[PATCH] softmmu/vl.c: fix too slow TCG regression

* [PATCH] softmmu/vl.c: fix too slow TCG regression
@ 2020-02-26 16:35 Igor Mammedov
  2020-02-26 18:21 ` Alex Bennée
  2020-02-27  9:15 ` Peter Maydell
  0 siblings, 2 replies; 5+ messages in thread
From: Igor Mammedov @ 2020-02-26 16:35 UTC (permalink / raw)
  To: qemu-devel
  Cc: peter.maydell, f4bug, nieklinnenbank, hsp.cat7, pbonzini,
	alex.bennee, rth

Commit a1b18df9a4 moved -m option parsing after configure_accelerators()
that broke TCG accelerator initialization which accesses global ram_size
from size_code_gen_buffer() which is equal to 0 at that moment.

Partially revert a1b18df9a4, by returning set_memory_options() to its
original location and only keep 32-bit host VA check and 'memory-backend'
size check introduced by fe64d06afc at current place.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---

PS:
This should take care of regression and give more time to think about
how to remove size_code_gen_buffer() dependency on ram_size
---
 softmmu/vl.c | 49 +++++++++++++++++++++++++------------------------
 1 file changed, 25 insertions(+), 24 deletions(-)

diff --git a/softmmu/vl.c b/softmmu/vl.c
index a9cce78f45..da7577129c 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -2634,29 +2634,6 @@ static void set_memory_options(uint64_t *ram_slots, ram_addr_t *maxram_size,
         exit(EXIT_FAILURE);
     }
 
-    if (current_machine->ram_memdev_id) {
-        Object *backend;
-        ram_addr_t backend_size;
-
-        backend = object_resolve_path_type(current_machine->ram_memdev_id,
-                                           TYPE_MEMORY_BACKEND, NULL);
-        backend_size = object_property_get_uint(backend, "size",  &error_abort);
-        if (mem_str && backend_size != ram_size) {
-                error_report("Size specified by -m option must match size of "
-                             "explicitly specified 'memory-backend' property");
-                exit(EXIT_FAILURE);
-        }
-        ram_size = backend_size;
-    }
-
-    if (!xen_enabled()) {
-        /* On 32-bit hosts, QEMU is limited by virtual address space */
-        if (ram_size > (2047 << 20) && HOST_LONG_BITS == 32) {
-            error_report("at most 2047 MB RAM can be simulated");
-            exit(1);
-        }
-    }
-
     loc_pop(&loc);
 }
 
@@ -3821,6 +3798,8 @@ void qemu_init(int argc, char **argv, char **envp)
     machine_class = select_machine();
     object_set_machine_compat_props(machine_class->compat_props);
 
+    set_memory_options(&ram_slots, &maxram_size, machine_class);
+
     os_daemonize();
 
     /*
@@ -4296,7 +4275,29 @@ void qemu_init(int argc, char **argv, char **envp)
         current_machine->cpu_type = parse_cpu_option(cpu_option);
     }
 
-    set_memory_options(&ram_slots, &maxram_size, machine_class);
+    if (!xen_enabled()) {
+        /* On 32-bit hosts, QEMU is limited by virtual address space */
+        if (ram_size > (2047 << 20) && HOST_LONG_BITS == 32) {
+            error_report("at most 2047 MB RAM can be simulated");
+            exit(1);
+        }
+    }
+
+    if (current_machine->ram_memdev_id) {
+        Object *backend;
+        ram_addr_t backend_size;
+
+        backend = object_resolve_path_type(current_machine->ram_memdev_id,
+                                           TYPE_MEMORY_BACKEND, NULL);
+        backend_size = object_property_get_uint(backend, "size",  &error_abort);
+        if (backend_size != ram_size) {
+                error_report("Size specified by -m option must match size of "
+                             "explicitly specified 'memory-backend' property");
+                exit(EXIT_FAILURE);
+        }
+        ram_size = backend_size;
+    }
+
     current_machine->ram_size = ram_size;
     current_machine->maxram_size = maxram_size;
     current_machine->ram_slots = ram_slots;
-- 
2.18.1



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