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kernel_optimize_test/virt/kvm/arm/psci.c
Marc Zyngier fdc9999e20 KVM: arm64: PSCI: Forbid 64bit functions for 32bit guests 
Implementing (and even advertising) 64bit PSCI functions to 32bit
guests is at least a bit odd, if not altogether violating the
spec which says ("5.2.1 Register usage in arguments and return values"):

"Adherence to the SMC Calling Conventions implies that any AArch32
caller of an SMC64 function will get a return code of 0xFFFFFFFF(int32).
This matches the NOT_SUPPORTED error code used in PSCI"

Tighten the implementation by pretending these functions are not
there for 32bit guests.

Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
2020-04-17 09:51:45 +01:00

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2012 - ARM Ltd
* Author: Marc Zyngier <marc.zyngier@arm.com>
*/
#include <linux/arm-smccc.h>
#include <linux/preempt.h>
#include <linux/kvm_host.h>
#include <linux/uaccess.h>
#include <linux/wait.h>
#include <asm/cputype.h>
#include <asm/kvm_emulate.h>
#include <kvm/arm_psci.h>
#include <kvm/arm_hypercalls.h>
/*
* This is an implementation of the Power State Coordination Interface
* as described in ARM document number ARM DEN 0022A.
*/
#define AFFINITY_MASK(level) ~((0x1UL << ((level) * MPIDR_LEVEL_BITS)) - 1)
static unsigned long psci_affinity_mask(unsigned long affinity_level)
{
if (affinity_level <= 3)
return MPIDR_HWID_BITMASK & AFFINITY_MASK(affinity_level);
return 0;
}
static unsigned long kvm_psci_vcpu_suspend(struct kvm_vcpu *vcpu)
{
/*
* NOTE: For simplicity, we make VCPU suspend emulation to be
* same-as WFI (Wait-for-interrupt) emulation.
*
* This means for KVM the wakeup events are interrupts and
* this is consistent with intended use of StateID as described
* in section 5.4.1 of PSCI v0.2 specification (ARM DEN 0022A).
*
* Further, we also treat power-down request to be same as
* stand-by request as-per section 5.4.2 clause 3 of PSCI v0.2
* specification (ARM DEN 0022A). This means all suspend states
* for KVM will preserve the register state.
*/
kvm_vcpu_block(vcpu);
kvm_clear_request(KVM_REQ_UNHALT, vcpu);
return PSCI_RET_SUCCESS;
}
static void kvm_psci_vcpu_off(struct kvm_vcpu *vcpu)
{
vcpu->arch.power_off = true;
kvm_make_request(KVM_REQ_SLEEP, vcpu);
kvm_vcpu_kick(vcpu);
}
static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
{
struct vcpu_reset_state *reset_state;
struct kvm *kvm = source_vcpu->kvm;
struct kvm_vcpu *vcpu = NULL;
unsigned long cpu_id;
cpu_id = smccc_get_arg1(source_vcpu) & MPIDR_HWID_BITMASK;
if (vcpu_mode_is_32bit(source_vcpu))
cpu_id &= ~((u32) 0);
vcpu = kvm_mpidr_to_vcpu(kvm, cpu_id);
/*
* Make sure the caller requested a valid CPU and that the CPU is
* turned off.
*/
if (!vcpu)
return PSCI_RET_INVALID_PARAMS;
if (!vcpu->arch.power_off) {
if (kvm_psci_version(source_vcpu, kvm) != KVM_ARM_PSCI_0_1)
return PSCI_RET_ALREADY_ON;
else
return PSCI_RET_INVALID_PARAMS;
}
reset_state = &vcpu->arch.reset_state;
reset_state->pc = smccc_get_arg2(source_vcpu);
/* Propagate caller endianness */
reset_state->be = kvm_vcpu_is_be(source_vcpu);
/*
* NOTE: We always update r0 (or x0) because for PSCI v0.1
* the general puspose registers are undefined upon CPU_ON.
*/
reset_state->r0 = smccc_get_arg3(source_vcpu);
WRITE_ONCE(reset_state->reset, true);
kvm_make_request(KVM_REQ_VCPU_RESET, vcpu);
/*
* Make sure the reset request is observed if the change to
* power_state is observed.
