2014-04-01 12:46:15

by Konrad Rzeszutek Wilk

Subject: Re: [PATCH] swiotlb: Correct kernel command line handler

On Tue, Apr 01, 2014 at 10:51:58AM +0900, Jungseok Lee wrote:
> This patch corrects kernel command line handler when io_tlb_nslabs
> is set to 0.
>
> A current implementation allocates default size memory (64MB) when
> 0 is given to io_tlb_nslabs ("swiotlb=0") by kernel command line.
> In other words, memory is allocated unintentionally.

What are the other IOMMUs that end up taking over the DMA ops?
Or do you end up with no DMA ops?

>
> Signed-off-by: Jungseok Lee <[email protected]>
> Signed-off-by: Sungjinn Chung <[email protected]>
> ---
> lib/swiotlb.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/lib/swiotlb.c b/lib/swiotlb.c
> index b604b83..9fe9f71 100644
> --- a/lib/swiotlb.c
> +++ b/lib/swiotlb.c
> @@ -55,6 +55,8 @@
>
> int swiotlb_force;
>
> +static int swiotlb_no_use;
> +
> /*
> * Used to do a quick range check in swiotlb_tbl_unmap_single and
> * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this
> @@ -102,6 +104,8 @@ setup_io_tlb_npages(char *str)
> io_tlb_nslabs = simple_strtoul(str, &str, 0);
> /* avoid tail segment of size < IO_TLB_SEGSIZE */
> io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> + if (!io_tlb_nslabs)
> + swiotlb_no_use = 1;
> }
> if (*str == ',')
> ++str;
> @@ -212,7 +216,7 @@ swiotlb_init(int verbose)
> unsigned char *vstart;
> unsigned long bytes;
>
> - if (!io_tlb_nslabs) {
> + if (!swiotlb_no_use && !io_tlb_nslabs) {
> io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> }
> @@ -244,7 +248,7 @@ swiotlb_late_init_with_default_size(size_t default_size)
> unsigned int order;
> int rc = 0;
>
> - if (!io_tlb_nslabs) {
> + if (!swiotlb_no_use && !io_tlb_nslabs) {
> io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> }
> --
> 1.7.10.4
>
>

2014-04-02 04:36:33

by Jungseok Lee

Subject: Re: [PATCH] swiotlb: Correct kernel command line handler

On Tuesday, April 01, 2014 9:46 PM, Konrad Rzeszutek Wilk wrote:
> On Tue, Apr 01, 2014 at 10:51:58AM +0900, Jungseok Lee wrote:
> > This patch corrects kernel command line handler when io_tlb_nslabs is
> > set to 0.
> >
> > A current implementation allocates default size memory (64MB) when
> > 0 is given to io_tlb_nslabs ("swiotlb=0") by kernel command line.
> > In other words, memory is allocated unintentionally.
>
> What are the other IOMMUs that end up taking over the DMA ops?

I think that no other IOMMUs take over it on ARM64 system, except Xen.

> Or do you end up with no DMA ops?

I focus on ARM64 system which uses swiotlb as default DMA ops.

If some ARM64 platforms would like to use memory only from
__get_free_pages in swiotlb_alloc_coherent function, an
interface would be needed to configure reserved memory size.

Thus, I add it to kernel command line handler.

Best Regards
Jungseok Lee

> >
> > Signed-off-by: Jungseok Lee <[email protected]>
> > Signed-off-by: Sungjinn Chung <[email protected]>
> > ---
> > lib/swiotlb.c | 8 ++++++--
> > 1 file changed, 6 insertions(+), 2 deletions(-)
> >
> > diff --git a/lib/swiotlb.c b/lib/swiotlb.c index b604b83..9fe9f71
> > 100644
> > --- a/lib/swiotlb.c
> > +++ b/lib/swiotlb.c
> > @@ -55,6 +55,8 @@
> >
> > int swiotlb_force;
> >
> > +static int swiotlb_no_use;
> > +
> > /*
> > * Used to do a quick range check in swiotlb_tbl_unmap_single and
> > * swiotlb_tbl_sync_single_*, to see if the memory was in fact
> > allocated by this @@ -102,6 +104,8 @@ setup_io_tlb_npages(char *str)
> > io_tlb_nslabs = simple_strtoul(str, &str, 0);
> > /* avoid tail segment of size < IO_TLB_SEGSIZE */
> > io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > + if (!io_tlb_nslabs)
> > + swiotlb_no_use = 1;
> > }
> > if (*str == ',')
> > ++str;
> > @@ -212,7 +216,7 @@ swiotlb_init(int verbose)
> > unsigned char *vstart;
> > unsigned long bytes;
> >
> > - if (!io_tlb_nslabs) {
> > + if (!swiotlb_no_use && !io_tlb_nslabs) {
> > io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> > io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > }
> > @@ -244,7 +248,7 @@ swiotlb_late_init_with_default_size(size_t default_size)
> > unsigned int order;
> > int rc = 0;
> >
> > - if (!io_tlb_nslabs) {
> > + if (!swiotlb_no_use && !io_tlb_nslabs) {
> > io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> > io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > }
> > --
> > 1.7.10.4
> >
> >
> --
> To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message
> to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html

