Re: [PATCH v4 3/3] KVM: PPC: epapr: install ev_idle hcall for e500 guest

On 02/16/2012 04:24 AM, Alexander Graf wrote:

On 16.02.2012, at 10:26, Liu Yu [off-list ref] wrote:

quoted

+_GLOBAL(epapr_ev_idle)
+epapr_ev_idle:
+    rlwinm    r3,r1,0,0,31-THREAD_SHIFT    /* current thread_info */
+    lwz    r4,TI_LOCAL_FLAGS(r3)    /* set napping bit */
+    ori    r4,r4,_TLF_NAPPING    /* so when we take an exception */
+    stw    r4,TI_LOCAL_FLAGS(r3)    /* it will return to our caller */
+
+    wrteei    1
+
+idle_loop:
+    LOAD_REG_IMMEDIATE(r11, HC_VENDOR_EPAPR | HC_EV_IDLE)
+
+.global epapr_ev_idle_start
+epapr_ev_idle_start:
+    li    r3, -1
+    nop
+    nop
+    nop

Can't you just bl into epapr_hypercall_start? You don't even have to save the old lr. because we never return anyways :)

The interrupt will branch to LR, so no, we can't trash it or put it
anywhere else.

-scott