Re: [PATCH v2 for-8.0] target/s390x/tcg: Fix and improve the SACF instruction

[Richard Henderson <richard.henderson@linaro.org>]

On 12/1/22 10:44, Thomas Huth wrote:
> The SET ADDRESS SPACE CONTROL FAST instruction is not privileged, it can be
> used from problem space, too. Just the switching to the home address space
> is privileged and should still generate a privilege exception. This bug is
> e.g. causing programs like Java that use the "getcpu" vdso kernel function
> to crash (see https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=990417#26 ).
> 
> While we're at it, also check if DAT is not enabled. In that case the
> instruction is supposed to generate a special operation exception.
> 
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/655
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---

Looks ok, as far as it goes.  We appear to be missing the check for CR0_SECONDARY, which 
is unpredictable for SACF but mandatory for SAC.

I'll give you

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

for fixing the incorrect IF_PRIV check, which by itself should be enough to fix the Java 
issue.


r~