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authorRusty Russell <rusty@rustcorp.com.au>2009-04-19 23:14:00 -0600
committerRusty Russell <rusty@rustcorp.com.au>2009-04-19 23:14:01 +0930
commita489f0b555b753f9df8ddc24c7e74f657ef7ee7b (patch)
tree560bd8c56524b658eb0b46e03ef42e262eb5f9b7 /arch/x86
parent88df781afb788fa588dbf2e77f205214022a8893 (diff)
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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
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/include/asm/lguest_hcall.h2
-rw-r--r--arch/x86/lguest/boot.c16
2 files changed, 10 insertions, 8 deletions
diff --git a/arch/x86/include/asm/lguest_hcall.h b/arch/x86/include/asm/lguest_hcall.h
index 0f4ee7148af..faae1996487 100644
--- a/arch/x86/include/asm/lguest_hcall.h
+++ b/arch/x86/include/asm/lguest_hcall.h
@@ -5,7 +5,6 @@
#define LHCALL_FLUSH_ASYNC 0
#define LHCALL_LGUEST_INIT 1
#define LHCALL_SHUTDOWN 2
-#define LHCALL_LOAD_GDT 3
#define LHCALL_NEW_PGTABLE 4
#define LHCALL_FLUSH_TLB 5
#define LHCALL_LOAD_IDT_ENTRY 6
@@ -17,6 +16,7 @@
#define LHCALL_SET_PMD 15
#define LHCALL_LOAD_TLS 16
#define LHCALL_NOTIFY 17
+#define LHCALL_LOAD_GDT_ENTRY 18
#define LGUEST_TRAP_ENTRY 0x1F
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index e94a11e42f9..a2085368a3d 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -273,15 +273,15 @@ static void lguest_load_idt(const struct desc_ptr *desc)
* controls the entire thing and the Guest asks it to make changes using the
* LOAD_GDT hypercall.
*
- * This is the opposite of the IDT code where we have a LOAD_IDT_ENTRY
- * hypercall and use that repeatedly to load a new IDT. I don't think it
- * really matters, but wouldn't it be nice if they were the same? Wouldn't
- * it be even better if you were the one to send the patch to fix it?
+ * This is the exactly like the IDT code.
*/
static void lguest_load_gdt(const struct desc_ptr *desc)
{
- BUG_ON((desc->size + 1) / 8 != GDT_ENTRIES);
- kvm_hypercall2(LHCALL_LOAD_GDT, __pa(desc->address), GDT_ENTRIES);
+ unsigned int i;
+ struct desc_struct *gdt = (void *)desc->address;
+
+ for (i = 0; i < (desc->size+1)/8; i++)
+ kvm_hypercall3(LHCALL_LOAD_GDT_ENTRY, i, gdt[i].a, gdt[i].b);
}
/* For a single GDT entry which changes, we do the lazy thing: alter our GDT,
@@ -291,7 +291,9 @@ static void lguest_write_gdt_entry(struct desc_struct *dt, int entrynum,
const void *desc, int type)
{
native_write_gdt_entry(dt, entrynum, desc, type);
- kvm_hypercall2(LHCALL_LOAD_GDT, __pa(dt), GDT_ENTRIES);
+ /* Tell Host about this new entry. */
+ kvm_hypercall3(LHCALL_LOAD_GDT_ENTRY, entrynum,
+ dt[entrynum].a, dt[entrynum].b);
}
/* OK, I lied. There are three "thread local storage" GDT entries which change