[PATCH v8 05/13] arm64: kvm: allows kvm cpu hotplug
James Morse
james.morse at arm.com
Mon Apr 25 10:10:42 PDT 2016
From: AKASHI Takahiro <takahiro.akashi at linaro.org>
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 at 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 at arm.com>
CC: Marc Zyngier <marc.zyngier at arm.com>
---
N.B. this patch conflicts with 06a71a24bae5 ("arm64: KVM: unregister notifiers
in hyp mode teardown path") in v4.6-rc4. See the cover letter for details.
Changes since v7:
* Moved the kvm-torn-down guest entry handling into handle_exit(),
* Added an exception type for hyp-stub to return to any kvm_call_hyp() caller
arch/arm/include/asm/kvm_host.h | 10 +++-
arch/arm/include/asm/kvm_mmu.h | 1 +
arch/arm/kvm/arm.c | 119 +++++++++++++++++++++++---------------
arch/arm/kvm/mmu.c | 5 ++
arch/arm64/include/asm/kvm_asm.h | 3 +
arch/arm64/include/asm/kvm_host.h | 13 ++++-
arch/arm64/include/asm/kvm_mmu.h | 1 +
arch/arm64/kernel/hyp-stub.S | 5 +-
arch/arm64/kvm/handle_exit.c | 7 +++
arch/arm64/kvm/hyp-init.S | 38 ++++++++++++
arch/arm64/kvm/reset.c | 14 +++++
11 files changed, 164 insertions(+), 52 deletions(-)
diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 385070180c25..738d5eee91de 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -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) {}
diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index da44be9db4fa..f17a8d41822c 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -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);
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index b5384311dec4..1687e1450c3a 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -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)
+{
+ 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);
}
+}
+
+int kvm_arch_hardware_enable(void)
+{
+ _kvm_arch_hardware_enable(NULL);
+ return 0;
+}
- return NOTIFY_OK;
+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);
+ }
}
-static struct notifier_block hyp_init_cpu_nb = {
- .notifier_call = hyp_init_cpu_notify,
-};
+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();
+ /*
+ * 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;
- }
- return NOTIFY_DONE;
+ 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
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 58dbd5c439df..7d86e15b5d85 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -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;
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index eb7490d232a0..a88da136f332 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -22,6 +22,8 @@
#define ARM_EXCEPTION_IRQ 0
#define ARM_EXCEPTION_TRAP 1
+/* The hyp-stub will return this for any kvm_call_hyp() call */
+#define ARM_EXCEPTION_HYP_GONE 2
#define KVM_ARM64_DEBUG_DIRTY_SHIFT 0
#define KVM_ARM64_DEBUG_DIRTY (1 << KVM_ARM64_DEBUG_DIRTY_SHIFT)
@@ -40,6 +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[];
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index b7e82a795ac9..b6f194d9f6b2 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -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) {}
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 22732a5e3119..e8d39d4f86b6 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -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);
diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S
index 894fb40fb378..8727f4490772 100644
--- a/arch/arm64/kernel/hyp-stub.S
+++ b/arch/arm64/kernel/hyp-stub.S
@@ -23,6 +23,7 @@
#include <asm/assembler.h>
#include <asm/kvm_arm.h>
+#include <asm/kvm_asm.h>
#include <asm/ptrace.h>
#include <asm/virt.h>
@@ -70,8 +71,8 @@ el1_sync:
msr vbar_el2, x1
b 9f
- /* Unrecognised call type */
-2: mov x0, xzr
+ /* Someone called kvm_call_hyp() against the hyp-stub... */
+2: mov x0, #ARM_EXCEPTION_HYP_GONE
9: eret
ENDPROC(el1_sync)
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index eba89e42f0ed..3246c4aba5b1 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -186,6 +186,13 @@ int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
exit_handler = kvm_get_exit_handler(vcpu);
return exit_handler(vcpu, run);
+ case ARM_EXCEPTION_HYP_GONE:
+ /*
+ * EL2 has been reset to the hyp-stub. This happens when a guest
+ * is pre-empted by kvm_reboot()'s shutdown call.
+ */
+ run->exit_reason = KVM_EXIT_FAIL_ENTRY;
+ return 0;
default:
kvm_pr_unimpl("Unsupported exception type: %d",
exception_index);
diff --git a/arch/arm64/kvm/hyp-init.S b/arch/arm64/kvm/hyp-init.S
index 5ce1b47ef770..44ec4cb23ae7 100644
--- a/arch/arm64/kvm/hyp-init.S
+++ b/arch/arm64/kvm/hyp-init.S
@@ -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
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 9677bf069bcc..4062e6dd4cc1 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -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;
+}
--
2.8.0.rc3
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