[PATCH 17/29] arm64: KVM: Exit handling

Marc Zyngier
2013-03-05T03:55:26Z

Handle the exit of a VM, decoding the exit reason from HYP mode
and calling the corresponding handler.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
arch/arm64/kvm/handle_exit.c | 119 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 119 insertions(+)
create mode 100644 arch/arm64/kvm/handle_exit.c

diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
new file mode 100644
index 0000000..0e1fa4e
--- /dev/null
+++ b/arch/arm64/kvm/handle_exit.c
@@ -0,0 +1,119 @@
+/*
+ * Copyright (C) 2012 - 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;
+ }
+}
--
1.7.12.4