[Xen-devel] [PATCH] x86/cpuid: Adjust the policies based on the boot time vPMU setting

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

The vPMU logic isn't integrated into the CPUID policy logic (and still
requires a fair amount of work before it can be).

The ARCH_PERFMON leaf was previously copied into all policies, unilaterally
overridden (to the same value in the general case) by the toolstack using
DOMCTL_set_cpuid, then unilaterally overridden again by Xen's runtime
logic (based on the boot time settings).

The policy retrieved with DOMCTL_get_cpu_policy needs to be accurate, so take
the boot time settings into account when creating and clipping the toolstack
policy.  The runtime logic is still required for now, to clip the maximum
reported version when necessary.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>
---
 xen/arch/x86/cpuid.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/xen/arch/x86/cpuid.c b/xen/arch/x86/cpuid.c
index 3c29191..5f093a9 100644
--- a/xen/arch/x86/cpuid.c
+++ b/xen/arch/x86/cpuid.c
@@ -389,6 +389,10 @@ static void __init calculate_host_policy(void)
     recalculate_xstate(p);
     recalculate_misc(p);
 
+    /* When vPMU is disabled, drop it from the host policy. */
+    if ( vpmu_mode == XENPMU_MODE_OFF )
+        p->basic.raw[0xa] = EMPTY_LEAF;
+
     if ( p->extd.svm )
     {
         /* Clamp to implemented features which require hardware support. */
@@ -689,6 +693,10 @@ void recalculate_cpuid_policy(struct domain *d)
         }
     }
 
+    if ( vpmu_mode == XENPMU_MODE_OFF ||
+         ((vpmu_mode & XENPMU_MODE_ALL) && !is_hardware_domain(d)) )
+        p->basic.raw[0xa] = EMPTY_LEAF;
+
     if ( !p->extd.svm )
         p->extd.raw[0xa] = EMPTY_LEAF;
 
-- 
2.1.4


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