[Qemu-devel] [patch v5 7/8] memory: introduce tls context to record nested dma

[Liu Ping Fan <pingfank@linux.vnet.ibm.com>]

Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
---
 cpus.c        |    3 ++
 exec.c        |   58 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 qemu-thread.h |    8 +++++++
 vl.c          |    1 +
 4 files changed, 70 insertions(+), 0 deletions(-)

diff --git a/cpus.c b/cpus.c
index 191cbf5..e67d80f 100644
--- a/cpus.c
+++ b/cpus.c
@@ -733,6 +733,7 @@ static void *qemu_kvm_cpu_thread_fn(void *arg)
 
     qemu_mutex_lock(&qemu_global_mutex);
     qemu_thread_get_self(cpu->thread);
+    qemu_thread_init_context();
     env->thread_id = qemu_get_thread_id();
     cpu_single_env = env;
 
@@ -774,6 +775,7 @@ static void *qemu_dummy_cpu_thread_fn(void *arg)
 
     qemu_mutex_lock_iothread();
     qemu_thread_get_self(cpu->thread);
+    qemu_thread_init_context();
     env->thread_id = qemu_get_thread_id();
 
     sigemptyset(&waitset);
@@ -813,6 +815,7 @@ static void *qemu_tcg_cpu_thread_fn(void *arg)
 
     qemu_tcg_init_cpu_signals();
     qemu_thread_get_self(cpu->thread);
+    qemu_thread_init_context();
 
     /* signal CPU creation */
     qemu_mutex_lock(&qemu_global_mutex);
diff --git a/exec.c b/exec.c
index 46da08c..ea672c6 100644
--- a/exec.c
+++ b/exec.c
@@ -3449,6 +3449,49 @@ static bool address_space_section_lookup_ref(AddressSpace *as,
     return safe_ref;
 }
 
+typedef struct ThreadContext {
+  DispatchType dispatch_type;
+  unsigned int mmio_req_pending;
+} ThreadContext;
+
+static __thread ThreadContext *thread_context;
+
+void qemu_thread_init_context(void)
+{
+    thread_context = g_new(ThreadContext, 1);
+    thread_context->dispatch_type = DISPATCH_INIT;
+    thread_context->mmio_req_pending = 0;
+}
+
+void qemu_thread_set_dispatch_type(DispatchType type)
+{
+    thread_context->dispatch_type = type;
+}
+
+void qemu_thread_reset_dispatch_type(void)
+{
+    thread_context->dispatch_type = DISPATCH_INIT;
+}
+
+static bool address_space_inc_req_pending(void)
+{
+    bool nested = false;
+
+    /* currently, only mmio out of big lock, and need this to avoid dead lock */
+    if (thread_context->dispatch_type == DISPATCH_MMIO) {
+        nested = ++thread_context->mmio_req_pending > 1 ? true : false;
+    }
+
+    return nested;
+}
+
+static void address_space_dec_req_pending(void)
+{
+    if (thread_context->dispatch_type == DISPATCH_MMIO) {
+        thread_context->mmio_req_pending--;
+    }
+}
+
 void address_space_rw(AddressSpace *as, target_phys_addr_t addr, uint8_t *buf,
                       int len, bool is_write)
 {
@@ -3459,6 +3502,7 @@ void address_space_rw(AddressSpace *as, target_phys_addr_t addr, uint8_t *buf,
     target_phys_addr_t page;
     bool safe_ref = false;
     MemoryRegionSection *section, obj_mrs;
+    bool nested_dma = false;
 
     while (len > 0) {
         page = addr & TARGET_PAGE_MASK;
@@ -3485,10 +3529,17 @@ void address_space_rw(AddressSpace *as, target_phys_addr_t addr, uint8_t *buf,
             memory_region_section_lookup_ref(d, page, &obj_mrs);
         }
         section = &obj_mrs;
+        nested_dma = address_space_inc_req_pending();
 
         if (is_write) {
             if (!memory_region_is_ram(section->mr)) {
                 target_phys_addr_t addr1;
+
+                /* To fix, will filter iommu case */
+                if (nested_dma) {
+                    fprintf(stderr, "can not support nested DMA");
+                    abort();
+                }
                 addr1 = memory_region_section_addr(section, addr);
                 /* XXX: could force cpu_single_env to NULL to avoid
                    potential bugs */
@@ -3522,6 +3573,12 @@ void address_space_rw(AddressSpace *as, target_phys_addr_t addr, uint8_t *buf,
             if (!(memory_region_is_ram(section->mr) ||
                   memory_region_is_romd(section->mr))) {
                 target_phys_addr_t addr1;
+
+                /* To fix, will filter iommu case */
+                if (nested_dma) {
+                    fprintf(stderr, "can not support nested DMA");
+                    abort();
+                }
                 /* I/O case */
                 addr1 = memory_region_section_addr(section, addr);
                 if (l >= 4 && ((addr1 & 3) == 0)) {
@@ -3549,6 +3606,7 @@ void address_space_rw(AddressSpace *as, target_phys_addr_t addr, uint8_t *buf,
                 qemu_put_ram_ptr(ptr);
             }
         }
+        address_space_dec_req_pending();
         memory_region_section_unref(&obj_mrs);
         len -= l;
         buf += l;
diff --git a/qemu-thread.h b/qemu-thread.h
index 05fdaaf..bb9535e 100644
--- a/qemu-thread.h
+++ b/qemu-thread.h
@@ -7,6 +7,11 @@
 typedef struct QemuMutex QemuMutex;
 typedef struct QemuCond QemuCond;
 typedef struct QemuThread QemuThread;
+typedef enum {
+  DISPATCH_INIT = 0,
+  DISPATCH_MMIO,
+  DISPATCH_IO,
+} DispatchType;
 
 #ifdef _WIN32
 #include "qemu-thread-win32.h"
@@ -46,4 +51,7 @@ void qemu_thread_get_self(QemuThread *thread);
 bool qemu_thread_is_self(QemuThread *thread);
 void qemu_thread_exit(void *retval);
 
+void qemu_thread_init_context(void);
+void qemu_thread_set_dispatch_type(DispatchType type);
+void qemu_thread_reset_dispatch_type(void);
 #endif
diff --git a/vl.c b/vl.c
index ee3c43a..be8d825 100644
--- a/vl.c
+++ b/vl.c
@@ -3439,6 +3439,7 @@ int main(int argc, char **argv, char **envp)
             add_device_config(DEV_VIRTCON, "vc:80Cx24C");
     }
 
+    qemu_thread_init_context();
     socket_init();
 
     if (qemu_opts_foreach(qemu_find_opts("chardev"), chardev_init_func, NULL, 1) != 0)
-- 
1.7.4.4