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Re: [Xen-devel] [PATCH v6 18/29] xen/x86: allow disabling the emulated pmu



On 09/21/2015 10:36 AM, Jan Beulich wrote:
On 04.09.15 at 14:08, <roger.pau@xxxxxxxxxx> wrote:
Hmm - this seems questionable to me: Isn't the vPMU an optional
feature anyway? I.e. doesn't need separate handling here? Boris?

It is optional system-wise, not per-guest, which is what I think Roger is trying to do. I in fact wanted to add ability to disable VPMU per guest myself.

However, VPMU has nothing to do with device model so I don't think it should be part of this series from that perspective.

-boris


Jan

Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
Changes since v4:
  - Add Andrew Cooper Acked-by.
---
  xen/arch/x86/cpu/vpmu.c | 3 +++
  1 file changed, 3 insertions(+)

diff --git a/xen/arch/x86/cpu/vpmu.c b/xen/arch/x86/cpu/vpmu.c
index 8af3df1..d5bb77d 100644
--- a/xen/arch/x86/cpu/vpmu.c
+++ b/xen/arch/x86/cpu/vpmu.c
@@ -439,6 +439,9 @@ void vpmu_initialise(struct vcpu *v)
      int ret;
      bool_t is_priv_vpmu = is_hardware_domain(v->domain);
+ if ( !has_vpmu(v->domain) )
+        return;
+
      BUILD_BUG_ON(sizeof(struct xen_pmu_intel_ctxt) > XENPMU_CTXT_PAD_SZ);
      BUILD_BUG_ON(sizeof(struct xen_pmu_amd_ctxt) > XENPMU_CTXT_PAD_SZ);
      BUILD_BUG_ON(sizeof(struct xen_pmu_regs) > XENPMU_REGS_PAD_SZ);
--
1.9.5 (Apple Git-50.3)



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