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authorAvi Kivity <avi@qumranet.com>2008-05-13 13:23:38 +0300
committerAvi Kivity <avi@qumranet.com>2008-07-20 12:41:43 +0300
commit4ecac3fd6dc2629ad76a658a486f081c44aef10e (patch)
treea078acb4c626432ac8cf887b911d912f4a316d06 /include/asm-x86
parent1b7fcd3263e5f12dba43d27b64e1578bec070c28 (diff)
KVM: Handle virtualization instruction #UD faults during reboot
KVM turns off hardware virtualization extensions during reboot, in order to disassociate the memory used by the virtualization extensions from the processor, and in order to have the system in a consistent state. Unfortunately virtual machines may still be running while this goes on, and once virtualization extensions are turned off, any virtulization instruction will #UD on execution. Fix by adding an exception handler to virtualization instructions; if we get an exception during reboot, we simply spin waiting for the reset to complete. If it's a true exception, BUG() so we can have our stack trace. Signed-off-by: Avi Kivity <avi@qumranet.com>
Diffstat (limited to 'include/asm-x86')
-rw-r--r--include/asm-x86/kvm_host.h24
1 files changed, 24 insertions, 0 deletions
diff --git a/include/asm-x86/kvm_host.h b/include/asm-x86/kvm_host.h
index c2d066e185f4..0df9d5fa281a 100644
--- a/include/asm-x86/kvm_host.h
+++ b/include/asm-x86/kvm_host.h
@@ -692,4 +692,28 @@ enum {
trace_mark(kvm_trace_##name, "%u %p %u %u %u %u %u %u", KVM_TRC_##evt, \
vcpu, 0, 0, 0, 0, 0, 0)
+#ifdef CONFIG_64BIT
+#define KVM_EX_ENTRY ".quad"
+#else
+#define KVM_EX_ENTRY ".long"
+#endif
+
+/*
+ * Hardware virtualization extension instructions may fault if a
+ * reboot turns off virtualization while processes are running.
+ * Trap the fault and ignore the instruction if that happens.
+ */
+asmlinkage void kvm_handle_fault_on_reboot(void);
+
+#define __kvm_handle_fault_on_reboot(insn) \
+ "666: " insn "\n\t" \
+ ".pushsection .text.fixup, \"ax\" \n" \
+ "667: \n\t" \
+ "push $666b \n\t" \
+ "jmp kvm_handle_fault_on_reboot \n\t" \
+ ".popsection \n\t" \
+ ".pushsection __ex_table, \"a\" \n\t" \
+ KVM_EX_ENTRY " 666b, 667b \n\t" \
+ ".popsection"
+
#endif