Messages in this thread Patch in this message |  | | From | Konrad Rzeszutek Wilk <> | Subject | [PATCH 2/4] xen/lowlevel: Implement pvop call for load_idt (sidt). | Date | Wed, 17 Oct 2012 09:49:44 -0400 |
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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@oracle.com> --- 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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