1 files changed, 370 insertions, 0 deletions

diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
new file mode 100644
index 000000000000..c2cb46ca4fb6
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -0,0 +1,370 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2015 - ARM Ltd
+ * Author: Marc Zyngier <marc.zyngier@arm.com>
+ */
+
+#include <hyp/switch.h>
+#include <hyp/sysreg-sr.h>
+
+#include <linux/arm-smccc.h>
+#include <linux/kvm_host.h>
+#include <linux/types.h>
+#include <linux/jump_label.h>
+#include <uapi/linux/psci.h>
+
+#include <kvm/arm_psci.h>
+
+#include <asm/barrier.h>
+#include <asm/cpufeature.h>
+#include <asm/kprobes.h>
+#include <asm/kvm_asm.h>
+#include <asm/kvm_emulate.h>
+#include <asm/kvm_hyp.h>
+#include <asm/kvm_mmu.h>
+#include <asm/fpsimd.h>
+#include <asm/debug-monitors.h>
+#include <asm/processor.h>
+
+#include <nvhe/fixed_config.h>
+#include <nvhe/mem_protect.h>
+
+/* Non-VHE specific context */
+DEFINE_PER_CPU(struct kvm_host_data, kvm_host_data);
+DEFINE_PER_CPU(struct kvm_cpu_context, kvm_hyp_ctxt);
+DEFINE_PER_CPU(unsigned long, kvm_hyp_vector);
+
+extern void kvm_nvhe_prepare_backtrace(unsigned long fp, unsigned long pc);
+
+static void __activate_traps(struct kvm_vcpu *vcpu)
+{
+	u64 val;
+
+	___activate_traps(vcpu);
+	__activate_traps_common(vcpu);
+
+	val = vcpu->arch.cptr_el2;
+	val |= CPTR_EL2_TTA | CPTR_EL2_TAM;
+	if (!guest_owns_fp_regs(vcpu)) {
+		val |= CPTR_EL2_TFP | CPTR_EL2_TZ;
+		__activate_traps_fpsimd32(vcpu);
+	}
+	if (cpus_have_final_cap(ARM64_SME))
+		val |= CPTR_EL2_TSM;
+
+	write_sysreg(val, cptr_el2);
+	write_sysreg(__this_cpu_read(kvm_hyp_vector), vbar_el2);
+
+	if (cpus_have_final_cap(ARM64_WORKAROUND_SPECULATIVE_AT)) {
+		struct kvm_cpu_context *ctxt = &vcpu->arch.ctxt;
+
+		isb();
+		/*
+		 * At this stage, and thanks to the above isb(), S2 is
+		 * configured and enabled. We can now restore the guest's S1
+		 * configuration: SCTLR, and only then TCR.
+		 */
+		write_sysreg_el1(ctxt_sys_reg(ctxt, SCTLR_EL1),	SYS_SCTLR);
+		isb();
+		write_sysreg_el1(ctxt_sys_reg(ctxt, TCR_EL1),	SYS_TCR);
+	}
+}
+
+static void __deactivate_traps(struct kvm_vcpu *vcpu)
+{
+	extern char __kvm_hyp_host_vector[];
+	u64 cptr;
+
+	___deactivate_traps(vcpu);
+
+	if (cpus_have_final_cap(ARM64_WORKAROUND_SPECULATIVE_AT)) {
+		u64 val;
+
+		/*
+		 * Set the TCR and SCTLR registers in the exact opposite
+		 * sequence as __activate_traps (first prevent walks,
+		 * then force the MMU on). A generous sprinkling of isb()
+		 * ensure that things happen in this exact order.
