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arm64: kvm: allows kvm cpu hotplug

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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: AKASHI 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: James Morse <james.morse@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
AKASHI Takahiro 2016-04-27 17:47:05 +01:00 committed by Will Deacon
parent c94b0cf282
commit 67f6919766
9 changed files with 155 additions and 53 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
arch/arm/include/asm/kvm_host.h
View File

@ -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) {}

1
arch/arm/include/asm/kvm_mmu.h
View File

@ -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);

125
arch/arm/kvm/arm.c
View File

@ -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;
@ -1065,43 +1056,87 @@ 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)
{
switch (action) {
case CPU_STARTING:
case CPU_STARTING_FROZEN:
cpu_hyp_reinit();
}
phys_addr_t boot_pgd_ptr;
phys_addr_t phys_idmap_start;
return NOTIFY_OK;
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 struct notifier_block hyp_init_cpu_nb = {
.notifier_call = hyp_init_cpu_notify,
};
static void _kvm_arch_hardware_enable(void *discard)
{
if (!__this_cpu_read(kvm_arm_hardware_enabled)) {
cpu_hyp_reinit();
__this_cpu_write(kvm_arm_hardware_enabled, 1);
}
}
int kvm_arch_hardware_enable(void)
{
_kvm_arch_hardware_enable(NULL);
return 0;
}
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) {
cpu_hyp_reinit();
return NOTIFY_OK;
}
/*
* 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_DONE;
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 = {
@ -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

5
arch/arm/kvm/mmu.c
View File

@ -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;

1
arch/arm64/include/asm/kvm_asm.h
View File

@ -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[];

13
arch/arm64/include/asm/kvm_host.h
View File

@ -46,6 +46,7 @@
int __attribute_const__ kvm_target_cpu(void);
int kvm_reset_vcpu(struct kvm_vcpu *vcpu);
int kvm_arch_dev_ioctl_check_extension(long ext);
phys_addr_t kvm_hyp_reset_entry(void);
struct kvm_arch {
/* The VMID generation used for the virt. memory system */
@ -352,7 +353,17 @@ static inline void __cpu_init_hyp_mode(phys_addr_t boot_pgd_ptr,
hyp_stack_ptr, vector_ptr);
}
static inline void kvm_arch_hardware_disable(void) {}
static inline void __cpu_reset_hyp_mode(phys_addr_t boot_pgd_ptr,
phys_addr_t phys_idmap_start)
{
/*
* Call reset code, and switch back to stub hyp vectors.
* Uses __kvm_call_hyp() to avoid kaslr's kvm_ksym_ref() translation.
*/
__kvm_call_hyp((void *)kvm_hyp_reset_entry(),
boot_pgd_ptr, phys_idmap_start);
}
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) {}

1
arch/arm64/include/asm/kvm_mmu.h
View File

@ -109,6 +109,7 @@ 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);

38
arch/arm64/kvm/hyp-init.S
View File

@ -139,6 +139,44 @@ merged:
eret
ENDPROC(__kvm_hyp_init)
/*
* x0: HYP boot pgd
* x1: HYP phys_idmap_start
*/
ENTRY(__kvm_hyp_reset)
/* We're in trampoline code in VA, switch back to boot page tables */
msr ttbr0_el2, x0
isb
/* Ensure the PA branch doesn't find a stale tlb entry or stale code. */
ic iallu
tlbi alle2
dsb sy
isb
/* Branch into PA space */
adr x0, 1f
bfi x1, x0, #0, #PAGE_SHIFT
br x1
/* We're now in idmap, disable MMU */
1: mrs x0, sctlr_el2
ldr x1, =SCTLR_ELx_FLAGS
bic x0, x0, x1 // Clear SCTL_M and etc
msr sctlr_el2, x0
isb
/* Invalidate the old TLBs */
tlbi alle2
dsb sy
/* Install stub vectors */
adr_l x0, __hyp_stub_vectors
msr vbar_el2, x0
eret
ENDPROC(__kvm_hyp_reset)
.ltorg
.popsection

14
arch/arm64/kvm/reset.c
View File

@ -29,7 +29,9 @@
#include <asm/cputype.h>
#include <asm/ptrace.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_asm.h>
#include <asm/kvm_coproc.h>
#include <asm/kvm_mmu.h>
/*
* ARMv8 Reset Values
@ -130,3 +132,15 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
/* Reset timer */
return kvm_timer_vcpu_reset(vcpu, cpu_vtimer_irq);
}
extern char __hyp_idmap_text_start[];
phys_addr_t kvm_hyp_reset_entry(void)
{
unsigned long offset;
offset = (unsigned long)__kvm_hyp_reset
- ((unsigned long)__hyp_idmap_text_start & PAGE_MASK);
return TRAMPOLINE_VA + offset;
}