In the past it used to point to 'sidt' (native_store_idt) operation
which is a non-privileged operation. This resulted in the
'struct desc_ptr' value containing the address of Xen's IDT table,
instead of the IDT table that Linux thinks its using. The end result
is that doing:
store_idt(&desc);
load_idt(&desc);
would blow up b/c xen_load_idt would try to parse the IDT contents
(desc) and de-reference a virtual address that is outside Linux's
__va (it is in Xen's virtual address).
With this patch we are providing the last written IDT address.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
arch/x86/xen/enlighten.c | 8 +++++++-
1 files changed, 7 insertions(+), 1 deletions(-)
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index e3497f2..f29d6d6 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -777,7 +777,13 @@ static void xen_load_idt(const struct desc_ptr *desc)
spin_unlock(&lock);
}
+static void xen_store_idt(struct desc_ptr *dtr)
+{
+ const struct desc_ptr *desc = &__get_cpu_var(idt_desc);
+ dtr->address = desc->address;
+ dtr->size = desc->size;
+}
/* Write a GDT descriptor entry. Ignore LDT descriptors, since
they're handled differently. */
static void xen_write_gdt_entry(struct desc_struct *dt, int entry,
@@ -1200,7 +1206,7 @@ static const struct pv_cpu_ops xen_cpu_ops __initconst = {
.free_ldt = xen_free_ldt,
.store_gdt = native_store_gdt,
- .store_idt = native_store_idt,
+ .store_idt = xen_store_idt,
.store_tr = xen_store_tr,
.write_ldt_entry = xen_write_ldt_entry,
--
1.7.7.6
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