git: 2cf580c694f6 - main - iflib: Permit SR-IOV configuration on a down interface

The branch main has been updated by kbowling:

URL: https://cgit.FreeBSD.org/src/commit/?id=2cf580c694f6f392531a63f01c3fb89c0244f89a

commit 2cf580c694f6f392531a63f01c3fb89c0244f89a
Author:     Kevin Bowling <kbowling@FreeBSD.org>
AuthorDate: 2026-08-06 11:03:28 +0000
Commit:     Kevin Bowling <kbowling@FreeBSD.org>
CommitDate: 2026-08-07 07:24:57 +0000

    iflib: Permit SR-IOV configuration on a down interface
    
    Drivers which remap PF queues need a stop/mutate/restart transaction
    only when the interface has live queues. Permit their IOV
    initialization callback while the interface is administratively down
    and leave it down afterward.
    
    This restores the standard boot-time iovctl.conf workflow for igb and
    lets other opt-in drivers configure VFs before netif brings the PF up.
    
    MFC after:      1 week
---
 share/man/man4/em.4        |  8 +++++---
 sys/dev/e1000/if_igb_iov.c |  4 ++++
 sys/net/iflib.c            | 22 +++++++++++-----------
 3 files changed, 20 insertions(+), 14 deletions(-)

diff --git a/share/man/man4/em.4 b/share/man/man4/em.4
index 328e1e77b18b..22898e894b00 100644
--- a/share/man/man4/em.4
+++ b/share/man/man4/em.4
@@ -32,7 +32,7 @@
 .\"
 .\" * Other names and brands may be claimed as the property of others.
 .\"
-.Dd July 29, 2026
+.Dd August 7, 2026
 .Dt EM 4
 .Os
 .Sh NAME
@@ -188,8 +188,10 @@ The supported SR-IOV configuration uses one PF transmit and receive queue and
 requires MSI-X.
 I350 requires this layout; 82576 hardware can combine VMDq with per-pool RSS,
 but that mode is not implemented by this driver.
-The PF must be administratively up and running when VFs are created and must
-remain up for VF mailbox and datapath service.
+The PF may be administratively down when VFs are created and remains down
+afterward.
+VF mailbox and datapath service begin when the PF is brought up, and the PF
+must remain up to provide those services.
 Creating or destroying VFs temporarily stops and restarts a running PF.
 Set the following per-device
 .Xr iflib 4
diff --git a/sys/dev/e1000/if_igb_iov.c b/sys/dev/e1000/if_igb_iov.c
index 7b6c18690db5..dc4b23397431 100644
--- a/sys/dev/e1000/if_igb_iov.c
+++ b/sys/dev/e1000/if_igb_iov.c
@@ -2003,6 +2003,10 @@ igb_if_iov_init(if_ctx_t ctx, u16 num_vfs, const nvlist_t *config)
 
 	sc = iflib_get_softc(ctx);
 	(void)config;
+	/*
+	 * This callback may run while the PF is down.  Record the software
+	 * layout here; igb_iov_initialize() programs it during interface init.
+	 */
 	atomic_store_rel_32(&sc->iov_teardown, 0);
 	error = igb_iov_validate(sc, num_vfs);
 	if (error != 0)
diff --git a/sys/net/iflib.c b/sys/net/iflib.c
index 63455fb46d70..da26926c8b17 100644
--- a/sys/net/iflib.c
+++ b/sys/net/iflib.c
@@ -5621,6 +5621,7 @@ iflib_device_iov_init_restart(device_t dev, uint16_t num_vfs,
 {
 	if_ctx_t ctx;
 	if_t ifp;
+	bool restart, running;
 	int error;
 
 	ctx = device_get_softc(dev);
@@ -5629,19 +5630,18 @@ iflib_device_iov_init_restart(device_t dev, uint16_t num_vfs,
 	CTX_LOCK(ctx);
 	/*
 	 * Drivers which change the PF queue layout need the complete iflib
-	 * stop/init sequence around their IOV callback.  Keep that transition
-	 * within one context-lock critical section.
+	 * stop/init sequence around their IOV callback when the interface is
+	 * active.  An administratively-down interface has no live queues to
+	 * quiesce, and must remain down after the new layout is installed.
+	 * Keep the transition within one context-lock critical section.
 	 */
-	if ((if_getflags(ifp) & IFF_UP) == 0 ||
-	    (if_getdrvflags(ifp) & IFF_DRV_RUNNING) == 0) {
-		error = ENETDOWN;
-		goto out;
-	}
-
-	iflib_stop(ctx);
+	restart = (if_getflags(ifp) & IFF_UP) != 0;
+	running = (if_getdrvflags(ifp) & IFF_DRV_RUNNING) != 0;
+	if (restart || running)
+		iflib_stop(ctx);
 	error = IFDI_IOV_INIT(ctx, num_vfs, params);
-	iflib_init_locked(ctx);
-out:
+	if (restart)
+		iflib_init_locked(ctx);
 	CTX_UNLOCK(ctx);
 	return (error);
 }