Hi, This is a prolog to a series where we try to maintain virtual machine and vcpu state for protected VMs at the hypervisor [1]. The main issue is that in KVM, the VM state (struct kvm) and the vcpu state (struct kvm_vcpu) are created by the host and are always accessible by it. For protected VMs (pKVM [2]), only the hypervisor should have access to their state and not trust the host to access it. Therefore, the hypervisor should maintain a copy of VM state for all protected VMs to use that is not accessible by the host. The problem with using and with maintaining a copy of the existing kvm_vcpu struct at the hypervisor is that it's big. Depending on the configuration, it is in the order of 10kB (ymmv) per vcpu. Whereas most of what it needs to run a VM is the kvm_cpu_ctxt and some hyp-related registers and flags, which amount to less than 2kB. Many of the functions use the vcpu struct when all they access is kvm_cpu_ctxt. Other functions only need that as well as a few hypervisor state variables. Moreover, we would like to use the existing code, rather than write new code for protected VMs that use new or special structures. This patch series reduces the scope of the functions that only need kvm_cpu_ctxt to just that. It also takes out the few elements that are relevant to the hypervisor from kvm_vcpu_arch into a new structure, vcpu_hyp_state. This allows the remainder of the series to reduce the scope of everything accessed by the hypervisor, at least for protected VMs, to kvm_cpu_ctxt and vcpu_hyp_state (and maybe vgic if supported for protected VMs). This series uses coccinelle semantic patches [3] as much as possible when changes are made repetitively across many files. All patches that use coccinelle are prefixed with COCCI. Based on Linux 5.13-rc6. Cheers, /fuad [1] https://android-kvm.googlesource.com/linux/+/refs/heads/tabba/el2-state-cocci-out [2] Once complete, protected KVM adds the ability to create protected VMs. These protected VMs are protected from the host Linux kernel (and from other VMs), where the host does not have access to guest memory,even if compromised. Normal (nVHE) guests can still be created and run in parallel with protected VMs. Their functionality should not be affected. For protected VMs, the host should not even have access to a protected guest's state or anything that would enable it to manipulate it (e.g., vcpu register context and el2 system registers); only hyp would have that access. If the host could access that state, then it might be able to get around the protection provided. Therefore, anything that is sensitive and that would require such access needs to happen at hyp, hence the code in nvhe running only at hyp. For more details about pKVM, please refer to Will's talk at KVM Forum 2020: https://mirrors.edge.kernel.org/pub/linux/kernel/people/will/slides/kvmforum-2020-edited.pdf https://www.youtube.com/watch?v=edqJSzsDRxk [3] https://coccinelle.gitlabpages.inria.fr/website/ Fuad Tabba (30): KVM: arm64: placeholder to check if VM is protected [DONOTMERGE] Temporarily disable unused variable warning [DONOTMERGE] Coccinelle scripts for refactoring KVM: arm64: remove unused parameters and asm offsets KVM: arm64: add accessors for kvm_cpu_context KVM: arm64: COCCI: use_ctxt_access.cocci: use kvm_cpu_context accessors KVM: arm64: COCCI: add_ctxt.cocci use_ctxt.cocci: reduce scope of functions to kvm_cpu_ctxt KVM: arm64: add hypervisor state accessors KVM: arm64: COCCI: vcpu_hyp_accessors.cocci: use accessors for hypervisor state vcpu variables KVM: arm64: Add accessors for hypervisor state in kvm_vcpu_arch KVM: arm64: create and use a new vcpu_hyp_state struct KVM: arm64: COCCI: add_hypstate.cocci use_hypstate.cocci: Reduce scope of functions to hyp_state KVM: arm64: change function parameters to use kvm_cpu_ctxt and hyp_state KVM: arm64: reduce scope of vgic v2 KVM: arm64: COCCI: vgic3_cpu.cocci: reduce scope of vgic v3 KVM: arm64: reduce scope of vgic_v3 access parameters KVM: arm64: access __hyp_running_vcpu via accessors only KVM: arm64: reduce scope of __guest_exit to only depend on kvm_cpu_context KVM: arm64: change calls of get_loaded_vcpu to get_loaded_vcpu_ctxt KVM: arm64: add __hyp_running_ctxt and __hyp_running_hyps KVM: arm64: transition code to __hyp_running_ctxt and __hyp_running_hyps KVM: arm64: reduce scope of __guest_enter to depend only on kvm_cpu_ctxt KVM: arm64: COCCI: remove_unused.cocci: remove unused ctxt and hypstate variables KVM: arm64: remove unused functions KVM: arm64: separate kvm_run() for protected VMs KVM: arm64: pVM activate_traps to use vcpu_ctxt and vcpu_hyp_state KVM: arm64: remove unsupported pVM features KVM: arm64: reduce scope of pVM fixup_guest_exit to hyp_state and kvm_cpu_ctxt [DONOTMERGE] Remove Coccinelle scripts added for refactoring [DONOTMERGE] Re-enable warnings arch/arm64/include/asm/kvm_asm.h | 33 ++- arch/arm64/include/asm/kvm_emulate.h | 292 ++++++++++++++++----- arch/arm64/include/asm/kvm_host.h | 110 ++++++-- arch/arm64/include/asm/kvm_hyp.h | 14 +- arch/arm64/kernel/asm-offsets.c | 7 +- arch/arm64/kvm/arm.c | 2 +- arch/arm64/kvm/debug.c | 28 +- arch/arm64/kvm/fpsimd.c | 22 +- arch/arm64/kvm/guest.c | 30 +-- arch/arm64/kvm/handle_exit.c | 8 +- arch/arm64/kvm/hyp/aarch32.c | 26 +- arch/arm64/kvm/hyp/entry.S | 23 +- arch/arm64/kvm/hyp/exception.c | 113 ++++---- arch/arm64/kvm/hyp/hyp-entry.S | 8 +- arch/arm64/kvm/hyp/include/hyp/adjust_pc.h | 26 +- arch/arm64/kvm/hyp/include/hyp/debug-sr.h | 6 +- arch/arm64/kvm/hyp/include/hyp/switch.h | 101 ++++--- arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h | 43 +-- arch/arm64/kvm/hyp/nvhe/debug-sr.c | 8 +- arch/arm64/kvm/hyp/nvhe/host.S | 4 +- arch/arm64/kvm/hyp/nvhe/switch.c | 155 ++++++++--- arch/arm64/kvm/hyp/nvhe/timer-sr.c | 4 +- arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c | 32 ++- arch/arm64/kvm/hyp/vgic-v3-sr.c | 242 +++++++++++------ arch/arm64/kvm/hyp/vhe/switch.c | 40 +-- arch/arm64/kvm/hyp/vhe/sysreg-sr.c | 3 +- arch/arm64/kvm/inject_fault.c | 10 +- arch/arm64/kvm/reset.c | 16 +- arch/arm64/kvm/sys_regs.c | 4 +- 29 files changed, 951 insertions(+), 459 deletions(-) base-commit: 6d53b3be3b9be497fbe054f35154f508deac729c -- 2.33.0.685.g46640cef36-goog _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
