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Subject[PATCH] lguest: fix on Intel when KVM loaded (unhandled trap 13)
Date
When KVM is loaded, and hence VT set up, the vmcall instruction in an
lguest guest causes a #GP, not #UD.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
drivers/lguest/x86/core.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/lguest/x86/core.c b/drivers/lguest/x86/core.c
--- a/drivers/lguest/x86/core.c
+++ b/drivers/lguest/x86/core.c
@@ -358,6 +358,16 @@ void lguest_arch_handle_trap(struct lg_c
if (emulate_insn(cpu))
return;
}
+ /* If KVM is active, the vmcall instruction triggers a
+ * General Protection Fault. Normally it triggers an
+ * invalid opcode fault (6): */
+ case 6:
+ /* We need to check if ring == GUEST_PL and
+ * faulting instruction == vmcall. */
+ if (is_hypercall(cpu)) {
+ rewrite_hypercall(cpu);
+ return;
+ }
break;
case 14: /* We've intercepted a Page Fault. */
/* The Guest accessed a virtual address that wasn't mapped.
@@ -403,15 +413,6 @@ void lguest_arch_handle_trap(struct lg_c
* up the pointer now to indicate a hypercall is pending. */
cpu->hcall = (struct hcall_args *)cpu->regs;
return;
- case 6:
- /* kvm hypercalls trigger an invalid opcode fault (6).
- * We need to check if ring == GUEST_PL and
- * faulting instruction == vmcall. */
- if (is_hypercall(cpu)) {
- rewrite_hypercall(cpu);
- return;
- }
- break;
}

/* We didn't handle the trap, so it needs to go to the Guest. */


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