[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

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



On 12/04/2014 03:51 AM, Jan Beulich wrote:
On 03.12.14 at 21:13, <boris.ostrovsky@xxxxxxxxxx> wrote:
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;
            break;
case X86_VENDOR_INTEL:
-        if ( vmx_vpmu_initialise(v, opt_vpmu_enabled) != 0 )
-            opt_vpmu_enabled = 0;
+        if ( vmx_vpmu_initialise(v) != 0 )
+            vpmu_mode = XENPMU_MODE_OFF;
            break;
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).
Funny that you say that - it was actually while reviewing that next
patch when I made that observation: svm_vpmu_initialise() get a
-ENOMEM return _added_ there for example, which is contrary to
what I asked for above.


Oh, *that* initialization code (I was looking at vpmu_init()). Yes, VPMU should not be turned off there.

-boris


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel


 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.