Re: [PATCH v11 2/2] KVM-INTEL: provide the vmclear function and a bitmap to support VMCLEAR in kdump

Zhang Yanfei
2012-12-06T15:43:45Z

From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>

The vmclear function will be assigned to the callback function pointer
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 | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 67 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 94833e2..1a30fd5 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -42,6 +42,7 @@
#include <asm/i387.h>
#include <asm/xcr.h>
#include <asm/perf_event.h>
+#include <asm/kexec.h>

#include "trace.h"

@@ -987,6 +988,46 @@ 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 crash_vmclear_local_loaded_vmcss(void)
+{
+ int cpu = raw_smp_processor_id();
+ struct loaded_vmcs *v;
+
+ if (!crash_local_vmclear_enabled(cpu))
+ return;
+
+ list_for_each_entry(v, &per_cpu(loaded_vmcss_on_cpu, cpu),
+ loaded_vmcss_on_cpu_link)
+ vmcs_clear(v->vmcs);
+}
+#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;
@@ -996,6 +1037,7 @@ 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);

/*
@@ -1007,6 +1049,7 @@ static void __loaded_vmcs_clear(void *arg)
smp_wmb();

loaded_vmcs_init(loaded_vmcs);
+ crash_enable_local_vmclear(cpu);
}

static void loaded_vmcs_clear(struct loaded_vmcs *loaded_vmcs)
@@ -1530,6 +1573,7 @@ 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);

/*
* Read loaded_vmcs->cpu should be before fetching
@@ -1540,6 +1584,7 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int 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();

/*
@@ -2353,6 +2398,18 @@ 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;
@@ -7383,6 +7440,11 @@ static int __init vmx_init(void)
if (r)
goto out3;

+#ifdef CONFIG_KEXEC
+ rcu_assign_pointer(crash_vmclear_loaded_vmcss,
+ crash_vmclear_local_loaded_vmcss);
+#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);
@@ -7420,6 +7482,11 @@ 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
+ rcu_assign_pointer(crash_vmclear_loaded_vmcss, NULL);
+ synchronize_rcu();
+#endif
+
kvm_exit();
}

--
1.7.1