2014-06-20 20:20:26

by Konrad Rzeszutek Wilk

Subject: Re: [PATCH] swiotlb: Correct kernel command line handler

On Wed, Apr 02, 2014 at 01:36:29PM +0900, Jungseok Lee wrote:
> On Tuesday, April 01, 2014 9:46 PM, Konrad Rzeszutek Wilk wrote:
> > On Tue, Apr 01, 2014 at 10:51:58AM +0900, Jungseok Lee wrote:
> > > This patch corrects kernel command line handler when io_tlb_nslabs is
> > > set to 0.
> > >
> > > A current implementation allocates default size memory (64MB) when
> > > 0 is given to io_tlb_nslabs ("swiotlb=0") by kernel command line.
> > > In other words, memory is allocated unintentionally.
> >
> > What are the other IOMMUs that end up taking over the DMA ops?
>
> I think that no other IOMMUs take over it on ARM64 system, except Xen.
>
> > Or do you end up with no DMA ops?
>
> I focus on ARM64 system which uses swiotlb as default DMA ops.
>
> If some ARM64 platforms would like to use memory only from
> __get_free_pages in swiotlb_alloc_coherent function, an
> interface would be needed to configure reserved memory size.
>
> Thus, I add it to kernel command line handler.

OK. I somehow have lost track of this patch. Is this patch
still valid?

>
> Best Regards
> Jungseok Lee
>
> > >
> > > Signed-off-by: Jungseok Lee <[email protected]>
> > > Signed-off-by: Sungjinn Chung <[email protected]>
> > > ---
> > > lib/swiotlb.c | 8 ++++++--
> > > 1 file changed, 6 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/lib/swiotlb.c b/lib/swiotlb.c index b604b83..9fe9f71
> > > 100644
> > > --- a/lib/swiotlb.c
> > > +++ b/lib/swiotlb.c
> > > @@ -55,6 +55,8 @@
> > >
> > > int swiotlb_force;
> > >
> > > +static int swiotlb_no_use;
> > > +
> > > /*
> > > * Used to do a quick range check in swiotlb_tbl_unmap_single and
> > > * swiotlb_tbl_sync_single_*, to see if the memory was in fact
> > > allocated by this @@ -102,6 +104,8 @@ setup_io_tlb_npages(char *str)
> > > io_tlb_nslabs = simple_strtoul(str, &str, 0);
> > > /* avoid tail segment of size < IO_TLB_SEGSIZE */
> > > io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > > + if (!io_tlb_nslabs)
> > > + swiotlb_no_use = 1;
> > > }
> > > if (*str == ',')
> > > ++str;
> > > @@ -212,7 +216,7 @@ swiotlb_init(int verbose)
> > > unsigned char *vstart;
> > > unsigned long bytes;
> > >
> > > - if (!io_tlb_nslabs) {
> > > + if (!swiotlb_no_use && !io_tlb_nslabs) {
> > > io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> > > io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > > }
> > > @@ -244,7 +248,7 @@ swiotlb_late_init_with_default_size(size_t default_size)
> > > unsigned int order;
> > > int rc = 0;
> > >
> > > - if (!io_tlb_nslabs) {
> > > + if (!swiotlb_no_use && !io_tlb_nslabs) {
> > > io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> > > io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> > > }
> > > --
> > > 1.7.10.4
> > >
> > >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message
> > to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
>