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[Qemu-devel] [PATCH v7 6/7] memory: introduce tls context to trace neste
From: |
Liu Ping Fan |
Subject: |
[Qemu-devel] [PATCH v7 6/7] memory: introduce tls context to trace nested mmio request issue |
Date: |
Sun, 25 Nov 2012 10:03:03 +0800 |
From: Liu Ping Fan <address@hidden>
After breaking down big lock, nested MMIO request which not targeting
at RAM can cause deadlock issue. Supposing the scene: dev_a,b with
fine-grain locks lockA/B, then ABBA dealock issue can be triggered.
We fix this by tracing and rejecting such request.
Signed-off-by: Liu Ping Fan <address@hidden>
---
exec.c | 37 ++++++++++++++++++++++++++++++++++++-
1 files changed, 36 insertions(+), 1 deletions(-)
diff --git a/exec.c b/exec.c
index fa34ef9..7eae54e 100644
--- a/exec.c
+++ b/exec.c
@@ -3442,6 +3442,32 @@ static bool
address_space_section_lookup_ref(AddressSpace *as,
return safe_ref;
}
+typedef struct ThreadContext {
+ unsigned int req_pending;
+} ThreadContext;
+
+static DEFINE_TLS(ThreadContext, thread_context) = {
+ .req_pending = 0
+};
+#define thread_context tls_var(thread_context)
+
+static bool address_space_check_inc_req_pending(MemoryRegionSection *section)
+{
+ bool nested;
+
+ nested = ++thread_context.req_pending > 1 ? true : false;
+ /* To fix, will filter iommu case */
+ if (nested && !memory_region_is_ram(section->mr)) {
+ fprintf(stderr, "waring: nested target not RAM is not support");
+ }
+ return nested;
+}
+
+static void address_space_dec_req_pending(void)
+{
+ thread_context.req_pending--;
+}
+
void address_space_rw(AddressSpace *as, target_phys_addr_t addr, uint8_t *buf,
int len, bool is_write)
{
@@ -3450,7 +3476,7 @@ void address_space_rw(AddressSpace *as,
target_phys_addr_t addr, uint8_t *buf,
uint8_t *ptr;
uint32_t val;
target_phys_addr_t page;
- bool safe_ref;
+ bool safe_ref, nested;
MemoryRegionSection *section, obj_mrs;
while (len > 0) {
@@ -3462,6 +3488,11 @@ void address_space_rw(AddressSpace *as,
target_phys_addr_t addr, uint8_t *buf,
qemu_mutex_lock(&as->lock);
safe_ref = memory_region_section_lookup_ref(d, page, &obj_mrs);
qemu_mutex_unlock(&as->lock);
+ nested = address_space_check_inc_req_pending(&obj_mrs);
+ if (nested) {
+ goto skip;
+ }
+
if (!safe_ref) {
qemu_mutex_lock_iothread();
qemu_mutex_lock(&as->lock);
@@ -3477,6 +3508,7 @@ void address_space_rw(AddressSpace *as,
target_phys_addr_t addr, uint8_t *buf,
if (is_write) {
if (!memory_region_is_ram(section->mr)) {
target_phys_addr_t addr1;
+
addr1 = memory_region_section_addr(section, addr);
/* XXX: could force cpu_single_env to NULL to avoid
potential bugs */
@@ -3510,6 +3542,7 @@ 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;
+
/* I/O case */
addr1 = memory_region_section_addr(section, addr);
if (l >= 4 && ((addr1 & 3) == 0)) {
@@ -3537,6 +3570,8 @@ void address_space_rw(AddressSpace *as,
target_phys_addr_t addr, uint8_t *buf,
qemu_put_ram_ptr(ptr);
}
}
+skip:
+ address_space_dec_req_pending();
memory_region_section_unref(&obj_mrs);
len -= l;
buf += l;
--
1.7.4.4
- [Qemu-devel] [PATCH v7 0/7] push mmio dispatch out of big lock, Liu Ping Fan, 2012/11/24
- [Qemu-devel] [PATCH v7 1/7] qom: apply atomic on object's refcount, Liu Ping Fan, 2012/11/24
- [Qemu-devel] [PATCH v7 2/7] hotplug: introduce qdev_unplug_complete() to remove device from views, Liu Ping Fan, 2012/11/24
- [Qemu-devel] [PATCH v7 3/7] pci: remove pci device from mem view when unplug, Liu Ping Fan, 2012/11/24
- [Qemu-devel] [PATCH v7 4/7] memory: introduce local lock for address space, Liu Ping Fan, 2012/11/24
- [Qemu-devel] [PATCH v7 5/7] memory: make mmio dispatch able to be out of biglock, Liu Ping Fan, 2012/11/24
- [Qemu-devel] [PATCH v7 6/7] memory: introduce tls context to trace nested mmio request issue,
Liu Ping Fan <=
- [Qemu-devel] [PATCH v7 7/7] vcpu: push mmio dispatcher out of big lock, Liu Ping Fan, 2012/11/24