[PATCH v2 07/19] KVM: Add arch hooks for PM events with empty stub

isaku.yamahata
2022-08-30T12:02:30Z

Add arch hooks for reboot, suspend, resume, and CPU-online/offline events
with empty stub functions.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
include/linux/kvm_host.h | 6 +++++
virt/kvm/Makefile.kvm | 2 +-
virt/kvm/kvm_arch.c | 44 ++++++++++++++++++++++++++++++++++
virt/kvm/kvm_main.c | 51 +++++++++++++++++++++++++---------------
4 files changed, 83 insertions(+), 20 deletions(-)
create mode 100644 virt/kvm/kvm_arch.c

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index eab352902de7..dd2a6d98d4de 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1448,6 +1448,12 @@ int kvm_arch_post_init_vm(struct kvm *kvm);
void kvm_arch_pre_destroy_vm(struct kvm *kvm);
int kvm_arch_create_vm_debugfs(struct kvm *kvm);

+int kvm_arch_suspend(int usage_count);
+void kvm_arch_resume(int usage_count);
+int kvm_arch_reboot(int val);
+int kvm_arch_online_cpu(unsigned int cpu, int usage_count);
+int kvm_arch_offline_cpu(unsigned int cpu, int usage_count);
+
#ifndef __KVM_HAVE_ARCH_VM_ALLOC
/*
* All architectures that want to use vzalloc currently also
diff --git a/virt/kvm/Makefile.kvm b/virt/kvm/Makefile.kvm
index 2c27d5d0c367..c4210acabd35 100644
--- a/virt/kvm/Makefile.kvm
+++ b/virt/kvm/Makefile.kvm
@@ -5,7 +5,7 @@

KVM ?= ../../../virt/kvm

-kvm-y := $(KVM)/kvm_main.o $(KVM)/eventfd.o $(KVM)/binary_stats.o
+kvm-y := $(KVM)/kvm_main.o $(KVM)/kvm_arch.o $(KVM)/eventfd.o $(KVM)/binary_stats.o
kvm-$(CONFIG_KVM_VFIO) += $(KVM)/vfio.o
kvm-$(CONFIG_KVM_MMIO) += $(KVM)/coalesced_mmio.o
kvm-$(CONFIG_KVM_ASYNC_PF) += $(KVM)/async_pf.o
diff --git a/virt/kvm/kvm_arch.c b/virt/kvm/kvm_arch.c
new file mode 100644
index 000000000000..4748a76bcb03
--- /dev/null
+++ b/virt/kvm/kvm_arch.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * kvm_arch.c: kvm default arch hooks for hardware enabling/disabling
+ * Copyright (c) 2022 Intel Corporation.
+ *
+ * Author:
+ * Isaku Yamahata <isaku.yamahata@intel.com>
+ * <isaku.yamahata@gmail.com>
+ */
+
+#include <linux/kvm_host.h>
+
+/*
+ * Called after the VM is otherwise initialized, but just before adding it to
+ * the vm_list.
+ */
+__weak int kvm_arch_post_init_vm(struct kvm *kvm)
+{
+ return 0;
+}
+
+__weak int kvm_arch_online_cpu(unsigned int cpu, int usage_count)
+{
+ return 0;
+}
+
+__weak int kvm_arch_offline_cpu(unsigned int cpu, int usage_count)
+{
+ return 0;
+}
+
+__weak int kvm_arch_reboot(int val)
+{
+ return NOTIFY_OK;
+}
+
+__weak int kvm_arch_suspend(int usage_count)
+{
+ return 0;
+}
+
+__weak void kvm_arch_resume(int usage_count)
+{
+}
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 606ac6bb67d0..de336fba902b 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -144,6 +144,7 @@ static int kvm_no_compat_open(struct inode *inode, struct file *file)
#endif
static int hardware_enable_all(void);
static void hardware_disable_all(void);
+static void hardware_disable_nolock(void *junk);

static void kvm_io_bus_destroy(struct kvm_io_bus *bus);

@@ -1097,15 +1098,6 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, const char *fdname)
return ret;
}

-/*
- * Called after the VM is otherwise initialized, but just before adding it to
- * the vm_list.
- */
-int __weak kvm_arch_post_init_vm(struct kvm *kvm)
-{
- return 0;
-}
-
/*
* Called just after removing the VM from the vm_list, but before doing any
* other destruction.
@@ -5028,6 +5020,11 @@ static int kvm_online_cpu(unsigned int cpu)
if (atomic_read(&hardware_enable_failed)) {
atomic_set(&hardware_enable_failed, 0);
ret = -EIO;
+ } else {
+ ret = kvm_arch_online_cpu(cpu, kvm_usage_count);
+ if (ret) {
+ hardware_disable_nolock(NULL);
+ }
}
}
mutex_unlock(&kvm_lock);
@@ -5048,11 +5045,19 @@ static void hardware_disable_nolock(void *junk)

static int kvm_offline_cpu(unsigned int cpu)
{
+ int ret = 0;
+
mutex_lock(&kvm_lock);
- if (kvm_usage_count)
+ if (kvm_usage_count) {
hardware_disable_nolock(NULL);
+ ret = kvm_arch_offline_cpu(cpu, kvm_usage_count);
+ if (ret) {
+ (void)hardware_enable_nolock(NULL);
+ atomic_set(&hardware_enable_failed, 0);
+ }
+ }
mutex_unlock(&kvm_lock);
- return 0;
+ return ret;
}

static void hardware_disable_all_nolock(void)
@@ -5100,6 +5105,8 @@ static int hardware_enable_all(void)
static int kvm_reboot(struct notifier_block *notifier, unsigned long val,
void *v)
{
+ int r;
+
/*
* Some (well, at least mine) BIOSes hang on reboot if
* in vmx root mode.
@@ -5108,8 +5115,15 @@ static int kvm_reboot(struct notifier_block *notifier, unsigned long val,
*/
pr_info("kvm: exiting hardware virtualization\n");
kvm_rebooting = true;
+
+ /* This hook is called without cpuhotplug disabled. */
+ cpus_read_lock();
+ mutex_lock(&kvm_lock);
on_each_cpu(hardware_disable_nolock, NULL, 1);
- return NOTIFY_OK;
+ r = kvm_arch_reboot(val);
+ mutex_unlock(&kvm_lock);
+ cpus_read_unlock();
+ return r;
}

static struct notifier_block kvm_reboot_notifier = {
@@ -5703,19 +5717,18 @@ static int kvm_suspend(void)
* cpu_hotplug_disable() and other CPUs are offlined. No need for
* locking.
*/
- if (kvm_usage_count) {
- lockdep_assert_not_held(&kvm_lock);
+ lockdep_assert_not_held(&kvm_lock);
+ if (kvm_usage_count)
hardware_disable_nolock(NULL);
- }
- return 0;
+ return kvm_arch_suspend(kvm_usage_count);
}

static void kvm_resume(void)
{
- if (kvm_usage_count) {
- lockdep_assert_not_held(&kvm_lock);
+ kvm_arch_resume(kvm_usage_count);
+ lockdep_assert_not_held(&kvm_lock);
+ if (kvm_usage_count)
hardware_enable_nolock(NULL);
- }
}

static struct syscore_ops kvm_syscore_ops = {
--
2.25.1