| Message ID | 1481894922-28828-4-git-send-email-geert+renesas@glider.be (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Geert Uytterhoeven |
| Headers | show |
On Fri, Dec 16, 2016 at 02:28:42PM +0100, Geert Uytterhoeven wrote: > On architectures like arm64, swiotlb is tied intimately to the core > architecture DMA support. In addition, ZONE_DMA cannot be disabled. > > To aid debugging and catch devices not supporting DMA to memory outside > the 32-bit address space, add a kernel command line option > "swiotlb=noforce", which disables the use of bounce buffers. > If specified, trying to map memory that cannot be used with DMA will > fail, and a rate-limited warning will be printed. > > Note that io_tlb_nslabs is set to 1, which is the minimal supported > value. > > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> What is this based on? I can't apply it on my latest that I had sent to Linus? Could you rebase this one please on: git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb.git stable/for-linus-4.9 Thanks? Or if alternatively that does not - then please rebase it on b5cab0da75c292ffa0fbd68dd2c820066b2842de Thanks!
Hi Konrad, On Mon, Dec 19, 2016 at 2:38 PM, Konrad Rzeszutek Wilk <konrad@darnok.org> wrote: > On Fri, Dec 16, 2016 at 02:28:42PM +0100, Geert Uytterhoeven wrote: >> On architectures like arm64, swiotlb is tied intimately to the core >> architecture DMA support. In addition, ZONE_DMA cannot be disabled. >> >> To aid debugging and catch devices not supporting DMA to memory outside >> the 32-bit address space, add a kernel command line option >> "swiotlb=noforce", which disables the use of bounce buffers. >> If specified, trying to map memory that cannot be used with DMA will >> fail, and a rate-limited warning will be printed. >> >> Note that io_tlb_nslabs is set to 1, which is the minimal supported >> value. >> >> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> > > What is this based on? I can't apply it on my latest that I had > sent to Linus? I rebased it on last Friday's linux-next, due to the recent move of kernel-parameters.txt. All the rest should be identical to your linux-next branch. > Could you rebase this one please on: > > git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb.git stable/for-linus-4.9 That one indeed doesn't have the move of kernel-parameters.txt. > Or if alternatively that does not - then please rebase it on > b5cab0da75c292ffa0fbd68dd2c820066b2842de However, my series already applies cleanly with git am on top of that commit? Please let me know what to do. Thanks! Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
On Mon, Dec 19, 2016 at 02:57:00PM +0100, Geert Uytterhoeven wrote: > Hi Konrad, > > On Mon, Dec 19, 2016 at 2:38 PM, Konrad Rzeszutek Wilk > <konrad@darnok.org> wrote: > > On Fri, Dec 16, 2016 at 02:28:42PM +0100, Geert Uytterhoeven wrote: > >> On architectures like arm64, swiotlb is tied intimately to the core > >> architecture DMA support. In addition, ZONE_DMA cannot be disabled. > >> > >> To aid debugging and catch devices not supporting DMA to memory outside > >> the 32-bit address space, add a kernel command line option > >> "swiotlb=noforce", which disables the use of bounce buffers. > >> If specified, trying to map memory that cannot be used with DMA will > >> fail, and a rate-limited warning will be printed. > >> > >> Note that io_tlb_nslabs is set to 1, which is the minimal supported > >> value. > >> > >> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> > > > > What is this based on? I can't apply it on my latest that I had > > sent to Linus? > > I rebased it on last Friday's linux-next, due to the recent move of > kernel-parameters.txt. > All the rest should be identical to your linux-next branch. > > > Could you rebase this one please on: > > > > git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb.git stable/for-linus-4.9 > > That one indeed doesn't have the move of kernel-parameters.txt. > > > Or if alternatively that does not - then please rebase it on > > b5cab0da75c292ffa0fbd68dd2c820066b2842de > > However, my series already applies cleanly with git am on top of > that commit? Ah that does indeed work. Which means I can't push it to Linus until rc2 at least. Linus is sad when he sees git pulls that hadn't "soaked" for two weeks in linux-next - and especially patches on top of merges during the merge window. > > Please let me know what to do. Thanks! Building and testing them now. Wish there was some travis script to do this.
On Fri, Dec 16, 2016 at 02:28:42PM +0100, Geert Uytterhoeven wrote: > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 21e2d88637050b7a..24fb691b2da5f78d 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -3811,10 +3811,11 @@ > it if 0 is given (See Documentation/cgroup-v1/memory.txt) > > swiotlb= [ARM,IA-64,PPC,MIPS,X86] > - Format: { <int> | force } > + Format: { <int> | force | noforce } > <int> -- Number of I/O TLB slabs > force -- force using of bounce buffers even if they > wouldn't be automatically used by the kernel > + noforce -- Never use bounce buffers (for debugging) Nitpick (bikeshedding, feel free to ignore): "noforce" looks to me like the current default behaviour if swiotlb= argument is passed. I would have preferred "never" or "disable" instead, it has a clearer intent.
