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Date:   Fri, 21 Oct 2022 14:38:50 -0700
From:   Jacob Keller <jacob.e.keller@...el.com>
To:     Jakub Kicinski <kuba@...nel.org>,
        David Miller <davem@...emloft.net>
Cc:     netdev@...r.kernel.org,
        Sylwester Dziedziuch <sylwesterx.dziedziuch@...el.com>,
        Mateusz Palczewski <mateusz.palczewski@...el.com>,
        Konrad Jankowski <konrad0.jankowski@...el.com>
Subject: [PATCH net] i40e: Fix VF hang when reset is triggered on another VF

From: Sylwester Dziedziuch <sylwesterx.dziedziuch@...el.com>

When a reset was triggered on one VF with i40e_reset_vf
global PF state __I40E_VF_DISABLE was set on a PF until
the reset finished. If immediately after triggering reset
on one VF there is a request to reset on another
it will cause a hang on VF side because VF will be notified
of incoming reset but the reset will never happen because
of this global state, we will get such error message:

[  +4.890195] iavf 0000:86:02.1: Never saw reset

and VF will hang waiting for the reset to be triggered.

Fix this by introducing new VF state I40E_VF_STATE_RESETTING
that will be set on a VF if it is currently resetting instead of
the global __I40E_VF_DISABLE PF state.

Fixes: 3ba9bcb4b68f ("i40e: add locking around VF reset")
Signed-off-by: Sylwester Dziedziuch <sylwesterx.dziedziuch@...el.com>
Signed-off-by: Mateusz Palczewski <mateusz.palczewski@...el.com>
Tested-by: Konrad Jankowski <konrad0.jankowski@...el.com>
---
 .../ethernet/intel/i40e/i40e_virtchnl_pf.c    | 43 ++++++++++++++-----
 .../ethernet/intel/i40e/i40e_virtchnl_pf.h    |  1 +
 2 files changed, 33 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
index 7e9f6a69eb10..72ddcefc45b1 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
@@ -1536,10 +1536,12 @@ bool i40e_reset_vf(struct i40e_vf *vf, bool flr)
 	if (test_bit(__I40E_VF_RESETS_DISABLED, pf->state))
 		return true;
 
-	/* If the VFs have been disabled, this means something else is
-	 * resetting the VF, so we shouldn't continue.
-	 */
-	if (test_and_set_bit(__I40E_VF_DISABLE, pf->state))
+	/* Bail out if VFs are disabled. */
+	if (test_bit(__I40E_VF_DISABLE, pf->state))
+		return true;
+
+	/* If VF is being reset already we don't need to continue. */
+	if (test_and_set_bit(I40E_VF_STATE_RESETTING, &vf->vf_states))
 		return true;
 
 	i40e_trigger_vf_reset(vf, flr);
@@ -1576,7 +1578,7 @@ bool i40e_reset_vf(struct i40e_vf *vf, bool flr)
 	i40e_cleanup_reset_vf(vf);
 
 	i40e_flush(hw);
-	clear_bit(__I40E_VF_DISABLE, pf->state);
+	clear_bit(I40E_VF_STATE_RESETTING, &vf->vf_states);
 
 	return true;
 }
@@ -1609,8 +1611,12 @@ bool i40e_reset_all_vfs(struct i40e_pf *pf, bool flr)
 		return false;
 
 	/* Begin reset on all VFs at once */
-	for (v = 0; v < pf->num_alloc_vfs; v++)
-		i40e_trigger_vf_reset(&pf->vf[v], flr);
+	for (v = 0; v < pf->num_alloc_vfs; v++) {
+		vf = &pf->vf[v];
+		/* If VF is being reset no need to trigger reset again */
+		if (!test_bit(I40E_VF_STATE_RESETTING, &vf->vf_states))
+			i40e_trigger_vf_reset(&pf->vf[v], flr);
+	}
 
 	/* HW requires some time to make sure it can flush the FIFO for a VF
 	 * when it resets it. Poll the VPGEN_VFRSTAT register for each VF in
@@ -1626,9 +1632,11 @@ bool i40e_reset_all_vfs(struct i40e_pf *pf, bool flr)
 		 */
 		while (v < pf->num_alloc_vfs) {
 			vf = &pf->vf[v];
-			reg = rd32(hw, I40E_VPGEN_VFRSTAT(vf->vf_id));
-			if (!(reg & I40E_VPGEN_VFRSTAT_VFRD_MASK))
-				break;
+			if (!test_bit(I40E_VF_STATE_RESETTING, &vf->vf_states)) {
+				reg = rd32(hw, I40E_VPGEN_VFRSTAT(vf->vf_id));
+				if (!(reg & I40E_VPGEN_VFRSTAT_VFRD_MASK))
+					break;
+			}
 
 			/* If the current VF has finished resetting, move on
 			 * to the next VF in sequence.
@@ -1656,6 +1664,10 @@ bool i40e_reset_all_vfs(struct i40e_pf *pf, bool flr)
 		if (pf->vf[v].lan_vsi_idx == 0)
 			continue;
 
+		/* If VF is reset in another thread just continue */
+		if (test_bit(I40E_VF_STATE_RESETTING, &vf->vf_states))
+			continue;
+
 		i40e_vsi_stop_rings_no_wait(pf->vsi[pf->vf[v].lan_vsi_idx]);
 	}
 
@@ -1667,6 +1679,10 @@ bool i40e_reset_all_vfs(struct i40e_pf *pf, bool flr)
 		if (pf->vf[v].lan_vsi_idx == 0)
 			continue;
 
+		/* If VF is reset in another thread just continue */
+		if (test_bit(I40E_VF_STATE_RESETTING, &vf->vf_states))
+			continue;
+
 		i40e_vsi_wait_queues_disabled(pf->vsi[pf->vf[v].lan_vsi_idx]);
 	}
 
@@ -1676,8 +1692,13 @@ bool i40e_reset_all_vfs(struct i40e_pf *pf, bool flr)
 	mdelay(50);
 
 	/* Finish the reset on each VF */
-	for (v = 0; v < pf->num_alloc_vfs; v++)
+	for (v = 0; v < pf->num_alloc_vfs; v++) {
+		/* If VF is reset in another thread just continue */
+		if (test_bit(I40E_VF_STATE_RESETTING, &vf->vf_states))
+			continue;
+
 		i40e_cleanup_reset_vf(&pf->vf[v]);
+	}
 
 	i40e_flush(hw);
 	clear_bit(__I40E_VF_DISABLE, pf->state);
diff --git a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.h b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.h
index a554d0a0b09b..358bbdb58795 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.h
+++ b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.h
@@ -39,6 +39,7 @@ enum i40e_vf_states {
 	I40E_VF_STATE_MC_PROMISC,
 	I40E_VF_STATE_UC_PROMISC,
 	I40E_VF_STATE_PRE_ENABLE,
+	I40E_VF_STATE_RESETTING
 };
 
 /* VF capabilities */

base-commit: 4d814b329a4d54cd10eee4bd2ce5a8175646cc16
prerequisite-patch-id: c24e3fc70eea2762c00e24407d82075758adb183
-- 
2.38.0.83.gd420dda05763

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