[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [patch v5 7/8] memory: introduce tls context to record
From: |
liu ping fan |
Subject: |
Re: [Qemu-devel] [patch v5 7/8] memory: introduce tls context to record nested dma |
Date: |
Mon, 5 Nov 2012 13:35:21 +0800 |
On Fri, Nov 2, 2012 at 6:39 PM, Jan Kiszka <address@hidden> wrote:
> On 2012-10-29 00:48, Liu Ping Fan wrote:
>> Signed-off-by: Liu Ping Fan <address@hidden>
>> ---
>> 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)
>>
>
> In fact, this is not targeting nested DMA but nesting of memory region
> callbacks, and there potential deadlock issue. Triggering a DMA with RAM
> as target from within an MMIO (or later PIO) handler is perfectly fine
> and not rejected here. You should clarify the scope and purpose of this
> patch in its changelog.
>
Applied, thanks.
> Jan
>
> --
> Siemens AG, Corporate Technology, CT RTC ITP SDP-DE
> Corporate Competence Center Embedded Linux
>