Commit 67f69197 authored by AKASHI Takahiro's avatar AKASHI Takahiro Committed by Will Deacon
Browse files

arm64: kvm: allows kvm cpu hotplug 



The current kvm implementation on arm64 does cpu-specific initialization
at system boot, and has no way to gracefully shutdown a core in terms of
kvm. This prevents kexec from rebooting the system at EL2.

This patch adds a cpu tear-down function and also puts an existing cpu-init
code into a separate function, kvm_arch_hardware_disable() and
kvm_arch_hardware_enable() respectively.
We don't need the arm64 specific cpu hotplug hook any more.

Since this patch modifies common code between arm and arm64, one stub
definition, __cpu_reset_hyp_mode(), is added on arm side to avoid
compilation errors.

Signed-off-by: default avatarAKASHI Takahiro <takahiro.akashi@linaro.org>
[Rebase, added separate VHE init/exit path, changed resets use of
 kvm_call_hyp() to the __version, en/disabled hardware in init_subsystems(),
 added icache maintenance to __kvm_hyp_reset() and removed lr restore, removed
 guest-enter after teardown handling]
Signed-off-by: default avatarJames Morse <james.morse@arm.com>
Acked-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent c94b0cf2

arch/arm/include/asm/kvm_host.h

+9 −1
Original line number Diff line number Diff line
@@ -265,6 +265,15 @@ static inline void __cpu_init_stage2(void) 
	kvm_call_hyp(__init_stage2_translation);

}



static inline void __cpu_reset_hyp_mode(phys_addr_t boot_pgd_ptr,

					phys_addr_t phys_idmap_start)

{

	/*

	 * TODO

	 * kvm_call_reset(boot_pgd_ptr, phys_idmap_start);

	 */

}



static inline int kvm_arch_dev_ioctl_check_extension(long ext)

{

	return 0;
@@ -277,7 +286,6 @@ void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot); 


struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr);



static inline void kvm_arch_hardware_disable(void) {}

static inline void kvm_arch_hardware_unsetup(void) {}

static inline void kvm_arch_sync_events(struct kvm *kvm) {}

static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}

arch/arm/include/asm/kvm_mmu.h

+1 −0
Original line number Diff line number Diff line
@@ -66,6 +66,7 @@ void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu); 
phys_addr_t kvm_mmu_get_httbr(void);

phys_addr_t kvm_mmu_get_boot_httbr(void);

phys_addr_t kvm_get_idmap_vector(void);

phys_addr_t kvm_get_idmap_start(void);

int kvm_mmu_init(void);

void kvm_clear_hyp_idmap(void);

arch/arm/kvm/arm.c

+71 −48
Original line number Diff line number Diff line
@@ -16,7 +16,6 @@ 
 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

 */



#include <linux/cpu.h>

#include <linux/cpu_pm.h>

#include <linux/errno.h>

#include <linux/err.h>
@@ -66,6 +65,8 @@ static DEFINE_SPINLOCK(kvm_vmid_lock); 


static bool vgic_present;



static DEFINE_PER_CPU(unsigned char, kvm_arm_hardware_enabled);



static void kvm_arm_set_running_vcpu(struct kvm_vcpu *vcpu)

{

	BUG_ON(preemptible());
@@ -90,11 +91,6 @@ struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void) 
	return &kvm_arm_running_vcpu;

}



int kvm_arch_hardware_enable(void)

{

	return 0;

}



int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)

{

	return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE;
@@ -1033,11 +1029,6 @@ long kvm_arch_vm_ioctl(struct file *filp, 
	}

}



static void cpu_init_stage2(void *dummy)

{

	__cpu_init_stage2();

}



static void cpu_init_hyp_mode(void *dummy)

{

	phys_addr_t boot_pgd_ptr;
@@ -1065,44 +1056,88 @@ static void cpu_hyp_reinit(void) 
{

	if (is_kernel_in_hyp_mode()) {

		/*

		 * cpu_init_stage2() is safe to call even if the PM

		 * __cpu_init_stage2() is safe to call even if the PM

		 * event was cancelled before the CPU was reset.

		 */

		cpu_init_stage2(NULL);

		__cpu_init_stage2();

	} else {

		if (__hyp_get_vectors() == hyp_default_vectors)

			cpu_init_hyp_mode(NULL);

	}

}



static int hyp_init_cpu_notify(struct notifier_block *self,

			       unsigned long action, void *cpu)

static void cpu_hyp_reset(void)

{

	phys_addr_t boot_pgd_ptr;

	phys_addr_t phys_idmap_start;



	if (!is_kernel_in_hyp_mode()) {

		boot_pgd_ptr = kvm_mmu_get_boot_httbr();

		phys_idmap_start = kvm_get_idmap_start();



		__cpu_reset_hyp_mode(boot_pgd_ptr, phys_idmap_start);

	}

}



static void _kvm_arch_hardware_enable(void *discard)

