Release 4.16 virt/kvm/arm/psci.c

/*
 * Copyright (C) 2012 - ARM Ltd
 * Author: Marc Zyngier <marc.zyngier@arm.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/arm-smccc.h>
#include <linux/preempt.h>
#include <linux/kvm_host.h>
#include <linux/wait.h>

#include <asm/cputype.h>
#include <asm/kvm_emulate.h>
#include <asm/kvm_host.h>

#include <kvm/arm_psci.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 u32 smccc_get_function(struct kvm_vcpu *vcpu)
{
	return vcpu_get_reg(vcpu, 0);
}

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static unsigned long smccc_get_arg1(struct kvm_vcpu *vcpu)
{
	return vcpu_get_reg(vcpu, 1);
}

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static unsigned long smccc_get_arg2(struct kvm_vcpu *vcpu)
{
	return vcpu_get_reg(vcpu, 2);
}

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static unsigned long smccc_get_arg3(struct kvm_vcpu *vcpu)
{
	return vcpu_get_reg(vcpu, 3);
}

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static void smccc_set_retval(struct kvm_vcpu *vcpu,
			     unsigned long a0,
			     unsigned long a1,
			     unsigned long a2,
			     unsigned long a3)
{
	vcpu_set_reg(vcpu, 0, a0);
	vcpu_set_reg(vcpu, 1, a1);
	vcpu_set_reg(vcpu, 2, a2);
	vcpu_set_reg(vcpu, 3, a3);
}

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static unsigned long psci_affinity_mask(unsigned long affinity_level)
{
	if (affinity_level <= 3)
		return MPIDR_HWID_BITMASK & AFFINITY_MASK(affinity_level);

	return 0;
}

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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;
}

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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);
}

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static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
{
	struct kvm *kvm = source_vcpu->kvm;
	struct kvm_vcpu *vcpu = NULL;
	struct swait_queue_head *wq;
	unsigned long cpu_id;
	unsigned long context_id;
	phys_addr_t target_pc;

	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;
	}

	target_pc = smccc_get_arg2(source_vcpu);
	context_id = smccc_get_arg3(source_vcpu);

	kvm_reset_vcpu(vcpu);

	/* Gracefully handle Thumb2 entry point */
	if (vcpu_mode_is_32bit(vcpu) && (target_pc & 1)) {
		target_pc &= ~((phys_addr_t) 1);
		vcpu_set_thumb(vcpu);
	}

	/* Propagate caller endianness */
	if (kvm_vcpu_is_be(source_vcpu))
		kvm_vcpu_set_be(vcpu);

	*vcpu_pc(vcpu) = target_pc;
	/*
         * NOTE: We always update r0 (or x0) because for PSCI v0.1
         * the general puspose registers are undefined upon CPU_ON.
         */
	smccc_set_retval(vcpu, context_id, 0, 0, 0);
	vcpu->arch.power_off = false;
	smp_mb();		/* Make sure the above is visible */

	wq = kvm_arch_vcpu_wq(vcpu);
	swake_up(wq);

	return PSCI_RET_SUCCESS;
}

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Marcelo Tosatti
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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;
}

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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;
}

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static void kvm_psci_system_off(struct kvm_vcpu *vcpu)
{
	kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_SHUTDOWN);
}

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static void kvm_psci_system_reset(struct kvm_vcpu *vcpu)
{
	kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET);
}

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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;

	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:
	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:
	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;
	}

	smccc_set_retval(vcpu, val, 0, 0, 0);
	return ret;
}

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Lorenzo Pieralisi
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Pavel Fedin
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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);
		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;
}

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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;
}

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28.57%
Pavel Fedin
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14.29%
Lorenzo Pieralisi
1
1.00%
1
14.29%
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/**
 * 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
 */


static 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;
	};
}

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int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
{
	u32 func_id = smccc_get_function(vcpu);
	u32 val = PSCI_RET_NOT_SUPPORTED;
	u32 feature;

	switch (func_id) {
	case ARM_SMCCC_VERSION_FUNC_ID:
		val = ARM_SMCCC_VERSION_1_1;
		break;
	case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
		feature = smccc_get_arg1(vcpu);
		switch(feature) {
		case ARM_SMCCC_ARCH_WORKAROUND_1:
			if (kvm_arm_harden_branch_predictor())
				val = 0;
			break;
		}
		break;
	default:
		return kvm_psci_call(vcpu);
	}

	smccc_set_retval(vcpu, val, 0, 0, 0);
	return 1;
}
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37.22%
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23.33%
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5.86%
5
16.67%
Christoffer Dall
43
3.23%
2
6.67%
Alexander Spyridakis
19
1.43%
1
3.33%
Andre Przywara
10
0.75%
1
3.33%
Lorenzo Pieralisi
6
0.45%
1
3.33%
Pavel Fedin
6
0.45%
1
3.33%
Eric Auger
5
0.38%
1
3.33%
Marcelo Tosatti
3
0.23%
1
3.33%
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100.00%
30
100.00%
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