[PATCH 1/3] kvm: introduce a helper before creating the 1st vcpu

[Dongli Zhang <dongli.zhang@xxxxxxxxxx>]

Some per-VM kvm caps (e.g., KVM_CAP_PMU_CAPABILITY) can only be
enabled/disabled before creating the 1st vcpu, that is, when
(!kvm->created_vcpus) at the KVM side.

Unfortunately, some properties are still not set during kvm_arch_init().
The values of those properties are obtained during the init of each vcpu.

This is to add a new helper to provide the last chance before creating the
1st vcpu, in order for the QEMU to set kvm caps based on the per-vcpu
properties (e.g., "pmu").

In the future patch, we may disable KVM_CAP_PMU_CAPABILITY in the helper
if the "-pmu" is set for the vcpu.

Cc: Joe Jin <joe.jin@xxxxxxxxxx>
Signed-off-by: Dongli Zhang <dongli.zhang@xxxxxxxxxx>
---
 accel/kvm/kvm-all.c    | 7 +++++--
 include/sysemu/kvm.h   | 2 ++
 target/arm/kvm64.c     | 4 ++++
 target/i386/kvm/kvm.c  | 4 ++++
 target/mips/kvm.c      | 4 ++++
 target/ppc/kvm.c       | 4 ++++
 target/riscv/kvm.c     | 4 ++++
 target/s390x/kvm/kvm.c | 4 ++++
 8 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index f99b0becd8..335ff6ce4d 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -367,8 +367,9 @@ void kvm_destroy_vcpu(CPUState *cpu)
     }
 }
 
-static int kvm_get_vcpu(KVMState *s, unsigned long vcpu_id)
+static int kvm_get_vcpu(KVMState *s, CPUState *cs)
 {
+    unsigned long vcpu_id = kvm_arch_vcpu_id(cs);
     struct KVMParkedVcpu *cpu;
 
     QLIST_FOREACH(cpu, &s->kvm_parked_vcpus, node) {
@@ -382,6 +383,8 @@ static int kvm_get_vcpu(KVMState *s, unsigned long vcpu_id)
         }
     }
 
+    kvm_arch_pre_create_vcpu(cs);
+
     return kvm_vm_ioctl(s, KVM_CREATE_VCPU, (void *)vcpu_id);
 }
 
@@ -393,7 +396,7 @@ int kvm_init_vcpu(CPUState *cpu, Error **errp)
 
     trace_kvm_init_vcpu(cpu->cpu_index, kvm_arch_vcpu_id(cpu));
 
-    ret = kvm_get_vcpu(s, kvm_arch_vcpu_id(cpu));
+    ret = kvm_get_vcpu(s, cpu);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "kvm_init_vcpu: kvm_get_vcpu failed (%lu)",
                          kvm_arch_vcpu_id(cpu));
diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index e9a97eda8c..9a2e2ba012 100644
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -371,6 +371,8 @@ int kvm_arch_put_registers(CPUState *cpu, int level);
 
 int kvm_arch_init(MachineState *ms, KVMState *s);
 
+void kvm_arch_pre_create_vcpu(CPUState *cs);
+
 int kvm_arch_init_vcpu(CPUState *cpu);
 int kvm_arch_destroy_vcpu(CPUState *cpu);
 
diff --git a/target/arm/kvm64.c b/target/arm/kvm64.c
index 1197253d12..da4317ad06 100644
--- a/target/arm/kvm64.c
+++ b/target/arm/kvm64.c
@@ -834,6 +834,10 @@ static int kvm_arm_sve_set_vls(CPUState *cs)
     return kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, &reg);
 }
 
+void kvm_arch_pre_create_vcpu(CPUState *cs)
+{
+}
+
 #define ARM_CPU_ID_MPIDR       3, 0, 0, 0, 5
 
 int kvm_arch_init_vcpu(CPUState *cs)
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index a213209379..8fec0bc5b5 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -1723,6 +1723,10 @@ static void kvm_init_nested_state(CPUX86State *env)
     }
 }
 
+void kvm_arch_pre_create_vcpu(CPUState *cs)
+{
+}
+
 int kvm_arch_init_vcpu(CPUState *cs)
 {
     struct {
diff --git a/target/mips/kvm.c b/target/mips/kvm.c
index bcb8e06b2c..1be1695b6b 100644
--- a/target/mips/kvm.c
+++ b/target/mips/kvm.c
@@ -61,6 +61,10 @@ int kvm_arch_irqchip_create(KVMState *s)
     return 0;
 }
 
+void kvm_arch_pre_create_vcpu(CPUState *cs)
+{
+}
+
 int kvm_arch_init_vcpu(CPUState *cs)
 {
     MIPSCPU *cpu = MIPS_CPU(cs);
diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
index 7c25348b7b..9049c6eb5e 100644
--- a/target/ppc/kvm.c
+++ b/target/ppc/kvm.c
@@ -462,6 +462,10 @@ static void kvmppc_hw_debug_points_init(CPUPPCState *cenv)
     }
 }
 
+void kvm_arch_pre_create_vcpu(CPUState *cs)
+{
+}
+
 int kvm_arch_init_vcpu(CPUState *cs)
 {
     PowerPCCPU *cpu = POWERPC_CPU(cs);
diff --git a/target/riscv/kvm.c b/target/riscv/kvm.c
index 30f21453d6..811f65d4f6 100644
--- a/target/riscv/kvm.c
+++ b/target/riscv/kvm.c
@@ -394,6 +394,10 @@ void kvm_arch_init_irq_routing(KVMState *s)
 {
 }
 
+void kvm_arch_pre_create_vcpu(CPUState *cs)
+{
+}
+
 int kvm_arch_init_vcpu(CPUState *cs)
 {
     int ret = 0;
diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c
index 3ac7ec9acf..65f701894e 100644
--- a/target/s390x/kvm/kvm.c
+++ b/target/s390x/kvm/kvm.c
@@ -404,6 +404,10 @@ unsigned long kvm_arch_vcpu_id(CPUState *cpu)
     return cpu->cpu_index;
 }
 
+void kvm_arch_pre_create_vcpu(CPUState *cs)
+{
+}
+
 int kvm_arch_init_vcpu(CPUState *cs)
 {
     unsigned int max_cpus = MACHINE(qdev_get_machine())->smp.max_cpus;
-- 
2.34.1