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@xxxxxxxxxx>
---
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@xxxxxxxxxx
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@xxxxxxxxxx
---
Akihiko Odaki (6):
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: Reload PMCNTENSET_EL0
arch/arm64/kvm/arm.c | 8 ++++---
arch/arm64/kvm/guest.c | 12 +++++++++++
arch/arm64/kvm/pmu-emul.c | 54 ++++++++++++++++-------------------------------
arch/arm64/kvm/sys_regs.c | 53 ++++++++++++++++++++++++++--------------------
include/kvm/arm_pmu.h | 1 +
5 files changed, 66 insertions(+), 62 deletions(-)
---
base-commit: da2f480cb24d39d480b1e235eda0dd2d01f8765b
change-id: 20250302-pmc-b90a86af945c
Best regards,
--
Akihiko Odaki <akihiko.odaki@xxxxxxxxxx>
