x86/paravirt: split sysret and sysexit
Don't conflate sysret and sysexit; they're different instructions with
different semantics, and may be in use at the same time (at least
within the same kernel, depending on whether its an Intel or AMD
system).
sysexit - just return to userspace, does no register restoration of
any kind; must explicitly atomically enable interrupts.
sysret - reloads flags from r11, so no need to explicitly enable
interrupts on 64-bit, responsible for restoring usermode %gs
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citirx.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/asm-x86/paravirt.h b/include/asm-x86/paravirt.h
index 82cdcde..2668903 100644
--- a/include/asm-x86/paravirt.h
+++ b/include/asm-x86/paravirt.h
@@ -141,8 +141,9 @@
u64 (*read_pmc)(int counter);
unsigned long long (*read_tscp)(unsigned int *aux);
- /* These two are jmp to, not actually called. */
- void (*irq_enable_syscall_ret)(void);
+ /* These three are jmp to, not actually called. */
+ void (*irq_enable_sysexit)(void);
+ void (*usersp_sysret)(void);
void (*iret)(void);
void (*swapgs)(void);
@@ -1480,10 +1481,10 @@
call PARA_INDIRECT(pv_irq_ops+PV_IRQ_irq_enable); \
PV_RESTORE_REGS;)
-#define ENABLE_INTERRUPTS_SYSCALL_RET \
- PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_irq_enable_syscall_ret),\
+#define ENABLE_INTERRUPTS_SYSEXIT \
+ PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_irq_enable_sysexit), \
CLBR_NONE, \
- jmp PARA_INDIRECT(pv_cpu_ops+PV_CPU_irq_enable_syscall_ret))
+ jmp PARA_INDIRECT(pv_cpu_ops+PV_CPU_irq_enable_sysexit))
#ifdef CONFIG_X86_32
@@ -1504,6 +1505,10 @@
movq %rax, %rcx; \
xorq %rax, %rax;
+#define USERSP_SYSRET \
+ PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_usersp_sysret), \
+ CLBR_NONE, \
+ jmp PARA_INDIRECT(pv_cpu_ops+PV_CPU_usersp_sysret))
#endif
#endif /* __ASSEMBLY__ */