Hi, This patch series adds support for restricting CPU features for protected VMs in KVM [1]. Various feature configurations are allowed in KVM/arm64. Supporting all these features in pKVM is difficult, as it either involves moving much of the handling code to EL2, which adds bloat and results in a less verifiable trusted code base. Or it involves leaving the code handling at EL1, which risks having an untrusted host kernel feeding wrong information to the EL2 and to the protected guests. This series attempts to mitigate this by reducing the configuration space, providing a reduced amount of feature support at EL2 with the least amount of compromise of protected guests' capabilities. This is done by restricting CPU features exposed to protected guests through feature registers. These restrictions are enforced by trapping register accesses as well as instructions associated with these features, and injecting an undefined exception into the guest if it attempts to use a restricted feature. The features being restricted (only for protected VMs in protected mode) are the following: - Debug, Trace, and DoubleLock - Performance Monitoring (PMU) - Statistical Profiling (SPE) - Scalable Vector Extension (SVE) - Memory Partitioning and Monitoring (MPAM) - Activity Monitoring (AMU) - Memory Tagging (MTE) - Limited Ordering Regions (LOR) - AArch32 State - Generic Interrupt Controller (GIC) (depending on rVIC support) - Nested Virtualization (NV) - Reliability, Availability, and Serviceability (RAS) above V1 - Implementation-defined Features This series is based on kvmarm/next and Will's patches for an Initial pKVM user ABI [1]. You can find the applied series here [2]. Cheers, /fuad [1] https://lore.kernel.org/kvmarm/20210603183347.1695-1-will@xxxxxxxxxx/ For more details about pKVM, please refer to Will's talk at KVM Forum 2020: https://www.youtube.com/watch?v=edqJSzsDRxk [2] https://android-kvm.googlesource.com/linux/+/refs/heads/tabba/el2_fixed_feature_v1 To: kvmarm@xxxxxxxxxxxxxxxxxxxxx Cc: Marc Zyngier <maz@xxxxxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Cc: James Morse <james.morse@xxxxxxx> Cc: Alexandru Elisei <alexandru.elisei@xxxxxxx> Cc: Suzuki K Poulose <suzuki.poulose@xxxxxxx> Cc: Mark Rutland <mark.rutland@xxxxxxx> Cc: Christoffer Dall <christoffer.dall@xxxxxxx> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> Cc: Quentin Perret <qperret@xxxxxxxxxx> Cc: kvm@xxxxxxxxxxxxxxx Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx Cc: kernel-team@xxxxxxxxxxx Fuad Tabba (13): KVM: arm64: Remove trailing whitespace in comments KVM: arm64: MDCR_EL2 is a 64-bit register KVM: arm64: Fix name of HCR_TACR to match the spec KVM: arm64: Refactor sys_regs.h,c for nVHE reuse KVM: arm64: Restore mdcr_el2 from vcpu KVM: arm64: Add feature register flag definitions KVM: arm64: Add config register bit definitions KVM: arm64: Guest exit handlers for nVHE hyp KVM: arm64: Add trap handlers for protected VMs KVM: arm64: Move sanitized copies of CPU features KVM: arm64: Trap access to pVM restricted features KVM: arm64: Handle protected guests at 32 bits KVM: arm64: Check vcpu features at pVM creation arch/arm64/include/asm/kvm_arm.h | 34 +- arch/arm64/include/asm/kvm_asm.h | 2 +- arch/arm64/include/asm/kvm_host.h | 2 +- arch/arm64/include/asm/kvm_hyp.h | 4 + arch/arm64/include/asm/sysreg.h | 6 + arch/arm64/kvm/arm.c | 4 + arch/arm64/kvm/debug.c | 5 +- arch/arm64/kvm/hyp/include/hyp/switch.h | 42 ++ arch/arm64/kvm/hyp/nvhe/Makefile | 2 +- arch/arm64/kvm/hyp/nvhe/debug-sr.c | 2 +- arch/arm64/kvm/hyp/nvhe/mem_protect.c | 6 - arch/arm64/kvm/hyp/nvhe/switch.c | 114 +++++- arch/arm64/kvm/hyp/nvhe/sys_regs.c | 501 ++++++++++++++++++++++++ arch/arm64/kvm/hyp/vhe/debug-sr.c | 2 +- arch/arm64/kvm/pkvm.c | 31 ++ arch/arm64/kvm/sys_regs.c | 62 +-- arch/arm64/kvm/sys_regs.h | 35 ++ 17 files changed, 782 insertions(+), 72 deletions(-) create mode 100644 arch/arm64/kvm/hyp/nvhe/sys_regs.c base-commit: 35b256a5eebe3ac715b4ea6234aa4236a10d1a88 -- 2.32.0.rc1.229.g3e70b5a671-goog
