sfc: Cope with permissions enforcement added to firmware for SR-IOV

* Accept EPERM in some simple cases, the following cases are handled:
1) efx_mcdi_read_assertion()
Unprivileged PCI functions aren't allowed to GET_ASSERTS.
We return success as it's up to the primary PF to deal with asserts.
2) efx_mcdi_mon_probe() in efx_ef10_probe()
Unprivileged PCI functions aren't allowed to read sensor info, and
worrying about sensor data is the primary PF's job.
3) phy_op->reconfigure() in efx_init_port() and efx_reset_up()
Unprivileged functions aren't allowed to MC_CMD_SET_LINK, they just have
to accept the settings (including flow-control, which is what
efx_init_port() is worried about) they've been given.
4) Fallback to GET_WORKAROUNDS in efx_ef10_probe()
Unprivileged PCI functions aren't allowed to set workarounds. So if
efx_mcdi_set_workaround() fails EPERM, use efx_mcdi_get_workarounds()
to find out if workaround_35388 is enabled.
5) If DRV_ATTACH gets EPERM, try without specifying fw-variant
Unprivileged PCI functions have to use a FIRMWARE_ID of 0xffffffff
(MC_CMD_FW_DONT_CARE).
6) Don't try to exit_assertion unless one had fired
Previously we called efx_mcdi_exit_assertion even if
efx_mcdi_read_assertion had received MC_CMD_GET_ASSERTS_FLAGS_NO_FAILS.
This is unnecessary, and the resulting MC_CMD_REBOOT, even if the
AFTER_ASSERTION flag made it a no-op, would fail EPERM for unprivileged
PCI functions.
So make efx_mcdi_read_assertion return whether an assert happened, and only
call efx_mcdi_exit_assertion if it has.

Signed-off-by: Shradha Shah <sshah@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 2 deletions

diff --git a/drivers/net/ethernet/sfc/ef10.c b/drivers/net/ethernet/sfc/ef10.c
index 0dff8123da04..ae0ed2aa6eca 100644
--- a/drivers/net/ethernet/sfc/ef10.c
+++ b/drivers/net/ethernet/sfc/ef10.c
@@ -286,10 +286,22 @@ static int efx_ef10_probe(struct efx_nic *efx)
 		goto fail3;
 	efx->timer_quantum_ns = 1536000 / rc; /* 1536 cycles */
 
-	/* Check whether firmware supports bug 35388 workaround */
+	/* Check whether firmware supports bug 35388 workaround.
+	 * First try to enable it, then if we get EPERM, just
+	 * ask if it's already enabled
+	 */
 	rc = efx_mcdi_set_workaround(efx, MC_CMD_WORKAROUND_BUG35388, true);
 	if (rc == 0)
 		nic_data->workaround_35388 = true;
+	else if (rc == -EPERM) {
+		unsigned int enabled;
+
+		rc = efx_mcdi_get_workarounds(efx, NULL, &enabled);
+		if (rc)
+			goto fail3;
+		nic_data->workaround_35388 = enabled &
+			MC_CMD_GET_WORKAROUNDS_OUT_BUG35388;
+	}
 	else if (rc != -ENOSYS && rc != -ENOENT)
 		goto fail3;
 	netif_dbg(efx, probe, efx->net_dev,
@@ -297,7 +309,7 @@ static int efx_ef10_probe(struct efx_nic *efx)
 		  nic_data->workaround_35388 ? "en" : "dis");
 
 	rc = efx_mcdi_mon_probe(efx);
-	if (rc)
+	if (rc && rc != -EPERM)
 		goto fail3;
 
 	efx_ptp_probe(efx, NULL);