linux-kernel - [PATCH 04/28] thunderbolt: Add dummy read after port capability list walk on Light Ridge

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20190129150143.12681-5-mika.westerberg@linux.intel.com>
Date:   Tue, 29 Jan 2019 18:01:19 +0300
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     linux-kernel@...r.kernel.org
Cc:     Michael Jamet <michael.jamet@...el.com>,
        Yehezkel Bernat <YehezkelShB@...il.com>,
        Andreas Noever <andreas.noever@...il.com>,
        Lukas Wunner <lukas@...ner.de>,
        "David S . Miller" <davem@...emloft.net>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        netdev@...r.kernel.org
Subject: [PATCH 04/28] thunderbolt: Add dummy read after port capability list walk on Light Ridge

Light Ridge has an issue where reading the next capability pointer
location in port config space the read data is not cleared. It is fine
to read capabilities each after another so only thing we need to do is
to make sure we issue dummy read after tb_port_find_cap() is finished to
avoid the issue in next read.

Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
---
 drivers/thunderbolt/cap.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/thunderbolt/cap.c b/drivers/thunderbolt/cap.c
index 94a507f12b71..b7a3b62805a6 100644
--- a/drivers/thunderbolt/cap.c
+++ b/drivers/thunderbolt/cap.c
@@ -56,6 +56,21 @@ static int tb_port_enable_tmu(struct tb_port *port, bool enable)
 	return tb_sw_write(sw, &value, TB_CFG_SWITCH, offset, 1);
 }
 
+static void tb_port_dummy_read(struct tb_port *port)
+{
+	/*
+	 * When reading from next capability pointer location in port
+	 * config space the read data is not cleared on LR. To avoid
+	 * reading stale data on next read perform one dummy read after
+	 * port capabilities are walked.
+	 */
+	if (port->sw->config.device_id == PCI_DEVICE_ID_INTEL_LIGHT_RIDGE) {
+		u32 dummy;
+
+		tb_port_read(port, &dummy, TB_CFG_PORT, 0, 1);
+	}
+}
+
 static int __tb_port_find_cap(struct tb_port *port, enum tb_port_cap cap)
 {
 	u32 offset = 1;
@@ -96,6 +111,7 @@ int tb_port_find_cap(struct tb_port *port, enum tb_port_cap cap)
 
 	ret = __tb_port_find_cap(port, cap);
 
+	tb_port_dummy_read(port);
 	tb_port_enable_tmu(port, false);
 
 	return ret;
-- 
2.20.1