linux-kernel - [PATCH 3.10 070/180] powerpc/pseries/eeh: Handle RTAS delay requests in configure

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Date:   Sun, 21 Aug 2016 17:30:00 +0200
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Russell Currey <ruscur@...sell.cc>, stable@...r.kernel.org#3.10+,
        Michael Ellerman <mpe@...erman.id.au>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 070/180] powerpc/pseries/eeh: Handle RTAS delay requests in configure_bridge

From: Russell Currey <ruscur@...sell.cc>

commit 871e178e0f2c4fa788f694721a10b4758d494ce1 upstream.

In the "ibm,configure-pe" and "ibm,configure-bridge" RTAS calls, the
spec states that values of 9900-9905 can be returned, indicating that
software should delay for 10^x (where x is the last digit, i.e. 990x)
milliseconds and attempt the call again. Currently, the kernel doesn't
know about this, and respecting it fixes some PCI failures when the
hypervisor is busy.

The delay is capped at 0.2 seconds.

Cc: <stable@...r.kernel.org> # 3.10+
Signed-off-by: Russell Currey <ruscur@...sell.cc>
Acked-by: Gavin Shan <gwshan@...ux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Willy Tarreau <w@....eu>
---
 arch/powerpc/platforms/pseries/eeh_pseries.c | 51 ++++++++++++++++++++--------
 1 file changed, 36 insertions(+), 15 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/eeh_pseries.c b/arch/powerpc/platforms/pseries/eeh_pseries.c
index 68f97d5..dc0278e 100644
--- a/arch/powerpc/platforms/pseries/eeh_pseries.c
+++ b/arch/powerpc/platforms/pseries/eeh_pseries.c
@@ -551,29 +551,50 @@ static int pseries_eeh_configure_bridge(struct eeh_pe *pe)
 {
 	int config_addr;
 	int ret;
+	/* Waiting 0.2s maximum before skipping configuration */
+	int max_wait = 200;
 
 	/* Figure out the PE address */
 	config_addr = pe->config_addr;
 	if (pe->addr)
 		config_addr = pe->addr;
 
-	/* Use new configure-pe function, if supported */
-	if (ibm_configure_pe != RTAS_UNKNOWN_SERVICE) {
-		ret = rtas_call(ibm_configure_pe, 3, 1, NULL,
-				config_addr, BUID_HI(pe->phb->buid),
-				BUID_LO(pe->phb->buid));
-	} else if (ibm_configure_bridge != RTAS_UNKNOWN_SERVICE) {
-		ret = rtas_call(ibm_configure_bridge, 3, 1, NULL,
-				config_addr, BUID_HI(pe->phb->buid),
-				BUID_LO(pe->phb->buid));
-	} else {
-		return -EFAULT;
-	}
+	while (max_wait > 0) {
+		/* Use new configure-pe function, if supported */
+		if (ibm_configure_pe != RTAS_UNKNOWN_SERVICE) {
+			ret = rtas_call(ibm_configure_pe, 3, 1, NULL,
+					config_addr, BUID_HI(pe->phb->buid),
+					BUID_LO(pe->phb->buid));
+		} else if (ibm_configure_bridge != RTAS_UNKNOWN_SERVICE) {
+			ret = rtas_call(ibm_configure_bridge, 3, 1, NULL,
+					config_addr, BUID_HI(pe->phb->buid),
+					BUID_LO(pe->phb->buid));
+		} else {
+			return -EFAULT;
+		}
 
-	if (ret)
-		pr_warning("%s: Unable to configure bridge PHB#%d-PE#%x (%d)\n",
-			__func__, pe->phb->global_number, pe->addr, ret);
+		if (!ret)
+			return ret;
+
+		/*
+		 * If RTAS returns a delay value that's above 100ms, cut it
+		 * down to 100ms in case firmware made a mistake.  For more
+		 * on how these delay values work see rtas_busy_delay_time
+		 */
+		if (ret > RTAS_EXTENDED_DELAY_MIN+2 &&
+		    ret <= RTAS_EXTENDED_DELAY_MAX)
+			ret = RTAS_EXTENDED_DELAY_MIN+2;
+
+		max_wait -= rtas_busy_delay_time(ret);
+
+		if (max_wait < 0)
+			break;
+
+		rtas_busy_delay(ret);
+	}
 
+	pr_warn("%s: Unable to configure bridge PHB#%d-PE#%x (%d)\n",
+		__func__, pe->phb->global_number, pe->addr, ret);
 	return ret;
 }
 
-- 
2.8.0.rc2.1.gbe9624a