On Mon, 2024-07-01 at 16:35 +0100, Andrew Cooper wrote: > On 06/03/2024 1:44 pm, Jan Beulich wrote: > > --- a/xen/arch/x86/x86_64/entry.S > > +++ b/xen/arch/x86/x86_64/entry.S > > @@ -47,12 +55,13 @@ UNLIKELY_START(z, syscall_no_callback) / > > testb $4, X86_EXC_UD * TRAPINFO_sizeof + > > TRAPINFO_flags(%rdi) > > setnz %cl > > lea TBF_EXCEPTION(, %rcx, TBF_INTERRUPT), %ecx > > + or $~0, %esi # don't clear DF > > Our predominant comment style is /* */ > > > UNLIKELY_END(syscall_no_callback) > > > > movq %rax,TRAPBOUNCE_eip(%rdx) > > movb %cl,TRAPBOUNCE_flags(%rdx) > > call create_bounce_frame > > - andl $~X86_EFLAGS_DF,UREGS_eflags(%rsp) > > + and %esi, UREGS_eflags(%rsp) > > Could we gain a /* Conditionally clear DF */ comment here? > > Otherwise, Reviewed-by: Andrew Cooper <andrew.coop...@citrix.com> > > CC Oleksii for 4.19. This fixes a subtle regression in the PV ABI > caused by a post-XSA fix a few years ago. > > It's a low-risk fix to take; while I still don't have an XTF test > covering this, the corner case it's changing used to be completely > fatal > to guests, so it's a corner unused in practice. > Release-Acked-By: Oleksii Kurochko <oleksii.kuroc...@gmail.com>
~ Oleksii
