https://bugzilla.kernel.org/show_bug.cgi?id=213257 Bug ID: 213257 Summary: KVM-PR: FPU is broken when single-stepping Product: Virtualization Version: unspecified Kernel Version: 5.6 Hardware: PPC-64 OS: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: kvm Assignee: virtualization_kvm@xxxxxxxxxxxxxxxxxxxx Reporter: cand@xxxxxxx Regression: No The FPU is completely broken when single-stepping on KVM-PR. Registers stay zeroes, computation results are zeroes. If I disable single-stepping, computation results are correct, but of course then I cannot dump FPRs between every instruction. HW is POWER9, 18-core Talos II. 5.6 is slightly old, but there are no commits under arch/powerpc/kvm since that mention single stepping. Program: https://git.libre-soc.org/?p=kvm-minippc.git;a=summary Test file: https://ftp.libre-soc.org/mini-float-test-kvm.bin Repro instructions: git clone https://git.libre-soc.org/git/kvm-minippc.git cd kvm-minippc make wget https://ftp.libre-soc.org/mini-float-test-kvm.bin ./kvm-minippc -i mini-float-test-kvm.bin -t trace less trace # you will see FPRs stay zeroes. In larger test programs that dump the computed memory, that is wrong too (all zero). -- You may reply to this email to add a comment. You are receiving this mail because: You are watching the assignee of the bug.
