[tip:x86/hyperv] x86: Hyper-V: register clocksource only if its advertised
Commit-ID: 32068f6527b8f1822a30671dedaf59c567325026
Gitweb: http://git.kernel.org/tip/32068f6527b8f1822a30671dedaf59c567325026
Author: Olaf Hering <[mailto:o...@aepfle.de]>
AuthorDate: Sun, 3 Feb 2013 17:22:37 -0800
Committer: H. Peter Anvin
CommitDate: Tue, 12 Feb 2013 16:25:48 -0800
x86: Hyper-V: register clocksource only if its advertised
Enable hyperv_clocksource only if its advertised as a feature.
XenServer 6 returns the signature which is checked in
ms_hyperv_platform(), but it does not offer all features. Currently the
clocksource is enabled unconditionally in ms_hyperv_init_platform(), and
the result is a hanging guest.
Hyper-V spec Bit 1 indicates the availability of Partition Reference
Counter. Register the clocksource only if this bit is set.
The guest in question prints this in dmesg:
[0.00] Hypervisor detected: Microsoft HyperV
[0.00] HyperV: features 0x70, hints 0x0
This bug can be reproduced easily be setting 'viridian=1' in a HVM domU
.cfg file. A workaround without this patch is to boot the HVM guest with
'clocksource=jiffies'.
Signed-off-by: Olaf Hering
Link:
http://lkml.kernel.org/r/1359940959-32168-1-git-send-email-...@microsoft.com
Signed-off-by: K. Y. Srinivasan
Cc:
Cc: Greg KH
Signed-off-by: H. Peter Anvin
---
arch/x86/kernel/cpu/mshyperv.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 0a630dd..646d192 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -68,7 +68,8 @@ static void __init ms_hyperv_init_platform(void)
printk(KERN_INFO "HyperV: features 0x%x, hints 0x%x\n",
ms_hyperv.features, ms_hyperv.hints);
- clocksource_register_hz(_cs, NSEC_PER_SEC/100);
+ if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
+ clocksource_register_hz(_cs, NSEC_PER_SEC/100);
}
const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
--
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[tip:x86/hyperv] x86: Hyper-V: register clocksource only if its advertised
Commit-ID: 32068f6527b8f1822a30671dedaf59c567325026
Gitweb: http://git.kernel.org/tip/32068f6527b8f1822a30671dedaf59c567325026
Author: Olaf Hering [mailto:o...@aepfle.de]
AuthorDate: Sun, 3 Feb 2013 17:22:37 -0800
Committer: H. Peter Anvin h...@linux.intel.com
CommitDate: Tue, 12 Feb 2013 16:25:48 -0800
x86: Hyper-V: register clocksource only if its advertised
Enable hyperv_clocksource only if its advertised as a feature.
XenServer 6 returns the signature which is checked in
ms_hyperv_platform(), but it does not offer all features. Currently the
clocksource is enabled unconditionally in ms_hyperv_init_platform(), and
the result is a hanging guest.
Hyper-V spec Bit 1 indicates the availability of Partition Reference
Counter. Register the clocksource only if this bit is set.
The guest in question prints this in dmesg:
[0.00] Hypervisor detected: Microsoft HyperV
[0.00] HyperV: features 0x70, hints 0x0
This bug can be reproduced easily be setting 'viridian=1' in a HVM domU
.cfg file. A workaround without this patch is to boot the HVM guest with
'clocksource=jiffies'.
Signed-off-by: Olaf Hering o...@aepfle.de
Link:
http://lkml.kernel.org/r/1359940959-32168-1-git-send-email-...@microsoft.com
Signed-off-by: K. Y. Srinivasan k...@microsoft.com
Cc: sta...@vger.kernel.org
Cc: Greg KH gre...@linuxfoundation.org
Signed-off-by: H. Peter Anvin h...@linux.intel.com
---
arch/x86/kernel/cpu/mshyperv.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 0a630dd..646d192 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -68,7 +68,8 @@ static void __init ms_hyperv_init_platform(void)
printk(KERN_INFO HyperV: features 0x%x, hints 0x%x\n,
ms_hyperv.features, ms_hyperv.hints);
- clocksource_register_hz(hyperv_cs, NSEC_PER_SEC/100);
+ if (ms_hyperv.features HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
+ clocksource_register_hz(hyperv_cs, NSEC_PER_SEC/100);
}
const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
--
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