On 24/09/2026 18:29, Colton Lewis wrote:
Add the KVM_ARM_VCPU_PMU_V3_ENABLE_PARTITION vCPU device attribute to
enable a Partitioned PMU for a VM where PMUv3 and VHE are supported.
When partitioning is enabled (tracked via
KVM_ARCH_FLAG_PARTITION_PMU_ENABLED), userspace must explicitly
configure the number of guest event counters via
KVM_ARM_VCPU_PMU_V3_SET_NR_COUNTERS with a value strictly less than the
maximum number of general-purpose counters implemented by the PMU (or
0 only when FEAT_HPMN0 is supported), leaving at least one
general-purpose counter reserved for host profiling prior to calling
KVM_ARM_VCPU_PMU_V3_INIT.
Signed-off-by: Colton Lewis <[email protected]>
---
Documentation/virt/kvm/devices/vcpu.rst | 42 ++++++++++++++-
arch/arm64/include/asm/kvm_host.h | 1 +
arch/arm64/include/uapi/asm/kvm.h | 2 +
arch/arm64/kvm/pmu.c | 71 ++++++++++++++++++++++++-
arch/arm64/kvm/sys_regs.c | 5 +-
5 files changed, 118 insertions(+), 3 deletions(-)
diff --git a/Documentation/virt/kvm/devices/vcpu.rst
b/Documentation/virt/kvm/devices/vcpu.rst
index deb5c51bc00c8..fb5921ed9dea2 100644
--- a/Documentation/virt/kvm/devices/vcpu.rst
+++ b/Documentation/virt/kvm/devices/vcpu.rst
@@ -57,6 +57,9 @@ Returns:
hardware PMU, or interrupt number not set (non-GICv5
guests, only)
-EBUSY PMUv3 already initialized
+ -EINVAL Partitioning enabled without explicitly configuring
+ fewer than max_counters via
+ KVM_ARM_VCPU_PMU_V3_SET_NR_COUNTERS
======= ======================================================
Request the initialization of the PMUv3. If using the PMUv3 with an in-kernel
@@ -162,7 +165,8 @@ the cpu field to the processor id.
-EFAULT Error accessing the value pointed to by addr
-ENODEV PMUv3 not supported or GIC not initialized
-EINVAL No PMUv3 explicitly selected, or value of N out of
- range
+ range (or N >= max_counters when partitioning is
+ enabled)
"No PMUv3 explicitly selected, or value of N > max_counters, or N >
max_counters - 1 when partitioning is enabled".
That might be clearer, otherwise it seems like max_counters being
relevant to "out of range" only applies to when partitioning is enabled,
not that it's max_counters all the time but one is -1.
