linux-kernel - [PATCH 3.11 43/46] sparc64: Make sure %pil interrupts are enabled during hypervisor yield.

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: <1397644322-13905-44-git-send-email-luis.henriques@canonical.com>
Date:	Wed, 16 Apr 2014 11:31:59 +0100
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	"David S. Miller" <davem@...emloft.net>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.11 43/46] sparc64: Make sure %pil interrupts are enabled during hypervisor yield.

3.11.10.8 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: "David S. Miller" <davem@...emloft.net>

commit cb3042d609e30e6144024801c89be3925106752b upstream.

In arch_cpu_idle() we must enable %pil based interrupts before
potentially invoking the hypervisor cpu yield call.

As per the Hypervisor API documentation for cpu_yield:

	Interrupts which are blocked by some mechanism other that
	pstate.ie (for example %pil) are not guaranteed to cause
	a return from this service.

It seems that only first generation Niagara chips are hit by this
bug.  My best guess is that later chips implement this in hardware
and wake up anyways from %pil events, whereas in first generation
chips the yield is implemented completely in hypervisor code and
requires %pil to be enabled in order to wake properly from this
call.

Fixes: 87fa05aeb3a5 ("sparc: Use generic idle loop")
Reported-by: Fabio M. Di Nitto <fabbione@...bione.net>
Reported-by: Jan Engelhardt <jengelh@...i.de>
Tested-by: Jan Engelhardt <jengelh@...i.de>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 arch/sparc/kernel/process_64.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index baebab2..b9cc976 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -57,9 +57,12 @@ void arch_cpu_idle(void)
 {
 	if (tlb_type != hypervisor) {
 		touch_nmi_watchdog();
+		local_irq_enable();
 	} else {
 		unsigned long pstate;
 
+		local_irq_enable();
+
                 /* The sun4v sleeping code requires that we have PSTATE.IE cleared over
                  * the cpu sleep hypervisor call.
                  */
@@ -81,7 +84,6 @@ void arch_cpu_idle(void)
 			: "=&r" (pstate)
 			: "i" (PSTATE_IE));
 	}
-	local_irq_enable();
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
-- 
1.9.1

--
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/