linux-kernel - [PATCH] xen: disable PV spinlocks on HVM

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Message-ID: <1315327307-392-1-git-send-email-stefano.stabellini@eu.citrix.com>
Date:	Tue, 6 Sep 2011 17:41:47 +0100
From:	<stefano.stabellini@...citrix.com>
To:	konrad.wilk@...cle.com
CC:	linux-kernel@...r.kernel.org, Stefano.Stabellini@...citrix.com,
	xen-devel@...ts.xensource.com,
	Stefano Stabellini <stefano.stabellini@...citrix.com>
Subject: [PATCH] xen: disable PV spinlocks on HVM

From: Stefano Stabellini <stefano.stabellini@...citrix.com>

PV spinlocks cannot possibly work with the current code because they are
enabled after pvops patching has already been done, and because PV
spinlocks use a different data structure than native spinlocks so we
cannot switch between them dynamically. A spinlock that has been taken
once by the native code (__ticket_spin_lock) cannot be taken by
__xen_spin_lock even after it has been released.

Reported-by: Stefan Bader <stefan.bader@...onical.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@...citrix.com>
---
 arch/x86/xen/smp.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)

diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index e79dbb9..51339b4 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -522,7 +522,6 @@ static void __init xen_hvm_smp_prepare_cpus(unsigned int max_cpus)
 	WARN_ON(xen_smp_intr_init(0));
 
 	xen_init_lock_cpu(0);
-	xen_init_spinlocks();
 }
 
 static int __cpuinit xen_hvm_cpu_up(unsigned int cpu)
-- 
1.7.2.3

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