// SPDX-License-Identifier: GPL-2.0-only
/*
* 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>
*/
#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <asm/esr.h>
#include <asm/exception.h>
#include <asm/kvm_asm.h>
#include <asm/kvm_emulate.h>
#include <asm/kvm_mmu.h>
#include <asm/kvm_nested.h>
#include <asm/debug-monitors.h>
#include <asm/stacktrace/nvhe.h>
#include <asm/traps.h>
#include <kvm/arm_hypercalls.h>
#define CREATE_TRACE_POINTS
#include "trace_handle_exit.h"
typedef int (*exit_handle_fn)(struct kvm_vcpu *);
static void kvm_handle_guest_serror(struct kvm_vcpu *vcpu, u64 esr)
{
if (!arm64_is_ras_serror(esr) || arm64_is_fatal_ras_serror(NULL, esr))
kvm_inject_vabt(vcpu);
}
static int handle_hvc(struct kvm_vcpu *vcpu)
{
trace_kvm_hvc_arm64(*vcpu_pc(vcpu), vcpu_get_reg(vcpu, 0),
kvm_vcpu_hvc_get_imm(vcpu));
vcpu->stat.hvc_exit_stat++;
/* Forward hvc instructions to the virtual EL2 if the guest has EL2. */
if (vcpu_has_nv(vcpu)) {
if (vcpu_read_sys_reg(vcpu, HCR_EL2) & HCR_HCD)
kvm_inject_undefined(vcpu);
else
kvm_inject_nested_sync(vcpu, kvm_vcpu_get_esr(vcpu));
return 1;
}
return kvm_smccc_call_handler(vcpu);
}
static int handle_smc(struct kvm_vcpu *vcpu)
{
/*
* "If an SMC instruction executed at Non-secure EL1 is
* trapped to EL2 because HCR_EL2.TSC is 1, the exception is a
* Trap exception, not a Secure Monitor Call exception [...]"
*
* We need to advance the PC after the trap, as it would
* otherwise return to the same address. Furthermore, pre-incrementing
* the PC before potentially exiting to userspace maintains the same
* abstraction for both SMCs and HVCs.
*/
kvm_incr_pc(vcpu);
/*
* SMCs with a nonzero immediate are reserved according to DEN0028E 2.9
* "SMC and HVC immediate value".
*/
if (kvm_vcpu_hvc_get_imm(vcpu)) {
vcpu_set_reg(vcpu, 0, ~0UL);
return 1;
}
/*
* If imm is zero then it is likely an SMCCC call.
*
* Note that on ARMv8.3, even if EL3 is not implemented, SMC executed
* at Non-secure EL1 is trapped to EL2 if HCR_EL2.TSC==1, rather than
* being treated as UNDEFINED.
*/
return kvm_smccc_call_handler(vcpu);
}
/*
* Guest access to FP/ASIMD registers are routed to this handler only
* when the system doesn't support FP/ASIMD.
*/
static int handle_no_fpsimd(struct kvm_vcpu *vcpu)
{
kvm_inject_undefined(vcpu);
return 1;
}
/**
* kvm_handle_wfx - handle a wait-for-interrupts or wait-for-event
* instruction executed by a guest
*
* @vcpu: the vcpu pointer
*
* WFE[T]: Yield the CPU and come back to this vcpu when the scheduler
* decides to.
* WFI: Simply call kvm_vcpu_halt(), which will halt execution of
* world-switches and schedule other host processes until there is an
* incoming IRQ or FIQ to the VM.
* WFIT: Same as WFI, with a timed wakeup implemented as a background timer
*
* WF{I,E}T can immediately return if the deadline has already expired.
