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, 1 deletions

diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
index ac8a4a3741b8..af92a176697f 100644
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -158,7 +158,8 @@ void free_interrupts(void);
 /* segments.c: */
 void setup_default_gdt_entries(struct lguest_ro_state *state);
 void setup_guest_gdt(struct lg_cpu *cpu);
-void load_guest_gdt(struct lg_cpu *cpu, unsigned long table, u32 num);
+void load_guest_gdt_entry(struct lg_cpu *cpu, unsigned int i,
+                          u32 low, u32 hi);
 void guest_load_tls(struct lg_cpu *cpu, unsigned long tls_array);
 void copy_gdt(const struct lg_cpu *cpu, struct desc_struct *gdt);
 void copy_gdt_tls(const struct lg_cpu *cpu, struct desc_struct *gdt);