[RFC PATCH v1 25/30] KVM: arm64: separate kvm_run() for protected VMs

[Fuad Tabba]

Split kvm_run() for protected and non-protected VMs. Protected
VMs support fewer features, separating it out will ease the
refactoring and simplify the code.

This patch starts only by replicated the code from the
non-protected case, to make it easier to diff against future
patches.

Signed-off-by: Fuad Tabba <tabba at google.com>
---
 arch/arm64/kvm/hyp/nvhe/switch.c | 119 ++++++++++++++++++++++++++++++-
 1 file changed, 116 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index b90ec8db5864..9e79f97ba49e 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -119,7 +119,7 @@ static void __hyp_vgic_save_state(struct kvm_vcpu *vcpu)
 	}
 }
 
-/* Restore VGICv3 state on non_VEH systems */
+/* Restore VGICv3 state on nVHE systems */
 static void __hyp_vgic_restore_state(struct kvm_vcpu *vcpu)
 {
 	if (static_branch_unlikely(&kvm_vgic_global_state.gicv3_cpuif)) {
@@ -166,8 +166,110 @@ static void __pmu_switch_to_host(struct kvm_cpu_context *host_ctxt)
 		write_sysreg(pmu->events_host, pmcntenset_el0);
 }
 
-/* Switch to the guest for legacy non-VHE systems */
-int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
+/* Switch to the non-protected guest */
+static int __kvm_vcpu_run_nvhe(struct kvm_vcpu *vcpu)
+{
+	struct vcpu_hyp_state *vcpu_hyps = &vcpu->arch.hyp_state;
+	struct kvm_cpu_context *vcpu_ctxt = &vcpu->arch.ctxt;
+	struct kvm *kvm = kern_hyp_va(vcpu->kvm);
+	struct vgic_dist *vgic = &kvm->arch.vgic;
+	struct kvm_cpu_context *host_ctxt;
+	struct kvm_cpu_context *guest_ctxt;
+	bool pmu_switch_needed;
+	u64 exit_code;
+
+	/*
+	 * Having IRQs masked via PMR when entering the guest means the GIC
+	 * will not signal the CPU of interrupts of lower priority, and the
+	 * only way to get out will be via guest exceptions.
+	 * Naturally, we want to avoid this.
+	 */
+	if (system_uses_irq_prio_masking()) {
+		gic_write_pmr(GIC_PRIO_IRQON | GIC_PRIO_PSR_I_SET);
+		pmr_sync();
+	}
+
+	host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
+	set_hyp_running_vcpu(host_ctxt, vcpu);
+	guest_ctxt = &vcpu->arch.ctxt;
+
+	pmu_switch_needed = __pmu_switch_to_guest(host_ctxt);
+
+	__sysreg_save_state_nvhe(host_ctxt);
+	/*
+	 * We must flush and disable the SPE buffer for nVHE, as
+	 * the translation regime(EL1&0) is going to be loaded with
+	 * that of the guest. And we must do this before we change the
+	 * translation regime to EL2 (via MDCR_EL2_E2PB == 0) and
+	 * before we load guest Stage1.
+	 */
+	__debug_save_host_buffers_nvhe(vcpu);
+
+	kvm_adjust_pc(vcpu_ctxt, vcpu_hyps);
+
+	/*
+	 * We must restore the 32-bit state before the sysregs, thanks
+	 * to erratum #852523 (Cortex-A57) or #853709 (Cortex-A72).
+	 *
+	 * Also, and in order to be able to deal with erratum #1319537 (A57)
+	 * and #1319367 (A72), we must ensure that all VM-related sysreg are
+	 * restored before we enable S2 translation.
+	 */
+	__sysreg32_restore_state(vcpu);
+	__sysreg_restore_state_nvhe(guest_ctxt);
+
+	__load_guest_stage2(kern_hyp_va(vcpu->arch.hw_mmu));
+	__activate_traps(vcpu);
+
+	__hyp_vgic_restore_state(vcpu);
+	__timer_enable_traps();
+
+	__debug_switch_to_guest(vcpu);
+
+	do {
+		struct kvm_cpu_context *hyp_ctxt = this_cpu_ptr(&kvm_hyp_ctxt);
+		set_hyp_running_vcpu(hyp_ctxt, vcpu);
+
+		/* Jump in the fire! */
+		exit_code = __guest_enter(guest_ctxt);
+
+		/* And we're baaack! */
+	} while (fixup_guest_exit(vcpu, vgic, &exit_code));
+
+	__sysreg_save_state_nvhe(guest_ctxt);
+	__sysreg32_save_state(vcpu);
+	__timer_disable_traps();
+	__hyp_vgic_save_state(vcpu);
+
+	__deactivate_traps(vcpu_hyps);
+	__load_host_stage2();
+
+	__sysreg_restore_state_nvhe(host_ctxt);
+
+	if (hyp_state_flags(vcpu_hyps) & KVM_ARM64_FP_ENABLED)
+		__fpsimd_save_fpexc32(vcpu);
+
+	__debug_switch_to_host(vcpu);
+	/*
+	 * This must come after restoring the host sysregs, since a non-VHE
+	 * system may enable SPE here and make use of the TTBRs.
+	 */
+	__debug_restore_host_buffers_nvhe(vcpu);
+
+	if (pmu_switch_needed)
+		__pmu_switch_to_host(host_ctxt);
+
+	/* Returning to host will clear PSR.I, remask PMR if needed */
+	if (system_uses_irq_prio_masking())
+		gic_write_pmr(GIC_PRIO_IRQOFF);
+
+	set_hyp_running_vcpu(host_ctxt, NULL);
+
+	return exit_code;
+}
+
+/* Switch to the protected guest */
+static int __kvm_vcpu_run_pvm(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_hyp_state *vcpu_hyps = &hyp_state(vcpu);
 	struct kvm_cpu_context *vcpu_ctxt = &vcpu_ctxt(vcpu);
@@ -268,6 +370,17 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
 	return exit_code;
 }
 
+/* Switch to the guest for non-VHE and protected KVM systems */
+int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
+{
+	vcpu = kern_hyp_va(vcpu);
+
+	if (likely(!kvm_vm_is_protected(kern_hyp_va(vcpu->kvm))))
+		return __kvm_vcpu_run_nvhe(vcpu);
+	else
+		return __kvm_vcpu_run_pvm(vcpu);
+}
+
 void __noreturn hyp_panic(void)
 {
 	u64 spsr = read_sysreg_el2(SYS_SPSR);
-- 
2.33.0.685.g46640cef36-goog