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address_space_read: address_space_to_flatview needs RCU lock

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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.

Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2018-03-05 00:19:49 +01:00
parent 4c6ebbb364
commit b2a44fcad7
2 changed files with 35 additions and 28 deletions
Download patch file Download diff file Expand all files Collapse all files

25
include/exec/memory.h
View file

@ -1917,13 +1917,12 @@ 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)
@ -1942,25 +1941,28 @@ 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)) {
@ -1973,18 +1975,11 @@ 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
*