*/
smp_wmb();
vcpu->arch.power_off = false;
kvm_vcpu_wake_up(vcpu);
return PSCI_RET_SUCCESS;
}
static unsigned long kvm_psci_vcpu_affinity_info(struct kvm_vcpu *vcpu)
{
int i, matching_cpus = 0;
unsigned long mpidr;
unsigned long target_affinity;
unsigned long target_affinity_mask;
unsigned long lowest_affinity_level;
struct kvm *kvm = vcpu->kvm;
struct kvm_vcpu *tmp;
target_affinity = smccc_get_arg1(vcpu);
lowest_affinity_level = smccc_get_arg2(vcpu);
/* Determine target affinity mask */
target_affinity_mask = psci_affinity_mask(lowest_affinity_level);
if (!target_affinity_mask)
return PSCI_RET_INVALID_PARAMS;
/* Ignore other bits of target affinity */
target_affinity &= target_affinity_mask;
/*
* If one or more VCPU matching target affinity are running
* then ON else OFF
*/
kvm_for_each_vcpu(i, tmp, kvm) {
mpidr = kvm_vcpu_get_mpidr_aff(tmp);
if ((mpidr & target_affinity_mask) == target_affinity) {
matching_cpus++;
if (!tmp->arch.power_off)
return PSCI_0_2_AFFINITY_LEVEL_ON;
}
}
if (!matching_cpus)
return PSCI_RET_INVALID_PARAMS;
return PSCI_0_2_AFFINITY_LEVEL_OFF;
}
static void kvm_prepare_system_event(struct kvm_vcpu *vcpu, u32 type)
{
int i;
struct kvm_vcpu *tmp;
/*
* The KVM ABI specifies that a system event exit may call KVM_RUN
* again and may perform shutdown/reboot at a later time that when the
* actual request is made. Since we are implementing PSCI and a
* caller of PSCI reboot and shutdown expects that the system shuts
* down or reboots immediately, let's make sure that VCPUs are not run
* after this call is handled and before the VCPUs have been
* re-initialized.
*/
kvm_for_each_vcpu(i, tmp, vcpu->kvm)
tmp->arch.power_off = true;
kvm_make_all_cpus_request(vcpu->kvm, KVM_REQ_SLEEP);
memset(&vcpu->run->system_event, 0, sizeof(vcpu->run->system_event));
vcpu->run->system_event.type = type;
vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
}
static void kvm_psci_system_off(struct kvm_vcpu *vcpu)
{
kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_SHUTDOWN);
}
static void kvm_psci_system_reset(struct kvm_vcpu *vcpu)
{
kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET);
}
static void kvm_psci_narrow_to_32bit(struct kvm_vcpu *vcpu)
{
int i;
/*
* Zero the input registers' upper 32 bits. They will be fully
* zeroed on exit, so we're fine changing them in place.
*/
for (i = 1; i < 4; i++)
vcpu_set_reg(vcpu, i, lower_32_bits(vcpu_get_reg(vcpu, i)));
}
static unsigned long kvm_psci_check_allowed_function(struct kvm_vcpu *vcpu, u32 fn)
{
switch(fn) {
case PSCI_0_2_FN64_CPU_SUSPEND:
case PSCI_0_2_FN64_CPU_ON:
case PSCI_0_2_FN64_AFFINITY_INFO:
/* Disallow these functions for 32bit guests */
if (vcpu_mode_is_32bit(vcpu))
return PSCI_RET_NOT_SUPPORTED;
break;
}
return 0;
}
static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
{
struct kvm *kvm = vcpu->kvm;
u32 psci_fn = smccc_get_function(vcpu);
unsigned long val;
int ret = 1;
val = kvm_psci_check_allowed_function(vcpu, psci_fn);
if (val)
goto out;
switch (psci_fn) {
case PSCI_0_2_FN_PSCI_VERSION:
/*
* Bits[31:16] = Major Version = 0
* Bits[15:0] = Minor Version = 2
*/
val = KVM_ARM_PSCI_0_2;
break;
case PSCI_0_2_FN_CPU_SUSPEND:
case PSCI_0_2_FN64_CPU_SUSPEND:
val = kvm_psci_vcpu_suspend(vcpu);
break;
case PSCI_0_2_FN_CPU_OFF:
kvm_psci_vcpu_off(vcpu);
val = PSCI_RET_SUCCESS;
break;
case PSCI_0_2_FN_CPU_ON:
kvm_psci_narrow_to_32bit(vcpu);
fallthrough;
case PSCI_0_2_FN64_CPU_ON:
mutex_lock(&kvm->lock);
val = kvm_psci_vcpu_on(vcpu);
mutex_unlock(&kvm->lock);
break;
case PSCI_0_2_FN_AFFINITY_INFO:
kvm_psci_narrow_to_32bit(vcpu);
fallthrough;
case PSCI_0_2_FN64_AFFINITY_INFO:
val = kvm_psci_vcpu_affinity_info(vcpu);
break;
case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
/*
* Trusted OS is MP hence does not require migration
* or
* Trusted OS is not present
*/
val = PSCI_0_2_TOS_MP;
break;
case PSCI_0_2_FN_SYSTEM_OFF:
kvm_psci_system_off(vcpu);
/*
* We should'nt be going back to guest VCPU after
* receiving SYSTEM_OFF request.
