On Tue, Jul 24, 2012 at 01:46:27PM -0600, Shuah Khan wrote:
> Disable iotlb overflow support when CONFIG_ISA is disabled. Add deprecation
You need to check one more thing. In the email I mentioned that the bulk
of the drivers that utilize this are ISA, but there are also some that
are PCI dependent.
So I grepped for anything that does 'dma_map_page' and some of them are
even PCIe, for example: drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
Which means that the check for CONFIG_ISA is not sufficient.
> notice warning message and deprecation schedule documentation. This is the
> first step towards removing overflow support, to be consistent with other
> iommu implementations and return DMA_ERROR_CODE. This disabling step is for
> finding drivers that don't call dma_mapping_error to check for errors returned
> by the mapping interface. Once drivers are fixed overflow support can be
> removed.
>
> Signed-off-by: Shuah Khan <shuah.khan@xxxxxx>
Did you do a cross compile on IA64 just to double check? Comments below.
> ---
> Documentation/feature-removal-schedule.txt | 22 ++++++--
> lib/swiotlb.c | 79 +++++++++++++++++++++-------
> 2 files changed, 79 insertions(+), 22 deletions(-)
>
> diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
> index 5979c3e..ce6c0ae 100644
> --- a/Documentation/feature-removal-schedule.txt
> +++ b/Documentation/feature-removal-schedule.txt
> @@ -35,7 +35,7 @@ What: x86_32 "no-hlt" cmdline param
> When: 2012
> Why: remove a branch from idle path, simplify code used by everybody.
> This option disabled the use of HLT in idle and machine_halt()
> - for hardware that was flakey 15-years ago. Today we have
> + for hardware that was flaky 15-years ago. Today we have
Ummm, that is not part of what this patch should be doing.
> "idle=poll" that removed HLT from idle, and so if such a machine
> is still running the upstream kernel, "idle=poll" is likely sufficient.
> Who: Len Brown <len.brown@xxxxxxxxx>
> @@ -160,7 +160,7 @@ Files: arch/*/kernel/*_ksyms.c
> Check: kernel_thread
> Why: kernel_thread is a low-level implementation detail. Drivers should
> use the <linux/kthread.h> API instead which shields them from
> - implementation details and provides a higherlevel interface that
> + implementation details and provides a higher level interface that
Neither is this.
> prevents bugs and code duplication
> Who: Christoph Hellwig <hch@xxxxxx>
>
> @@ -236,7 +236,7 @@ Who: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
>
> What: b43 support for firmware revision < 410
> When: The schedule was July 2008, but it was decided that we are going to keep the
> - code as long as there are no major maintanance headaches.
> + code as long as there are no major maintenance headaches.
Or this.
> So it _could_ be removed _any_ time now, if it conflicts with something new.
> Why: The support code for the old firmware hurts code readability/maintainability
> and slightly hurts runtime performance. Bugfixes for the old firmware
> @@ -608,3 +608,19 @@ When: June 2013
> Why: Unsupported/unmaintained/unused since 2.6
>
> ----------------------------
> +
> +What: SWIOTLB overflow buffer support.
> +When: 3.8
> +Why: Remove SWIOTLB overflow buffer support and return DMA_ERROR_CODE
> + (a value of zero) to make it consistent with iommu implementation
> + on Intel, AMD, and swiotlb-xen. In 3.6, Disable iotlb overflow
> + support when CONFIG_ISA is disabled with the intent to find drivers
> + that don't call dma_mapping_error to check for errors returned by the
> + mapping interface. Once drivers are fixed overflow support can be
> + removed.
> + If you see any problems related to disabling SWIOTLB overflow buffer,
> + please report to us!
> + E-mail us at: linux-kernel@xxxxxxxxxxxxxxx
> +Who: Shuah Khan <shuah.khan@xxxxxx> <shuahkhan@xxxxxxxxx>
> +
> +----------------------------
> diff --git a/lib/swiotlb.c b/lib/swiotlb.c
> index 45bc1f8..0123bb8 100644
> --- a/lib/swiotlb.c
> +++ b/lib/swiotlb.c
> @@ -15,6 +15,9 @@
> * 05/09/10 linville Add support for syncing ranges, support syncing for
> * DMA_BIDIRECTIONAL mappings, miscellaneous cleanup.
> * 08/12/11 beckyb Add highmem support
> + * 07/2012 shuahkhan Disable iotlb overflow support when CONFIG_ISA
> + * is enabled. Remove it for all configs when drivers
> + * that don't check for mapping errors are fixed.
Don't bother. The changelog is now in the git commit.
> */
>
> #include <linux/cache.h>
> @@ -68,7 +71,11 @@ static unsigned long io_tlb_nslabs;
> /*
> * When the IOMMU overflows we return a fallback buffer. This sets the size.