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 21e2d88637050b7a..24fb691b2da5f78d 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3811,10 +3811,11 @@ it if 0 is given (See Documentation/cgroup-v1/memory.txt) swiotlb= [ARM,IA-64,PPC,MIPS,X86] - Format: { <int> | force } + Format: { <int> | force | noforce } <int> -- Number of I/O TLB slabs force -- force using of bounce buffers even if they wouldn't be automatically used by the kernel + noforce -- Never use bounce buffers (for debugging) switches= [HW,M68k] diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index 71d104e4c8490763..d9c84a9cde3dd7d7 100644 --- a/include/linux/swiotlb.h +++ b/include/linux/swiotlb.h @@ -12,6 +12,7 @@ enum swiotlb_force { SWIOTLB_NORMAL, /* Default - depending on HW DMA mask etc. */ SWIOTLB_FORCE, /* swiotlb=force */ + SWIOTLB_NO_FORCE, /* swiotlb=noforce */ }; extern enum swiotlb_force swiotlb_force; diff --git a/include/trace/events/swiotlb.h b/include/trace/events/swiotlb.h index 5e2e30a7efce0ebd..288c0c54a2b4ace6 100644 --- a/include/trace/events/swiotlb.h +++ b/include/trace/events/swiotlb.h @@ -39,7 +39,8 @@ __entry->size, __print_symbolic(__entry->swiotlb_force, { SWIOTLB_NORMAL, "NORMAL" }, - { SWIOTLB_FORCE, "FORCE" })) + { SWIOTLB_FORCE, "FORCE" }, + { SWIOTLB_NO_FORCE, "NO_FORCE" })) ); #endif /* _TRACE_SWIOTLB_H */ diff --git a/lib/swiotlb.c b/lib/swiotlb.c index a32dce6d5101f408..9def738af4f4e568 100644 --- a/lib/swiotlb.c +++ b/lib/swiotlb.c @@ -106,8 +106,12 @@ } if (*str == ',') ++str; - if (!strcmp(str, "force")) + if (!strcmp(str, "force")) { swiotlb_force = SWIOTLB_FORCE; + } else if (!strcmp(str, "noforce")) { + swiotlb_force = SWIOTLB_NO_FORCE; + io_tlb_nslabs = 1; + } return 0; } @@ -543,8 +547,15 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, map_single(struct device *hwdev, phys_addr_t phys, size_t size, enum dma_data_direction dir, unsigned long attrs) { - dma_addr_t start_dma_addr = phys_to_dma(hwdev, io_tlb_start); + dma_addr_t start_dma_addr; + + if (swiotlb_force == SWIOTLB_NO_FORCE) { + dev_warn_ratelimited(hwdev, "Cannot do DMA to address %pa\n", + &phys); + return SWIOTLB_MAP_ERROR; + } + start_dma_addr = phys_to_dma(hwdev, io_tlb_start); return swiotlb_tbl_map_single(hwdev, start_dma_addr, phys, size, dir, attrs); } @@ -721,6 +732,9 @@ void swiotlb_tbl_sync_single(struct device *hwdev, phys_addr_t tlb_addr, swiotlb_full(struct device *dev, size_t size, enum dma_data_direction dir, int do_panic) { + if (swiotlb_force == SWIOTLB_NO_FORCE) + return; + /* * Ran out of IOMMU space for this operation. This is very bad. * Unfortunately the drivers cannot handle this operation properly.
On architectures like arm64, swiotlb is tied intimately to the core architecture DMA support. In addition, ZONE_DMA cannot be disabled. To aid debugging and catch devices not supporting DMA to memory outside the 32-bit address space, add a kernel command line option "swiotlb=noforce", which disables the use of bounce buffers. If specified, trying to map memory that cannot be used with DMA will fail, and a rate-limited warning will be printed. Note that io_tlb_nslabs is set to 1, which is the minimal supported value. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> --- v2: - Change kernel parameter value from "nobounce" to "noforce", - Extend swiotlb_force enum instead of adding swiotlb_nobounce variable (both requested by Konrad Wilk). --- Documentation/admin-guide/kernel-parameters.txt | 3 ++- include/linux/swiotlb.h | 1 + include/trace/events/swiotlb.h | 3 ++- lib/swiotlb.c | 18 ++++++++++++++++-- 4 files changed, 21 insertions(+), 4 deletions(-)