linux-kernel - [PATCH 4/4] Add check for suspended vm in softlockup detector

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 for Android: free password hash cracker in your pocket

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

Message-Id: <1323379379-6529-5-git-send-email-emunson@mgebm.net>
Date:	Thu,  8 Dec 2011 16:22:59 -0500
From:	Eric B Munson <emunson@...bm.net>
To:	avi@...hat.com
Cc:	Eric B Munson <emunson@...bm.net>, mingo@...hat.com, hpa@...or.com,
	arnd@...db.de, ryanh@...ux.vnet.ibm.com, aliguori@...ibm.com,
	mtosatti@...hat.com, jeremy.fitzhardinge@...rix.com,
	kvm@...r.kernel.org, linux-arch@...r.kernel.org, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 4/4] Add check for suspended vm in softlockup detector

A suspended VM can cause spurious soft lockup warnings.  To avoid these, the
watchdog now checks if the kernel knows it was stopped by the host and skips
the warning if so.  When the watchdog is reset successfully, clear the guest
paused flag.

Signed-off-by: Eric B Munson <emunson@...bm.net>
Cc: mingo@...hat.com
Cc: hpa@...or.com
Cc: arnd@...db.de
Cc: ryanh@...ux.vnet.ibm.com
Cc: aliguori@...ibm.com
Cc: mtosatti@...hat.com
Cc: jeremy.fitzhardinge@...rix.com
Cc: kvm@...r.kernel.org
Cc: linux-arch@...r.kernel.org
Cc: x86@...nel.org
Cc: linux-kernel@...r.kernel.org
---
Changes from V3:
 Clear the PAUSED flag when the watchdog is reset

 kernel/watchdog.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 1d7bca7..91485e5 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -25,6 +25,7 @@
 #include <linux/sysctl.h>
 
 #include <asm/irq_regs.h>
+#include <linux/kvm_para.h>
 #include <linux/perf_event.h>
 
 int watchdog_enabled = 1;
@@ -280,6 +281,9 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
 			__this_cpu_write(softlockup_touch_sync, false);
 			sched_clock_tick();
 		}
+
+		/* Clear the guest paused flag on watchdog reset */
+		kvm_check_and_clear_guest_paused();
 		__touch_watchdog();
 		return HRTIMER_RESTART;
 	}
@@ -292,6 +296,14 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
 	 */
 	duration = is_softlockup(touch_ts);
 	if (unlikely(duration)) {
+		/*
+		 * If a virtual machine is stopped by the host it can look to
+		 * the watchdog like a soft lockup, check to see if the host
+		 * stopped the vm before we issue the warning
+		 */
+		if (kvm_check_and_clear_guest_paused())
+			return HRTIMER_RESTART;
+
 		/* only warn once */
 		if (__this_cpu_read(soft_watchdog_warn) == true)
 			return HRTIMER_RESTART;
-- 
1.7.5.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/