if (!status) {
> -		status = ice_read_sr_word_aq(hw, offset, data);
> -		ice_release_nvm(hw);
> -	}
> -
> -	return status;
> +	return ice_read_sr_word_aq(hw, offset, data);

ice_read_sr_word() is now a wrapper - can we remove it and use
ice_read_sr_word_aq() directly?

>  }
>  
>  /**
> @@ -856,20 +876,18 @@ int ice_get_inactive_netlist_ver(struct ice_hw *hw, struct ice_netlist_info *net
>  static int ice_discover_flash_size(struct ice_hw *hw)
>  {
>  	u32 min_size = 0, max_size = ICE_AQC_NVM_MAX_OFFSET + 1;
> -	int status;
> -
> -	status = ice_acquire_nvm(hw, ICE_RES_READ);
> -	if (status)
> -		return status;
> +	int status = 0;
>  
>  	while ((max_size - min_size) > 1) {
>  		u32 offset = (max_size + min_size) / 2;
> +		enum libie_aq_err read_aq_err = LIBIE_AQ_RC_OK;

RCT

>  		u32 len = 1;
>  		u8 data;

---8<---

Thanks,
Marcin