*/
static int kvm_handle_wfx(struct kvm_vcpu *vcpu)
{
u64 esr = kvm_vcpu_get_esr(vcpu);
if (esr & ESR_ELx_WFx_ISS_WFE) {
trace_kvm_wfx_arm64(*vcpu_pc(vcpu), true);
vcpu->stat.wfe_exit_stat++;
} else {
trace_kvm_wfx_arm64(*vcpu_pc(vcpu), false);
vcpu->stat.wfi_exit_stat++;
}
if (esr & ESR_ELx_WFx_ISS_WFxT) {
if (esr & ESR_ELx_WFx_ISS_RV) {
u64 val, now;
now = kvm_arm_timer_get_reg(vcpu, KVM_REG_ARM_TIMER_CNT);
val = vcpu_get_reg(vcpu, kvm_vcpu_sys_get_rt(vcpu));
if (now >= val)
goto out;
} else {
/* Treat WFxT as WFx if RN is invalid */
esr &= ~ESR_ELx_WFx_ISS_WFxT;
}
}
if (esr & ESR_ELx_WFx_ISS_WFE) {
kvm_vcpu_on_spin(vcpu, vcpu_mode_priv(vcpu));
} else {
if (esr & ESR_ELx_WFx_ISS_WFxT)
vcpu_set_flag(vcpu, IN_WFIT);
kvm_vcpu_wfi(vcpu);
}
out:
kvm_incr_pc(vcpu);
return 1;
}
/**
* kvm_handle_guest_debug - handle a debug exception instruction
*
* @vcpu: the vcpu pointer
*
* We route all debug exceptions through the same handler. If both the
* guest and host are using the same debug facilities it will be up to
* userspace to re-inject the correct exception for guest delivery.
*
* @return: 0 (while setting vcpu->run->exit_reason)
*/
static int kvm_handle_guest_debug(struct kvm_vcpu *vcpu)
{
struct kvm_run *run = vcpu->run;
u64 esr = kvm_vcpu_get_esr(vcpu);
run->exit_reason = KVM_EXIT_DEBUG;
run->debug.arch.hsr = lower_32_bits(esr);
run->debug.arch.hsr_high = upper_32_bits(esr);
run->flags = KVM_DEBUG_ARCH_HSR_HIGH_VALID;
switch (ESR_ELx_EC(esr)) {
case ESR_ELx_EC_WATCHPT_LOW:
run->debug.arch.far = vcpu->arch.fault.far_el2;
break;
case ESR_ELx_EC_SOFTSTP_LOW:
vcpu_clear_flag(vcpu, DBG_SS_ACTIVE_PENDING);
break;
}
return 0;
}
static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu)
{
u64 esr = kvm_vcpu_get_esr(vcpu);
kvm_pr_unimpl("Unknown exception class: esr: %#016llx -- %s\n",
esr, esr_get_class_string(esr));
kvm_inject_undefined(vcpu);
return 1;
}
/*
* Guest access to SVE registers should be routed to this handler only
* when the system doesn't support SVE.
*/
static int handle_sve(struct kvm_vcpu *vcpu)
{
kvm_inject_undefined(vcpu);
return 1;
}
/*
* Guest usage of a ptrauth instruction (which the guest EL1 did not turn into
* a NOP). If we get here, it is that we didn't fixup ptrauth on exit, and all
* that we can do is give the guest an UNDEF.
*/
static int kvm_handle_ptrauth(struct kvm_vcpu *vcpu)
{
kvm_inject_undefined(vcpu);
return 1;
}
static int kvm_handle_eret(struct kvm_vcpu *vcpu)
{
if (kvm_vcpu_get_esr(vcpu) & ESR_ELx_ERET_ISS_ERET)
return kvm_handle_ptrauth(vcpu);
/*
* If we got here, two possibilities:
*
* - the guest is in EL2, and we need to fully emulate ERET
*
* - the guest is in EL1, and we need to reinject the
* exception into the L1 hypervisor.
*
* If KVM ever traps ERET for its own use, we'll have to
* revisit this.
