[PATCH v4 1/3] hw: misc: edu: fix 2 off-by-one errors

[PATCH v4 1/3] hw: misc: edu: fix 2 off-by-one errors

[Chris Friedt]

In the case that size1 was zero, because of the explicit
'end1 > addr' check, the range check would fail and the error
message would read as shown below. The correct comparison
is 'end1 >= addr'.

EDU: DMA range 0x40000-0x3ffff out of bounds (0x40000-0x40fff)!

At the opposite end, in the case that size1 was 4096, within()
would fail because of the non-inclusive check 'end1 < end2',
which should have been 'end1 <= end2'. The error message would
previously say

EDU: DMA range 0x40000-0x40fff out of bounds (0x40000-0x40fff)!

Signed-off-by: Chris Friedt <cfriedt@meta.com>
---
 hw/misc/edu.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/hw/misc/edu.c b/hw/misc/edu.c
index e935c418d4..b3de8d206a 100644
--- a/hw/misc/edu.c
+++ b/hw/misc/edu.c
@@ -103,19 +103,18 @@ static void edu_lower_irq(EduState *edu, uint32_t val)
     }
 }
 
-static bool within(uint64_t addr, uint64_t start, uint64_t end)
-{
-    return start <= addr && addr < end;
-}
-
-static void edu_check_range(uint64_t addr, uint64_t size1, uint64_t start,
-                uint64_t size2)
+static void edu_check_range(uint64_t addr, uint64_t size1,
+                uint64_t start, uint64_t size2)
 {
     uint64_t end1 = addr + size1;
     uint64_t end2 = start + size2;
 
-    if (within(addr, start, end2) &&
-            end1 > addr && within(end1, start, end2)) {
+    /*
+     * 1. ensure we aren't overflowing
+     * 2. ensure that [addr, end1) is within [start, size2)
+     */
+    if (end2 >= start && end1 >= addr &&
+        addr >= start && end1 <= end2) {
         return;
     }
 
-- 
2.36.1

[PATCH v4 2/3] hw: misc: edu: rename local vars in edu_check_range

[Chris Friedt]

This serves to make the local variables a bit less ambiguous.

The latter two arguments are named to match DMA_START, and
DMA_SIZE.

Signed-off-by: Chris Friedt <cfriedt@meta.com>
---
 hw/misc/edu.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/hw/misc/edu.c b/hw/misc/edu.c
index b3de8d206a..52afbd792a 100644
--- a/hw/misc/edu.c
+++ b/hw/misc/edu.c
@@ -103,24 +103,24 @@ static void edu_lower_irq(EduState *edu, uint32_t val)
     }
 }
 
-static void edu_check_range(uint64_t addr, uint64_t size1,
-                uint64_t start, uint64_t size2)
+static void edu_check_range(uint64_t xfer_start, uint64_t xfer_size,
+                uint64_t dma_start, uint64_t dma_size)
 {
-    uint64_t end1 = addr + size1;
-    uint64_t end2 = start + size2;
+    uint64_t xfer_end = xfer_start + xfer_size;
+    uint64_t dma_end = dma_start + dma_size;
 
     /*
      * 1. ensure we aren't overflowing
-     * 2. ensure that [addr, end1) is within [start, size2)
+     * 2. ensure that xfer is within dma address range
      */
-    if (end2 >= start && end1 >= addr &&
-        addr >= start && end1 <= end2) {
+    if (dma_end >= dma_start && xfer_end >= xfer_start &&
+        xfer_start >= dma_start && xfer_end <= dma_end) {
         return;
     }
 
     hw_error("EDU: DMA range 0x%016"PRIx64"-0x%016"PRIx64
              " out of bounds (0x%016"PRIx64"-0x%016"PRIx64")!",
-            addr, end1 - 1, start, end2 - 1);
+            xfer_start, xfer_end - 1, dma_start, dma_end - 1);
 }
 
 static dma_addr_t edu_clamp_addr(const EduState *edu, dma_addr_t addr)
-- 
2.36.1

[PATCH v4 3/3] hw: misc: edu: use qemu_log_mask instead of hw_error

[Chris Friedt]

Log a guest error instead of a hardware error when
the guest tries to DMA to / from an invalid address.

Signed-off-by: Chris Friedt <cfriedt@meta.com>
---
 hw/misc/edu.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/hw/misc/edu.c b/hw/misc/edu.c
index 52afbd792a..a18f803815 100644
--- a/hw/misc/edu.c
+++ b/hw/misc/edu.c
@@ -118,9 +118,10 @@ static void edu_check_range(uint64_t xfer_start, uint64_t xfer_size,
         return;
     }
 
-    hw_error("EDU: DMA range 0x%016"PRIx64"-0x%016"PRIx64
-             " out of bounds (0x%016"PRIx64"-0x%016"PRIx64")!",
-            xfer_start, xfer_end - 1, dma_start, dma_end - 1);
+    qemu_log_mask(LOG_GUEST_ERROR,
+                  "EDU: DMA range 0x%016"PRIx64"-0x%016"PRIx64
+                  " out of bounds (0x%016"PRIx64"-0x%016"PRIx64")!",
+                  xfer_start, xfer_end - 1, dma_start, dma_end - 1);
 }
 
 static dma_addr_t edu_clamp_addr(const EduState *edu, dma_addr_t addr)
@@ -128,7 +129,9 @@ static dma_addr_t edu_clamp_addr(const EduState *edu, dma_addr_t addr)
     dma_addr_t res = addr & edu->dma_mask;
 
     if (addr != res) {
-        printf("EDU: clamping DMA %#.16"PRIx64" to %#.16"PRIx64"!\n", addr, res);
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "EDU: clamping DMA %#.16"PRIx64" to %#.16"PRIx64"!",
+                      addr, res);
     }
 
     return res;
-- 
2.36.1