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Re: [Xen-devel] [PATCH v15 11/21] x86/VPMU: Interface for setting PMU mode and flags

On 11/27/2014 03:57 AM, Jan Beulich wrote:
On 26.11.14 at 15:32, <boris.ostrovsky@xxxxxxxxxx> wrote:
On 11/25/2014 08:49 AM, Jan Beulich wrote:
On 17.11.14 at 00:07, <boris.ostrovsky@xxxxxxxxxx> wrote:
@@ -244,19 +256,19 @@ void vpmu_initialise(struct vcpu *v)
       switch ( vendor )
       case X86_VENDOR_AMD:
-        if ( svm_vpmu_initialise(v, opt_vpmu_enabled) != 0 )
-            opt_vpmu_enabled = 0;
+        if ( svm_vpmu_initialise(v) != 0 )
+            vpmu_mode = XENPMU_MODE_OFF;
-        if ( vmx_vpmu_initialise(v, opt_vpmu_enabled) != 0 )
-            opt_vpmu_enabled = 0;
+        if ( vmx_vpmu_initialise(v) != 0 )
+            vpmu_mode = XENPMU_MODE_OFF;
So this turns off the vPMU globally upon failure of initializing
some random vCPU. Why is that? I see this was the case even
before your entire series, but shouldn't this be fixed _before_
enhancing the whole thing to support PV/PVH?
Yes, that's probably too strong. Do you want to fix this as an early
patch (before PV(H)) support gets in? I'd rather do it in the patch that
moves things into initcalls.
Yes, I think this should be fixed in a prereq patch, thus allowing it
to be easily backported if so desired.

I started to make this change and then I realized that the next patch (12/21) is actually already taking care of this problem: most of the *_vpmu_initialise() will be executed as initcalls during host boot and if any of those fail then we do want to disable VPMU globally (those failures would not be VCPU-specific).


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