Merge tag 'driver-core-4.9-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git...

[cascardo/linux.git] / arch / powerpc / kernel / idle_book3s.S

diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S
index bd739fe..72dac0b 100644 (file)
--- a/arch/powerpc/kernel/idle_book3s.S
+++ b/arch/powerpc/kernel/idle_book3s.S
@@ -90,6 +90,7 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_ARCH_300)
  * Threads will spin in HMT_LOW until the lock bit is cleared.
  * r14 - pointer to core_idle_state
  * r15 - used to load contents of core_idle_state
+ * r9  - used as a temporary variable
  */
 
 core_idle_lock_held:
@@ -99,6 +100,8 @@ core_idle_lock_held:
        bne     3b
        HMT_MEDIUM
        lwarx   r15,0,r14
+       andi.   r9,r15,PNV_CORE_IDLE_LOCK_BIT
+       bne     core_idle_lock_held
        blr
 
 /*
@@ -163,12 +166,6 @@ _GLOBAL(pnv_powersave_common)
        std     r9,_MSR(r1)
        std     r1,PACAR1(r13)
 
-#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
-       /* Tell KVM we're entering idle */
-       li      r4,KVM_HWTHREAD_IN_IDLE
-       stb     r4,HSTATE_HWTHREAD_STATE(r13)
-#endif
-
        /*
         * Go to real mode to do the nap, as required by the architecture.
         * Also, we need to be in real mode before setting hwthread_state,
@@ -185,6 +182,26 @@ _GLOBAL(pnv_powersave_common)
 
        .globl pnv_enter_arch207_idle_mode
 pnv_enter_arch207_idle_mode:
+#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
+       /* Tell KVM we're entering idle */
+       li      r4,KVM_HWTHREAD_IN_IDLE
+       /******************************************************/
+       /*  N O T E   W E L L    ! ! !    N O T E   W E L L   */
+       /* The following store to HSTATE_HWTHREAD_STATE(r13)  */
+       /* MUST occur in real mode, i.e. with the MMU off,    */
+       /* and the MMU must stay off until we clear this flag */
+       /* and test HSTATE_HWTHREAD_REQ(r13) in the system    */
+       /* reset interrupt vector in exceptions-64s.S.        */
+       /* The reason is that another thread can switch the   */
+       /* MMU to a guest context whenever this flag is set   */
+       /* to KVM_HWTHREAD_IN_IDLE, and if the MMU was on,    */
+       /* that would potentially cause this thread to start  */
+       /* executing instructions from guest memory in        */
+       /* hypervisor mode, leading to a host crash or data   */
+       /* corruption, or worse.                              */
+       /******************************************************/
+       stb     r4,HSTATE_HWTHREAD_STATE(r13)
+#endif
        stb     r3,PACA_THREAD_IDLE_STATE(r13)
        cmpwi   cr3,r3,PNV_THREAD_SLEEP
        bge     cr3,2f
@@ -250,6 +267,12 @@ enter_winkle:
  * r3 - requested stop state
  */
 power_enter_stop:
+#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
+       /* Tell KVM we're entering idle */
+       li      r4,KVM_HWTHREAD_IN_IDLE
+       /* DO THIS IN REAL MODE!  See comment above. */
+       stb     r4,HSTATE_HWTHREAD_STATE(r13)
+#endif
 /*
  * Check if the requested state is a deep idle state.
  */