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[Qemu-stable] [PATCH 4/7] address_space_read: address_space_to_flatview
From: |
Paolo Bonzini |
Subject: |
[Qemu-stable] [PATCH 4/7] address_space_read: address_space_to_flatview needs RCU lock |
Date: |
Mon, 5 Mar 2018 09:36:52 +0100 |
address_space_read is calling address_space_to_flatview but it can
be called outside the RCU lock. To fix it, push the rcu_read_lock/unlock
pair up from flatview_read_full to address_space_read's constant size
fast path and address_space_read_full.
Cc: address@hidden
Signed-off-by: Paolo Bonzini <address@hidden>
---
exec.c | 44 ++++++++++++++++++++++++++++----------------
include/exec/memory.h | 25 ++++++++++---------------
2 files changed, 38 insertions(+), 31 deletions(-)
diff --git a/exec.c b/exec.c
index 0b74b58d45..55b7452bd7 100644
--- a/exec.c
+++ b/exec.c
@@ -2612,6 +2612,8 @@ static const MemoryRegionOps watch_mem_ops = {
},
};
+static MemTxResult flatview_read(FlatView *fv, hwaddr addr,
+ MemTxAttrs attrs, uint8_t *buf, int len);
static MemTxResult flatview_write(FlatView *fv, hwaddr addr, MemTxAttrs attrs,
const uint8_t *buf, int len);
static bool flatview_access_valid(FlatView *fv, hwaddr addr, int len,
@@ -3161,24 +3163,18 @@ MemTxResult flatview_read_continue(FlatView *fv, hwaddr
addr,
return result;
}
-MemTxResult flatview_read_full(FlatView *fv, hwaddr addr,
- MemTxAttrs attrs, uint8_t *buf, int len)
+/* Called from RCU critical section. */
+static MemTxResult flatview_read(FlatView *fv, hwaddr addr,
+ MemTxAttrs attrs, uint8_t *buf, int len)
{
hwaddr l;
hwaddr addr1;
MemoryRegion *mr;
- MemTxResult result = MEMTX_OK;
-
- if (len > 0) {
- rcu_read_lock();
- l = len;
- mr = flatview_translate(fv, addr, &addr1, &l, false);
- result = flatview_read_continue(fv, addr, attrs, buf, len,
- addr1, l, mr);
- rcu_read_unlock();
- }
- return result;
+ l = len;
+ mr = flatview_translate(fv, addr, &addr1, &l, false);
+ return flatview_read_continue(fv, addr, attrs, buf, len,
+ addr1, l, mr);
}
static MemTxResult flatview_rw(FlatView *fv, hwaddr addr, MemTxAttrs attrs,
@@ -3199,6 +3195,22 @@ MemTxResult address_space_rw(AddressSpace *as, hwaddr
addr,
addr, attrs, buf, len, is_write);
}
+MemTxResult address_space_read_full(AddressSpace *as, hwaddr addr,
+ MemTxAttrs attrs, uint8_t *buf, int len)
+{
+ MemTxResult result = MEMTX_OK;
+ FlatView *fv;
+
+ if (len > 0) {
+ rcu_read_lock();
+ fv = address_space_to_flatview(as);
+ result = flatview_read(fv, addr, attrs, buf, len);
+ rcu_read_unlock();
+ }
+
+ return result;
+}
+
MemTxResult address_space_write(AddressSpace *as, hwaddr addr,
MemTxAttrs attrs,
const uint8_t *buf, int len)
diff --git a/include/exec/memory.h b/include/exec/memory.h
index 6c8e394675..54ff81fbd1 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -1894,13 +1894,12 @@ void address_space_unmap(AddressSpace *as, void
*buffer, hwaddr len,
/* Internal functions, part of the implementation of address_space_read. */
+MemTxResult address_space_read_full(AddressSpace *as, hwaddr addr,
+ MemTxAttrs attrs, uint8_t *buf, int len);
MemTxResult flatview_read_continue(FlatView *fv, hwaddr addr,
MemTxAttrs attrs, uint8_t *buf,
int len, hwaddr addr1, hwaddr l,
MemoryRegion *mr);
-
-MemTxResult flatview_read_full(FlatView *fv, hwaddr addr,
- MemTxAttrs attrs, uint8_t *buf, int len);
void *qemu_map_ram_ptr(RAMBlock *ram_block, ram_addr_t addr);
static inline bool memory_access_is_direct(MemoryRegion *mr, bool is_write)
@@ -1919,25 +1918,28 @@ static inline bool memory_access_is_direct(MemoryRegion
*mr, bool is_write)
*
* Return a MemTxResult indicating whether the operation succeeded
* or failed (eg unassigned memory, device rejected the transaction,
- * IOMMU fault).
+ * IOMMU fault). Called within RCU critical section.
*
- * @fv: #FlatView to be accessed
+ * @as: #AddressSpace to be accessed
* @addr: address within that address space
* @attrs: memory transaction attributes
* @buf: buffer with the data transferred
*/
static inline __attribute__((__always_inline__))
-MemTxResult flatview_read(FlatView *fv, hwaddr addr, MemTxAttrs attrs,
- uint8_t *buf, int len)
+MemTxResult address_space_read(AddressSpace *as, hwaddr addr,
+ MemTxAttrs attrs, uint8_t *buf,
+ int len)
{
MemTxResult result = MEMTX_OK;
hwaddr l, addr1;
void *ptr;
MemoryRegion *mr;
+ FlatView *fv;
if (__builtin_constant_p(len)) {
if (len) {
rcu_read_lock();
+ fv = address_space_to_flatview(as);
l = len;
mr = flatview_translate(fv, addr, &addr1, &l, false);
if (len == l && memory_access_is_direct(mr, false)) {
@@ -1950,18 +1952,11 @@ MemTxResult flatview_read(FlatView *fv, hwaddr addr,
MemTxAttrs attrs,
rcu_read_unlock();
}
} else {
- result = flatview_read_full(fv, addr, attrs, buf, len);
+ result = address_space_read_full(as, addr, attrs, buf, len);
}
return result;
}
-static inline MemTxResult address_space_read(AddressSpace *as, hwaddr addr,
- MemTxAttrs attrs, uint8_t *buf,
- int len)
-{
- return flatview_read(address_space_to_flatview(as), addr, attrs, buf, len);
-}
-
/**
* address_space_read_cached: read from a cached RAM region
*
--
2.14.3
- [Qemu-stable] [PATCH 4/7] address_space_read: address_space_to_flatview needs RCU lock,
Paolo Bonzini <=