net: hns3: fix permanent link down deadlock after reset

net: hns3: fix permanent link down deadlock after reset

Fix a critical race condition deadlock where the network interface
remains permanently Link Down after a hardware reset under specific
ethtool sequences.

This issue exclusively manifests in firmware-controlled PHY topologies
where the driver relies on the IMP firmware to arbitrate link parameters.
Standard devices driven by the kernel's native PHY_LIB are unaffected.

The deadlock occurs via the following path:
1. User disables autoneg and forces an unmatched speed, forcing link
   down: `ethtool -s ethx autoneg off speed 10 duplex full`
2. User re-enables autoneg: `ethtool -s ethx autoneg on`. The netdev
   stack passes cmd->base.speed as SPEED_UNKNOWN (0xffffffff).
3. Driver saves req_autoneg=1, but before the interface can link up,
   a hardware reset is triggered.
4. During reset recovery, MAC init reads the un-synchronized runtime
   state mac.autoneg (which is still 0/OFF), misinterprets it as
   forced mode, and pushes the cached SPEED_UNKNOWN into the hardware
   registers, causing the MAC firmware state machine to freeze.
   Meanwhile, PHY init reads req_autoneg=1 and enables PHY autoneg.

Since the MAC is frozen with 0xffffffff and PHY is running autoneg,
they mismatch permanently.

Fix this by:
1. Intercepting SPEED_UNKNOWN/DUPLEX_UNKNOWN in
   hclge_set_phy_link_ksettings() and hclge_cfg_mac_speed_dup_h() to
   prevent it from corrupting the driver's cached valid configuration.
2. Save req_autoneg in hclge_set_autoneg().
3. Aligning the state judgment in hclge_set_autoneg_speed_dup() to use
   req_autoneg instead of the un-synchronized runtime mac.autoneg,
   ensuring both MAC and PHY consistently enter the autoneg branch to
   eliminate configuration discrepancies during reset recovery.

Fixes: 05eb60e9648c ("net: hns3: using user configure after hardware reset")
Signed-off-by: Shuaisong Yang <yangshuaisong@h-partners.com>
Signed-off-by: Jijie Shao <shaojijie@huawei.com>
Link: https://patch.msgid.link/20260624141319.271439-4-shaojijie@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>