[PATCH 7/9] hw/ppc/spapr_hcall.c: log H_QUERY_VAS_CAPABILITIES as unsupported

[Daniel Henrique Barboza]

This hcall is VAS (Virtual Accelerator Switchboard) related. VAS is a
hardware feature that allows kernelspace and userspace to communicate
directly with Nested Accelerators (NX). A description of VAS can be
found at [1].

QEMU does not implement neither VAS nor NXs. AIX guests will query VAS
capabilities once during boot.

Log this hcall as unsupported. It is worth noticing that VAS has a
handful of other hcalls (H_ALLOCATE_VAS_WINDOW, H_QUERY_VAS_WINDOW,
H_GET_NX_FAULT and others), but the AIX guest seems to be satisfied
when H_QUERY_VAS_CAPABILITIES returns H_FUNCTION and give up trying
the others. This means that there is no need to log all of them as
unsupported in QEMU.

[1] https://www.kernel.org/doc/html/latest/powerpc/vas-api.html

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/ppc/spapr_hcall.c   | 18 ++++++++++++++++++
 include/hw/ppc/spapr.h |  1 +
 2 files changed, 19 insertions(+)

diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
index db6cb6bb89..fdce44daf7 100644
--- a/hw/ppc/spapr_hcall.c
+++ b/hw/ppc/spapr_hcall.c
@@ -1589,6 +1589,20 @@ static target_ulong h_best_energy(PowerPCCPU *cpu,
     return H_FUNCTION;
 }
 
+static target_ulong h_query_vas_capabilities(PowerPCCPU *cpu,
+                                             SpaprMachineState *spapr,
+                                             target_ulong opcode,
+                                             target_ulong *args)
+{
+    /*
+     * This HCALL is VAS (Virtual Accelerator Switchboard) related. VAS
+     * is not supported in QEMU.
+     */
+    qemu_log_mask(LOG_UNSUPP, "Unsupported SPAPR hcall 0x"TARGET_FMT_lx"%s\n",
+                  opcode, " (H_QUERY_VAS_CAPABILITIES)");
+    return H_FUNCTION;
+}
+
 /*
  * When this handler returns, the environment is switched to the L2 guest
  * and TCG begins running that. spapr_exit_nested() performs the switch from
@@ -1931,6 +1945,10 @@ static void hypercall_register_types(void)
     /* Unsupported PEM option h-calls */
     spapr_register_hypercall(H_GET_EM_PARMS, h_get_em_parms);
     spapr_register_hypercall(H_BEST_ENERGY, h_best_energy);
+
+    /* Unsupported VAS h-calls */
+    spapr_register_hypercall(H_QUERY_VAS_CAPABILITIES,
+                             h_query_vas_capabilities);
 }
 
 type_init(hypercall_register_types)
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 7995bc0cb6..10df519b0a 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -545,6 +545,7 @@ struct SpaprMachineState {
 #define H_INVALIDATE_PID        0x378
 #define H_REGISTER_PROC_TBL     0x37C
 #define H_SIGNAL_SYS_RESET      0x380
+#define H_QUERY_VAS_CAPABILITIES 0x398
 
 #define H_INT_GET_SOURCE_INFO   0x3A8
 #define H_INT_SET_SOURCE_CONFIG 0x3AC
-- 
2.35.1