Subject: [RFC 06/11] powerpc: kvm: introduce online in paca to indicate whether cpu is needed by host

From: [email-masked]
Date: Thu, 16 Oct 2014 15:29:55 -0400

Nowadays, powerKVM runs with secondary hwthread offline. Although
we can make all secondary hwthread online later, we still preserve
this behavior for dedicated KVM env. Achieve this by setting
paca->online as false.

Signed-off-by: Liu Ping Fan <[email-masked]>
---
 arch/powerpc/include/asm/paca.h         |  3 +++
 arch/powerpc/kernel/asm-offsets.c       |  3 +++
 arch/powerpc/kernel/smp.c               |  3 +++
 arch/powerpc/kvm/book3s_hv_rmhandlers.S | 12 ++++++++++++
 4 files changed, 21 insertions(+)

diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index a5139ea..67c2500 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h
@@ -84,6 +84,9 @@ struct paca_struct {
 	u8 cpu_start;			/* At startup, processor spins until */
 					/* this becomes non-zero. */
 	u8 kexec_state;		/* set when kexec down has irqs off */
+#ifdef CONFIG_KVMPPC_ENABLE_SECONDARY
+	u8 online;
+#endif
 #ifdef CONFIG_PPC_STD_MMU_64
 	struct slb_shadow *slb_shadow_ptr;
 	struct dtl_entry *dispatch_log;
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 9d7dede..0faa8fe 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -182,6 +182,9 @@ int main(void)
 	DEFINE(PACATOC, offsetof(struct paca_struct, kernel_toc));
 	DEFINE(PACAKBASE, offsetof(struct paca_struct, kernelbase));
 	DEFINE(PACAKMSR, offsetof(struct paca_struct, kernel_msr));
+#ifdef CONFIG_KVMPPC_ENABLE_SECONDARY
+	DEFINE(PACAONLINE, offsetof(struct paca_struct, online));
+#endif
 	DEFINE(PACASOFTIRQEN, offsetof(struct paca_struct, soft_enabled));
 	DEFINE(PACAIRQHAPPENED, offsetof(struct paca_struct, irq_happened));
 	DEFINE(PACACONTEXTID, offsetof(struct paca_struct, context.id));
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index a0738af..4c3843e 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -736,6 +736,9 @@ void start_secondary(void *unused)
 
 	cpu_startup_entry(CPUHP_ONLINE);
 
+#ifdef CONFIG_KVMPPC_ENABLE_SECONDARY
+	get_paca()->online = true;
+#endif 
 	BUG();
 }
 
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index f0c4db7..d5594b0 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -322,6 +322,13 @@ kvm_no_guest:
 	li	r0, KVM_HWTHREAD_IN_NAP
 	stb	r0, HSTATE_HWTHREAD_STATE(r13)
 kvm_do_nap:
+#ifdef PPCKVM_ENABLE_SECONDARY
+	/* check the cpu is needed by host or not */
+	ld      r2, PACAONLINE(r13)
+	ld      r3, 0
+	cmp     r2, r3
+	bne     kvm_secondary_exit_trampoline
+#endif
 	/* Clear the runlatch bit before napping */
 	mfspr	r2, SPRN_CTRLF
 	clrrdi	r2, r2, 1
@@ -340,6 +347,11 @@ kvm_do_nap:
 	nap
 	b	.
 
+#ifdef PPCKVM_ENABLE_SECONDARY
+kvm_secondary_exit_trampoline:
+	b	.
+#endif
+
 /******************************************************************************
  *                                                                            *
  *                               Entry code                                   *
-- 
1.8.3.1