Merge branch kvm-arm64/nv-pmu-fixes into kvmarm-master/next

* kvm-arm64/nv-pmu-fixes:
  : .
  : Fixes for NV PMU emulation. From the cover letter:
  :
  : "Joey reports that some of his PMU tests do not behave quite as
  : expected:
  :
  : - MDCR_EL2.HPMN is set to 0 out of reset
  :
  : - PMCR_EL0.P should reset all the counters when written from EL2
  :
  : Oliver points out that setting PMCR_EL0.N from userspace by writing to
  : the register is silly with NV, and that we need a new PMU attribute
  : instead.
  :
  : On top of that, I figured out that we had a number of little gotchas:
  :
  : - It is possible for a guest to write an HPMN value that is out of
  :   bound, and it seems valuable to limit it
  :
  : - PMCR_EL0.N should be the maximum number of counters when read from
  :   EL2, and MDCR_EL2.HPMN when read from EL0/EL1
  :
  : - Prevent userspace from updating PMCR_EL0.N when EL2 is available"
  : .
  KVM: arm64: Let kvm_vcpu_read_pmcr() return an EL-dependent value for PMCR_EL0.N
  KVM: arm64: Handle out-of-bound write to MDCR_EL2.HPMN
  KVM: arm64: Don't let userspace write to PMCR_EL0.N when the vcpu has EL2
  KVM: arm64: Allow userspace to limit the number of PMU counters for EL2 VMs
  KVM: arm64: Contextualise the handling of PMCR_EL0.P writes
  KVM: arm64: Fix MDCR_EL2.HPMN reset value
  KVM: arm64: Repaint pmcr_n into nr_pmu_counters

Signed-off-by: Marc Zyngier <maz@kernel.org>

1 files changed, 24 insertions, 0 deletions

diff --git a/Documentation/virt/kvm/devices/vcpu.rst b/Documentation/virt/kvm/devices/vcpu.rst
index 31a9576c07af..60bf205cb373 100644
--- a/Documentation/virt/kvm/devices/vcpu.rst
+++ b/Documentation/virt/kvm/devices/vcpu.rst
@@ -137,6 +137,30 @@ exit_reason = KVM_EXIT_FAIL_ENTRY and populate the fail_entry struct by setting
 hardare_entry_failure_reason field to KVM_EXIT_FAIL_ENTRY_CPU_UNSUPPORTED and
 the cpu field to the processor id.
 
+1.5 ATTRIBUTE: KVM_ARM_VCPU_PMU_V3_SET_NR_COUNTERS
+--------------------------------------------------
+
+:Parameters: in kvm_device_attr.addr the address to an unsigned int
+	     representing the maximum value taken by PMCR_EL0.N
+
+:Returns:
+
+	 =======  ====================================================
+	 -EBUSY   PMUv3 already initialized, a VCPU has already run or
+                  an event filter has already been set
+	 -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
+	 =======  ====================================================
+
+Set the number of implemented event counters in the virtual PMU. This
+mandates that a PMU has explicitly been selected via
+KVM_ARM_VCPU_PMU_V3_SET_PMU, and will fail when no PMU has been
+explicitly selected, or the number of counters is out of range for the
+selected PMU. Selecting a new PMU cancels the effect of setting this
+attribute.
+
 2. GROUP: KVM_ARM_VCPU_TIMER_CTRL
 =================================