target/arm: do_ats_write(): avoid assertion when ptw failed

In do_ats_write() we try to assert that the cacheattrs from get_phys_addr_for_at() are in the form we expect: /* * ATS operations only do S1 or S1+S2 translations, so we never * have to deal with the ARMCacheAttrs format for S2 only. */ assert(!res.cacheattrs.is_s2_format); However, the GetPhysAddrResult struct documents that its fields are only valid when the page table walk succeeded. For a two stage page table walk which fails during stage two, we will return early from get_phys_addr_twostage() and depending on the fault type the res.cacheattrs may have been initialized with the stage 2 cache attr information in stage 2 format. In this case we will incorrectly assert here. Fix the assertion to not look at the res fields if the lookup failed. Note for stable backports: the do_ats_write() function is in target/arm/helper.c in older QEMU versions, but the change to the assert line is the same. Cc: qemu-stable@nongnu.org Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3328 Fixes: 9f225e607f21 ("target/arm: Postpone interpretation of stage 2 descriptor attribute bits") Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-id: 20260331092305.2062580-1-peter.maydell@linaro.org