lguest: fix guest crash on non-linear addresses in gdt pvops

Fixes guest crash 'lguest: bad read address 0x4800000 len 256'

The new per-cpu allocator ends up handing a non-linear address to
write_gdt_entry.  We do __pa() on it, and hand it to the host, which
kills us.

I've long wanted to make the hypercall "LOAD_GDT_ENTRY" to match the IDT
code, but had no pressing reason until now.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: lguest@ozlabs.org

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/lguest/x86/core.c b/drivers/lguest/x86/core.c
index d6d7ac0982ab..1a83910f674f 100644
--- a/drivers/lguest/x86/core.c
+++ b/drivers/lguest/x86/core.c
@@ -568,8 +568,8 @@ void __exit lguest_arch_host_fini(void)
 int lguest_arch_do_hcall(struct lg_cpu *cpu, struct hcall_args *args)
 {
         switch (args->arg0) {
-        case LHCALL_LOAD_GDT:
-                load_guest_gdt(cpu, args->arg1, args->arg2);
+        case LHCALL_LOAD_GDT_ENTRY:
+                load_guest_gdt_entry(cpu, args->arg1, args->arg2, args->arg3);
                 break;
         case LHCALL_LOAD_IDT_ENTRY:
                 load_guest_idt_entry(cpu, args->arg1, args->arg2, args->arg3);