powerpc/powernv: Fixes for hypervisor doorbell handling

Since we can now use hypervisor doorbells for host IPIs, this makes
sure we clear the host IPI flag when taking a doorbell interrupt, and
clears any pending doorbell IPI in pnv_smp_cpu_kill_self() (as we
already do for IPIs sent via the XICS interrupt controller).  Otherwise
if there did happen to be a leftover pending doorbell interrupt for
an offline CPU thread for any reason, it would prevent that thread from
going into a power-saving mode; it would instead keep waking up because
of the interrupt.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

4 files changed, 20 insertions, 2 deletions

diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
index 03cd858a401c..4cbe23af400a 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -153,6 +153,7 @@
 #define PPC_INST_MFSPR_PVR_MASK         0xfc1fffff
 #define PPC_INST_MFTMR                  0x7c0002dc
 #define PPC_INST_MSGSND                 0x7c00019c
+#define PPC_INST_MSGCLR                 0x7c0001dc
 #define PPC_INST_MSGSNDP                0x7c00011c
 #define PPC_INST_MTTMR                  0x7c0003dc
 #define PPC_INST_NOP                    0x60000000
@@ -309,6 +310,8 @@
                                         ___PPC_RB(b) | __PPC_EH(eh))
 #define PPC_MSGSND(b)           stringify_in_c(.long PPC_INST_MSGSND | \
                                         ___PPC_RB(b))
+#define PPC_MSGCLR(b)           stringify_in_c(.long PPC_INST_MSGCLR | \
+                                        ___PPC_RB(b))
 #define PPC_MSGSNDP(b)          stringify_in_c(.long PPC_INST_MSGSNDP | \
                                         ___PPC_RB(b))
 #define PPC_POPCNTB(a, s)       stringify_in_c(.long PPC_INST_POPCNTB | \
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 1c874fb533bb..af56b5c6c81a 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -608,13 +608,16 @@
 #define   SRR1_ISI_N_OR_G       0x10000000 /* ISI: Access is no-exec or G */
 #define   SRR1_ISI_PROT         0x08000000 /* ISI: Other protection fault */
 #define   SRR1_WAKEMASK         0x00380000 /* reason for wakeup */
+#define   SRR1_WAKEMASK_P8      0x003c0000 /* reason for wakeup on POWER8 */
 #define   SRR1_WAKESYSERR       0x00300000 /* System error */
 #define   SRR1_WAKEEE           0x00200000 /* External interrupt */
 #define   SRR1_WAKEMT           0x00280000 /* mtctrl */
 #define   SRR1_WAKEHMI          0x00280000 /* Hypervisor maintenance */
 #define   SRR1_WAKEDEC          0x00180000 /* Decrementer interrupt */
+#define   SRR1_WAKEDBELL        0x00140000 /* Privileged doorbell on P8 */
 #define   SRR1_WAKETHERM        0x00100000 /* Thermal management interrupt */
 #define   SRR1_WAKERESET        0x00100000 /* System reset */
+#define   SRR1_WAKEHDBELL       0x000c0000 /* Hypervisor doorbell on P8 */
 #define   SRR1_WAKESTATE        0x00030000 /* Powersave exit mask [46:47] */
 #define   SRR1_WS_DEEPEST       0x00030000 /* Some resources not maintained,
                                           * may not be recoverable */
diff --git a/arch/powerpc/kernel/dbell.c b/arch/powerpc/kernel/dbell.c
index f4217819cc31..2128f3a96c32 100644
--- a/arch/powerpc/kernel/dbell.c
+++ b/arch/powerpc/kernel/dbell.c
@@ -17,6 +17,7 @@
 
 #include <asm/dbell.h>
 #include <asm/irq_regs.h>
+#include <asm/kvm_ppc.h>
 
 #ifdef CONFIG_SMP
 void doorbell_setup_this_cpu(void)
@@ -41,6 +42,7 @@ void doorbell_exception(struct pt_regs *regs)
 
         may_hard_irq_enable();
 
+        kvmppc_set_host_ipi(smp_processor_id(), 0);
         __this_cpu_inc(irq_stat.doorbell_irqs);
 
         smp_ipi_demux();
diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c
index fc34025ef822..38a45088f633 100644
--- a/arch/powerpc/platforms/powernv/smp.c
+++ b/arch/powerpc/platforms/powernv/smp.c
@@ -33,6 +33,8 @@
 #include <asm/runlatch.h>
 #include <asm/code-patching.h>
 #include <asm/dbell.h>
+#include <asm/kvm_ppc.h>
+#include <asm/ppc-opcode.h>
 
 #include "powernv.h"
 
@@ -149,7 +151,7 @@ static int pnv_smp_cpu_disable(void)
 static void pnv_smp_cpu_kill_self(void)
 {
         unsigned int cpu;
-        unsigned long srr1;
+        unsigned long srr1, wmask;
         u32 idle_states;
 
         /* Standard hot unplug procedure */
@@ -161,6 +163,10 @@ static void pnv_smp_cpu_kill_self(void)
         generic_set_cpu_dead(cpu);
         smp_wmb();
 
+        wmask = SRR1_WAKEMASK;
+        if (cpu_has_feature(CPU_FTR_ARCH_207S))
+                wmask = SRR1_WAKEMASK_P8;
+
         idle_states = pnv_get_supported_cpuidle_states();
         /* We don't want to take decrementer interrupts while we are offline,
          * so clear LPCR:PECE1. We keep PECE2 enabled.
@@ -191,10 +197,14 @@ static void pnv_smp_cpu_kill_self(void)
                  * having finished executing in a KVM guest, then srr1
                  * contains 0.
                  */
-                if ((srr1 & SRR1_WAKEMASK) == SRR1_WAKEEE) {
+                if ((srr1 & wmask) == SRR1_WAKEEE) {
                         icp_native_flush_interrupt();
                         local_paca->irq_happened &= PACA_IRQ_HARD_DIS;
                         smp_mb();
+                } else if ((srr1 & wmask) == SRR1_WAKEHDBELL) {
+                        unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER);
+                        asm volatile(PPC_MSGCLR(%0) : : "r" (msg));
+                        kvmppc_set_host_ipi(cpu, 0);
                 }
 
                 if (cpu_core_split_required())