Re: [PATCH v3 19/41] KVM: PPC: Book3S HV P9: Stop handling hcalls in real-mode in the P9 path

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 497f216ad724..1f2ba8955c6a 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c

@@ -1147,7 +1147,7 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu)
  * This has to be done early, not in kvmppc_pseries_do_hcall(), so
  * that the cede logic in kvmppc_run_single_vcpu() works properly.
  */
-static void kvmppc_nested_cede(struct kvm_vcpu *vcpu)
+static void kvmppc_cede(struct kvm_vcpu *vcpu)

 {
 	vcpu->arch.shregs.msr |= MSR_EE;
 	vcpu->arch.ceded = 1;

@@ -1403,9 +1403,15 @@ static int kvmppc_handle_exit_hv(struct kvm_vcpu *vcpu,
 		/* hcall - punt to userspace */
 		int i;

-		/* hypercall with MSR_PR has already been handled in rmode,
-		 * and never reaches here.
-		 */
+		if (unlikely(vcpu->arch.shregs.msr & MSR_PR)) {
+			/*
+			 * Guest userspace executed sc 1, reflect it back as a
+			 * privileged program check interrupt.
+			 */
+			kvmppc_core_queue_program(vcpu, SRR1_PROGPRIV);
+			r = RESUME_GUEST;
+			break;
+		}

 		run->papr_hcall.nr = kvmppc_get_gpr(vcpu, 3);
 		for (i = 0; i < 9; ++i)

@@ -3740,15 +3746,36 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit,
 		/* H_CEDE has to be handled now, not later */
 		if (trap == BOOK3S_INTERRUPT_SYSCALL && !vcpu->arch.nested &&
 		    kvmppc_get_gpr(vcpu, 3) == H_CEDE) {
-			kvmppc_nested_cede(vcpu);
+			kvmppc_cede(vcpu);
 			kvmppc_set_gpr(vcpu, 3, 0);
 			trap = 0;
 		}
 	} else {
 		kvmppc_xive_push_vcpu(vcpu);
 		trap = kvmhv_load_hv_regs_and_go(vcpu, time_limit, lpcr);
-		kvmppc_xive_pull_vcpu(vcpu);
+		/* H_CEDE has to be handled now, not later */
+		/* XICS hcalls must be handled before xive is pulled */
+		if (trap == BOOK3S_INTERRUPT_SYSCALL &&
+		    !(vcpu->arch.shregs.msr & MSR_PR)) {
+			unsigned long req = kvmppc_get_gpr(vcpu, 3);

+			if (req == H_CEDE) {
+				kvmppc_cede(vcpu);
+				kvmppc_xive_cede_vcpu(vcpu); /* may un-cede */
+				kvmppc_set_gpr(vcpu, 3, 0);
+				trap = 0;
+			}
+			if (req == H_EOI || req == H_CPPR ||
+			    req == H_IPI || req == H_IPOLL ||
+			    req == H_XIRR || req == H_XIRR_X) {
+				unsigned long ret;
+
+				ret = kvmppc_xive_xics_hcall(vcpu, req);
+				kvmppc_set_gpr(vcpu, 3, ret);
+				trap = 0;
+			}
+		}

+		kvmppc_xive_pull_vcpu(vcpu);
 	}

 	vcpu->arch.slb_max = 0;

@@ -4408,8 +4435,11 @@ static int kvmppc_vcpu_run_hv(struct kvm_vcpu *vcpu)
 		else
 			r = kvmppc_run_vcpu(vcpu);

-		if (run->exit_reason == KVM_EXIT_PAPR_HCALL &&
-		    !(vcpu->arch.shregs.msr & MSR_PR)) {
+		if (run->exit_reason == KVM_EXIT_PAPR_HCALL) {
+			if (WARN_ON_ONCE(vcpu->arch.shregs.msr & MSR_PR)) {
+				r = RESUME_GUEST;
+				continue;
+			}
 			trace_kvm_hcall_enter(vcpu);
 			r = kvmppc_pseries_do_hcall(vcpu);
 			trace_kvm_hcall_exit(vcpu, r);

diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index c11597f815e4..2d0d14ed1d92 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S

