On Tue, 12 May 2009, Jeremy Fitzhardinge wrote:
> From: Christophe Saout <chtephan@xxxxxxxxxxxxxxxxxxxx>
>
> A PV Xen guest kernel has no TSS of its own, so the IO permission
> bitmap must be paravirtualized. This patch adds set_io_bitmap
> as a paravirt op, and defines a native version which updates the tss,
> and a Xen version which uses a hypercall.
>
> This is much easier now that 32 and 64-bit use the same code to
> manage the IO bitmap.
Sigh, is there a plan to limit the paravirt horror at some point or
are we keeping on adding to it forever ?
> --- a/arch/x86/kernel/ioport.c
> +++ b/arch/x86/kernel/ioport.c
> @@ -30,14 +30,31 @@ static void set_bitmap(unsigned long *bitmap, unsigned
> int base,
> }
> }
This needs kernel doc annotation and a comment about the calling
conventions i.e. preemption disabled.
> +void native_set_io_bitmap(struct thread_struct *t,
> + int changed, unsigned long bytes_updated)
> +{
> + struct tss_struct *tss;
> +
> + if (!bytes_updated)
> + return;
> +
> + tss = &__get_cpu_var(init_tss);
> +
> + /* Update the TSS: */
> + if (t->io_bitmap_ptr)
> + memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated);
> + else
> + memset(tss->io_bitmap, 0xff, bytes_updated);
> +}
> +
Thanks,
tglx
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