[PATCH] x86/mwait-idle: Graceful probe failure when MWAIT is disabled

[PATCH] x86/mwait-idle: Graceful probe failure when MWAIT is disabled

[Jan Beulich]

When MWAIT is disabled, intel_idle refuses to probe.
But it may mis-lead the user by blaming this on the model number:

intel_idle: does not run on family 6 modesl 79

So defer the check for MWAIT until after the model# white-list check succeeds,
and if the MWAIT check fails, tell the user how to fix it:

intel_idle: Please enable MWAIT in BIOS SETUP

Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
[Linux commit: a4c447533a18ee86e07232d6344ba12b1f9c5077]
Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/cpu/mwait-idle.c
+++ b/xen/arch/x86/cpu/mwait-idle.c
@@ -917,8 +917,7 @@ static const struct idle_cpu idle_cpu_dn
 };
 
 #define ICPU(model, cpu) \
-    { X86_VENDOR_INTEL, 6, model, X86_FEATURE_MONITOR, \
-        &idle_cpu_##cpu}
+	{ X86_VENDOR_INTEL, 6, model, X86_FEATURE_ALWAYS, &idle_cpu_##cpu}
 
 static const struct x86_cpu_id intel_idle_ids[] __initconstrel = {
 	ICPU(0x1a, nehalem),
@@ -1121,6 +1120,11 @@ static int __init mwait_idle_probe(void)
 		return -ENODEV;
 	}
 
+	if (!boot_cpu_has(X86_FEATURE_MONITOR)) {
+		pr_debug(PREFIX "Please enable MWAIT in BIOS SETUP\n");
+		return -ENODEV;
+	}
+
 	if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
 		return -ENODEV;
 





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Re: [PATCH] x86/mwait-idle: Graceful probe failure when MWAIT is disabled

[Roger Pau Monné]

On Thu, Nov 22, 2018 at 02:58:03AM -0700, Jan Beulich wrote:
> When MWAIT is disabled, intel_idle refuses to probe.
> But it may mis-lead the user by blaming this on the model number:
> 
> intel_idle: does not run on family 6 modesl 79
> 
> So defer the check for MWAIT until after the model# white-list check succeeds,
> and if the MWAIT check fails, tell the user how to fix it:
> 
> intel_idle: Please enable MWAIT in BIOS SETUP
> 
> Signed-off-by: Len Brown <len.brown@intel.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> [Linux commit: a4c447533a18ee86e07232d6344ba12b1f9c5077]
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>

Thanks.

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Re: [PATCH] x86/mwait-idle: Graceful probe failure when MWAIT is disabled

[Andrew Cooper]

On 22/11/2018 09:58, Jan Beulich wrote:
> When MWAIT is disabled, intel_idle refuses to probe.
> But it may mis-lead the user by blaming this on the model number:
>
> intel_idle: does not run on family 6 modesl 79
>
> So defer the check for MWAIT until after the model# white-list check succeeds,
> and if the MWAIT check fails, tell the user how to fix it:
>
> intel_idle: Please enable MWAIT in BIOS SETUP
>
> Signed-off-by: Len Brown <len.brown@intel.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> [Linux commit: a4c447533a18ee86e07232d6344ba12b1f9c5077]
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

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