[PATCH 0/2] KVM: arm64: PMU: Preserve vPMC registers properly on migration

Reiji Watanabe reijiw at google.com
Wed Mar 1 21:50:31 PST 2023


The series fixes two problems in preserving vPMU counter (vPMC)
registers (PMCCNTR_EL0/PMEVCNTR<n>_EL0) during migration.

One of the problems is that KVM may not return the current values
of the vPMC registers for KVM_GET_ONE_REG.

The other one might cause KVM to reset the vPMC registers on the
first KVM_RUN on the destination. This is because userspace might
save PMCR_EL0 with PMCR_EL0.{C,P} bits set on the source, and
restore it on the destination.

See patch-1 and patch-2 for details on these issues respectively.

The series is based on v6.2.

Reiji Watanabe (2):
  KVM: arm64: PMU: Fix GET_ONE_REG for vPMC regs to return the current
    value
  KVM: arm64: PMU: Don't save PMCR_EL0.{C,P} for the vCPU

 arch/arm64/kvm/pmu-emul.c |  4 +++-
 arch/arm64/kvm/sys_regs.c | 21 +++++++++++++++++++--
 2 files changed, 22 insertions(+), 3 deletions(-)


base-commit: c9c3395d5e3dcc6daee66c6908354d47bf98cb0c
-- 
2.39.2.722.g9855ee24e9-goog




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