kernel/arch/arm64/kvm/hyp/vhe/switch.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2015 - ARM Ltd
 * Author: Marc Zyngier <marc.zyngier@arm.com>
 */

#include <hyp/switch.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 <asm/thread_info.h>
#include <asm/vectors.h>

const char __hyp_panic_string[] = "HYP panic:\nPS:%08llx PC:%016llx ESR:%08llx\nFAR:%016llx HPFAR:%016llx PAR:%016llx\nVCPU:%p\n";

static void __activate_traps(struct kvm_vcpu *vcpu)
{
	u64 val;

	___activate_traps(vcpu);

	val = read_sysreg(cpacr_el1);
	val |= CPACR_EL1_TTA;
	val &= ~CPACR_EL1_ZEN;

	/*
	 * With VHE (HCR.E2H == 1), accesses to CPACR_EL1 are routed to
	 * CPTR_EL2. In general, CPACR_EL1 has the same layout as CPTR_EL2,
	 * except for some missing controls, such as TAM.
	 * In this case, CPTR_EL2.TAM has the same position with or without
	 * VHE (HCR.E2H == 1) which allows us to use here the CPTR_EL2.TAM
	 * shift value for trapping the AMU accesses.
	 */

	val |= CPTR_EL2_TAM;

	if (update_fp_enabled(vcpu)) {
		if (vcpu_has_sve(vcpu))
			val |= CPACR_EL1_ZEN;
	} else {
		val &= ~CPACR_EL1_FPEN;
		__activate_traps_fpsimd32(vcpu);
	}

	write_sysreg(val, cpacr_el1);

	write_sysreg(kvm_get_hyp_vector(), vbar_el1);
}
NOKPROBE_SYMBOL(__activate_traps);

static void __deactivate_traps(struct kvm_vcpu *vcpu)
{
	const char *host_vectors = vectors;

	___deactivate_traps(vcpu);

	write_sysreg(HCR_HOST_VHE_FLAGS, hcr_el2);

	/*
	 * ARM errata 1165522 and 1530923 require the actual execution of the
	 * above before we can switch to the EL2/EL0 translation regime used by
	 * the host.
	 */
	asm(ALTERNATIVE("nop", "isb", ARM64_WORKAROUND_SPECULATIVE_AT));

	write_sysreg(CPACR_EL1_DEFAULT, cpacr_el1);
	if (!arm64_kernel_unmapped_at_el0())
		host_vectors = __this_cpu_read(this_cpu_vector);
	write_sysreg(host_vectors, vbar_el1);
}
NOKPROBE_SYMBOL(__deactivate_traps);

/*
 * Disable IRQs in {activate,deactivate}_traps_vhe_{load,put}() to
 * prevent a race condition between context switching of PMUSERENR_EL0
 * in __{activate,deactivate}_traps_common() and IPIs that attempts to
 * update PMUSERENR_EL0. See also kvm_set_pmuserenr().
 */
void activate_traps_vhe_load(struct kvm_vcpu *vcpu)
{
	unsigned long flags;

	local_irq_save(flags);
	__activate_traps_common(vcpu);
	local_irq_restore(flags);
}

void deactivate_traps_vhe_put(struct kvm_vcpu *vcpu)
{
	unsigned long flags;

	vcpu->arch.mdcr_el2_host &= MDCR_EL2_HPMN_MASK |
				    MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT |
				    MDCR_EL2_TPMS;

	local_irq_save(flags);
	__deactivate_traps_common(vcpu);
	local_irq_restore(flags);
}

/* Switch to the guest for VHE systems running in EL2 */
static int __kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
{
	struct kvm_cpu_context *host_ctxt;
	struct kvm_cpu_context *guest_ctxt;
	u64 exit_code;

	host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
	host_ctxt->__hyp_running_vcpu = vcpu;
	guest_ctxt = &vcpu->arch.ctxt;

	sysreg_save_host_state_vhe(host_ctxt);

	/*
	 * ARM erratum 1165522 requires us to configure both stage 1 and
	 * stage 2 translation for the guest context before we clear
	 * HCR_EL2.TGE.
	 *
	 * We have already configured the guest's stage 1 translation in
	 * kvm_vcpu_load_sysregs_vhe above.  We must now call __activate_vm
	 * before __activate_traps, because __activate_vm configures
	 * stage 2 translation, and __activate_traps clear HCR_EL2.TGE
	 * (among other things).
	 */
	__activate_vm(vcpu->kvm);
	__activate_traps(vcpu);

	sysreg_restore_guest_state_vhe(guest_ctxt);
	__debug_switch_to_guest(vcpu);

	__set_guest_arch_workaround_state(vcpu);

	do {
		/* Jump in the fire! */
		exit_code = __guest_enter(vcpu, host_ctxt);

		/* And we're baaack! */
	} while (fixup_guest_exit(vcpu, &exit_code));

	__set_host_arch_workaround_state(vcpu);

	sysreg_save_guest_state_vhe(guest_ctxt);

	__deactivate_traps(vcpu);

	sysreg_restore_host_state_vhe(host_ctxt);

	if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED)
		__fpsimd_save_fpexc32(vcpu);

	__debug_switch_to_host(vcpu);

	return exit_code;
}
NOKPROBE_SYMBOL(__kvm_vcpu_run_vhe);

int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
{
	int ret;

	local_daif_mask();

	/*
	 * 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.
	 *
	 * local_daif_mask() already sets GIC_PRIO_PSR_I_SET, we just need a
	 * dsb to ensure the redistributor is forwards EL2 IRQs to the CPU.
	 */
	pmr_sync();

	ret = __kvm_vcpu_run_vhe(vcpu);

	/*
	 * local_daif_restore() takes care to properly restore PSTATE.DAIF
	 * and the GIC PMR if the host is using IRQ priorities.
	 */
	local_daif_restore(DAIF_PROCCTX_NOIRQ);

	/*
	 * When we exit from the guest we change a number of CPU configuration
	 * parameters, such as traps.  Make sure these changes take effect
	 * before running the host or additional guests.
	 */
	isb();

	return ret;
}

static void __hyp_call_panic(u64 spsr, u64 elr, u64 par,
			     struct kvm_cpu_context *host_ctxt)
{
	struct kvm_vcpu *vcpu;
	vcpu = host_ctxt->__hyp_running_vcpu;

	__deactivate_traps(vcpu);
	sysreg_restore_host_state_vhe(host_ctxt);

	panic(__hyp_panic_string,
	      spsr, elr,
	      read_sysreg_el2(SYS_ESR), read_sysreg_el2(SYS_FAR),
	      read_sysreg(hpfar_el2), par, vcpu);
}
NOKPROBE_SYMBOL(__hyp_call_panic);

void __noreturn hyp_panic(struct kvm_cpu_context *host_ctxt)
{
	u64 spsr = read_sysreg_el2(SYS_SPSR);
	u64 elr = read_sysreg_el2(SYS_ELR);
	u64 par = read_sysreg_par();

	__hyp_call_panic(spsr, elr, par, host_ctxt);
	unreachable();
}

asmlinkage void kvm_unexpected_el2_exception(void)
{
	__kvm_unexpected_el2_exception();
}