nvmm: Fix support for stable version

NVMM user version 1 is the version being shipped with netbsd-9,
which is the most recent stable branch of NetBSD. This makes it
possible to use the NVMM accelerator on the most recent NetBSD
release, 9.2, which lacks nvmm_cpu_stop.

(CC'ing maintainers)

Signed-off-by: Nia Alarie <nia@NetBSD.org>
Reviewed-by: Kamil Rytarowski <kamil@netbsd.org>
Message-Id: <YWblCe2J8GwCaV9U@homeworld.netbsd.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

meson.build

@@ -323,9 +323,7 @@ if not get_option('hax').disabled()
   endif
 endif
 if targetos == 'netbsd'
-  if cc.has_header_symbol('nvmm.h', 'nvmm_cpu_stop', required: get_option('nvmm'))
-    nvmm = cc.find_library('nvmm', required: get_option('nvmm'))
-  endif
+  nvmm = cc.find_library('nvmm', required: get_option('nvmm'))
   if nvmm.found()
     accelerators += 'CONFIG_NVMM'
   endif

target/i386/nvmm/nvmm-all.c

@@ -750,7 +750,11 @@ nvmm_vcpu_loop(CPUState *cpu)
         nvmm_vcpu_pre_run(cpu);
 
         if (qatomic_read(&cpu->exit_request)) {
+#if NVMM_USER_VERSION >= 2
             nvmm_vcpu_stop(vcpu);
+#else
+            qemu_cpu_kick_self();
+#endif
         }
 
         /* Read exit_request before the kernel reads the immediate exit flag */
@@ -767,6 +771,7 @@ nvmm_vcpu_loop(CPUState *cpu)
         switch (exit->reason) {
         case NVMM_VCPU_EXIT_NONE:
             break;
+#if NVMM_USER_VERSION >= 2
         case NVMM_VCPU_EXIT_STOPPED:
             /*
              * The kernel cleared the immediate exit flag; cpu->exit_request
@@ -775,6 +780,7 @@ nvmm_vcpu_loop(CPUState *cpu)
             smp_wmb();
             qcpu->stop = true;
             break;
+#endif
         case NVMM_VCPU_EXIT_MEMORY:
             ret = nvmm_handle_mem(mach, vcpu);
             break;
@@ -888,8 +894,12 @@ nvmm_ipi_signal(int sigcpu)
 {
     if (current_cpu) {
         struct qemu_vcpu *qcpu = get_qemu_vcpu(current_cpu);
+#if NVMM_USER_VERSION >= 2
         struct nvmm_vcpu *vcpu = &qcpu->vcpu;
         nvmm_vcpu_stop(vcpu);
+#else
+        qcpu->stop = true;
+#endif
     }
 }