Prepare vPMC registers for user-initiated changes after first run. This is important specifically for debugging Windows on QEMU with GDB; QEMU tries to write back all visible registers when resuming the VM execution with GDB, corrupting the PMU state. Windows always uses the PMU so this can cause adverse effects on that particular OS.
This series also contains patch "KVM: arm64: PMU: Set raw values from user to PM{C,I}NTEN{SET,CLR}, PMOVS{SET,CLR}", which reverts semantic changes made for the mentioned registers in the past. It is necessary to migrate the PMU state properly on Firecracker, QEMU, and crosvm.
Signed-off-by: Akihiko Odaki akihiko.odaki@daynix.com --- Changes in v4: - Reverted changes for functions implementing ioctls in patch "KVM: arm64: PMU: Assume PMU presence in pmu-emul.c". - Removed kvm_pmu_vcpu_reset(). - Reordered function calls in kvm_vcpu_reload_pmu() for better style. - Link to v3: https://lore.kernel.org/r/20250312-pmc-v3-0-0411cab5dc3d@daynix.com
Changes in v3: - Added patch "KVM: arm64: PMU: Assume PMU presence in pmu-emul.c". - Added an explanation of this path series' motivation to each patch. - Explained why userspace register writes and register reset should be covered in patch "KVM: arm64: PMU: Reload when user modifies registers". - Marked patch "KVM: arm64: PMU: Set raw values from user to PM{C,I}NTEN{SET,CLR}, PMOVS{SET,CLR}" for stable. - Reoreded so that patch "KVM: arm64: PMU: Set raw values from user to PM{C,I}NTEN{SET,CLR}, PMOVS{SET,CLR}" would come first. - Added patch "KVM: arm64: PMU: Call kvm_pmu_handle_pmcr() after masking PMCNTENSET_EL0". - Added patch "KVM: arm64: Reload PMCNTENSET_EL0". - Link to v2: https://lore.kernel.org/r/20250307-pmc-v2-0-6c3375a5f1e4@daynix.com
Changes in v2: - Changed to utilize KVM_REQ_RELOAD_PMU as suggested by Oliver Upton. - Added patch "KVM: arm64: PMU: Reload when user modifies registers" to cover more registers. - Added patch "KVM: arm64: PMU: Set raw values from user to PM{C,I}NTEN{SET,CLR}, PMOVS{SET,CLR}". - Link to v1: https://lore.kernel.org/r/20250302-pmc-v1-1-caff989093dc@daynix.com
--- Akihiko Odaki (7): KVM: arm64: PMU: Set raw values from user to PM{C,I}NTEN{SET,CLR}, PMOVS{SET,CLR} KVM: arm64: PMU: Assume PMU presence in pmu-emul.c KVM: arm64: PMU: Fix SET_ONE_REG for vPMC regs KVM: arm64: PMU: Reload when user modifies registers KVM: arm64: PMU: Call kvm_pmu_handle_pmcr() after masking PMCNTENSET_EL0 KVM: arm64: PMU: Reload PMCNTENSET_EL0 KVM: arm64: PMU: Reload when resetting
arch/arm64/kvm/arm.c | 8 ++++--- arch/arm64/kvm/pmu-emul.c | 60 ++++++++++++++--------------------------------- arch/arm64/kvm/reset.c | 3 --- arch/arm64/kvm/sys_regs.c | 53 +++++++++++++++++++++++------------------ include/kvm/arm_pmu.h | 3 +-- 5 files changed, 53 insertions(+), 74 deletions(-) --- base-commit: da2f480cb24d39d480b1e235eda0dd2d01f8765b change-id: 20250302-pmc-b90a86af945c
Best regards,