[Intel-wired-lan] [PATCH iwl-net v3] ixgbevf: fix link speed reporting for Hyper-V E610 VFs

[Intel-wired-lan] [PATCH iwl-net v3] ixgbevf: fix link speed reporting for Hyper-V E610 VFs

[Tomasz Lichwala]

When an E610 VF is running under Hyper-V, the VFLINKS register does not
carry valid link speed. The existing code reads speed from VFLINKS, which
does not reflect the actual negotiated speed. This results in ethtool
reporting a stale or incorrect link speed.

The Hyper-V synthetic NIC exposes the actual link status through
emulated PCI config space at offset 0x209 in VFLINKS register format.
Read and decode link status from there when checking link on E610 VFs.

Fixes: 4c44b450c69b ("ixgbevf: Add support for Intel(R) E610 device")
Reviewed-by: Marcin Szycik <marcin.szycik@linux.intel.com>
Signed-off-by: Tomasz Lichwala <tomasz.lichwala@linux.intel.com>
---
 drivers/net/ethernet/intel/ixgbevf/vf.c | 77 +++++++++++++++++++++----
 1 file changed, 65 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbevf/vf.c b/drivers/net/ethernet/intel/ixgbevf/vf.c
index f6df86d124b9..8ad06e28b5de 100644
--- a/drivers/net/ethernet/intel/ixgbevf/vf.c
+++ b/drivers/net/ethernet/intel/ixgbevf/vf.c
@@ -1,14 +1,17 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright(c) 1999 - 2024 Intel Corporation. */
 
+#include <linux/unaligned.h>
+
 #include "vf.h"
 #include "ixgbevf.h"
 
-/* On Hyper-V, to reset, we need to read from this offset
- * from the PCI config space. This is the mechanism used on
- * Hyper-V to support PF/VF communication.
+/* On Hyper-V the PF/VF communication is through emulated PCI config
+ * space. The reset and link status are exposed at the offsets below.
  */
-#define IXGBE_HV_RESET_OFFSET           0x201
+#define IXGBE_HV_RESET_OFFSET		0x201
+#define IXGBE_HV_LINK_STATUS_OFFSET	0x209
+#define IXGBE_HV_LINK_STATUS_SIZE	4
 
 static inline s32 ixgbevf_write_msg_read_ack(struct ixgbe_hw *hw, u32 *msg,
 					     u32 *retmsg, u16 size)
@@ -901,6 +904,34 @@ static s32 ixgbevf_check_mac_link_vf(struct ixgbe_hw *hw,
 	return ret_val;
 }
 
+/**
+ * ixgbevf_hv_read_links_e610 - read link status from PCI config space
+ * @hw: pointer to hardware structure
+ * @links_reg: pointer to store read value
+ *
+ * On Hyper-V E610 VFs the VFLINKS register does not carry valid link speed.
+ * Instead, link status is exposed through emulated PCI config space at offset
+ * 0x209 in VFLINKS register format.
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+static s32 ixgbevf_hv_read_links_e610(struct ixgbe_hw *hw, u32 *links_reg)
+{
+	struct ixgbevf_adapter *adapter = hw->back;
+	u8 data[IXGBE_HV_LINK_STATUS_SIZE];
+
+	for (int i = 0; i < IXGBE_HV_LINK_STATUS_SIZE; i++) {
+		int ret = pci_read_config_byte(adapter->pdev,
+					       IXGBE_HV_LINK_STATUS_OFFSET + i,
+					       &data[i]);
+		if (ret)
+			return pcibios_err_to_errno(ret);
+	}
+
+	*links_reg = get_unaligned_le32(data);
+	return 0;
+}
+
 /**
  * ixgbevf_hv_check_mac_link_vf - check link
  * @hw: pointer to private hardware struct
@@ -909,6 +940,7 @@ static s32 ixgbevf_check_mac_link_vf(struct ixgbe_hw *hw,
  * @autoneg_wait_to_complete: unused
  *
  * Hyper-V variant; there is no mailbox communication.
+ * For E610 VFs, link status is read from emulated PCI config space.
  */
 static s32 ixgbevf_hv_check_mac_link_vf(struct ixgbe_hw *hw,
 					ixgbe_link_speed *speed,
@@ -923,13 +955,28 @@ static s32 ixgbevf_hv_check_mac_link_vf(struct ixgbe_hw *hw,
 	if (!mbx->ops.check_for_rst(hw) || !mbx->timeout)
 		mac->get_link_status = true;
 