> */
> +#if defined(CONFIG_ISA)
> static unsigned long io_tlb_overflow = 32*1024;
> +#else
> +static unsigned long io_tlb_overflow;
> +#endif
>
> static void *io_tlb_overflow_buffer;
>
> @@ -92,6 +99,24 @@ static DEFINE_SPINLOCK(io_tlb_lock);
>
> static int late_alloc;
>
> +static void swiotlb_print_overflow_deprecation_notice(void)
> +{
> + if (io_tlb_overflow) {
> + pr_warn("SWIOTLB overflow buffer will be deprecated.\n"
> + " If you have a driver that depends on this feature\n"
> + " please Email us at: linux-kernel@xxxxxxxxxxxxxxx,\n"
> + " Shuah Khan (shuahkhan@xxxxxxxxx), and\n"
> + " Konrad Wilk (konrad.wilk@xxxxxxxxxx)\n");
> + } else {
> + pr_warn("SWIOTLB overflow buffer is disabled and will be\n"
> + " deprecated. Please report problems related to\n"
> + " disabling overflow buffer to\n"
> + " linux-kernel@xxxxxxxxxxxxxxx,\n"
> + " Shuah Khan (shuahkhan@xxxxxxxxx), and\n"
> + " Konrad Wilk (konrad.wilk@xxxxxxxxxx)\n");
> + }
> +}
> +
> static int __init
> setup_io_tlb_npages(char *str)
> {
> @@ -108,7 +133,6 @@ setup_io_tlb_npages(char *str)
> return 1;
> }
> __setup("swiotlb=", setup_io_tlb_npages);
> -/* make io_tlb_overflow tunable too? */
>
> unsigned long swiotlb_nr_tbl(void)
> {
> @@ -156,12 +180,18 @@ void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
> io_tlb_index = 0;
> io_tlb_orig_addr = alloc_bootmem_pages(PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t)));
>
> - /*
> - * Get the overflow emergency buffer
> - */
> - io_tlb_overflow_buffer = alloc_bootmem_low_pages(PAGE_ALIGN(io_tlb_overflow));
> - if (!io_tlb_overflow_buffer)
> - panic("Cannot allocate SWIOTLB overflow buffer!\n");
> + if (io_tlb_overflow) {
> + /*
> + * Get the overflow emergency buffer
> + */
> + io_tlb_overflow_buffer = alloc_bootmem_low_pages(
> + PAGE_ALIGN(io_tlb_overflow));
> + if (!io_tlb_overflow_buffer)
> + panic("Cannot allocate SWIOTLB overflow buffer!\n");
> + }
> +
> + swiotlb_print_overflow_deprecation_notice();
> +
> if (verbose)
> swiotlb_print_info();
> }
> @@ -264,14 +294,17 @@ swiotlb_late_init_with_default_size(size_t default_size)
>
> memset(io_tlb_orig_addr, 0, io_tlb_nslabs * sizeof(phys_addr_t));
>
> - /*
> - * Get the overflow emergency buffer
> - */
> - io_tlb_overflow_buffer = (void *)__get_free_pages(GFP_DMA,
> - get_order(io_tlb_overflow));
> - if (!io_tlb_overflow_buffer)
> - goto cleanup4;
> + if (io_tlb_overflow) {
> + /*
> + * Get the overflow emergency buffer
> + */
> + io_tlb_overflow_buffer = (void *)
> + __get_free_pages(GFP_DMA, get_order(io_tlb_overflow));
> + if (!io_tlb_overflow_buffer)
> + goto cleanup4;
> + }
>
> + swiotlb_print_overflow_deprecation_notice();
> swiotlb_print_info();
>
> late_alloc = 1;
> @@ -297,12 +330,13 @@ cleanup1:
>
> void __init swiotlb_free(void)
> {
> - if (!io_tlb_overflow_buffer)
> + if (!io_tlb_orig_addr)
> return;
>
> if (late_alloc) {
> - free_pages((unsigned long)io_tlb_overflow_buffer,
> - get_order(io_tlb_overflow));
> + if (io_tlb_overflow_buffer)
> + free_pages((unsigned long)io_tlb_overflow_buffer,
> + get_order(io_tlb_overflow));
> free_pages((unsigned long)io_tlb_orig_addr,
> get_order(io_tlb_nslabs * sizeof(phys_addr_t)));
> free_pages((unsigned long)io_tlb_list, get_order(io_tlb_nslabs *
> @@ -310,8 +344,9 @@ void __init swiotlb_free(void)
> free_pages((unsigned long)io_tlb_start,
> get_order(io_tlb_nslabs << IO_TLB_SHIFT));
> } else {
> - free_bootmem_late(__pa(io_tlb_overflow_buffer),
> - PAGE_ALIGN(io_tlb_overflow));
> + if (io_tlb_overflow_buffer)
> + free_bootmem_late(__pa(io_tlb_overflow_buffer),
> + PAGE_ALIGN(io_tlb_overflow));
> free_bootmem_late(__pa(io_tlb_orig_addr),
> PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t)));
> free_bootmem_late(__pa(io_tlb_list),
> @@ -681,6 +716,8 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
> map = map_single(dev, phys, size, dir);
> if (!map) {
> swiotlb_full(dev, size, dir, 1);
> + if (!io_tlb_overflow)
> + return DMA_ERROR_CODE;
> map = io_tlb_overflow_buffer;
> }
>
> @@ -691,6 +728,8 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
> */
> if (!dma_capable(dev, dev_addr, size)) {
> swiotlb_tbl_unmap_single(dev, map, size, dir);
> + if (!io_tlb_overflow)
> + return DMA_ERROR_CODE;
> dev_addr = swiotlb_virt_to_bus(dev, io_tlb_overflow_buffer);
> }
>
> @@ -910,6 +949,8 @@ EXPORT_SYMBOL(swiotlb_sync_sg_for_device);
> int
> swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr)
> {
> + if (!io_tlb_overflow)
> + return DMA_ERROR_CODE;
> return (dma_addr == swiotlb_virt_to_bus(hwdev, io_tlb_overflow_buffer));
> }
> EXPORT_SYMBOL(swiotlb_dma_mapping_error);
> --
> 1.7.9.5
>
>
>
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