From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Stefano Stabellini <sstabellini@kernel.org>
Cc: xen-devel@lists.xenproject.org, iommu@lists.linux-foundation.org,
linux-kernel@vger.kernel.org, hch@lst.de
Subject: Re: [PATCH] fix swiotlb panic on Xen
Date: Tue, 27 Oct 2020 09:37:01 -0400 [thread overview]
Message-ID: <20201027133701.GB6077@char.us.oracle.com> (raw)
In-Reply-To: <alpine.DEB.2.21.2010261653320.12247@sstabellini-ThinkPad-T480s>
On Mon, Oct 26, 2020 at 05:02:14PM -0700, Stefano Stabellini wrote:
> From: Stefano Stabellini <stefano.stabellini@xilinx.com>
>
> kernel/dma/swiotlb.c:swiotlb_init gets called first and tries to
> allocate a buffer for the swiotlb. It does so by calling
>
> memblock_alloc_low(PAGE_ALIGN(bytes), PAGE_SIZE);
>
> If the allocation must fail, no_iotlb_memory is set.
>
>
> Later during initialization swiotlb-xen comes in
> (drivers/xen/swiotlb-xen.c:xen_swiotlb_init) and given that io_tlb_start
> is != 0, it thinks the memory is ready to use when actually it is not.
>
> When the swiotlb is actually needed, swiotlb_tbl_map_single gets called
> and since no_iotlb_memory is set the kernel panics.
>
> Instead, if swiotlb-xen.c:xen_swiotlb_init knew the swiotlb hadn't been
> initialized, it would do the initialization itself, which might still
> succeed.
>
>
> Fix the panic by setting io_tlb_start to 0 on swiotlb initialization
> failure, and also by setting no_iotlb_memory to false on swiotlb
> initialization success.
Should this have a Fixes: flag?
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
>
>
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index c19379fabd20..9924214df60a 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -231,6 +231,7 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
> io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
> }
> io_tlb_index = 0;
> + no_iotlb_memory = false;
>
> if (verbose)
> swiotlb_print_info();
> @@ -262,9 +263,11 @@ swiotlb_init(int verbose)
> if (vstart && !swiotlb_init_with_tbl(vstart, io_tlb_nslabs, verbose))
> return;
>
> - if (io_tlb_start)
> + if (io_tlb_start) {
> memblock_free_early(io_tlb_start,
> PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
> + io_tlb_start = 0;
> + }
> pr_warn("Cannot allocate buffer");
> no_iotlb_memory = true;
> }
> @@ -362,6 +365,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
> io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
> }
> io_tlb_index = 0;
> + no_iotlb_memory = false;
>
> swiotlb_print_info();
>
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WARNING: multiple messages have this Message-ID (diff)
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Stefano Stabellini <sstabellini@kernel.org>
Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
xen-devel@lists.xenproject.org, hch@lst.de
Subject: Re: [PATCH] fix swiotlb panic on Xen
Date: Tue, 27 Oct 2020 09:37:01 -0400 [thread overview]
Message-ID: <20201027133701.GB6077@char.us.oracle.com> (raw)
In-Reply-To: <alpine.DEB.2.21.2010261653320.12247@sstabellini-ThinkPad-T480s>
On Mon, Oct 26, 2020 at 05:02:14PM -0700, Stefano Stabellini wrote:
> From: Stefano Stabellini <stefano.stabellini@xilinx.com>
>
> kernel/dma/swiotlb.c:swiotlb_init gets called first and tries to
> allocate a buffer for the swiotlb. It does so by calling
>
> memblock_alloc_low(PAGE_ALIGN(bytes), PAGE_SIZE);
>
> If the allocation must fail, no_iotlb_memory is set.
>
>
> Later during initialization swiotlb-xen comes in
> (drivers/xen/swiotlb-xen.c:xen_swiotlb_init) and given that io_tlb_start
> is != 0, it thinks the memory is ready to use when actually it is not.
>
> When the swiotlb is actually needed, swiotlb_tbl_map_single gets called
> and since no_iotlb_memory is set the kernel panics.
>
> Instead, if swiotlb-xen.c:xen_swiotlb_init knew the swiotlb hadn't been
> initialized, it would do the initialization itself, which might still
> succeed.
>
>
> Fix the panic by setting io_tlb_start to 0 on swiotlb initialization
> failure, and also by setting no_iotlb_memory to false on swiotlb
> initialization success.
Should this have a Fixes: flag?
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
>
>
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index c19379fabd20..9924214df60a 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -231,6 +231,7 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
> io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
> }
> io_tlb_index = 0;
> + no_iotlb_memory = false;
>
> if (verbose)
> swiotlb_print_info();
> @@ -262,9 +263,11 @@ swiotlb_init(int verbose)
> if (vstart && !swiotlb_init_with_tbl(vstart, io_tlb_nslabs, verbose))
> return;
>
> - if (io_tlb_start)
> + if (io_tlb_start) {
> memblock_free_early(io_tlb_start,
> PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
> + io_tlb_start = 0;
> + }
> pr_warn("Cannot allocate buffer");
> no_iotlb_memory = true;
> }
> @@ -362,6 +365,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
> io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
> }
> io_tlb_index = 0;
> + no_iotlb_memory = false;
>
> swiotlb_print_info();
>
next prev parent reply other threads:[~2020-10-27 13:35 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-27 0:02 [PATCH] fix swiotlb panic on Xen Stefano Stabellini
2020-10-27 0:02 ` Stefano Stabellini
2020-10-27 7:58 ` Christoph Hellwig
2020-10-27 7:58 ` Christoph Hellwig
2020-10-27 13:37 ` Konrad Rzeszutek Wilk [this message]
2020-10-27 13:37 ` Konrad Rzeszutek Wilk
2020-10-27 17:43 ` Stefano Stabellini
2020-10-27 17:43 ` Stefano Stabellini
2020-10-27 17:51 ` Elliott Mitchell
2020-10-27 17:51 ` Elliott Mitchell
2020-10-27 19:27 ` Konrad Rzeszutek Wilk
2020-10-27 19:27 ` Konrad Rzeszutek Wilk
2020-10-27 21:53 ` Stefano Stabellini
2020-10-27 21:53 ` Stefano Stabellini
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