Schspa Shi recently reported[1] that some of the vgic code interacting with userspace was reading uninitialised stack memory, and although that read wasn't used any further, it prompted me to revisit this part of the code. Needless to say, this area of the kernel is pretty crufty, and shows a bunch of issues in other parts of the KVM/arm64 infrastructure. This series tries to remedy a bunch of them: - Sanitise the way we deal with sysregs from userspace: at the moment, each and every .set_user/.get_user callback has to implement its own userspace accesses (directly or indirectly). It'd be much better if that was centralised so that we can reason about it. - Enforce that all AArch64 sysregs are 64bit. Always. This was sort of implied by the code, but it took some effort to convince myself that this was actually the case. - Move the vgic-v3 sysreg userspace accessors to the userspace callbacks instead of hijacking the vcpu trap callback. This allows us to reuse the sysreg infrastructure. - Consolidate userspace accesses for both GICv2, GICv3 and common code as much as possible. - Cleanup a bunch of not-very-useful helpers, tidy up some of the code as we touch it. Overall, this is essentially a cosmetic exercise, as there is no new feature here. But I have the feeling that the result is somehow more maintainable. This has been (lightly) tested on my Synquacer, and nothing exploded. Yet. YMMV. [1] https://lore.kernel.org/r/m2h740zz1i.fsf@xxxxxxxxx Marc Zyngier (19): KVM: arm64: Add get_reg_by_id() as a sys_reg_desc retrieving helper KVM: arm64: Reorder handling of invariant sysregs from userspace KVM: arm64: Introduce generic get_user/set_user helpers for system registers KVM: arm64: Push checks for 64bit registers into the low-level accessors KVM: arm64: Consolidate sysreg userspace accesses KVM: arm64: Get rid of reg_from/to_user() KVM: arm64: vgic-v3: Simplify vgic_v3_has_cpu_sysregs_attr() KVM: arm64: vgic-v3: Push user access into vgic_v3_cpu_sysregs_uaccess() KVM: arm64: vgic-v3: Make the userspace accessors use sysreg API KVM: arm64: vgic-v3: Convert userspace accessors over to FIELD_GET/FIELD_PREP KVM: arm64: vgic-v3: Use u32 to manage the line level from userspace KVM: arm64: vgic-v3: Consolidate userspace access for MMIO registers KVM: arm64: vgic-v2: Consolidate userspace access for MMIO registers KVM: arm64: vgic: Use {get,put}_user() instead of copy_{from.to}_user KVM: arm64: vgic-v2: Add helper for legacy dist/cpuif base address setting KVM: arm64: vgic: Consolidate userspace access for base address setting KVM: arm64: Get rid of find_reg_by_id() KVM: arm64: Descope kvm_arm_sys_reg_{get,set}_reg() KVM: arm64: Get rid or outdated comments arch/arm64/include/asm/kvm_host.h | 2 - arch/arm64/kvm/arm.c | 11 +- arch/arm64/kvm/sys_regs.c | 291 +++++++--------- arch/arm64/kvm/sys_regs.h | 18 +- arch/arm64/kvm/vgic-sys-reg-v3.c | 461 +++++++++++++++----------- arch/arm64/kvm/vgic/vgic-kvm-device.c | 269 +++++++-------- arch/arm64/kvm/vgic/vgic-mmio-v3.c | 10 +- arch/arm64/kvm/vgic/vgic-mmio.c | 6 +- arch/arm64/kvm/vgic/vgic-mmio.h | 4 +- arch/arm64/kvm/vgic/vgic.h | 9 +- include/kvm/arm_vgic.h | 2 +- 11 files changed, 535 insertions(+), 548 deletions(-) -- 2.34.1