-	if (!mac->get_link_status)
-		goto out;
+	/* E610 VFs always read link status from emulated PCI config space
+	 * because VFLINKS does not carry valid speed for these devices.
+	 * Skip get_link_status caching since PCI config reads are cheap.
+	 */
+	if (mac->type == ixgbe_mac_e610_vf) {
+		if (ixgbevf_hv_read_links_e610(hw, &links_reg)) {
+			*link_up = false;
+			*speed = IXGBE_LINK_SPEED_UNKNOWN;
+			return 0;
+		}
+	} else {
+		if (!mac->get_link_status)
+			goto out;
 
-	/* if link status is down no point in checking to see if pf is up */
-	links_reg = IXGBE_READ_REG(hw, IXGBE_VFLINKS);
-	if (!(links_reg & IXGBE_LINKS_UP))
-		goto out;
+		links_reg = IXGBE_READ_REG(hw, IXGBE_VFLINKS);
+	}
+
+	if (!(links_reg & IXGBE_LINKS_UP)) {
+		*link_up = false;
+		*speed = IXGBE_LINK_SPEED_UNKNOWN;
+		return 0;
+	}
 
 	/* for SFP+ modules and DA cables on 82599 it can take up to 500usecs
 	 * before the link status is correct
@@ -941,8 +988,11 @@ static s32 ixgbevf_hv_check_mac_link_vf(struct ixgbe_hw *hw,
 			udelay(100);
 			links_reg = IXGBE_READ_REG(hw, IXGBE_VFLINKS);
 
-			if (!(links_reg & IXGBE_LINKS_UP))
-				goto out;
+			if (!(links_reg & IXGBE_LINKS_UP)) {
+				*link_up = false;
+				*speed = IXGBE_LINK_SPEED_UNKNOWN;
+				return 0;
+			}
 		}
 	}
 
@@ -956,6 +1006,9 @@ static s32 ixgbevf_hv_check_mac_link_vf(struct ixgbe_hw *hw,
 	case IXGBE_LINKS_SPEED_100_82599:
 		*speed = IXGBE_LINK_SPEED_100_FULL;
 		break;
+	default:
+		*speed = IXGBE_LINK_SPEED_UNKNOWN;
+		break;
 	}
 
 	/* if we passed all the tests above then the link is up and we no
-- 
2.54.0

Re: [Intel-wired-lan] [PATCH iwl-net v3] ixgbevf: fix link speed reporting for Hyper-V E610 VFs

[Przemek Kitszel]

On 8/6/26 12:46, Tomasz Lichwala wrote:
> When an E610 VF is running under Hyper-V, the VFLINKS register does not
> carry valid link speed. The existing code reads speed from VFLINKS, which
> does not reflect the actual negotiated speed. This results in ethtool
> reporting a stale or incorrect link speed.
> 
> The Hyper-V synthetic NIC exposes the actual link status through
> emulated PCI config space at offset 0x209 in VFLINKS register format.
> Read and decode link status from there when checking link on E610 VFs.
> 
> Fixes: 4c44b450c69b ("ixgbevf: Add support for Intel(R) E610 device")
> Reviewed-by: Marcin Szycik <marcin.szycik@linux.intel.com>
> Signed-off-by: Tomasz Lichwala <tomasz.lichwala@linux.intel.com>
> ---

next time please provide changelog section here

>   drivers/net/ethernet/intel/ixgbevf/vf.c | 77 +++++++++++++++++++++----
>   1 file changed, 65 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/ixgbevf/vf.c b/drivers/net/ethernet/intel/ixgbevf/vf.c
> index f6df86d124b9..8ad06e28b5de 100644
> --- a/drivers/net/ethernet/intel/ixgbevf/vf.c
> +++ b/drivers/net/ethernet/intel/ixgbevf/vf.c
> @@ -1,14 +1,17 @@
>   // SPDX-License-Identifier: GPL-2.0
>   /* Copyright(c) 1999 - 2024 Intel Corporation. */
>   
> +#include <linux/unaligned.h>
> +
>   #include "vf.h"
>   #include "ixgbevf.h"
>   

[..]

