[PATCH v1] KVM: PPC: Book3S HV P9: implement kvmppc_xive_pull_vcpu in C

[Nicholas Piggin]

This is more symmetric with kvmppc_xive_push_vcpu, and has the advantage
that it runs with the MMU on.

The extra test added to the asm will go away with a future change.

Reviewed-by: Cédric Le Goater <clg at kaod.org>
Reviewed-by: Alexey Kardashevskiy <aik at ozlabs.ru>
Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
---
Another bit that came from the KVM Cify series.

Thanks,
Nick

 arch/powerpc/include/asm/kvm_ppc.h      |  2 ++
 arch/powerpc/kvm/book3s_hv.c            |  2 ++
 arch/powerpc/kvm/book3s_hv_rmhandlers.S |  5 ++++
 arch/powerpc/kvm/book3s_xive.c          | 31 +++++++++++++++++++++++++
 4 files changed, 40 insertions(+)

diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index 9531b1c1b190..73b1ca5a6471 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -672,6 +672,7 @@ extern int kvmppc_xive_set_icp(struct kvm_vcpu *vcpu, u64 icpval);
 extern int kvmppc_xive_set_irq(struct kvm *kvm, int irq_source_id, u32 irq,
 			       int level, bool line_status);
 extern void kvmppc_xive_push_vcpu(struct kvm_vcpu *vcpu);
+extern void kvmppc_xive_pull_vcpu(struct kvm_vcpu *vcpu);
 
 static inline int kvmppc_xive_enabled(struct kvm_vcpu *vcpu)
 {
@@ -712,6 +713,7 @@ static inline int kvmppc_xive_set_icp(struct kvm_vcpu *vcpu, u64 icpval) { retur
 static inline int kvmppc_xive_set_irq(struct kvm *kvm, int irq_source_id, u32 irq,
 				      int level, bool line_status) { return -ENODEV; }
 static inline void kvmppc_xive_push_vcpu(struct kvm_vcpu *vcpu) { }
+static inline void kvmppc_xive_pull_vcpu(struct kvm_vcpu *vcpu) { }
 
 static inline int kvmppc_xive_enabled(struct kvm_vcpu *vcpu)
 	{ return 0; }
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 4a532410e128..981bcaf787a8 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -3570,6 +3570,8 @@ static int kvmhv_load_hv_regs_and_go(struct kvm_vcpu *vcpu, u64 time_limit,
 
 	trap = __kvmhv_vcpu_entry_p9(vcpu);
 
+	kvmppc_xive_pull_vcpu(vcpu);
+
 	/* Advance host PURR/SPURR by the amount used by guest */
 	purr = mfspr(SPRN_PURR);
 	spurr = mfspr(SPRN_SPURR);
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 75405ef53238..c11597f815e4 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -1442,6 +1442,11 @@ guest_exit_cont:		/* r9 = vcpu, r12 = trap, r13 = paca */
 	bl	kvmhv_accumulate_time
 #endif
 #ifdef CONFIG_KVM_XICS
+	/* If we came in through the P9 short path, xive pull is done in C */
+	lwz	r0, STACK_SLOT_SHORT_PATH(r1)
+	cmpwi	r0, 0
+	bne	1f
+
 	/* We are exiting, pull the VP from the XIVE */
 	lbz	r0, VCPU_XIVE_PUSHED(r9)
 	cmpwi	cr0, r0, 0
diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
index e7219b6f5f9a..741bf1f4387a 100644
--- a/arch/powerpc/kvm/book3s_xive.c
+++ b/arch/powerpc/kvm/book3s_xive.c
@@ -127,6 +127,37 @@ void kvmppc_xive_push_vcpu(struct kvm_vcpu *vcpu)
 }
 EXPORT_SYMBOL_GPL(kvmppc_xive_push_vcpu);
 
+/*
+ * Pull a vcpu's context from the XIVE on guest exit.
+ * This assumes we are in virtual mode (MMU on)
+ */
+void kvmppc_xive_pull_vcpu(struct kvm_vcpu *vcpu)
+{
+	void __iomem *tima = local_paca->kvm_hstate.xive_tima_virt;
+
+	if (!vcpu->arch.xive_pushed)
+		return;
+
+	/*
+	 * Should not have been pushed if there is no tima
+	 */
+	if (WARN_ON(!tima))
+		return;
+
+	eieio();
+	/* First load to pull the context, we ignore the value */
+	__raw_readl(tima + TM_SPC_PULL_OS_CTX);
+	/* Second load to recover the context state (Words 0 and 1) */
+	vcpu->arch.xive_saved_state.w01 = __raw_readq(tima + TM_QW1_OS);
+
+	/* Fixup some of the state for the next load */
+	vcpu->arch.xive_saved_state.lsmfb = 0;
+	vcpu->arch.xive_saved_state.ack = 0xff;
+	vcpu->arch.xive_pushed = 0;
+	eieio();
+}
+EXPORT_SYMBOL_GPL(kvmppc_xive_pull_vcpu);
+
 /*
  * This is a simple trigger for a generic XIVE IRQ. This must
  * only be called for interrupts that support a trigger page
-- 
2.23.0