{

	switch (action) {

	case CPU_STARTING:

	case CPU_STARTING_FROZEN:

	if (!__this_cpu_read(kvm_arm_hardware_enabled)) {

		cpu_hyp_reinit();

		__this_cpu_write(kvm_arm_hardware_enabled, 1);

	}

}



	return NOTIFY_OK;

int kvm_arch_hardware_enable(void)

{

	_kvm_arch_hardware_enable(NULL);

	return 0;

}



static struct notifier_block hyp_init_cpu_nb = {

	.notifier_call = hyp_init_cpu_notify,

};

static void _kvm_arch_hardware_disable(void *discard)

{

	if (__this_cpu_read(kvm_arm_hardware_enabled)) {

		cpu_hyp_reset();

		__this_cpu_write(kvm_arm_hardware_enabled, 0);

	}

}



void kvm_arch_hardware_disable(void)

{

	_kvm_arch_hardware_disable(NULL);

}



#ifdef CONFIG_CPU_PM

static int hyp_init_cpu_pm_notifier(struct notifier_block *self,

				    unsigned long cmd,

				    void *v)

{

	if (cmd == CPU_PM_EXIT) {

	/*

	 * kvm_arm_hardware_enabled is left with its old value over

	 * PM_ENTER->PM_EXIT. It is used to indicate PM_EXIT should

	 * re-enable hyp.

	 */

	switch (cmd) {

	case CPU_PM_ENTER:

		if (__this_cpu_read(kvm_arm_hardware_enabled))

			/*

			 * don't update kvm_arm_hardware_enabled here

			 * so that the hardware will be re-enabled

			 * when we resume. See below.

			 */

			cpu_hyp_reset();



		return NOTIFY_OK;

	case CPU_PM_EXIT:

		if (__this_cpu_read(kvm_arm_hardware_enabled))

			/* The hardware was enabled before suspend. */

			cpu_hyp_reinit();



		return NOTIFY_OK;

	}



	default:

		return NOTIFY_DONE;

	}

}



static struct notifier_block hyp_init_cpu_pm_nb = {

	.notifier_call = hyp_init_cpu_pm_notifier,
@@ -1136,18 +1171,12 @@ static int init_common_resources(void) 


static int init_subsystems(void)

{

	int err;

	int err = 0;



	/*

	 * Register CPU Hotplug notifier

	 * Enable hardware so that subsystem initialisation can access EL2.

	 */

	cpu_notifier_register_begin();

	err = __register_cpu_notifier(&hyp_init_cpu_nb);

	cpu_notifier_register_done();

	if (err) {

		kvm_err("Cannot register KVM init CPU notifier (%d)\n", err);

		return err;

	}

	on_each_cpu(_kvm_arch_hardware_enable, NULL, 1);



	/*

	 * Register CPU lower-power notifier
@@ -1165,9 +1194,10 @@ static int init_subsystems(void) 
	case -ENODEV:

	case -ENXIO:

		vgic_present = false;

		err = 0;

		break;

	default:

		return err;

		goto out;

	}



	/*
@@ -1175,12 +1205,15 @@ static int init_subsystems(void) 
	 */

	err = kvm_timer_hyp_init();

	if (err)

		return err;

		goto out;



	kvm_perf_init();

	kvm_coproc_table_init();



	return 0;

out:

	on_each_cpu(_kvm_arch_hardware_disable, NULL, 1);



	return err;

}



static void teardown_hyp_mode(void)
@@ -1197,11 +1230,6 @@ static void teardown_hyp_mode(void) 


static int init_vhe_mode(void)

{

	/*

	 * Execute the init code on each CPU.

	 */

	on_each_cpu(cpu_init_stage2, NULL, 1);



	/* set size of VMID supported by CPU */

	kvm_vmid_bits = kvm_get_vmid_bits();

	kvm_info("%d-bit VMID\n", kvm_vmid_bits);
@@ -1288,11 +1316,6 @@ static int init_hyp_mode(void) 
		}

	}



	/*

	 * Execute the init code on each CPU.

	 */

	on_each_cpu(cpu_init_hyp_mode, NULL, 1);



#ifndef CONFIG_HOTPLUG_CPU

	free_boot_hyp_pgd();

#endif

arch/arm/kvm/mmu.c

+5 −0
Original line number Diff line number Diff line
@@ -1666,6 +1666,11 @@ phys_addr_t kvm_get_idmap_vector(void) 
	return hyp_idmap_vector;

}



phys_addr_t kvm_get_idmap_start(void)

{

	return hyp_idmap_start;

}



int kvm_mmu_init(void)

{

	int err;

arch/arm64/include/asm/kvm_asm.h

+1 −0
Original line number Diff line number Diff line
@@ -42,6 +42,7 @@ struct kvm_vcpu; 


extern char __kvm_hyp_init[];

extern char __kvm_hyp_init_end[];

extern char __kvm_hyp_reset[];



extern char __kvm_hyp_vector[];

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