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[RFC PATCH v2 1/2] memory: fix dma-reentrancy issues at the MMIO level
From: |
Alexander Bulekov |
Subject: |
[RFC PATCH v2 1/2] memory: fix dma-reentrancy issues at the MMIO level |
Date: |
Fri, 17 Dec 2021 09:37:49 -0500 |
Add a flag to the DeviceState, which is set/checked when we call an
accessor associated with the device's IO MRs. This should prevent a
device's MMIO handler from using DMA apis to access it's own MMIO
regions.
Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
---
include/hw/qdev-core.h | 1 +
softmmu/memory.c | 15 +++++++++++++++
softmmu/trace-events | 1 +
3 files changed, 17 insertions(+)
diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index 20d3066595..7b93b017c5 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -193,6 +193,7 @@ struct DeviceState {
int instance_id_alias;
int alias_required_for_version;
ResettableState reset;
+ int engaged_in_io;
};
struct DeviceListener {
diff --git a/softmmu/memory.c b/softmmu/memory.c
index 7340e19ff5..229c63a68d 100644
--- a/softmmu/memory.c
+++ b/softmmu/memory.c
@@ -532,6 +532,7 @@ static MemTxResult access_with_adjusted_size(hwaddr addr,
uint64_t access_mask;
unsigned access_size;
unsigned i;
+ DeviceState *dev = NULL;
MemTxResult r = MEMTX_OK;
if (!access_size_min) {
@@ -541,6 +542,17 @@ static MemTxResult access_with_adjusted_size(hwaddr addr,
access_size_max = 4;
}
+ /* Do not allow more than one simultanous access to a device's IO Regions
*/
+ if (mr->owner &&
+ !mr->ram_device && !mr->ram && !mr->rom_device && !mr->readonly) {
+ dev = (DeviceState *) object_dynamic_cast(mr->owner, TYPE_DEVICE);
+ if (dev->engaged_in_io) {
+ trace_memory_region_reentrant_io(get_cpu_index(), mr, addr, size);
+ return MEMTX_ERROR;
+ }
+ dev->engaged_in_io = true;
+ }
+
/* FIXME: support unaligned access? */
access_size = MAX(MIN(size, access_size_max), access_size_min);
access_mask = MAKE_64BIT_MASK(0, access_size * 8);
@@ -555,6 +567,9 @@ static MemTxResult access_with_adjusted_size(hwaddr addr,
access_mask, attrs);
}
}
+ if (dev) {
+ dev->engaged_in_io = false;
+ }
return r;
}
diff --git a/softmmu/trace-events b/softmmu/trace-events
index 9c88887b3c..d7228316db 100644
--- a/softmmu/trace-events
+++ b/softmmu/trace-events
@@ -13,6 +13,7 @@ memory_region_ops_read(int cpu_index, void *mr, uint64_t
addr, uint64_t value, u
memory_region_ops_write(int cpu_index, void *mr, uint64_t addr, uint64_t
value, unsigned size, const char *name) "cpu %d mr %p addr 0x%"PRIx64" value
0x%"PRIx64" size %u name '%s'"
memory_region_subpage_read(int cpu_index, void *mr, uint64_t offset, uint64_t
value, unsigned size) "cpu %d mr %p offset 0x%"PRIx64" value 0x%"PRIx64" size
%u"
memory_region_subpage_write(int cpu_index, void *mr, uint64_t offset, uint64_t
value, unsigned size) "cpu %d mr %p offset 0x%"PRIx64" value 0x%"PRIx64" size
%u"
+memory_region_reentrant_io(int cpu_index, void *mr, uint64_t offset, unsigned
size) "cpu %d mr %p offset 0x%"PRIx64" size %u"
memory_region_ram_device_read(int cpu_index, void *mr, uint64_t addr, uint64_t
value, unsigned size) "cpu %d mr %p addr 0x%"PRIx64" value 0x%"PRIx64" size %u"
memory_region_ram_device_write(int cpu_index, void *mr, uint64_t addr,
uint64_t value, unsigned size) "cpu %d mr %p addr 0x%"PRIx64" value 0x%"PRIx64"
size %u"
memory_region_sync_dirty(const char *mr, const char *listener, int global) "mr
'%s' listener '%s' synced (global=%d)"
--
2.33.0