Re: [PATCH v7 36/45] arm64: RME: Set breakpoint parameters through SET_ONE_REG

From: Gavin Shan
Date: Tue Mar 04 2025 - 18:47:03 EST


On 2/14/25 2:14 AM, Steven Price wrote:
From: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>

Allow userspace to configure the number of breakpoints and watchpoints
of a Realm VM through KVM_SET_ONE_REG ID_AA64DFR0_EL1.

The KVM sys_reg handler checks the user value against the maximum value
given by RMM (arm64_check_features() gets it from the
read_sanitised_id_aa64dfr0_el1() reset handler).

Userspace discovers that it can write these fields by issuing a
KVM_ARM_GET_REG_WRITABLE_MASKS ioctl.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
Signed-off-by: Steven Price <steven.price@xxxxxxx>
---
arch/arm64/kvm/guest.c | 2 ++
arch/arm64/kvm/rme.c | 3 +++
arch/arm64/kvm/sys_regs.c | 17 +++++++++++------
3 files changed, 16 insertions(+), 6 deletions(-)


Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx>