On Mon, Oct 22, 2012 at 05:23:52PM +0800, Liu Ping Fan wrote:
> Rejecting the nested mmio request which does not aim at RAM, so we
> can avoid the potential deadlock caused by the random lock sequence
> of two device's local lock.
>
> Signed-off-by: Liu Ping Fan <pingf...@linux.vnet.ibm.com>
> ---
> cpus.c | 14 ++++++++++++++
> exec.c | 50 ++++++++++++++++++++++++++++++++++++--------------
> hw/hw.h | 1 +
> kvm-all.c | 2 ++
> qemu-thread-posix.h | 3 +++
> qemu-thread.h | 2 ++
> 6 files changed, 58 insertions(+), 14 deletions(-)
>
> diff --git a/cpus.c b/cpus.c
> index 4cd7f85..365a512 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -729,6 +729,18 @@ static void qemu_kvm_wait_io_event(CPUArchState *env)
> qemu_wait_io_event_common(env);
> }
>
> +int get_context_type(void)
> +{
> + QemuThread *t = pthread_getspecific(qemu_thread_key);
> + return t->context_type;
> +}
> +
You defined the function but not use it.
What 0/1 context_type means?
> +void set_context_type(int type)
> +{
> + QemuThread *t = pthread_getspecific(qemu_thread_key);
> + t->context_type = type;
> +}
> +
> static void *qemu_kvm_cpu_thread_fn(void *arg)
> {
> CPUArchState *env = arg;
> @@ -736,6 +748,8 @@ static void *qemu_kvm_cpu_thread_fn(void *arg)
> int r;
>
> pthread_setspecific(qemu_thread_key, cpu->thread);
> + set_context_type(0);
> +
> qemu_mutex_lock(&qemu_global_mutex);
> qemu_thread_get_self(cpu->thread);
> env->thread_id = qemu_get_thread_id();
> diff --git a/exec.c b/exec.c
> index 91b859b..a0327a1 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -3490,7 +3490,9 @@ void cpu_physical_memory_rw(target_phys_addr_t addr,
> uint8_t *buf,
> uint32_t val;
> target_phys_addr_t page;
> MemoryRegionSection *section, obj_mrs;
> - int safe_ref;
> + int safe_ref, nested_dma = 0;
> + QemuThread *thread = pthread_getspecific(qemu_thread_key);
> + int context = thread->context_type;
>
> while (len > 0) {
> page = addr & TARGET_PAGE_MASK;
> @@ -3500,7 +3502,8 @@ void cpu_physical_memory_rw(target_phys_addr_t addr,
> uint8_t *buf,
> qemu_mutex_lock(&mem_map_lock);
> safe_ref = phys_page_lookup(page, &obj_mrs);
> qemu_mutex_unlock(&mem_map_lock);
> - if (safe_ref == 0) {
> +
> + if (safe_ref == 0 && context == 1) {
> qemu_mutex_lock_iothread();
> qemu_mutex_lock(&mem_map_lock);
> /* At the 2nd try, mem map can change, so need to judge it again
> */
> @@ -3511,7 +3514,9 @@ void cpu_physical_memory_rw(target_phys_addr_t addr,
> uint8_t *buf,
> }
> }
> section = &obj_mrs;
> -
> + if (context == 1) {
> + nested_dma = thread->mmio_request_pending++ > 1 ? 1 : 0;
> + }
> if (is_write) {
> if (!memory_region_is_ram(section->mr)) {
> target_phys_addr_t addr1;
> @@ -3521,17 +3526,23 @@ void cpu_physical_memory_rw(target_phys_addr_t addr,
> uint8_t *buf,
> if (l >= 4 && ((addr1 & 3) == 0)) {
> /* 32 bit write access */
> val = ldl_p(buf);
> - io_mem_write(section->mr, addr1, val, 4);
> + if (!nested_dma) {
> + io_mem_write(section->mr, addr1, val, 4);
> + }
> l = 4;
> } else if (l >= 2 && ((addr1 & 1) == 0)) {
> /* 16 bit write access */
> val = lduw_p(buf);
> - io_mem_write(section->mr, addr1, val, 2);
> + if (!nested_dma) {
> + io_mem_write(section->mr, addr1, val, 2);
> + }
> l = 2;
> } else {
> /* 8 bit write access */
> val = ldub_p(buf);
> - io_mem_write(section->mr, addr1, val, 1);
> + if (!nested_dma) {
> + io_mem_write(section->mr, addr1, val, 1);
> + }
> l = 1;
> }
> } else if (!section->readonly) {
> @@ -3552,24 +3563,31 @@ void cpu_physical_memory_rw(target_phys_addr_t addr,
> uint8_t *buf,
> }
> } else {
> if (!(memory_region_is_ram(section->mr) ||
> - memory_region_is_romd(section->mr))) {
> + memory_region_is_romd(section->mr)) &&
> + !nested_dma) {
> target_phys_addr_t addr1;
> /* I/O case */
> addr1 = memory_region_section_addr(section, addr);
> if (l >= 4 && ((addr1 & 3) == 0)) {
> /* 32 bit read access */
> - val = io_mem_read(section->mr, addr1, 4);
> - stl_p(buf, val);
> + if (!nested_dma) {
> + val = io_mem_read(section->mr, addr1, 4);
> + stl_p(buf, val);
> + }
> l = 4;
> } else if (l >= 2 && ((addr1 & 1) == 0)) {
> /* 16 bit read access */
> - val = io_mem_read(section->mr, addr1, 2);
> - stw_p(buf, val);
> + if (!nested_dma) {
> + val = io_mem_read(section->mr, addr1, 2);
> + stw_p(buf, val);
> + }
> l = 2;
> } else {
> /* 8 bit read access */
> - val = io_mem_read(section->mr, addr1, 1);
> - stb_p(buf, val);
> + if (!nested_dma) {
> + val = io_mem_read(section->mr, addr1, 1);
> + stb_p(buf, val);
> + }
> l = 1;
> }
> } else {
> @@ -3586,7 +3604,11 @@ void cpu_physical_memory_rw(target_phys_addr_t addr,
> uint8_t *buf,
> len -= l;
> buf += l;
> addr += l;
> - if (safe_ref == 0) {
> +
> + if (context == 1) {
> + thread->mmio_request_pending--;
> + }
> + if (safe_ref == 0 && context == 1) {
> qemu_mutex_unlock_iothread();
> }
> }
> diff --git a/hw/hw.h b/hw/hw.h
> index e5cb9bf..935b045 100644
> --- a/hw/hw.h
> +++ b/hw/hw.h
> @@ -12,6 +12,7 @@
> #include "irq.h"
> #include "qemu-file.h"
> #include "vmstate.h"
> +#include "qemu-thread.h"
>
> #ifdef NEED_CPU_H
> #if TARGET_LONG_BITS == 64
> diff --git a/kvm-all.c b/kvm-all.c
> index 34b02c1..b3fa597 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -1562,10 +1562,12 @@ int kvm_cpu_exec(CPUArchState *env)
> break;
> case KVM_EXIT_MMIO:
> DPRINTF("handle_mmio\n");
> + set_context_type(1);
> cpu_physical_memory_rw(run->mmio.phys_addr,
> run->mmio.data,
> run->mmio.len,
> run->mmio.is_write);
> + set_context_type(0);
> ret = 0;
> break;
> case KVM_EXIT_IRQ_WINDOW_OPEN:
> diff --git a/qemu-thread-posix.h b/qemu-thread-posix.h
> index 2607b1c..9fcc6f8 100644
> --- a/qemu-thread-posix.h
> +++ b/qemu-thread-posix.h
> @@ -12,6 +12,9 @@ struct QemuCond {
>
> struct QemuThread {
> pthread_t thread;
> + /* 0 clean; 1 mmio; 2 io */
> + int context_type;
> + int mmio_request_pending;
> };
>
> extern pthread_key_t qemu_thread_key;
> diff --git a/qemu-thread.h b/qemu-thread.h
> index 4a6427d..88eaf94 100644
> --- a/qemu-thread.h
> +++ b/qemu-thread.h
> @@ -45,6 +45,8 @@ void *qemu_thread_join(QemuThread *thread);
> void qemu_thread_get_self(QemuThread *thread);
> bool qemu_thread_is_self(QemuThread *thread);
> void qemu_thread_exit(void *retval);
> +int get_context_type(void);
> +void set_context_type(int type);
>
> void qemu_thread_key_create(void);
> #endif
> --
> 1.7.4.4
>
--
Gleb.
