target/arm: Check supported KVM features globally (not per vCPU)

Since commit d70c996df23f, when enabling the PMU we get:

  $ qemu-system-aarch64 -cpu host,pmu=on -M virt,accel=kvm,gic-version=3
  Segmentation fault (core dumped)

  Thread 1 "qemu-system-aar" received signal SIGSEGV, Segmentation fault.
  0x0000aaaaaae356d0 in kvm_ioctl (s=0x0, type=44547) at accel/kvm/kvm-all.c:2588
  2588        ret = ioctl(s->fd, type, arg);
  (gdb) bt
  #0  0x0000aaaaaae356d0 in kvm_ioctl (s=0x0, type=44547) at accel/kvm/kvm-all.c:2588
  #1  0x0000aaaaaae31568 in kvm_check_extension (s=0x0, extension=126) at accel/kvm/kvm-all.c:916
  #2  0x0000aaaaaafce254 in kvm_arm_pmu_supported (cpu=0xaaaaac214ab0) at target/arm/kvm.c:213
  #3  0x0000aaaaaafc0f94 in arm_set_pmu (obj=0xaaaaac214ab0, value=true, errp=0xffffffffe438) at target/arm/cpu.c:1111
  #4  0x0000aaaaab5533ac in property_set_bool (obj=0xaaaaac214ab0, v=0xaaaaac223a80, name=0xaaaaac11a970 "pmu", opaque=0xaaaaac222730, errp=0xffffffffe438) at qom/object.c:2170
  #5  0x0000aaaaab5512f0 in object_property_set (obj=0xaaaaac214ab0, v=0xaaaaac223a80, name=0xaaaaac11a970 "pmu", errp=0xffffffffe438) at qom/object.c:1328
  #6  0x0000aaaaab551e10 in object_property_parse (obj=0xaaaaac214ab0, string=0xaaaaac11b4c0 "on", name=0xaaaaac11a970 "pmu", errp=0xffffffffe438) at qom/object.c:1561
  #7  0x0000aaaaab54ee8c in object_apply_global_props (obj=0xaaaaac214ab0, props=0xaaaaac018e20, errp=0xaaaaabd6fd88 <error_fatal>) at qom/object.c:407
  #8  0x0000aaaaab1dd5a4 in qdev_prop_set_globals (dev=0xaaaaac214ab0) at hw/core/qdev-properties.c:1218
  #9  0x0000aaaaab1d9fac in device_post_init (obj=0xaaaaac214ab0) at hw/core/qdev.c:1050
  ...
  #15 0x0000aaaaab54f310 in object_initialize_with_type (obj=0xaaaaac214ab0, size=52208, type=0xaaaaabe237f0) at qom/object.c:512
  #16 0x0000aaaaab54fa24 in object_new_with_type (type=0xaaaaabe237f0) at qom/object.c:687
  #17 0x0000aaaaab54fa80 in object_new (typename=0xaaaaabe23970 "host-arm-cpu") at qom/object.c:702
  #18 0x0000aaaaaaf04a74 in machvirt_init (machine=0xaaaaac0a8550) at hw/arm/virt.c:1770
  #19 0x0000aaaaab1e8720 in machine_run_board_init (machine=0xaaaaac0a8550) at hw/core/machine.c:1138
  #20 0x0000aaaaaaf95394 in qemu_init (argc=5, argv=0xffffffffea58, envp=0xffffffffea88) at softmmu/vl.c:4348
  #21 0x0000aaaaaada3f74 in main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>) at softmmu/main.c:48

This is because in frame #2, cpu->kvm_state is still NULL
(the vCPU is not yet realized).

KVM has a hard requirement of all cores supporting the same
feature set. We only need to check if the accelerator supports
a feature, not each vCPU individually.

Fix by removing the 'CPUState *cpu' argument from the
kvm_arm_<FEATURE>_supported() functions.

Fixes: d70c996df23f ('Use CPUState::kvm_state in kvm_arm_pmu_supported')
Reported-by: Haibo Xu <haibo.xu@linaro.org>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 5 insertions, 9 deletions

diff --git a/target/arm/kvm64.c b/target/arm/kvm64.c
index f09ed9f..3dc494a 100644
--- a/target/arm/kvm64.c
+++ b/target/arm/kvm64.c
@@ -652,18 +652,14 @@ bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
     return true;
 }
 
-bool kvm_arm_aarch32_supported(CPUState *cpu)
+bool kvm_arm_aarch32_supported(void)
 {
-    KVMState *s = KVM_STATE(current_accel());
-
-    return kvm_check_extension(s, KVM_CAP_ARM_EL1_32BIT);
+    return kvm_check_extension(kvm_state, KVM_CAP_ARM_EL1_32BIT);
 }
 
-bool kvm_arm_sve_supported(CPUState *cpu)
+bool kvm_arm_sve_supported(void)
 {
-    KVMState *s = KVM_STATE(current_accel());
-
-    return kvm_check_extension(s, KVM_CAP_ARM_SVE);
+    return kvm_check_extension(kvm_state, KVM_CAP_ARM_SVE);
 }
 
 QEMU_BUILD_BUG_ON(KVM_ARM64_SVE_VQ_MIN != 1);
@@ -798,7 +794,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
         env->features &= ~(1ULL << ARM_FEATURE_PMU);
     }
     if (cpu_isar_feature(aa64_sve, cpu)) {
-        assert(kvm_arm_sve_supported(cs));
+        assert(kvm_arm_sve_supported());
         cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_SVE;
     }