*
* If user space accidently/deliberately resumes
* guest VCPU after SYSTEM_OFF request then guest
* VCPU should see internal failure from PSCI return
* value. To achieve this, we preload r0 (or x0) with
* PSCI return value INTERNAL_FAILURE.
*/
val = PSCI_RET_INTERNAL_FAILURE;
ret = 0;
break;
case PSCI_0_2_FN_SYSTEM_RESET:
kvm_psci_system_reset(vcpu);
/*
* Same reason as SYSTEM_OFF for preloading r0 (or x0)
* with PSCI return value INTERNAL_FAILURE.
*/
val = PSCI_RET_INTERNAL_FAILURE;
ret = 0;
break;
default:
val = PSCI_RET_NOT_SUPPORTED;
break;
}
out:
smccc_set_retval(vcpu, val, 0, 0, 0);
return ret;
}
static int kvm_psci_1_0_call(struct kvm_vcpu *vcpu)
{
u32 psci_fn = smccc_get_function(vcpu);
u32 feature;
unsigned long val;
int ret = 1;
switch(psci_fn) {
case PSCI_0_2_FN_PSCI_VERSION:
val = KVM_ARM_PSCI_1_0;
break;
case PSCI_1_0_FN_PSCI_FEATURES:
feature = smccc_get_arg1(vcpu);
val = kvm_psci_check_allowed_function(vcpu, feature);
if (val)
break;
switch(feature) {
case PSCI_0_2_FN_PSCI_VERSION:
case PSCI_0_2_FN_CPU_SUSPEND:
case PSCI_0_2_FN64_CPU_SUSPEND:
case PSCI_0_2_FN_CPU_OFF:
case PSCI_0_2_FN_CPU_ON:
case PSCI_0_2_FN64_CPU_ON:
case PSCI_0_2_FN_AFFINITY_INFO:
case PSCI_0_2_FN64_AFFINITY_INFO:
case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
case PSCI_0_2_FN_SYSTEM_OFF:
case PSCI_0_2_FN_SYSTEM_RESET:
case PSCI_1_0_FN_PSCI_FEATURES:
case ARM_SMCCC_VERSION_FUNC_ID:
val = 0;
break;
default:
val = PSCI_RET_NOT_SUPPORTED;
break;
}
break;
default:
return kvm_psci_0_2_call(vcpu);
}
smccc_set_retval(vcpu, val, 0, 0, 0);
return ret;
}
static int kvm_psci_0_1_call(struct kvm_vcpu *vcpu)
{
struct kvm *kvm = vcpu->kvm;
u32 psci_fn = smccc_get_function(vcpu);
unsigned long val;
switch (psci_fn) {
case KVM_PSCI_FN_CPU_OFF:
kvm_psci_vcpu_off(vcpu);
val = PSCI_RET_SUCCESS;
break;
case KVM_PSCI_FN_CPU_ON:
mutex_lock(&kvm->lock);
val = kvm_psci_vcpu_on(vcpu);
mutex_unlock(&kvm->lock);
break;
default:
val = PSCI_RET_NOT_SUPPORTED;
break;
}
smccc_set_retval(vcpu, val, 0, 0, 0);
return 1;
}
/**
* kvm_psci_call - handle PSCI call if r0 value is in range
* @vcpu: Pointer to the VCPU struct
*
* Handle PSCI calls from guests through traps from HVC instructions.
* The calling convention is similar to SMC calls to the secure world
* where the function number is placed in r0.
