[Qemu-devel] [PATCH RFC 1/1] arm64: add an option to turn on/off vpmu support

[Wei Huang <wei@redhat.com>]

This patch adds a pmu=[on/off] option to enable/disable vpmu support
in guest vm. There are several reasons to justify this option. First
vpmu can be problematic for cross-migration between different SoC as
perf counters is architecture-dependent. It is more flexible to
have an option to turn it on/off. Secondly it matches the -cpu pmu
option in libivrt. This patch has been tested on both DT/ACPI modes.

Signed-off-by: Wei Huang <wei@redhat.com>
---
 hw/arm/virt-acpi-build.c |  2 +-
 hw/arm/virt.c            |  2 +-
 target-arm/cpu.c         |  1 +
 target-arm/cpu.h         |  5 +++--
 target-arm/kvm64.c       | 10 +++++-----
 5 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index 28fc59c..dc5f66d 100644
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -540,7 +540,7 @@ build_madt(GArray *table_data, BIOSLinker *linker, VirtGuestInfo *guest_info)
         gicc->uid = i;
         gicc->flags = cpu_to_le32(ACPI_GICC_ENABLED);
 
-        if (armcpu->has_pmu) {
+        if (armcpu->enable_pmu) {
             gicc->performance_interrupt = cpu_to_le32(PPI(VIRTUAL_PMU_IRQ));
         }
     }
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index a193b5a..6aea901 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -477,7 +477,7 @@ static void fdt_add_pmu_nodes(const VirtBoardInfo *vbi, int gictype)
 
     CPU_FOREACH(cpu) {
         armcpu = ARM_CPU(cpu);
-        if (!armcpu->has_pmu ||
+        if (!armcpu->enable_pmu ||
             !kvm_arm_pmu_create(cpu, PPI(VIRTUAL_PMU_IRQ))) {
             return;
         }
diff --git a/target-arm/cpu.c b/target-arm/cpu.c
index ce8b8f4..f7daf81 100644
--- a/target-arm/cpu.c
+++ b/target-arm/cpu.c
@@ -1412,6 +1412,7 @@ static const ARMCPUInfo arm_cpus[] = {
 };
 
 static Property arm_cpu_properties[] = {
+    DEFINE_PROP_BOOL("pmu", ARMCPU, enable_pmu, true),
     DEFINE_PROP_BOOL("start-powered-off", ARMCPU, start_powered_off, false),
     DEFINE_PROP_UINT32("psci-conduit", ARMCPU, psci_conduit, 0),
     DEFINE_PROP_UINT32("midr", ARMCPU, midr, 0),
diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index 76d824d..f2341c0 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -579,8 +579,9 @@ struct ARMCPU {
     bool powered_off;
     /* CPU has security extension */
     bool has_el3;
-    /* CPU has PMU (Performance Monitor Unit) */
-    bool has_pmu;
+
+    /* CPU has vPMU (Performance Monitor Unit) support */
+    bool enable_pmu;
 
     /* CPU has memory protection unit */
     bool has_mpu;
diff --git a/target-arm/kvm64.c b/target-arm/kvm64.c
index 5faa76c..ca21670 100644
--- a/target-arm/kvm64.c
+++ b/target-arm/kvm64.c
@@ -501,11 +501,11 @@ int kvm_arch_init_vcpu(CPUState *cs)
     if (!arm_feature(&cpu->env, ARM_FEATURE_AARCH64)) {
         cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_EL1_32BIT;
     }
-    if (kvm_irqchip_in_kernel() &&
-        kvm_check_extension(cs->kvm_state, KVM_CAP_ARM_PMU_V3)) {
-        cpu->has_pmu = true;
-        cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_PMU_V3;
-    }
+
+    /* enable vPMU based on KVM mode and hardware capability */
+    cpu->enable_pmu &= (kvm_irqchip_in_kernel() &&
+        kvm_check_extension(cs->kvm_state, KVM_CAP_ARM_PMU_V3));
+    cpu->kvm_init_features[0] |= cpu->enable_pmu << KVM_ARM_VCPU_PMU_V3;
 
     /* Do KVM_ARM_VCPU_INIT ioctl */
     ret = kvm_arm_vcpu_init(cs);
-- 
2.4.11