For now, disable hardware PMU facilities in secure virtual
machines (SVMs) to prevent any information leak between SVMs
and the (untrusted) HV.

With this, a simple 'myperf' program that uses the perf_event_open()
fails for SVMs (with the corresponding fix to UV). In normal VMs and
on the bare-metal HV the syscall and performance counters work

Signed-off-by: Sukadev Bhattiprolu <suka...@linux.ibm.com>
---
 arch/powerpc/kernel/cpu_setup_power.S | 22 ++++++++++++++++++++++
 arch/powerpc/perf/core-book3s.c       |  6 ++++++
 2 files changed, 28 insertions(+)

diff --git a/arch/powerpc/kernel/cpu_setup_power.S 
b/arch/powerpc/kernel/cpu_setup_power.S
index a460298c7ddb..d5eb06e20b5a 100644
--- a/arch/powerpc/kernel/cpu_setup_power.S
+++ b/arch/powerpc/kernel/cpu_setup_power.S
@@ -206,14 +206,36 @@ __init_PMU_HV_ISA207:
        blr
 
 __init_PMU:
+#ifdef CONFIG_PPC_SVM
+       /*
+        * For now, SVM's are restricted from accessing PMU
+        * features, so skip accordingly.
+        */
+       mfmsr   r5
+       rldicl  r5, r5, 64-MSR_S_LG, 62
+       cmpwi   r5,1
+       beq     skip1
+#endif
        li      r5,0
        mtspr   SPRN_MMCRA,r5
        mtspr   SPRN_MMCR0,r5
        mtspr   SPRN_MMCR1,r5
        mtspr   SPRN_MMCR2,r5
+skip1:
        blr
 
 __init_PMU_ISA207:
+#ifdef CONFIG_PPC_SVM
+       /*
+        * For now, SVM's are restricted from accessing PMU
+        * features, so skip accordingly.
+        */
+       mfmsr   r5
+       rldicl  r5, r5, 64-MSR_S_LG, 62
+       cmpwi   r5,1
+       beq     skip2
+#endif
        li      r5,0
        mtspr   SPRN_MMCRS,r5
+skip2:
        blr
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 4e76b2251801..9e6a9f1803f6 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -2275,6 +2275,12 @@ static int power_pmu_prepare_cpu(unsigned int cpu)
 
 int register_power_pmu(struct power_pmu *pmu)
 {
+       /*
+        * PMU events are not currently supported in SVMs
+        */
+       if (is_secure_guest())
+               return -ENOSYS;
+
        if (ppmu)
                return -EBUSY;          /* something's already registered */
 
-- 
2.17.2

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