commit 99ab4d500af638ba3ebb20e8aa89d72201b70860
author Eric Auger <eric.auger@redhat.com> Fri Feb 03 18:15:10 2023 +0100
committer Richard Henderson <richard.henderson@linaro.org> Sat Feb 04 06:19:42 2023 -1000
tree 63bc6420c21864834d7236a8535291f3e44cb78b
parent 579510e196a544b42bd8bca9cc61688d4d1211ac

accel/tcg: Test CPUJumpCache in tb_jmp_cache_clear_page

After commit 4e4fa6c12d ("accel/tcg: Complete cpu initialization
before registration"), it looks the CPUJumpCache pointer can be NULL.
This causes a SIGSEV when running debug-wp-migration kvm unit test.

At the first place it should be clarified why this TCG code is called
with KVM acceleration. This may hide another bug.

Fixes: 4e4fa6c12d ("accel/tcg: Complete cpu initialization before registration")
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Message-Id: <20230203171510.2867451-1-eric.auger@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

accel/tcg/cputlb.c

diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
index 4e040a1..04e2707 100644
--- a/accel/tcg/cputlb.c
+++ b/accel/tcg/cputlb.c
@@ -100,9 +100,14 @@
 
 static void tb_jmp_cache_clear_page(CPUState *cpu, target_ulong page_addr)
 {
-    int i, i0 = tb_jmp_cache_hash_page(page_addr);
     CPUJumpCache *jc = cpu->tb_jmp_cache;
+    int i, i0;
 
+    if (unlikely(!jc)) {
+        return;
+    }
+
+    i0 = tb_jmp_cache_hash_page(page_addr);
     for (i = 0; i < TB_JMP_PAGE_SIZE; i++) {
         qatomic_set(&jc->array[i0 + i].tb, NULL);
     }