| Message ID | alpine.DEB.2.21.2010261653320.12247@sstabellini-ThinkPad-T480s (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | e9696d259d0fb5d239e8c28ca41089838ea76d13 |
| Headers | show |
| Series | fix swiotlb panic on Xen | expand |
Looks good for now:
Reviewed-by: Christoph Hellwig <hch@lst.de>
But we really need to clean up the mess with all these magic variables
eventually.
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(); >
On Tue, 27 Oct 2020, Konrad Rzeszutek Wilk wrote: > 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? That would be Fixes: ac2cbab21f31 ("x86: Don't panic if can not alloc buffer for swiotlb") > > 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(); > > >
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. > > 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(); > As the person who first found this and then confirmed this fixes a bug: Tested-by: Elliott Mitchell <ehem+xen@m5p.com>
> As the person who first found this and then confirmed this fixes a bug: > > Tested-by: Elliott Mitchell <ehem+xen@m5p.com> Thank you!! I changed the title and added the various tags and will put it in linux-next later this week. From a1eb2768bf5954d25aa0f0136b38f0aa5d92d984 Mon Sep 17 00:00:00 2001 From: Stefano Stabellini <stefano.stabellini@xilinx.com> Date: Mon, 26 Oct 2020 17:02:14 -0700 Subject: [PATCH] swiotlb: fix "x86: Don't panic if can not alloc buffer for swiotlb" 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. Fixes: ac2cbab21f31 ("x86: Don't panic if can not alloc buffer for swiotlb") Reported-by: Elliott Mitchell <ehem+xen@m5p.com> Tested-by: Elliott Mitchell <ehem+xen@m5p.com> Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com> Reviewed-by: Christoph Hellwig <hch@lst.de> CC: stable@vger.kernel.org Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> --- kernel/dma/swiotlb.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 465a567678d9..e08cac39c0ba 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -229,6 +229,7 @@ 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(); @@ -260,9 +261,11 @@ 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; } @@ -360,6 +363,7 @@ 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();
On Tue, 27 Oct 2020, Konrad Rzeszutek Wilk wrote: > > As the person who first found this and then confirmed this fixes a bug: > > > > Tested-by: Elliott Mitchell <ehem+xen@m5p.com> > > Thank you!! > > I changed the title and added the various tags and will put it in > linux-next later this week. Looks fine, thank you > >From a1eb2768bf5954d25aa0f0136b38f0aa5d92d984 Mon Sep 17 00:00:00 2001 > From: Stefano Stabellini <stefano.stabellini@xilinx.com> > Date: Mon, 26 Oct 2020 17:02:14 -0700 > Subject: [PATCH] swiotlb: fix "x86: Don't panic if can not alloc buffer for > swiotlb" > > 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. > > Fixes: ac2cbab21f31 ("x86: Don't panic if can not alloc buffer for swiotlb") > > Reported-by: Elliott Mitchell <ehem+xen@m5p.com> > Tested-by: Elliott Mitchell <ehem+xen@m5p.com> > Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com> > Reviewed-by: Christoph Hellwig <hch@lst.de> > CC: stable@vger.kernel.org > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > --- > kernel/dma/swiotlb.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c > index 465a567678d9..e08cac39c0ba 100644 > --- a/kernel/dma/swiotlb.c > +++ b/kernel/dma/swiotlb.c > @@ -229,6 +229,7 @@ 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(); > @@ -260,9 +261,11 @@ 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; > } > @@ -360,6 +363,7 @@ 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(); > > -- > 2.13.6 >
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();