[PATCH v5 19/30] KVM: kvm_arch.c: Remove a global variable, hardware_enable_failed

From: isaku . yamahata
Date: Thu Sep 22 2022 - 14:23:33 EST


From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>

A global variable hardware_enable_failed in kvm_arch.c is used only by
kvm_arch_add_vm() and hardware_enable(). It doesn't have to be a global
variable. Make it function local.

Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
---
virt/kvm/kvm_arch.c | 61 ++++++++++++++++++++++-----------------------
1 file changed, 30 insertions(+), 31 deletions(-)

diff --git a/virt/kvm/kvm_arch.c b/virt/kvm/kvm_arch.c
index e6bf9de18cba..10fd29bdd6e1 100644
--- a/virt/kvm/kvm_arch.c
+++ b/virt/kvm/kvm_arch.c
@@ -13,7 +13,6 @@
#include <linux/kvm_host.h>

static cpumask_t cpus_hardware_enabled = CPU_MASK_NONE;
-static atomic_t hardware_enable_failed;

/*
* Called after the VM is otherwise initialized, but just before adding it to
@@ -24,7 +23,7 @@ int __weak kvm_arch_post_init_vm(struct kvm *kvm)
return 0;
}

-static void hardware_enable(void *junk)
+static int __hardware_enable(void)
{
int cpu = raw_smp_processor_id();
int r;
@@ -32,18 +31,22 @@ static void hardware_enable(void *junk)
WARN_ON_ONCE(preemptible());

if (cpumask_test_cpu(cpu, &cpus_hardware_enabled))
- return;
-
- cpumask_set_cpu(cpu, &cpus_hardware_enabled);
-
+ return 0;
r = kvm_arch_hardware_enable();
-
- if (r) {
- cpumask_clear_cpu(cpu, &cpus_hardware_enabled);
- atomic_inc(&hardware_enable_failed);
+ if (r)
pr_warn("kvm: enabling virtualization on CPU%d failed during %pSb\n",
cpu, __builtin_return_address(0));
- }
+ else
+ cpumask_set_cpu(cpu, &cpus_hardware_enabled);
+ return r;
+}
+
+static void hardware_enable(void *arg)
+{
+ atomic_t *failed = arg;
+
+ if (__hardware_enable())
+ atomic_inc(failed);
}

static void hardware_disable(void *junk)
@@ -64,15 +67,15 @@ static void hardware_disable(void *junk)
*/
int __weak kvm_arch_add_vm(struct kvm *kvm, int usage_count)
{
+ atomic_t failed = ATOMIC_INIT(0);
int r = 0;

if (usage_count != 1)
return 0;

- atomic_set(&hardware_enable_failed, 0);
- on_each_cpu(hardware_enable, NULL, 1);
+ on_each_cpu(hardware_enable, &failed, 1);

- if (atomic_read(&hardware_enable_failed)) {
+ if (atomic_read(&failed)) {
r = -EBUSY;
goto err;
}
@@ -95,33 +98,29 @@ int __weak kvm_arch_del_vm(int usage_count)

int __weak kvm_arch_online_cpu(unsigned int cpu, int usage_count)
{
- int ret = 0;
+ int ret;

ret = kvm_arch_check_processor_compat();
if (ret)
return ret;

+ if (!usage_count)
+ return 0;
+
+ /*
+ * arch callback kvm_arch_hardware_enable() assumes that
+ * preemption is disabled for historical reason. Disable
+ * preemption until all arch callbacks are fixed.
+ */
+ preempt_disable();
/*
* Abort the CPU online process if hardware virtualization cannot
* be enabled. Otherwise running VMs would encounter unrecoverable
* errors when scheduled to this CPU.
*/
- if (usage_count) {
- WARN_ON_ONCE(atomic_read(&hardware_enable_failed));
+ ret = __hardware_enable();
+ preempt_enable();

- /*
- * arch callback kvm_arch_hardware_eanble() assumes that
- * preemption is disabled for historical reason. Disable
- * preemption until all arch callbacks are fixed.
- */
- preempt_disable();
- hardware_enable(NULL);
- preempt_enable();
- if (atomic_read(&hardware_enable_failed)) {
- atomic_set(&hardware_enable_failed, 0);
- ret = -EIO;
- }
- }
return ret;
}

@@ -160,5 +159,5 @@ int __weak kvm_arch_suspend(int usage_count)
void __weak kvm_arch_resume(int usage_count)
{
if (usage_count)
- hardware_enable(NULL);
+ (void)__hardware_enable();
}
--
2.25.1