arm64: KVM: Exit handling

/*

 * Copyright (C) 2012,2013 - ARM Ltd

 * Author: Marc Zyngier <marc.zyngier@arm.com>

 *

 * Derived from arch/arm/kvm/handle_exit.c:

 * Copyright (C) 2012 - Virtual Open Systems and Columbia University

 * Author: Christoffer Dall <c.dall@virtualopensystems.com>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */

#include <linux/kvm.h>

#include <linux/kvm_host.h>

#include <asm/kvm_emulate.h>

#include <asm/kvm_coproc.h>

#include <asm/kvm_mmu.h>

typedef int (*exit_handle_fn)(struct kvm_vcpu *, struct kvm_run *);

static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)

{

	/*

	 * Guest called HVC instruction:

	 * Let it know we don't want that by injecting an undefined exception.

	 */

	kvm_debug("hvc: %x (at %08lx)", kvm_vcpu_get_hsr(vcpu) & ((1 << 16) - 1),

		  *vcpu_pc(vcpu));

	kvm_debug("         HSR: %8x", kvm_vcpu_get_hsr(vcpu));

	kvm_inject_undefined(vcpu);

	return 1;

}

static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run)

{

	/* We don't support SMC; don't do that. */

	kvm_debug("smc: at %08lx", *vcpu_pc(vcpu));

	kvm_inject_undefined(vcpu);

	return 1;

}

/**

 * kvm_handle_wfi - handle a wait-for-interrupts instruction executed by a guest

 * @vcpu:	the vcpu pointer

 *

 * Simply call kvm_vcpu_block(), which will halt execution of

 * world-switches and schedule other host processes until there is an

 * incoming IRQ or FIQ to the VM.

 */

static int kvm_handle_wfi(struct kvm_vcpu *vcpu, struct kvm_run *run)

{

	kvm_vcpu_block(vcpu);

	return 1;

}

static exit_handle_fn arm_exit_handlers[] = {

	[ESR_EL2_EC_WFI]	= kvm_handle_wfi,

	[ESR_EL2_EC_HVC64]	= handle_hvc,

	[ESR_EL2_EC_SMC64]	= handle_smc,

	[ESR_EL2_EC_SYS64]	= kvm_handle_sys_reg,

	[ESR_EL2_EC_IABT]	= kvm_handle_guest_abort,

	[ESR_EL2_EC_DABT]	= kvm_handle_guest_abort,

};

static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu)

{

	u8 hsr_ec = kvm_vcpu_trap_get_class(vcpu);

	if (hsr_ec >= ARRAY_SIZE(arm_exit_handlers) ||

	    !arm_exit_handlers[hsr_ec]) {

		kvm_err("Unkown exception class: hsr: %#08x\n",

			(unsigned int)kvm_vcpu_get_hsr(vcpu));

		BUG();

	}

	return arm_exit_handlers[hsr_ec];

}

/*

 * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on

 * proper exit to userspace.

 */

int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,

		       int exception_index)

{

	exit_handle_fn exit_handler;

	switch (exception_index) {

	case ARM_EXCEPTION_IRQ:

		return 1;

	case ARM_EXCEPTION_TRAP:

		/*

		 * See ARM ARM B1.14.1: "Hyp traps on instructions

		 * that fail their condition code check"

		 */

		if (!kvm_condition_valid(vcpu)) {

			kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));

			return 1;

		}

		exit_handler = kvm_get_exit_handler(vcpu);

		return exit_handler(vcpu, run);

	default:

		kvm_pr_unimpl("Unsupported exception type: %d",

			      exception_index);

		run->exit_reason = KVM_EXIT_INTERNAL_ERROR;

		return 0;

	}

}