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Date: Fri, 25 Jan 2013 11:47:49 -0500
From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To: Yinghai Lu <yinghai@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
"H. Peter Anvin" <hpa@...or.com>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Jan Kiszka <jan.kiszka@....de>,
Jason Wessel <jason.wessel@...driver.com>,
Borislav Petkov <bp@...en8.de>, linux-kernel@...r.kernel.org,
Joerg Roedel <joro@...tes.org>,
Ralf Baechle <ralf@...ux-mips.org>,
Jeremy Fitzhardinge <jeremy@...p.org>,
Kyungmin Park <kyungmin.park@...sung.com>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Arnd Bergmann <arnd@...db.de>,
Andrzej Pietrasiewicz <andrzej.p@...sung.com>,
linux-mips@...ux-mips.org, xen-devel@...ts.xensource.com,
virtualization@...ts.linux-foundation.org,
Shuah Khan <shuahkhan@...il.com>
Subject: Re: [PATCH 35/35] x86: Don't panic if can not alloc buffer for
swiotlb
On Thu, Jan 24, 2013 at 12:20:16PM -0800, Yinghai Lu wrote:
> Normal boot path on system with iommu support:
> swiotlb buffer will be allocated early at first and then try to initialize
> iommu, if iommu for intel or AMD could setup properly, swiotlb buffer
> will be freed.
>
> The early allocating is with bootmem, and could panic when we try to use
> kdump with buffer above 4G only, or with memmap to limit mem under 4G.
> for example: memmap=4095M$1M to remove memory under 4G.
>
> According to Eric, add _nopanic version and no_iotlb_memory to fail
> map single later if swiotlb is still needed.
>
> -v2: don't pass nopanic, and use -ENOMEM return value according to Eric.
> panic early instead of using swiotlb_full to panic...according to Eric/Konrad.
> -v3: make swiotlb_init to be notpanic, but will affect:
> arm64, ia64, powerpc, tile, unicore32, x86.
> -v4: cleanup swiotlb_init by removing swiotlb_init_with_default_size.
>
> Suggested-by: Eric W. Biederman <ebiederm@...ssion.com>
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
:-)
> Cc: Joerg Roedel <joro@...tes.org>
> Cc: Ralf Baechle <ralf@...ux-mips.org>
> Cc: Jeremy Fitzhardinge <jeremy@...p.org>
> Cc: Kyungmin Park <kyungmin.park@...sung.com>
> Cc: Marek Szyprowski <m.szyprowski@...sung.com>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Andrzej Pietrasiewicz <andrzej.p@...sung.com>
> Cc: linux-mips@...ux-mips.org
> Cc: xen-devel@...ts.xensource.com
> Cc: virtualization@...ts.linux-foundation.org
> Cc: Shuah Khan <shuahkhan@...il.com>
> ---
> arch/mips/cavium-octeon/dma-octeon.c | 3 ++-
> drivers/xen/swiotlb-xen.c | 4 ++-
> include/linux/swiotlb.h | 2 +-
> lib/swiotlb.c | 47 +++++++++++++++++++++-------------
> 4 files changed, 35 insertions(+), 21 deletions(-)
>
> diff --git a/arch/mips/cavium-octeon/dma-octeon.c b/arch/mips/cavium-octeon/dma-octeon.c
> index 41dd0088..02f2444 100644
> --- a/arch/mips/cavium-octeon/dma-octeon.c
> +++ b/arch/mips/cavium-octeon/dma-octeon.c
> @@ -317,7 +317,8 @@ void __init plat_swiotlb_setup(void)
>
> octeon_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
>
> - swiotlb_init_with_tbl(octeon_swiotlb, swiotlb_nslabs, 1);
> + if (swiotlb_init_with_tbl(octeon_swiotlb, swiotlb_nslabs, 1) == -ENOMEM)
> + panic("Cannot allocate SWIOTLB buffer");
>
> mips_dma_map_ops = &octeon_linear_dma_map_ops.dma_map_ops;
> }
> diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> index af47e75..1d94316 100644
> --- a/drivers/xen/swiotlb-xen.c
> +++ b/drivers/xen/swiotlb-xen.c
> @@ -231,7 +231,9 @@ retry:
> }
> start_dma_addr = xen_virt_to_bus(xen_io_tlb_start);
> if (early) {
> - swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs, verbose);
> + if (swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs,
> + verbose))
> + panic("Cannot allocate SWIOTLB buffer");
> rc = 0;
> } else
> rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs);
> diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
> index 071d62c..2de42f9 100644
> --- a/include/linux/swiotlb.h
> +++ b/include/linux/swiotlb.h
> @@ -23,7 +23,7 @@ extern int swiotlb_force;
> #define IO_TLB_SHIFT 11
>
> extern void swiotlb_init(int verbose);
> -extern void swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose);
> +int swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose);
> extern unsigned long swiotlb_nr_tbl(void);
> extern int swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs);
>
> diff --git a/lib/swiotlb.c b/lib/swiotlb.c
> index 196b069..bfe02b8 100644
> --- a/lib/swiotlb.c
> +++ b/lib/swiotlb.c
> @@ -122,11 +122,18 @@ static dma_addr_t swiotlb_virt_to_bus(struct device *hwdev,
> return phys_to_dma(hwdev, virt_to_phys(address));
> }
>
> +static bool no_iotlb_memory;
> +
> void swiotlb_print_info(void)
> {
> unsigned long bytes = io_tlb_nslabs << IO_TLB_SHIFT;
> unsigned char *vstart, *vend;
>
> + if (no_iotlb_memory) {
> + pr_warn("software IO TLB: No low mem\n");
> + return;
> + }
> +
> vstart = phys_to_virt(io_tlb_start);
> vend = phys_to_virt(io_tlb_end);
>
> @@ -136,7 +143,7 @@ void swiotlb_print_info(void)
> bytes >> 20, vstart, vend - 1);
> }
>
> -void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
> +int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
> {
> void *v_overflow_buffer;
> unsigned long i, bytes;
> @@ -150,9 +157,10 @@ void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
> /*
> * Get the overflow emergency buffer
> */
> - v_overflow_buffer = alloc_bootmem_low_pages(PAGE_ALIGN(io_tlb_overflow));
> + v_overflow_buffer = alloc_bootmem_low_pages_nopanic(
> + PAGE_ALIGN(io_tlb_overflow));
> if (!v_overflow_buffer)
> - panic("Cannot allocate SWIOTLB overflow buffer!\n");
> + return -ENOMEM;
>
> io_tlb_overflow_buffer = __pa(v_overflow_buffer);
>
> @@ -169,15 +177,19 @@ void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
>
> if (verbose)
> swiotlb_print_info();
> +
> + return 0;
> }
>
> /*
> * Statically reserve bounce buffer space and initialize bounce buffer data
> * structures for the software IO TLB used to implement the DMA API.
> */
> -static void __init
> -swiotlb_init_with_default_size(size_t default_size, int verbose)
> +void __init
> +swiotlb_init(int verbose)
> {
> + /* default to 64MB */
> + size_t default_size = 64UL<<20;
> unsigned char *vstart;
> unsigned long bytes;
>
> @@ -188,20 +200,16 @@ swiotlb_init_with_default_size(size_t default_size, int verbose)
>
> bytes = io_tlb_nslabs << IO_TLB_SHIFT;
>
> - /*
> - * Get IO TLB memory from the low pages
> - */
> - vstart = alloc_bootmem_low_pages(PAGE_ALIGN(bytes));
> - if (!vstart)
> - panic("Cannot allocate SWIOTLB buffer");
> -
> - swiotlb_init_with_tbl(vstart, io_tlb_nslabs, verbose);
> -}
> + /* Get IO TLB memory from the low pages */
> + vstart = alloc_bootmem_low_pages_nopanic(PAGE_ALIGN(bytes));
> + if (vstart && !swiotlb_init_with_tbl(vstart, io_tlb_nslabs, verbose))
> + return;
>
> -void __init
> -swiotlb_init(int verbose)
> -{
> - swiotlb_init_with_default_size(64 * (1<<20), verbose); /* default to 64MB */
> + if (io_tlb_start)
> + free_bootmem(io_tlb_start,
> + PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
> + pr_warn("Cannot allocate SWIOTLB buffer");
> + no_iotlb_memory = true;
> }
>
> /*
> @@ -405,6 +413,9 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
> unsigned long offset_slots;
> unsigned long max_slots;
>
> + if (no_iotlb_memory)
> + panic("Can not allocate SWIOTLB buffer earlier and can't now provide you with the DMA bounce buffer");
> +
> mask = dma_get_seg_boundary(hwdev);
>
> tbl_dma_addr &= mask;
> --
> 1.7.10.4
>
--
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