arch/arm/kvm/psci.c - kernel/lockdown - Git at Google

 /*
  * 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/preempt.h>
 #include <linux/kvm_host.h>
 #include <linux/wait.h>

 #include <asm/cputype.h>
 #include <asm/kvm_emulate.h>
 #include <asm/kvm_psci.h>
 #include <asm/kvm_host.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);

 	return PSCI_RET_SUCCESS;
 }

 static void kvm_psci_vcpu_off(struct kvm_vcpu *vcpu)
 {
 	vcpu->arch.pause = true;
 }

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

 	cpu_id = *vcpu_reg(source_vcpu, 1) & 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.pause) {
 		if (kvm_psci_version(source_vcpu) != KVM_ARM_PSCI_0_1)
 			return PSCI_RET_ALREADY_ON;
 		else
 			return PSCI_RET_INVALID_PARAMS;
 	}

 	target_pc = *vcpu_reg(source_vcpu, 2);
 	context_id = *vcpu_reg(source_vcpu, 3);

 	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.
 	 */
 	*vcpu_reg(vcpu, 0) = context_id;
 	vcpu->arch.pause = false;
 	smp_mb();		/* Make sure the above is visible */

 	wq = kvm_arch_vcpu_wq(vcpu);
 	wake_up_interruptible(wq);

 	return PSCI_RET_SUCCESS;
 }

 static unsigned long kvm_psci_vcpu_affinity_info(struct kvm_vcpu *vcpu)
 {
 	int i;
 	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 = *vcpu_reg(vcpu, 1);
 	lowest_affinity_level = *vcpu_reg(vcpu, 2);

 	/* 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) &&
 		    !tmp->arch.pause) {
 			return PSCI_0_2_AFFINITY_LEVEL_ON;
 		}
 	}

 	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.pause = true;
 		kvm_vcpu_kick(tmp);
 	}

 	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);
 }

 int kvm_psci_version(struct kvm_vcpu *vcpu)
 {
 	if (test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features))
 		return KVM_ARM_PSCI_0_2;

 	return KVM_ARM_PSCI_0_1;
 }

 static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
 {
 	int ret = 1;
 	unsigned long psci_fn = *vcpu_reg(vcpu, 0) & ~((u32) 0);
 	unsigned long val;

 	switch (psci_fn) {
 	case PSCI_0_2_FN_PSCI_VERSION:
 		/*
 		 * Bits[31:16] = Major Version = 0
 		 * Bits[15:0] = Minor Version = 2
 		 */
 		val = 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:
 		val = kvm_psci_vcpu_on(vcpu);
 		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;
 	}

 	*vcpu_reg(vcpu, 0) = val;
 	return ret;
 }

 static int kvm_psci_0_1_call(struct kvm_vcpu *vcpu)
 {
 	unsigned long psci_fn = *vcpu_reg(vcpu, 0) & ~((u32) 0);
 	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:
 		val = kvm_psci_vcpu_on(vcpu);
 		break;
 	default:
 		val = PSCI_RET_NOT_SUPPORTED;
 		break;
 	}

 	*vcpu_reg(vcpu, 0) = val;
 	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)) {
 	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;
 	};
 }
	/*
	* 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/preempt.h>
	#include <linux/kvm_host.h>
	#include <linux/wait.h>

	#include <asm/cputype.h>
	#include <asm/kvm_emulate.h>
	#include <asm/kvm_psci.h>
	#include <asm/kvm_host.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);

	return PSCI_RET_SUCCESS;
	}

	static void kvm_psci_vcpu_off(struct kvm_vcpu *vcpu)
	{
	vcpu->arch.pause = true;
	}

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

	cpu_id = *vcpu_reg(source_vcpu, 1) & 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.pause) {
	if (kvm_psci_version(source_vcpu) != KVM_ARM_PSCI_0_1)
	return PSCI_RET_ALREADY_ON;
	else
	return PSCI_RET_INVALID_PARAMS;
	}

	target_pc = *vcpu_reg(source_vcpu, 2);
	context_id = *vcpu_reg(source_vcpu, 3);

	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.
	*/
	*vcpu_reg(vcpu, 0) = context_id;
	vcpu->arch.pause = false;
	smp_mb(); /* Make sure the above is visible */

	wq = kvm_arch_vcpu_wq(vcpu);
	wake_up_interruptible(wq);

	return PSCI_RET_SUCCESS;
	}

	static unsigned long kvm_psci_vcpu_affinity_info(struct kvm_vcpu *vcpu)
	{
	int i;
	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 = *vcpu_reg(vcpu, 1);
	lowest_affinity_level = *vcpu_reg(vcpu, 2);

	/* 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) &&
	!tmp->arch.pause) {
	return PSCI_0_2_AFFINITY_LEVEL_ON;
	}
	}

	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.pause = true;
	kvm_vcpu_kick(tmp);
	}

	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);
	}

	int kvm_psci_version(struct kvm_vcpu *vcpu)
	{
	if (test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features))
	return KVM_ARM_PSCI_0_2;

	return KVM_ARM_PSCI_0_1;
	}

	static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
	{
	int ret = 1;
	unsigned long psci_fn = *vcpu_reg(vcpu, 0) & ~((u32) 0);
	unsigned long val;

	switch (psci_fn) {
	case PSCI_0_2_FN_PSCI_VERSION:
	/*
	* Bits[31:16] = Major Version = 0
	* Bits[15:0] = Minor Version = 2
	*/
	val = 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:
	val = kvm_psci_vcpu_on(vcpu);
	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;
	}

	*vcpu_reg(vcpu, 0) = val;
	return ret;
	}

	static int kvm_psci_0_1_call(struct kvm_vcpu *vcpu)
	{
	unsigned long psci_fn = *vcpu_reg(vcpu, 0) & ~((u32) 0);
	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:
	val = kvm_psci_vcpu_on(vcpu);
	break;
	default:
	val = PSCI_RET_NOT_SUPPORTED;
	break;
	}

	*vcpu_reg(vcpu, 0) = val;
	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)) {
	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;
	};
	}