target/i386: Fix test for paging enabled

If CR0.PG is unset, pg_mode will be zero, but it will also be zero
for non-PAE/non-PSE page tables with CR0.WP=0.  Restore the
correct test for paging enabled.

Fixes: 98281984a37 ("target/i386: Add MMU_PHYS_IDX and MMU_NESTED_IDX")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1269
Reported-by: Andreas Gustafsson <gson@gson.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20221102091232.1092552-1-richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/target/i386/tcg/sysemu/excp_helper.c b/target/i386/tcg/sysemu/excp_helper.c
index d51b5d7431a0c219d38683f06633c7a4bde40a76..405a5d414a14ed29112736d9417324fe12fee4a3 100644 (file)
--- a/target/i386/tcg/sysemu/excp_helper.c
+++ b/target/i386/tcg/sysemu/excp_helper.c
@@ -553,12 +553,12 @@ static bool get_physical_address(CPUX86State *env, vaddr addr,
         break;
 
     default:
-        in.cr3 = env->cr[3];
-        in.mmu_idx = mmu_idx;
-        in.ptw_idx = use_stage2 ? MMU_NESTED_IDX : MMU_PHYS_IDX;
-        in.pg_mode = get_pg_mode(env);
+        if (likely(env->cr[0] & CR0_PG_MASK)) {
+            in.cr3 = env->cr[3];
+            in.mmu_idx = mmu_idx;
+            in.ptw_idx = use_stage2 ? MMU_NESTED_IDX : MMU_PHYS_IDX;
+            in.pg_mode = get_pg_mode(env);
 
-        if (likely(in.pg_mode)) {
             if (in.pg_mode & PG_MODE_LMA) {
                 /* test virtual address sign extension */
                 int shift = in.pg_mode & PG_MODE_LA57 ? 56 : 47;