[PATCH v3 1/2] x86/kexec: VMCLEAR vmcss on all cpus if necessary

zhangyanfei
2012-10-31T03:34:13Z

This patch provides a way to VMCLEAR vmcss related to guests
on all cpus before executing the VMXOFF when doing kdump. This
is used to ensure the VMCSs in the vmcore updated and
non-corrupted.

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
---
arch/x86/include/asm/kexec.h | 2 ++
arch/x86/kernel/crash.c | 25 +++++++++++++++++++++++++
2 files changed, 27 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index 317ff17..fc05440 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -163,6 +163,8 @@ struct kimage_arch {
};
#endif

+extern void (*crash_clear_loaded_vmcss)(void);
+
#endif /* __ASSEMBLY__ */

#endif /* _ASM_X86_KEXEC_H */
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index 13ad899..9ed65c1 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -16,6 +16,7 @@
#include <linux/delay.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
+#include <linux/module.h>

#include <asm/processor.h>
#include <asm/hardirq.h>
@@ -30,6 +31,20 @@

int in_crash_kexec;

+/*
+ * This is used to VMCLEAR vmcss loaded on all
+ * cpus. And when loading kvm_intel module, the
+ * function pointer will be made valid.
+ */
+void (*crash_clear_loaded_vmcss)(void) = NULL;
+EXPORT_SYMBOL_GPL(crash_clear_loaded_vmcss);
+
+static void cpu_emergency_clear_loaded_vmcss(void)
+{
+ if (crash_clear_loaded_vmcss)
+ crash_clear_loaded_vmcss();
+}
+
#if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)

static void kdump_nmi_callback(int cpu, struct pt_regs *regs)
@@ -46,6 +61,11 @@ static void kdump_nmi_callback(int cpu, struct pt_regs *regs)
#endif
crash_save_cpu(regs, cpu);

+ /*
+ * VMCLEAR vmcss loaded on all cpus if needed.
+ */
+ cpu_emergency_clear_loaded_vmcss();
+
/* Disable VMX or SVM if needed.
*
* We need to disable virtualization on all CPUs.
@@ -88,6 +108,11 @@ void native_machine_crash_shutdown(struct pt_regs *regs)

kdump_nmi_shootdown_cpus();

+ /*
+ * VMCLEAR vmcss loaded on this cpu if needed.
+ */
+ cpu_emergency_clear_loaded_vmcss();
+
/* Booting kdump kernel with VMX or SVM enabled won't work,
* because (among other limitations) we can't disable paging
* with the virt flags.
--
1.7.1