target/ppc: Introduce a vhyp framework for nested HV support

Introduce virtual hypervisor methods that can support a "Nested KVM HV"
implementation using the bare metal 2-level radix MMU, and using HV
exceptions to return from H_ENTER_NESTED (rather than cause interrupts).

HV exceptions can now be raised in the TCG spapr machine when running a
nested KVM HV guest. The main ones are the lev==1 syscall, the hdecr,
hdsi and hisi, hv fu, and hv emu, and h_virt external interrupts.

HV exceptions are intercepted in the exception handler code and instead
of causing interrupts in the guest and switching the machine to HV mode,
they go to the vhyp where it may exit the H_ENTER_NESTED hcall with the
interrupt vector numer as return value as required by the hcall API.

Address translation is provided by the 2-level page table walker that is
implemented for the bare metal radix MMU. The partition scope page table
is pointed to the L1's partition scope by the get_pate vhc method.

Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20220216102545.1808018-9-npiggin@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
index c79ae74..2baa750 100644
--- a/target/ppc/cpu.h
+++ b/target/ppc/cpu.h
@@ -1311,6 +1311,8 @@ PowerPCCPUClass *ppc_cpu_get_family_class(PowerPCCPUClass *pcc);
 #ifndef CONFIG_USER_ONLY
 struct PPCVirtualHypervisorClass {
     InterfaceClass parent;
+    bool (*cpu_in_nested)(PowerPCCPU *cpu);
+    void (*deliver_hv_excp)(PowerPCCPU *cpu, int excp);
     void (*hypercall)(PPCVirtualHypervisor *vhyp, PowerPCCPU *cpu);
     hwaddr (*hpt_mask)(PPCVirtualHypervisor *vhyp);
     const ppc_hash_pte64_t *(*map_hptes)(PPCVirtualHypervisor *vhyp,
@@ -1330,6 +1332,11 @@ struct PPCVirtualHypervisorClass {
 #define TYPE_PPC_VIRTUAL_HYPERVISOR "ppc-virtual-hypervisor"
 DECLARE_OBJ_CHECKERS(PPCVirtualHypervisor, PPCVirtualHypervisorClass,
                      PPC_VIRTUAL_HYPERVISOR, TYPE_PPC_VIRTUAL_HYPERVISOR)
+
+static inline bool vhyp_cpu_in_nested(PowerPCCPU *cpu)
+{
+    return PPC_VIRTUAL_HYPERVISOR_GET_CLASS(cpu->vhyp)->cpu_in_nested(cpu);
+}
 #endif /* CONFIG_USER_ONLY */
 
 void ppc_cpu_dump_state(CPUState *cpu, FILE *f, int flags);