@@ -1397,9 +1397,14 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 	mr	r4,r9
 	bge	fast_guest_return
 2:
+	/* If we came in through the P9 short path, no real mode hcalls */
+	lwz	r0, STACK_SLOT_SHORT_PATH(r1)
+	cmpwi	r0, 0
+	bne	no_try_real
 	/* See if this is an hcall we can handle in real mode */
 	cmpwi	r12,BOOK3S_INTERRUPT_SYSCALL
 	beq	hcall_try_real_mode
+no_try_real:

 	/* Hypervisor doorbell - exit only if host IPI flag set */
 	cmpwi	r12, BOOK3S_INTERRUPT_H_DOORBELL

diff --git a/arch/powerpc/kvm/book3s_xive.c b/arch/powerpc/kvm/book3s_xive.c
index 52cdb9e2660a..1e4871bbcad4 100644
--- a/arch/powerpc/kvm/book3s_xive.c
+++ b/arch/powerpc/kvm/book3s_xive.c

@@ -158,6 +158,40 @@ void kvmppc_xive_pull_vcpu(struct kvm_vcpu *vcpu)
 }
 EXPORT_SYMBOL_GPL(kvmppc_xive_pull_vcpu);

+void kvmppc_xive_cede_vcpu(struct kvm_vcpu *vcpu)
+{
+	void __iomem *esc_vaddr = (void __iomem *)vcpu->arch.xive_esc_vaddr;
+
+	if (!esc_vaddr)
+		return;
+
+	/* we are using XIVE with single escalation */
+
+	if (vcpu->arch.xive_esc_on) {
+		/*
+		 * If we still have a pending escalation, abort the cede,
+		 * and we must set PQ to 10 rather than 00 so that we don't
+		 * potentially end up with two entries for the escalation
+		 * interrupt in the XIVE interrupt queue.  In that case
+		 * we also don't want to set xive_esc_on to 1 here in
+		 * case we race with xive_esc_irq().
+		 */
+		vcpu->arch.ceded = 0;
+		/*
+		 * The escalation interrupts are special as we don't EOI them.
+		 * There is no need to use the load-after-store ordering offset
+		 * to set PQ to 10 as we won't use StoreEOI.
+		 */
+		__raw_readq(esc_vaddr + XIVE_ESB_SET_PQ_10);
+	} else {
+		vcpu->arch.xive_esc_on = true;
+		mb();
+		__raw_readq(esc_vaddr + XIVE_ESB_SET_PQ_00);
+	}
+	mb();
+}
+EXPORT_SYMBOL_GPL(kvmppc_xive_cede_vcpu);
+
 /*
  * This is a simple trigger for a generic XIVE IRQ. This must
  * only be called for interrupts that support a trigger page

@@ -2106,6 +2140,32 @@ static int kvmppc_xive_create(struct kvm_device *dev, u32 type)
 	return 0;
 }

+int kvmppc_xive_xics_hcall(struct kvm_vcpu *vcpu, u32 req)
+{
+	struct kvmppc_vcore *vc = vcpu->arch.vcore;
+
+	switch (req) {
+	case H_XIRR:
+		return xive_vm_h_xirr(vcpu);
+	case H_CPPR:
+		return xive_vm_h_cppr(vcpu, kvmppc_get_gpr(vcpu, 4));
+	case H_EOI:
+		return xive_vm_h_eoi(vcpu, kvmppc_get_gpr(vcpu, 4));
+	case H_IPI:
+		return xive_vm_h_ipi(vcpu, kvmppc_get_gpr(vcpu, 4),
+					  kvmppc_get_gpr(vcpu, 5));
+	case H_IPOLL:
+		return xive_vm_h_ipoll(vcpu, kvmppc_get_gpr(vcpu, 4));
+	case H_XIRR_X:
+		xive_vm_h_xirr(vcpu);
+		kvmppc_set_gpr(vcpu, 5, get_tb() + vc->tb_offset);
+		return H_SUCCESS;
+	}
+
+	return H_UNSUPPORTED;
+}
+EXPORT_SYMBOL_GPL(kvmppc_xive_xics_hcall);
+
 int kvmppc_xive_debug_show_queues(struct seq_file *m, struct kvm_vcpu *vcpu)
 {
 	struct kvmppc_xive_vcpu *xc = vcpu->arch.xive_vcpu;