*
* This function returns: > 0 (success), 0 (success but exit to user
* space), and < 0 (errors)
*
* Errors:
* -EINVAL: Unrecognized PSCI function
*/
int kvm_psci_call(struct kvm_vcpu *vcpu)
{
switch (kvm_psci_version(vcpu, vcpu->kvm)) {
case KVM_ARM_PSCI_1_0:
return kvm_psci_1_0_call(vcpu);
case KVM_ARM_PSCI_0_2:
return kvm_psci_0_2_call(vcpu);
case KVM_ARM_PSCI_0_1:
return kvm_psci_0_1_call(vcpu);
default:
return -EINVAL;
};
}
int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
{
return 3; /* PSCI version and two workaround registers */
}
int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
{
if (put_user(KVM_REG_ARM_PSCI_VERSION, uindices++))
return -EFAULT;
if (put_user(KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1, uindices++))
return -EFAULT;
if (put_user(KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2, uindices++))
return -EFAULT;
return 0;
}
#define KVM_REG_FEATURE_LEVEL_WIDTH 4
#define KVM_REG_FEATURE_LEVEL_MASK (BIT(KVM_REG_FEATURE_LEVEL_WIDTH) - 1)
/*
* Convert the workaround level into an easy-to-compare number, where higher
* values mean better protection.
*/
static int get_kernel_wa_level(u64 regid)
{
switch (regid) {
case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
switch (kvm_arm_harden_branch_predictor()) {
case KVM_BP_HARDEN_UNKNOWN:
return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL;
case KVM_BP_HARDEN_WA_NEEDED:
return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_AVAIL;
case KVM_BP_HARDEN_NOT_REQUIRED:
return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_REQUIRED;
}
return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL;
case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
switch (kvm_arm_have_ssbd()) {
case KVM_SSBD_FORCE_DISABLE:
return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
case KVM_SSBD_KERNEL:
return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL;
case KVM_SSBD_FORCE_ENABLE:
case KVM_SSBD_MITIGATED:
return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED;
case KVM_SSBD_UNKNOWN:
default:
return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_UNKNOWN;
}
}
return -EINVAL;
}
int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
{
void __user *uaddr = (void __user *)(long)reg->addr;
u64 val;
switch (reg->id) {
case KVM_REG_ARM_PSCI_VERSION:
val = kvm_psci_version(vcpu, vcpu->kvm);
break;
case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
val = get_kernel_wa_level(reg->id) & KVM_REG_FEATURE_LEVEL_MASK;
break;
case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
val = get_kernel_wa_level(reg->id) & KVM_REG_FEATURE_LEVEL_MASK;
if (val == KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL &&
kvm_arm_get_vcpu_workaround_2_flag(vcpu))
val |= KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED;
break;
default:
return -ENOENT;
}
if (copy_to_user(uaddr, &val, KVM_REG_SIZE(reg->id)))
return -EFAULT;
return 0;
}
int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
{
void __user *uaddr = (void __user *)(long)reg->addr;
u64 val;
int wa_level;
if (copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id)))
return -EFAULT;
switch (reg->id) {
case KVM_REG_ARM_PSCI_VERSION:
{
bool wants_02;
wants_02 = test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features);
switch (val) {
case KVM_ARM_PSCI_0_1:
if (wants_02)
return -EINVAL;
vcpu->kvm->arch.psci_version = val;
return 0;
case KVM_ARM_PSCI_0_2:
case KVM_ARM_PSCI_1_0:
if (!wants_02)
return -EINVAL;
vcpu->kvm->arch.psci_version = val;
return 0;
}
break;
}
case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
if (val & ~KVM_REG_FEATURE_LEVEL_MASK)
return -EINVAL;
if (get_kernel_wa_level(reg->id) < val)
return -EINVAL;
return 0;
case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
if (val & ~(KVM_REG_FEATURE_LEVEL_MASK |
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED))
return -EINVAL;
wa_level = val & KVM_REG_FEATURE_LEVEL_MASK;
if (get_kernel_wa_level(reg->id) < wa_level)
return -EINVAL;
/* The enabled bit must not be set unless the level is AVAIL. */
if (wa_level != KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL &&
wa_level != val)
return -EINVAL;
/* Are we finished or do we need to check the enable bit ? */
if (kvm_arm_have_ssbd() != KVM_SSBD_KERNEL)
return 0;
/*
* If this kernel supports the workaround to be switched on
* or off, make sure it matches the requested setting.
*/
switch (wa_level) {
case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL:
kvm_arm_set_vcpu_workaround_2_flag(vcpu,
val & KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED);
break;
case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED:
kvm_arm_set_vcpu_workaround_2_flag(vcpu, true);
break;
}
return 0;
default:
return -ENOENT;
}
return -EINVAL;
}
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