target/ppc: Fix nested-hv HEAI delivery

ppc hypervisors turn HEAI interrupts into program interrupts injected
into the guest that executed the illegal instruction, if the hypervisor
doesn't handle it some other way.

The nested-hv implementation failed to account for this HEAI->program
conversion. The virtual hypervisor wants to see the HEAI when running
a nested guest, so that interrupt type can be returned to its KVM
caller.

Fixes: 7cebc5d ("target/ppc: Introduce a vhyp framework for nested HV support")
Cc: balaton@eik.bme.hu
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Message-Id: <20230530132127.385001-1-npiggin@gmail.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
(cherry picked from commit 6c242e7)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

target/ppc/excp_helper.c

@@ -1358,9 +1358,12 @@ static void powerpc_excp_books(PowerPCCPU *cpu, int excp)
 
     /*
      * We don't want to generate a Hypervisor Emulation Assistance
-     * Interrupt if we don't have HVB in msr_mask (PAPR mode).
+     * Interrupt if we don't have HVB in msr_mask (PAPR mode),
+     * unless running a nested-hv guest, in which case the L1
+     * kernel wants the interrupt.
      */
-    if (excp == POWERPC_EXCP_HV_EMU && !(env->msr_mask & MSR_HVB)) {
+    if (excp == POWERPC_EXCP_HV_EMU && !(env->msr_mask & MSR_HVB) &&
+            !books_vhyp_handles_hv_excp(cpu)) {
         excp = POWERPC_EXCP_PROGRAM;
     }