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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2016-04-16 15:30:54 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2016-04-16 15:30:54 -0300
commitbdcfd44fb5b5fb8fd660e7f93f1095c507481024 (patch)
treee423b07154d422b711ddfadedb87c43317d3c4f6 /arch/x86/kernel/process_64.c
parent4a327fcef90ba27150a3e8741441b68c605ae248 (diff)
Linux-libre 4.5.1-gnupck-4.5.1-gnu
Diffstat (limited to 'arch/x86/kernel/process_64.c')
-rw-r--r--arch/x86/kernel/process_64.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index b9d99e0f8..9f7518760 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