KVM: PPC: Book3S HV: Handle hypercalls correctly when nested

When we are running as a nested hypervisor, we use a hypercall to
enter the guest rather than code in book3s_hv_rmhandlers.S. This means
that the hypercall handlers listed in hcall_real_table never get called.
There are some hypercalls that are handled there and not in
kvmppc_pseries_do_hcall(), which therefore won't get processed for
a nested guest.

To fix this, we add cases to kvmppc_pseries_do_hcall() to handle those
hypercalls, with the following exceptions:

- The HPT hypercalls (H_ENTER, H_REMOVE, etc.) are not handled because
we only support radix mode for nested guests.

- H_CEDE has to be handled specially because the cede logic in
kvmhv_run_single_vcpu assumes that it has been processed by the time
that kvmhv_p9_guest_entry() returns. Therefore we put a special
case for H_CEDE in kvmhv_p9_guest_entry().

For the XICS hypercalls, if real-mode processing is enabled, then the
virtual-mode handlers assume that they are being called only to finish
up the operation. Therefore we turn off the real-mode flag in the XICS
code when running as a nested hypervisor.

Reviewed-by: David Gibson <[e-mail]>
Signed-off-by: Paul Mackerras <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>

arch/powerpc/include/asm/asm-prototypes.h

···
 
 int __kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu);
 
+long kvmppc_h_set_dabr(struct kvm_vcpu *vcpu, unsigned long dabr);
+long kvmppc_h_set_xdabr(struct kvm_vcpu *vcpu, unsigned long dabr,
+			unsigned long dabrx);
+
 #endif /* _ASM_POWERPC_ASM_PROTOTYPES_H */

arch/powerpc/kvm/book3s_hv.c

···
 #include <asm/reg.h>
 #include <asm/ppc-opcode.h>
 #include <asm/asm-prototypes.h>
+#include <asm/archrandom.h>
 #include <asm/debug.h>
 #include <asm/disassemble.h>
 #include <asm/cputable.h>
···
 			break;
 		}
 		return RESUME_HOST;
+	case H_SET_DABR:
+		ret = kvmppc_h_set_dabr(vcpu, kvmppc_get_gpr(vcpu, 4));
+		break;
+	case H_SET_XDABR:
+		ret = kvmppc_h_set_xdabr(vcpu, kvmppc_get_gpr(vcpu, 4),
+						kvmppc_get_gpr(vcpu, 5));
+		break;
+	case H_GET_TCE:
+		ret = kvmppc_h_get_tce(vcpu, kvmppc_get_gpr(vcpu, 4),
+						kvmppc_get_gpr(vcpu, 5));
+		if (ret == H_TOO_HARD)
+			return RESUME_HOST;
+		break;
 	case H_PUT_TCE:
 		ret = kvmppc_h_put_tce(vcpu, kvmppc_get_gpr(vcpu, 4),
 						kvmppc_get_gpr(vcpu, 5),
···
 						kvmppc_get_gpr(vcpu, 7));
 		if (ret == H_TOO_HARD)
 			return RESUME_HOST;
+		break;
+	case H_RANDOM:
+		if (!powernv_get_random_long(&vcpu->arch.regs.gpr[4]))
+			ret = H_HARDWARE;
 		break;
 
 	case H_SET_PARTITION_TABLE:
···
 	kvmppc_set_gpr(vcpu, 3, ret);
 	vcpu->arch.hcall_needed = 0;
 	return RESUME_GUEST;
+}
+
+/*
+ * Handle H_CEDE in the nested virtualization case where we haven't
+ * called the real-mode hcall handlers in book3s_hv_rmhandlers.S.
+ * 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)
+{
+	vcpu->arch.shregs.msr |= MSR_EE;
+	vcpu->arch.ceded = 1;
+	smp_mb();
+	if (vcpu->arch.prodded) {
+		vcpu->arch.prodded = 0;
+		smp_mb();
+		vcpu->arch.ceded = 0;
+	}
 }
 
 static int kvmppc_hcall_impl_hv(unsigned long cmd)
···
 		vcpu->arch.shregs.msr = vcpu->arch.regs.msr;
 		vcpu->arch.shregs.dar = mfspr(SPRN_DAR);
 		vcpu->arch.shregs.dsisr = mfspr(SPRN_DSISR);
+
+		/* 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);
+			trap = 0;
+		}
 	} else {
 		trap = kvmhv_load_hv_regs_and_go(vcpu, time_limit, lpcr);
 	}

arch/powerpc/kvm/book3s_hv_rmhandlers.S

···
 hcall_real_table_end:
 
 _GLOBAL(kvmppc_h_set_xdabr)
+EXPORT_SYMBOL_GPL(kvmppc_h_set_xdabr)
 	andi.	r0, r5, DABRX_USER | DABRX_KERNEL
 	beq	6f
 	li	r0, DABRX_USER | DABRX_KERNEL | DABRX_BTI
···
 	blr
 
 _GLOBAL(kvmppc_h_set_dabr)
+EXPORT_SYMBOL_GPL(kvmppc_h_set_dabr)
 	li	r5, DABRX_USER | DABRX_KERNEL
 3:
 BEGIN_FTR_SECTION

arch/powerpc/kvm/book3s_xics.c

···
 	}
 
 #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
-	if (cpu_has_feature(CPU_FTR_ARCH_206)) {
+	if (cpu_has_feature(CPU_FTR_ARCH_206) &&
+	    cpu_has_feature(CPU_FTR_HVMODE)) {
 		/* Enable real mode support */
 		xics->real_mode = ENABLE_REALMODE;
 		xics->real_mode_dbg = DEBUG_REALMODE;