>>> On 14.02.18 at 12:10, <andrew.coop...@citrix.com> wrote: > DO_OVERWRITE_RSB clobbers %rax, meaning in practice that that the bti_ist_info > field gets zeroed. Older versions of this code had the DO_OVERWRITE_RSB > register selectable, so reintroduce this ability and use it to cause the > INTR_IST path to use %rdx instead. > > The use of %dl for the %cs.rpl check means that when an IST interrupt hits > Xen, we try to load 1 into the high 32 bits of MSR_SPEC_CTRL, suffering a #GP > fault instead. > > Also, drop an unused label which was a copy/paste mistake. > > Reported-by: Boris Ostrovsky <boris.ostrov...@oracle.com> > Reported-by: Zhenzhong Duan <zhenzhong.d...@oracle.com> > Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
Reviewed-by: Jan Beulich <jbeul...@suse.com> with one remark/suggestion: > --- a/xen/include/asm-x86/spec_ctrl_asm.h > +++ b/xen/include/asm-x86/spec_ctrl_asm.h > @@ -79,10 +79,10 @@ > * - SPEC_CTRL_EXIT_TO_GUEST > */ > > -.macro DO_OVERWRITE_RSB > +.macro DO_OVERWRITE_RSB tmp=%rax If only registers are supposed to be passed as macro arguments, I generally consider it better to leave specifying at least the % to the macro body - that way nothing else (like a memory operand, perhaps referencing %rsp in a dangerous way) can be passed, as the assembler will choke on invalid names following %. In order to have the flexibility to also use the 32-bit register name inside the macro, I would also generally omit the r (but this is less of a concern here, as it's quite unlikely for the 32-bit name to be needed). Jan Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
