RE: [v4 2/8] iommu, x86: Define new irte structure for VT-d Posted-Interrupts
> -Original Message- > From: Joerg Roedel [mailto:j...@8bytes.org] > Sent: Tuesday, March 31, 2015 11:17 PM > To: Wu, Feng > Cc: dw...@infradead.org; jiang@linux.intel.com; > io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org > Subject: Re: [v4 2/8] iommu, x86: Define new irte structure for VT-d > Posted-Interrupts > > On Tue, Mar 24, 2015 at 02:32:01AM +, Wu, Feng wrote: > > > I think it is better to put this as a union into struct irte. It saves > > > memory and unnecessary casting in later patches. > > > > Thanks for the comments! > > Thinking more about this, I think its probably fine to keep the two > versions of the irte seperate like in this patch-set. It allows to > update the non-posted irte when the posted irte is active at the moment > and makes the transition between both irte variants easier. > > But what I still don't like is the type casting necessary when calling > modify_irte(). Can you abstract this and put the decission whether irte > or irte_pi is set active into modify_irte? It required to change the > interface of modify_irte, but that should be easy. > Sound good! Then we can keep the difference inside modify_irte(). BTW, could you please have a look at other patches in this series? Thanks, Feng > > Joerg -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [v4 2/8] iommu, x86: Define new irte structure for VT-d Posted-Interrupts
On Tue, Mar 24, 2015 at 02:32:01AM +, Wu, Feng wrote: > > I think it is better to put this as a union into struct irte. It saves > > memory and unnecessary casting in later patches. > > Thanks for the comments! Thinking more about this, I think its probably fine to keep the two versions of the irte seperate like in this patch-set. It allows to update the non-posted irte when the posted irte is active at the moment and makes the transition between both irte variants easier. But what I still don't like is the type casting necessary when calling modify_irte(). Can you abstract this and put the decission whether irte or irte_pi is set active into modify_irte? It required to change the interface of modify_irte, but that should be easy. Joerg -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
RE: [v4 2/8] iommu, x86: Define new irte structure for VT-d Posted-Interrupts
> -Original Message-
> From: Joerg Roedel [mailto:j...@8bytes.org]
> Sent: Monday, March 23, 2015 7:58 PM
> To: Wu, Feng
> Cc: dw...@infradead.org; jiang@linux.intel.com;
> io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org
> Subject: Re: [v4 2/8] iommu, x86: Define new irte structure for VT-d
> Posted-Interrupts
>
> Hi Feng,
>
> On Mon, Feb 02, 2015 at 04:06:58PM +0800, Feng Wu wrote:
> > Add a new irte_pi structure for VT-d Posted-Interrupts.
> >
> > Signed-off-by: Feng Wu
> > Reviewed-by: Jiang Liu
> > Acked-by: David Woodhouse
> > ---
> > include/linux/dmar.h | 32
> > 1 files changed, 32 insertions(+), 0 deletions(-)
> >
> > diff --git a/include/linux/dmar.h b/include/linux/dmar.h
> > index 8473756..c7f9cda 100644
> > --- a/include/linux/dmar.h
> > +++ b/include/linux/dmar.h
> > @@ -212,6 +212,38 @@ struct irte {
> > };
> > };
> >
> > +struct irte_pi {
>
> I think it is better to put this as a union into struct irte. It saves
> memory and unnecessary casting in later patches.
Thanks for the comments!
Do you mean doing it like the following?
struct irte {
union {
struct {
__u64 present : 1,
fpd : 1,
dst_mode: 1,
redir_hint : 1,
trigger_mode: 1,
dlvry_mode : 3,
avail : 4,
__reserved_1: 4,
vector : 8,
__reserved_2: 8,
dest_id : 32;
};
struct {
__u64 present : 1,
fpd : 1,
__reserved_1: 6,
avail : 4,
__reserved_2: 2,
urg : 1,
pst : 1,
vector : 8,
__reserved_3: 14,
pda_l : 26;
};
__u64 low;
};
union {
struct {
__u64 sid : 16,
sq : 2,
svt : 2,
__reserved_3: 44;
};
struct {
__u64 sid : 16,
sq : 2,
svt : 2,
__reserved_4: 12,
pda_h : 32;
};
__u64 high;
};
};
In fact, I also intended to make these two defines as one, however, this code
will get build
error ("duplicated member") with new version of GCC, such as, gcc 4.9.1. I
cannot find a
good way to handle this gracefully, since I don't want to impact the existing
usage of this
structure . Do you have any ideas about this? Thanks a lot!
Thanks,
Feng
>
>
> Joerg
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Re: [v4 2/8] iommu, x86: Define new irte structure for VT-d Posted-Interrupts
Hi Feng,
On Mon, Feb 02, 2015 at 04:06:58PM +0800, Feng Wu wrote:
> Add a new irte_pi structure for VT-d Posted-Interrupts.
>
> Signed-off-by: Feng Wu
> Reviewed-by: Jiang Liu
> Acked-by: David Woodhouse
> ---
> include/linux/dmar.h | 32
> 1 files changed, 32 insertions(+), 0 deletions(-)
>
> diff --git a/include/linux/dmar.h b/include/linux/dmar.h
> index 8473756..c7f9cda 100644
> --- a/include/linux/dmar.h
> +++ b/include/linux/dmar.h
> @@ -212,6 +212,38 @@ struct irte {
> };
> };
>
> +struct irte_pi {
I think it is better to put this as a union into struct irte. It saves
memory and unnecessary casting in later patches.
Joerg
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