id = 1370
title = "x86 BLSI and BLSR semantic bug"
state = "closed"
created_at = "2022-12-16T06:35:03.247Z"
closed_at = "2023-02-16T13:09:22.665Z"
labels = ["Closed::Fixed", "accel: TCG", "target: i386"]
url = "https://gitlab.com/qemu-project/qemu/-/issues/1370"
host-os = "Windows 10 20H2"
host-arch = "x86"
qemu-version = "7.1.90 (v7.2.0-rc0)"
guest-os = "None"
guest-arch = "x86"
description = """The result of instruction BLSI and BLSR is different from the CPU. The value of CF is different."""
reproduce = """1. Compile this code
```
void main() {
    asm("blsi rax, rbx");
}
```
2. Execute and compare the result with the CPU. The value of `CF` is exactly the opposite. This problem happens with BLSR, too."""
additional = """This bug is discovered by research conducted by KAIST SoftSec."""