netdev - [PATCH iwl-next 7/8] ice: avoid rebuilding if MSI-X vector count is unchanged

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Message-Id: <20250618-e810-live-migration-jk-migration-prep-v1-7-72a37485453e@intel.com>
Date: Wed, 18 Jun 2025 15:24:42 -0700
From: Jacob Keller <jacob.e.keller@...el.com>
To: Intel Wired LAN <intel-wired-lan@...ts.osuosl.org>
Cc: Jacob Keller <jacob.e.keller@...el.com>, netdev@...r.kernel.org, 
 Madhu Chittim <madhu.chittim@...el.com>, Yahui Cao <yahui.cao@...el.com>, 
 Anthony Nguyen <anthony.l.nguyen@...el.com>, 
 Przemek Kitszel <przemyslaw.kitszel@...el.com>
Subject: [PATCH iwl-next 7/8] ice: avoid rebuilding if MSI-X vector count
 is unchanged

Commit 05c16687e0cc ("ice: set MSI-X vector count on VF") added support to
change the vector count for VFs as part of ice_sriov_set_msix_vec_count().
This function modifies and rebuilds the target VF with the requested number
of MSI-X vectors.

Future support for live migration will add a call to
ice_sriov_set_msix_vec_count() to ensure that a migrated VF has the proper
MSI-X vector count. In most cases, this request will be to set the MSI-X
vector count to its current value. In that case, no work is necessary.
Rather than requiring the caller to check this, update the function to
check and exit early if the vector count is already at the requested value.
This avoids an unnecessary VF rebuild.

Signed-off-by: Jacob Keller <jacob.e.keller@...el.com>
---
 drivers/net/ethernet/intel/ice/ice_sriov.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/ethernet/intel/ice/ice_sriov.c b/drivers/net/ethernet/intel/ice/ice_sriov.c
index 4c0955be2ad20c3902cf891a66f857585fcab98b..964c474322196fa8875767ac2667be5d550a6765 100644
--- a/drivers/net/ethernet/intel/ice/ice_sriov.c
+++ b/drivers/net/ethernet/intel/ice/ice_sriov.c
@@ -966,6 +966,12 @@ int ice_sriov_set_msix_vec_count(struct pci_dev *vf_dev, int msix_vec_count)
 		return -ENOENT;
 	}

+	/* No need to rebuild if we're setting to the same value */
+	if (msix_vec_count == vf->num_msix) {
+		ice_put_vf(vf);
+		return 0;
+	}
+
 	prev_msix = vf->num_msix;
 	prev_queues = vf->num_vf_qs;

-- 
2.48.1.397.gec9d649cc640