> +static s32 ixgbevf_hv_read_links_e610(struct ixgbe_hw *hw, u32 *links_reg)
> +{
> +	struct ixgbevf_adapter *adapter = hw->back;
> +	u8 data[IXGBE_HV_LINK_STATUS_SIZE];

following Paul's suggestion, you could add:
	if (IS_ENABLED(CONFIG_PCI_MMCONFIG)) {
		dev_err_once(&adapter->pdev->dev, "cannot read link status, 
PCI_MMCONFIG is required for Hyper-V\n");
		return -EOPNOTSUPP;
	}

and this will give user more information

IS_ENABLED() is really nice macro :)

> +
> +	for (int i = 0; i < IXGBE_HV_LINK_STATUS_SIZE; i++) {
> +		int ret = pci_read_config_byte(adapter->pdev,
> +					       IXGBE_HV_LINK_STATUS_OFFSET + i,
> +					       &data[i]);
> +		if (ret)
> +			return pcibios_err_to_errno(ret);
> +	}
> +
> +	*links_reg = get_unaligned_le32(data);
> +	return 0;
> +}
> +

Re: [Intel-wired-lan] [PATCH iwl-net v3] ixgbevf: fix link speed reporting for Hyper-V E610 VFs

[Tomasz Lichwala]

On 6.08.2026 15:04, Przemek Kitszel wrote:
> On 8/6/26 12:46, Tomasz Lichwala wrote:
>> When an E610 VF is running under Hyper-V, the VFLINKS register does not
>> carry valid link speed. The existing code reads speed from VFLINKS, which
>> does not reflect the actual negotiated speed. This results in ethtool
>> reporting a stale or incorrect link speed.
>>
>> The Hyper-V synthetic NIC exposes the actual link status through
>> emulated PCI config space at offset 0x209 in VFLINKS register format.
>> Read and decode link status from there when checking link on E610 VFs.
>>
>> Fixes: 4c44b450c69b ("ixgbevf: Add support for Intel(R) E610 device")
>> Reviewed-by: Marcin Szycik <marcin.szycik@linux.intel.com>
>> Signed-off-by: Tomasz Lichwala <tomasz.lichwala@linux.intel.com>
>> ---
> 
> next time please provide changelog section here
> 

Noted, will include changelog in subsequent versions.

>>   drivers/net/ethernet/intel/ixgbevf/vf.c | 77 +++++++++++++++++++++----
>>   1 file changed, 65 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/intel/ixgbevf/vf.c b/drivers/net/ethernet/intel/ixgbevf/vf.c
>> index f6df86d124b9..8ad06e28b5de 100644
>> --- a/drivers/net/ethernet/intel/ixgbevf/vf.c
>> +++ b/drivers/net/ethernet/intel/ixgbevf/vf.c
>> @@ -1,14 +1,17 @@
>>   // SPDX-License-Identifier: GPL-2.0
>>   /* Copyright(c) 1999 - 2024 Intel Corporation. */
>>   +#include <linux/unaligned.h>
>> +
>>   #include "vf.h"
>>   #include "ixgbevf.h"
>>   
> 
> [..]
> 
>> +static s32 ixgbevf_hv_read_links_e610(struct ixgbe_hw *hw, u32 *links_reg)
>> +{
>> +    struct ixgbevf_adapter *adapter = hw->back;
>> +    u8 data[IXGBE_HV_LINK_STATUS_SIZE];
> 
> following Paul's suggestion, you could add:
>     if (IS_ENABLED(CONFIG_PCI_MMCONFIG)) {
>         dev_err_once(&adapter->pdev->dev, "cannot read link status, PCI_MMCONFIG is required for Hyper-V\n");
>         return -EOPNOTSUPP;
>     }
> 
> and this will give user more information
> 
> IS_ENABLED() is really nice macro :)
> 

I think you meant !IS_ENABLED() here. Without MMCONFIG, pci_read_config_byte() at offset 0x209 (extended config space) will return a PCIBIOS error anyway, and the caller handles that gracefully by reporting link down. I could add the explicit IS_ENABLED check for a friendlier diagnostic message, but the behavior is correct either way. Let me know if you'd prefer I add it in a v4.

>> +
>> +    for (int i = 0; i < IXGBE_HV_LINK_STATUS_SIZE; i++) {
>> +        int ret = pci_read_config_byte(adapter->pdev,
>> +                           IXGBE_HV_LINK_STATUS_OFFSET + i,
>> +                           &data[i]);
>> +        if (ret)
>> +            return pcibios_err_to_errno(ret);
>> +    }
>> +
>> +    *links_reg = get_unaligned_le32(data);
>> +    return 0;
>> +}
>> +

Thanks,
Tomasz