*/
if (is_hyp_ctxt(vcpu))
kvm_emulate_nested_eret(vcpu);
else
kvm_inject_nested_sync(vcpu, kvm_vcpu_get_esr(vcpu));
return 1;
}
static int handle_svc(struct kvm_vcpu *vcpu)
{
/*
* So far, SVC traps only for NV via HFGITR_EL2. A SVC from a
* 32bit guest would be caught by vpcu_mode_is_bad_32bit(), so
* we should only have to deal with a 64 bit exception.
*/
kvm_inject_nested_sync(vcpu, kvm_vcpu_get_esr(vcpu));
return 1;
}
static exit_handle_fn arm_exit_handlers[] = {
[0 ... ESR_ELx_EC_MAX] = kvm_handle_unknown_ec,
[ESR_ELx_EC_WFx] = kvm_handle_wfx,
[ESR_ELx_EC_CP15_32] = kvm_handle_cp15_32,
[ESR_ELx_EC_CP15_64] = kvm_handle_cp15_64,
[ESR_ELx_EC_CP14_MR] = kvm_handle_cp14_32,
[ESR_ELx_EC_CP14_LS] = kvm_handle_cp14_load_store,
[ESR_ELx_EC_CP10_ID] = kvm_handle_cp10_id,
[ESR_ELx_EC_CP14_64] = kvm_handle_cp14_64,
[ESR_ELx_EC_HVC32] = handle_hvc,
[ESR_ELx_EC_SMC32] = handle_smc,
[ESR_ELx_EC_HVC64] = handle_hvc,
[ESR_ELx_EC_SMC64] = handle_smc,
[ESR_ELx_EC_SVC64] = handle_svc,
[ESR_ELx_EC_SYS64] = kvm_handle_sys_reg,
[ESR_ELx_EC_SVE] = handle_sve,
[ESR_ELx_EC_ERET] = kvm_handle_eret,
[ESR_ELx_EC_IABT_LOW] = kvm_handle_guest_abort,
[ESR_ELx_EC_DABT_LOW] = kvm_handle_guest_abort,
[ESR_ELx_EC_SOFTSTP_LOW]= kvm_handle_guest_debug,
[ESR_ELx_EC_WATCHPT_LOW]= kvm_handle_guest_debug,
[ESR_ELx_EC_BREAKPT_LOW]= kvm_handle_guest_debug,
[ESR_ELx_EC_BKPT32] = kvm_handle_guest_debug,
[ESR_ELx_EC_BRK64] = kvm_handle_guest_debug,
[ESR_ELx_EC_FP_ASIMD] = handle_no_fpsimd,
[ESR_ELx_EC_PAC] = kvm_handle_ptrauth,
};
static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu)
{
u64 esr = kvm_vcpu_get_esr(vcpu);
u8 esr_ec = ESR_ELx_EC(esr);
return arm_exit_handlers[esr_ec];
}
/*
* We may be single-stepping an emulated instruction. If the emulation
* has been completed in the kernel, we can return to userspace with a
* KVM_EXIT_DEBUG, otherwise userspace needs to complete its
* emulation first.
*/
static int handle_trap_exceptions(struct kvm_vcpu *vcpu)
{
int handled;
/*
* See ARM ARM B1.14.1: "Hyp traps on instructions
* that fail their condition code check"
*/
if (!kvm_condition_valid(vcpu)) {
kvm_incr_pc(vcpu);
handled = 1;
} else {
exit_handle_fn exit_handler;
exit_handler = kvm_get_exit_handler(vcpu);
handled = exit_handler(vcpu);
}
return handled;
}
/*
* 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, int exception_index)
{
struct kvm_run *run = vcpu->run;
if (ARM_SERROR_PENDING(exception_index)) {
/*
* The SError is handled by handle_exit_early(). If the guest
* survives it will re-execute the original instruction.
