[PATCH 3/6] IOPL handling for paravirt guests
I found a clever way to make the extra IOPL switching invisible to non-paravirt compiles - since kernel_rpl is statically defined to be zero there, and only non-zero rpl kernel have a problem restoring IOPL, as popf does not restore IOPL flags unless run at CPL-0. Subject: IOPL handling for paravirt guests Signed-off-by: Zachary Amsden <[EMAIL PROTECTED]> diff -r 8110943fd7ad arch/i386/kernel/process.c --- a/arch/i386/kernel/process.cThu Dec 14 16:15:20 2006 -0800 +++ b/arch/i386/kernel/process.cThu Dec 14 16:21:57 2006 -0800 @@ -665,6 +665,15 @@ struct task_struct fastcall * __switch_t load_TLS(next, cpu); /* +* Restore IOPL if needed. In normal use, the flags restore +* in the switch assembly will handle this. But if the kernel +* is running virtualized at a non-zero CPL, the popf will +* not restore flags, so it must be done in a separate step. +*/ + if (get_kernel_rpl() && unlikely(prev->iopl != next->iopl)) + set_iopl_mask(next->iopl); + + /* * Now maybe handle debug registers and/or IO bitmaps */ if (unlikely((task_thread_info(next_p)->flags & _TIF_WORK_CTXSW) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH 3/6] IOPL handling for paravirt guests
I found a clever way to make the extra IOPL switching invisible to non-paravirt compiles - since kernel_rpl is statically defined to be zero there, and only non-zero rpl kernel have a problem restoring IOPL, as popf does not restore IOPL flags unless run at CPL-0. Subject: IOPL handling for paravirt guests Signed-off-by: Zachary Amsden [EMAIL PROTECTED] diff -r 8110943fd7ad arch/i386/kernel/process.c --- a/arch/i386/kernel/process.cThu Dec 14 16:15:20 2006 -0800 +++ b/arch/i386/kernel/process.cThu Dec 14 16:21:57 2006 -0800 @@ -665,6 +665,15 @@ struct task_struct fastcall * __switch_t load_TLS(next, cpu); /* +* Restore IOPL if needed. In normal use, the flags restore +* in the switch assembly will handle this. But if the kernel +* is running virtualized at a non-zero CPL, the popf will +* not restore flags, so it must be done in a separate step. +*/ + if (get_kernel_rpl() unlikely(prev-iopl != next-iopl)) + set_iopl_mask(next-iopl); + + /* * Now maybe handle debug registers and/or IO bitmaps */ if (unlikely((task_thread_info(next_p)-flags _TIF_WORK_CTXSW) - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
