arm: Fail early if KVM_CAP_ARM_PMU_V3 is not supported
pmu__generate_fdt_nodes() checks if the host has support for PMU in a guest
and prints a warning if that's not the case. However, this check is too
late because the function is called after the VCPU has been created, and
VCPU creation fails if KVM_CAP_ARM_PMU_V3 is not available with a rather
unhelpful error:
$ ./vm run -c1 -m64 -f selftest.flat --pmu
# lkvm run --firmware selftest.flat -m 64 -c 1 --name guest-1039
Info: Placing fdt at 0x80200000 - 0x80210000
Fatal: Unable to initialise vcpu
Move the check for KVM_CAP_ARM_PMU_V3 to kvm_cpu__arch_init() before the
VCPU is created so the user can get a more useful error message. This
also matches the behaviour of KVM_CAP_ARM_EL1_32BIT.
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Link: https://lore.kernel.org/r/20210415131725.105675-1-alexandru.elisei@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c
index 2acecae..6a2408c 100644
--- a/arm/kvm-cpu.c
+++ b/arm/kvm-cpu.c
@@ -50,6 +50,10 @@
!kvm__supports_extension(kvm, KVM_CAP_ARM_EL1_32BIT))
die("32bit guests are not supported\n");
+ if (kvm->cfg.arch.has_pmuv3 &&
+ !kvm__supports_extension(kvm, KVM_CAP_ARM_PMU_V3))
+ die("PMUv3 is not supported");
+
vcpu = calloc(1, sizeof(struct kvm_cpu));
if (!vcpu)
return NULL;
diff --git a/arm/pmu.c b/arm/pmu.c
index ffd152e..5b058ea 100644
--- a/arm/pmu.c
+++ b/arm/pmu.c
@@ -43,11 +43,6 @@
if (!kvm->cfg.arch.has_pmuv3)
return;
- if (!kvm__supports_extension(kvm, KVM_CAP_ARM_PMU_V3)) {
- pr_info("PMU unsupported\n");
- return;
- }
-
for (i = 0; i < kvm->nrcpus; i++) {
struct kvm_device_attr pmu_attr;