*/
return 1;
}
exception_index = ARM_EXCEPTION_CODE(exception_index);
switch (exception_index) {
case ARM_EXCEPTION_IRQ:
return 1;
case ARM_EXCEPTION_EL1_SERROR:
return 1;
case ARM_EXCEPTION_TRAP:
return handle_trap_exceptions(vcpu);
case ARM_EXCEPTION_HYP_GONE:
/*
* EL2 has been reset to the hyp-stub. This happens when a guest
* is pre-emptied by kvm_reboot()'s shutdown call.
*/
run->exit_reason = KVM_EXIT_FAIL_ENTRY;
return 0;
case ARM_EXCEPTION_IL:
/*
* We attempted an illegal exception return. Guest state must
* have been corrupted somehow. Give up.
*/
run->exit_reason = KVM_EXIT_FAIL_ENTRY;
return -EINVAL;
default:
kvm_pr_unimpl("Unsupported exception type: %d",
exception_index);
run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
return 0;
}
}
/* For exit types that need handling before we can be preempted */
void handle_exit_early(struct kvm_vcpu *vcpu, int exception_index)
{
if (ARM_SERROR_PENDING(exception_index)) {
if (this_cpu_has_cap(ARM64_HAS_RAS_EXTN)) {
u64 disr = kvm_vcpu_get_disr(vcpu);
kvm_handle_guest_serror(vcpu, disr_to_esr(disr));
} else {
kvm_inject_vabt(vcpu);
}
return;
}
exception_index = ARM_EXCEPTION_CODE(exception_index);
if (exception_index == ARM_EXCEPTION_EL1_SERROR)
kvm_handle_guest_serror(vcpu, kvm_vcpu_get_esr(vcpu));
}
void __noreturn __cold nvhe_hyp_panic_handler(u64 esr, u64 spsr,
u64 elr_virt, u64 elr_phys,
u64 par, uintptr_t vcpu,
u64 far, u64 hpfar) {
u64 elr_in_kimg = __phys_to_kimg(elr_phys);
u64 hyp_offset = elr_in_kimg - kaslr_offset() - elr_virt;
u64 mode = spsr & PSR_MODE_MASK;
u64 panic_addr = elr_virt + hyp_offset;
if (mode != PSR_MODE_EL2t && mode != PSR_MODE_EL2h) {
kvm_err("Invalid host exception to nVHE hyp!\n");
} else if (ESR_ELx_EC(esr) == ESR_ELx_EC_BRK64 &&
(esr & ESR_ELx_BRK64_ISS_COMMENT_MASK) == BUG_BRK_IMM) {
const char *file = NULL;
unsigned int line = 0;
/* All hyp bugs, including warnings, are treated as fatal. */
if (!is_protected_kvm_enabled() ||
IS_ENABLED(CONFIG_NVHE_EL2_DEBUG)) {
struct bug_entry *bug = find_bug(elr_in_kimg);
if (bug)
bug_get_file_line(bug, &file, &line);
}
if (file)
kvm_err("nVHE hyp BUG at: %s:%u!\n", file, line);
else
kvm_err("nVHE hyp BUG at: [<%016llx>] %pB!\n", panic_addr,
(void *)(panic_addr + kaslr_offset()));
} else {
kvm_err("nVHE hyp panic at: [<%016llx>] %pB!\n", panic_addr,
(void *)(panic_addr + kaslr_offset()));
}
/* Dump the nVHE hypervisor backtrace */
kvm_nvhe_dump_backtrace(hyp_offset);
/*
* Hyp has panicked and we're going to handle that by panicking the
* kernel. The kernel offset will be revealed in the panic so we're
* also safe to reveal the hyp offset as a debugging aid for translating
* hyp VAs to vmlinux addresses.
*/
kvm_err("Hyp Offset: 0x%llx\n", hyp_offset);
panic("HYP panic:\nPS:%08llx PC:%016llx ESR:%016llx\nFAR:%016llx HPFAR:%016llx PAR:%016llx\nVCPU:%016lx\n",
spsr, elr_virt, esr, far, hpfar, par, vcpu);
}