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-rw-r--r--arch/x86/include/asm/xen/hypervisor.h2
-rw-r--r--arch/x86/kernel/process_64.c12
-rw-r--r--arch/x86/xen/enlighten.c2
3 files changed, 15 insertions, 1 deletions
diff --git a/arch/x86/include/asm/xen/hypervisor.h b/arch/x86/include/asm/xen/hypervisor.h
index 8b2d4be..39171b3 100644
--- a/arch/x86/include/asm/xen/hypervisor.h
+++ b/arch/x86/include/asm/xen/hypervisor.h
@@ -62,4 +62,6 @@ void xen_arch_register_cpu(int num);
void xen_arch_unregister_cpu(int num);
#endif
+extern void xen_set_iopl_mask(unsigned mask);
+
#endif /* _ASM_X86_XEN_HYPERVISOR_H */
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index b9d99e0..9f75187 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -48,6 +48,7 @@
#include <asm/syscalls.h>
#include <asm/debugreg.h>
#include <asm/switch_to.h>
+#include <asm/xen/hypervisor.h>
asmlinkage extern void ret_from_fork(void);
@@ -411,6 +412,17 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV))
__switch_to_xtra(prev_p, next_p, tss);
+#ifdef CONFIG_XEN
+ /*
+ * On Xen PV, IOPL bits in pt_regs->flags have no effect, and
+ * current_pt_regs()->flags may not match the current task's
+ * intended IOPL. We need to switch it manually.
+ */
+ if (unlikely(static_cpu_has(X86_FEATURE_XENPV) &&
+ prev->iopl != next->iopl))
+ xen_set_iopl_mask(next->iopl);
+#endif
+
if (static_cpu_has_bug(X86_BUG_SYSRET_SS_ATTRS)) {
/*
* AMD CPUs have a misfeature: SYSRET sets the SS selector but
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 2c26108..8381fb9 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -961,7 +961,7 @@ static void xen_load_sp0(struct tss_struct *tss,
tss->x86_tss.sp0 = thread->sp0;
}
-static void xen_set_iopl_mask(unsigned mask)
+void xen_set_iopl_mask(unsigned mask)
{
struct physdev_set_iopl set_iopl;
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