Re: [PATCH] fix swiotlb panic on Xen
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
>
> 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
> 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
> Tested-by: Elliott Mitchell
> Signed-off-by: Stefano Stabellini
> Reviewed-by: Christoph Hellwig
> CC: sta...@vger.kernel.org
> Signed-off-by: Konrad Rzeszutek Wilk
> ---
> 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
>
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Re: [PATCH] fix swiotlb panic on Xen
On Mon, Oct 26, 2020 at 05:02:14PM -0700, Stefano Stabellini wrote:
> From: Stefano Stabellini
>
> 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
>
>
> 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
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Re: [PATCH] fix swiotlb panic on Xen
> As the person who first found this and then confirmed this fixes a bug:
>
> Tested-by: Elliott Mitchell
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
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
Tested-by: Elliott Mitchell
Signed-off-by: Stefano Stabellini
Reviewed-by: Christoph Hellwig
CC: sta...@vger.kernel.org
Signed-off-by: Konrad Rzeszutek Wilk
---
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
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Re: [PATCH] fix swiotlb panic on Xen
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
> >
> > 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
> >
> >
> > 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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Re: [PATCH] fix swiotlb panic on Xen
On Mon, Oct 26, 2020 at 05:02:14PM -0700, Stefano Stabellini wrote:
> From: Stefano Stabellini
>
> 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
>
>
> 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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Re: [PATCH] fix swiotlb panic on Xen
Looks good for now: Reviewed-by: Christoph Hellwig But we really need to clean up the mess with all these magic variables eventually. ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
[PATCH] fix swiotlb panic on Xen
From: Stefano Stabellini
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
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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