[PATCH v8 2/2] KVM-INTEL: add a notifier and a bitmap to support VMCLEAR in kdump

Zhang Yanfei
2012-11-22T08:26:59Z

The notifier will be registered in crash_notifier_list when loading
kvm-intel module. And the bitmap indicates whether we should do
VMCLEAR operation in kdump. The bits in the bitmap are set/unset
according to different conditions.

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
---
arch/x86/kvm/vmx.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 70 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 4ff0ab9..d890372 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -41,6 +41,7 @@
#include <asm/i387.h>
#include <asm/xcr.h>
#include <asm/perf_event.h>
+#include <asm/kexec.h>

#include "trace.h"

@@ -963,6 +964,49 @@ static void vmcs_load(struct vmcs *vmcs)
vmcs, phys_addr);
}

+#ifdef CONFIG_KEXEC
+/*
+ * This bitmap is used to indicate whether the vmclear
+ * operation is enabled on all cpus. All disabled by
+ * default.
+ */
+static cpumask_t crash_vmclear_enabled_bitmap = CPU_MASK_NONE;
+
+static inline void crash_enable_local_vmclear(int cpu)
+{
+ cpumask_set_cpu(cpu, &crash_vmclear_enabled_bitmap);
+}
+
+static inline void crash_disable_local_vmclear(int cpu)
+{
+ cpumask_clear_cpu(cpu, &crash_vmclear_enabled_bitmap);
+}
+
+static inline int crash_local_vmclear_enabled(int cpu)
+{
+ return cpumask_test_cpu(cpu, &crash_vmclear_enabled_bitmap);
+}
+
+static void vmclear_local_loaded_vmcss(void);
+static int crash_vmclear_local_loaded_vmcss(struct notifier_block *this,
+ unsigned long val, void *ptr)
+{
+ int cpu = raw_smp_processor_id();
+
+ if (crash_local_vmclear_enabled(cpu))
+ vmclear_local_loaded_vmcss();
+
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block crash_vmclear_notifier = {
+ .notifier_call = crash_vmclear_local_loaded_vmcss,
+};
+#else
+static inline void crash_enable_local_vmclear(int cpu) { }
+static inline void crash_disable_local_vmclear(int cpu) { }
+#endif /* CONFIG_KEXEC */
+
static void __loaded_vmcs_clear(void *arg)
{
struct loaded_vmcs *loaded_vmcs = arg;
@@ -972,8 +1016,10 @@ static void __loaded_vmcs_clear(void *arg)
return; /* vcpu migration can race with cpu offline */
if (per_cpu(current_vmcs, cpu) == loaded_vmcs->vmcs)
per_cpu(current_vmcs, cpu) = NULL;
+ crash_disable_local_vmclear(cpu);
list_del(&loaded_vmcs->loaded_vmcss_on_cpu_link);
loaded_vmcs_init(loaded_vmcs);
+ crash_enable_local_vmclear(cpu);
}

static void loaded_vmcs_clear(struct loaded_vmcs *loaded_vmcs)
@@ -1491,8 +1537,10 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)

kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
local_irq_disable();
+ crash_disable_local_vmclear(cpu);
list_add(&vmx->loaded_vmcs->loaded_vmcss_on_cpu_link,
&per_cpu(loaded_vmcss_on_cpu, cpu));
+ crash_enable_local_vmclear(cpu);
local_irq_enable();

/*
@@ -2302,6 +2350,18 @@ static int hardware_enable(void *garbage)
return -EBUSY;

INIT_LIST_HEAD(&per_cpu(loaded_vmcss_on_cpu, cpu));
+
+ /*
+ * Now we can enable the vmclear operation in kdump
+ * since the loaded_vmcss_on_cpu list on this cpu
+ * has been initialized.
+ *
+ * Though the cpu is not in VMX operation now, there
+ * is no problem to enable the vmclear operation
+ * for the loaded_vmcss_on_cpu list is empty!
+ */
+ crash_enable_local_vmclear(cpu);
+
rdmsrl(MSR_IA32_FEATURE_CONTROL, old);

test_bits = FEATURE_CONTROL_LOCKED;
@@ -7230,6 +7290,11 @@ static int __init vmx_init(void)
if (r)
goto out3;

+#ifdef CONFIG_KEXEC
+ atomic_notifier_chain_register(&crash_notifier_list,
+ &crash_vmclear_notifier);
+#endif
+
vmx_disable_intercept_for_msr(MSR_FS_BASE, false);
vmx_disable_intercept_for_msr(MSR_GS_BASE, false);
vmx_disable_intercept_for_msr(MSR_KERNEL_GS_BASE, true);
@@ -7265,6 +7330,11 @@ static void __exit vmx_exit(void)
free_page((unsigned long)vmx_io_bitmap_b);
free_page((unsigned long)vmx_io_bitmap_a);

+#ifdef CONFIG_KEXEC
+ atomic_notifier_chain_unregister(&crash_notifier_list,
+ &crash_vmclear_notifier);
+#endif
+
kvm_exit();
}

--
1.7.1