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[3/3] fuzz: configure a sparse-mem device, by default

Message ID 20210311053614.940352-4-alxndr@bu.edu (mailing list archive)
State New, archived
Headers show
Series fuzz: Add a sparse-memory device to accelerate fuzzing | expand

Commit Message

Alexander Bulekov March 11, 2021, 5:36 a.m. UTC 
The generic-fuzzer often provides randomized DMA addresses to
virtual-devices. For a 64-bit address-space, the chance of these
randomized addresses coinciding with RAM regions, is fairly small. Even
though the fuzzer's instrumentation eventually finds valid addresses,
this can take some-time, and slows-down fuzzing progress (especially,
when multiple DMA buffers are involved). To work around this, create
"fake" sparse-memory that spans all of the 64-bit address-space.

Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
---
 tests/qtest/fuzz/generic_fuzz.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

diff --git a/tests/qtest/fuzz/generic_fuzz.c b/tests/qtest/fuzz/generic_fuzz.c
index 387ae2020a..08a6c5ac5e 100644
--- a/tests/qtest/fuzz/generic_fuzz.c
+++ b/tests/qtest/fuzz/generic_fuzz.c
@@ -940,7 +940,7 @@  static GString *generic_fuzz_cmdline(FuzzTarget *t)
     if (!getenv("QEMU_FUZZ_ARGS")) {
         usage();
     }
-    g_string_append_printf(cmd_line, " -display none \
+    g_string_append_printf(cmd_line, " -display none -device sparse-mem \
                                       -machine accel=qtest, \
                                       -m 512M %s ", getenv("QEMU_FUZZ_ARGS"));
     return cmd_line;