+		 */
+		val = read_sysreg_el1(SYS_TCR);
+		write_sysreg_el1(val | TCR_EPD1_MASK | TCR_EPD0_MASK, SYS_TCR);
+		isb();
+		val = read_sysreg_el1(SYS_SCTLR);
+		write_sysreg_el1(val | SCTLR_ELx_M, SYS_SCTLR);
+		isb();
+	}
+
+	__deactivate_traps_common(vcpu);
+
+	write_sysreg(this_cpu_ptr(&kvm_init_params)->hcr_el2, hcr_el2);
+
+	cptr = CPTR_EL2_DEFAULT;
+	if (vcpu_has_sve(vcpu) && (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED))
+		cptr |= CPTR_EL2_TZ;
+	if (cpus_have_final_cap(ARM64_SME))
+		cptr &= ~CPTR_EL2_TSM;
+
+	write_sysreg(cptr, cptr_el2);
+	write_sysreg(__kvm_hyp_host_vector, vbar_el2);
+}
+
+/* Save VGICv3 state on non-VHE systems */
+static void __hyp_vgic_save_state(struct kvm_vcpu *vcpu)
+{
+	if (static_branch_unlikely(&kvm_vgic_global_state.gicv3_cpuif)) {
+		__vgic_v3_save_state(&vcpu->arch.vgic_cpu.vgic_v3);
+		__vgic_v3_deactivate_traps(&vcpu->arch.vgic_cpu.vgic_v3);
+	}
+}
+
+/* Restore VGICv3 state on non-VHE systems */
+static void __hyp_vgic_restore_state(struct kvm_vcpu *vcpu)
+{
+	if (static_branch_unlikely(&kvm_vgic_global_state.gicv3_cpuif)) {
+		__vgic_v3_activate_traps(&vcpu->arch.vgic_cpu.vgic_v3);
+		__vgic_v3_restore_state(&vcpu->arch.vgic_cpu.vgic_v3);
+	}
+}
+
+/*
+ * Disable host events, enable guest events
+ */
+#ifdef CONFIG_HW_PERF_EVENTS
+static bool __pmu_switch_to_guest(struct kvm_vcpu *vcpu)
+{
+	struct kvm_pmu_events *pmu = &vcpu->arch.pmu.events;
+
+	if (pmu->events_host)
+		write_sysreg(pmu->events_host, pmcntenclr_el0);
+
+	if (pmu->events_guest)
+		write_sysreg(pmu->events_guest, pmcntenset_el0);
+
+	return (pmu->events_host || pmu->events_guest);
+}
+
+/*
+ * Disable guest events, enable host events
+ */
+static void __pmu_switch_to_host(struct kvm_vcpu *vcpu)
+{
+	struct kvm_pmu_events *pmu = &vcpu->arch.pmu.events;
+
+	if (pmu->events_guest)
+		write_sysreg(pmu->events_guest, pmcntenclr_el0);
+
+	if (pmu->events_host)
+		write_sysreg(pmu->events_host, pmcntenset_el0);
+}
+#else
+#define __pmu_switch_to_guest(v)	({ false; })
+#define __pmu_switch_to_host(v)		do {} while (0)
+#endif
+
+/*
+ * Handler for protected VM MSR, MRS or System instruction execution in AArch64.
+ *
+ * Returns true if the hypervisor has handled the exit, and control should go
+ * back to the guest, or false if it hasn't.
+ */
+static bool kvm_handle_pvm_sys64(struct kvm_vcpu *vcpu, u64 *exit_code)
+{
+	/*
+	 * Make sure we handle the exit for workarounds and ptrauth
+	 * before the pKVM handling, as the latter could decide to
+	 * UNDEF.
+	 */
+	return (kvm_hyp_handle_sysreg(vcpu, exit_code) ||
+		kvm_handle_pvm_sysreg(vcpu, exit_code));
+}
+
+static const exit_handler_fn hyp_exit_handlers[] = {
+	[0 ... ESR_ELx_EC_MAX]		= NULL,
+	[ESR_ELx_EC_CP15_32]		= kvm_hyp_handle_cp15_32,
+	[ESR_ELx_EC_SYS64]		= kvm_hyp_handle_sysreg,
+	[ESR_ELx_EC_SVE]		= kvm_hyp_handle_fpsimd,
+	[ESR_ELx_EC_FP_ASIMD]		= kvm_hyp_handle_fpsimd,
+	[ESR_ELx_EC_IABT_LOW]		= kvm_hyp_handle_iabt_low,
+	[ESR_ELx_EC_DABT_LOW]		= kvm_hyp_handle_dabt_low,
+	[ESR_ELx_EC_PAC]		= kvm_hyp_handle_ptrauth,
+};
+
+static const exit_handler_fn pvm_exit_handlers[] = {
+	[0 ... ESR_ELx_EC_MAX]		= NULL,
+	[ESR_ELx_EC_SYS64]		= kvm_handle_pvm_sys64,
+	[ESR_ELx_EC_SVE]		= kvm_handle_pvm_restricted,
+	[ESR_ELx_EC_FP_ASIMD]		= kvm_hyp_handle_fpsimd,
+	[ESR_ELx_EC_IABT_LOW]		= kvm_hyp_handle_iabt_low,
+	[ESR_ELx_EC_DABT_LOW]		= kvm_hyp_handle_dabt_low,
+	[ESR_ELx_EC_PAC]		= kvm_hyp_handle_ptrauth,
+};
+
+static const exit_handler_fn *kvm_get_exit_handler_array(struct kvm_vcpu *vcpu)
+{
+	if (unlikely(kvm_vm_is_protected(kern_hyp_va(vcpu->kvm))))
+		return pvm_exit_handlers;
+
+	return hyp_exit_handlers;
+}
+
+/*
+ * Some guests (e.g., protected VMs) are not be allowed to run in AArch32.
