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memory: stricter checks prior to unsetting engaged_in_io 

engaged_in_io could be unset by an MR with re-entrancy checks disabled.
Ensure that only MRs that can set the engaged_in_io flag can unset it.

Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
Message-Id: <20230516084002.3813836-1-alxndr@bu.edu>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
This commit is contained in:
Alexander Bulekov 2023-05-16 04:40:02 -04:00 committed by Thomas Huth
parent 1afae3b881
commit 3884bf6468
1 changed files with 3 additions and 1 deletions
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4
softmmu/memory.c
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@ -534,6 +534,7 @@ static MemTxResult access_with_adjusted_size(hwaddr addr,
unsigned access_size; unsigned access_size;
unsigned i; unsigned i;
MemTxResult r = MEMTX_OK; MemTxResult r = MEMTX_OK;
bool reentrancy_guard_applied = false;
if (!access_size_min) { if (!access_size_min) {
access_size_min = 1; access_size_min = 1;
@ -552,6 +553,7 @@ static MemTxResult access_with_adjusted_size(hwaddr addr,
return MEMTX_ACCESS_ERROR; return MEMTX_ACCESS_ERROR;
} }
mr->dev->mem_reentrancy_guard.engaged_in_io = true; mr->dev->mem_reentrancy_guard.engaged_in_io = true;
reentrancy_guard_applied = true;
} }
/* FIXME: support unaligned access? */ /* FIXME: support unaligned access? */
@ -568,7 +570,7 @@ static MemTxResult access_with_adjusted_size(hwaddr addr,
access_mask, attrs); access_mask, attrs);
} }
} }
if (mr->dev) { if (mr->dev && reentrancy_guard_applied) {
mr->dev->mem_reentrancy_guard.engaged_in_io = false; mr->dev->mem_reentrancy_guard.engaged_in_io = false;
} }
return r; return r;