+ * The ARMv8 architecture does not give the hypervisor a mechanism to prevent a
+ * guest from dropping to AArch32 EL0 if implemented by the CPU. If the
+ * hypervisor spots a guest in such a state ensure it is handled, and don't
+ * trust the host to spot or fix it.  The check below is based on the one in
+ * kvm_arch_vcpu_ioctl_run().
+ *
+ * Returns false if the guest ran in AArch32 when it shouldn't have, and
+ * thus should exit to the host, or true if a the guest run loop can continue.
+ */
+static void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code)
+{
+	struct kvm *kvm = kern_hyp_va(vcpu->kvm);
+
+	if (kvm_vm_is_protected(kvm) && vcpu_mode_is_32bit(vcpu)) {
+		/*
+		 * As we have caught the guest red-handed, decide that it isn't
+		 * fit for purpose anymore by making the vcpu invalid. The VMM
+		 * can try and fix it by re-initializing the vcpu with
+		 * KVM_ARM_VCPU_INIT, however, this is likely not possible for
+		 * protected VMs.
+		 */
+		vcpu->arch.target = -1;
+		*exit_code &= BIT(ARM_EXIT_WITH_SERROR_BIT);
+		*exit_code |= ARM_EXCEPTION_IL;
+	}
+}
+
+/* Switch to the guest for legacy non-VHE systems */
+int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
+{
+	struct kvm_cpu_context *host_ctxt;
+	struct kvm_cpu_context *guest_ctxt;
+	struct kvm_s2_mmu *mmu;
+	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;
+	host_ctxt->__hyp_running_vcpu = vcpu;
+	guest_ctxt = &vcpu->arch.ctxt;
+
+	pmu_switch_needed = __pmu_switch_to_guest(vcpu);
+
+	__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);
+
+	/*
+	 * 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);
+
+	mmu = kern_hyp_va(vcpu->arch.hw_mmu);
+	__load_stage2(mmu, kern_hyp_va(mmu->arch));
+	__activate_traps(vcpu);
+
+	__hyp_vgic_restore_state(vcpu);
+	__timer_enable_traps(vcpu);
+
+	__debug_switch_to_guest(vcpu);
+
+	do {
+		/* Jump in the fire! */
+		exit_code = __guest_enter(vcpu);
+
+		/* And we're baaack! */
+	} while (fixup_guest_exit(vcpu, &exit_code));
+
+	__sysreg_save_state_nvhe(guest_ctxt);
+	__sysreg32_save_state(vcpu);
+	__timer_disable_traps(vcpu);
+	__hyp_vgic_save_state(vcpu);
+
+	__deactivate_traps(vcpu);
+	__load_host_stage2();
+
+	__sysreg_restore_state_nvhe(host_ctxt);
+
+	if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED)
+		__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(vcpu);
+
+	/* Returning to host will clear PSR.I, remask PMR if needed */
+	if (system_uses_irq_prio_masking())
+		gic_write_pmr(GIC_PRIO_IRQOFF);
+
+	host_ctxt->__hyp_running_vcpu = NULL;
+
+	return exit_code;
+}
+
+asmlinkage void __noreturn hyp_panic(void)
+{
+	u64 spsr = read_sysreg_el2(SYS_SPSR);
+	u64 elr = read_sysreg_el2(SYS_ELR);
+	u64 par = read_sysreg_par();
+	struct kvm_cpu_context *host_ctxt;
+	struct kvm_vcpu *vcpu;
+
+	host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
+	vcpu = host_ctxt->__hyp_running_vcpu;
+
+	if (vcpu) {
+		__timer_disable_traps(vcpu);
+		__deactivate_traps(vcpu);
+		__load_host_stage2();
+		__sysreg_restore_state_nvhe(host_ctxt);
+	}
+
+	/* Prepare to dump kvm nvhe hyp stacktrace */
+	kvm_nvhe_prepare_backtrace((unsigned long)__builtin_frame_address(0),
+				   _THIS_IP_);
+
+	__hyp_do_panic(host_ctxt, spsr, elr, par);
+	unreachable();
+}
+
+asmlinkage void __noreturn hyp_panic_bad_stack(void)
+{
+	hyp_panic();
+}
+
+asmlinkage void kvm_unexpected_el2_exception(void)
+{
+	__kvm_unexpected_el2_exception();
+}