Subject: Re: [PATCH 8/8] iommu/io-pgtable-arm: Prepare for TTBR1 usage

From: Stephan Gerhold <[email-masked]>
Date: Wed, 19 Feb 2020 13:27:11 +0100

Hi Will, Hi Robin,

On Fri, Jan 10, 2020 at 03:28:52PM +0000, Will Deacon wrote:
> From: Robin Murphy <[email-masked]>
> 
> Now that we can correctly extract top-level indices without relying on
> the remaining upper bits being zero, the only remaining impediments to
> using a given table for TTBR1 are the address validation on map/unmap
> and the awkward TCR translation granule format. Add a quirk so that we
> can do the right thing at those points.
> 
> Tested-by: Jordan Crouse <[email-masked]>
> Signed-off-by: Robin Murphy <[email-masked]>
> Signed-off-by: Will Deacon <[email-masked]>
> ---
>  drivers/iommu/io-pgtable-arm.c | 25 +++++++++++++++++++------
>  include/linux/io-pgtable.h     |  4 ++++
>  2 files changed, 23 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
> index 846963c87e0f..5e966ef0bacf 100644
> --- a/drivers/iommu/io-pgtable-arm.c
> +++ b/drivers/iommu/io-pgtable-arm.c
> @@ -104,6 +104,10 @@
>  #define ARM_LPAE_TCR_TG0_64K		1
>  #define ARM_LPAE_TCR_TG0_16K		2
>  
> +#define ARM_LPAE_TCR_TG1_16K		1
> +#define ARM_LPAE_TCR_TG1_4K		2
> +#define ARM_LPAE_TCR_TG1_64K		3
> +
>  #define ARM_LPAE_TCR_SH_NS		0
>  #define ARM_LPAE_TCR_SH_OS		2
>  #define ARM_LPAE_TCR_SH_IS		3
> @@ -463,6 +467,7 @@ static int arm_lpae_map(struct io_pgtable_ops *ops, unsigned long iova,
>  	arm_lpae_iopte *ptep = data->pgd;
>  	int ret, lvl = data->start_level;
>  	arm_lpae_iopte prot;
> +	long iaext = (long)iova >> cfg->ias;
>  
>  	/* If no access, then nothing to do */
>  	if (!(iommu_prot & (IOMMU_READ | IOMMU_WRITE)))
> @@ -471,7 +476,9 @@ static int arm_lpae_map(struct io_pgtable_ops *ops, unsigned long iova,
>  	if (WARN_ON(!size || (size & cfg->pgsize_bitmap) != size))
>  		return -EINVAL;
>  
> -	if (WARN_ON(iova >> data->iop.cfg.ias || paddr >> data->iop.cfg.oas))
> +	if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_TTBR1)
> +		iaext = ~iaext;
> +	if (WARN_ON(iaext || paddr >> cfg->oas))
>  		return -ERANGE;
>  
>  	prot = arm_lpae_prot_to_pte(data, iommu_prot);
> @@ -637,11 +644,14 @@ static size_t arm_lpae_unmap(struct io_pgtable_ops *ops, unsigned long iova,
>  	struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops);
>  	struct io_pgtable_cfg *cfg = &data->iop.cfg;
>  	arm_lpae_iopte *ptep = data->pgd;
> +	long iaext = (long)iova >> cfg->ias;
>  
>  	if (WARN_ON(!size || (size & cfg->pgsize_bitmap) != size))
>  		return 0;
>  
> -	if (WARN_ON(iova >> data->iop.cfg.ias))
> +	if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_TTBR1)
> +		iaext = ~iaext;
> +	if (WARN_ON(iaext))
>  		return 0;
>  
>  	return __arm_lpae_unmap(data, gather, iova, size, data->start_level, ptep);

This part of the patch seems to break io-pgtable-arm.c on ARM32 to some
extent. I have a device using qcom_iommu that could normally run ARM64,
but I'm unable to because of outdated (signed) firmware. :(
So it's running a lot of code that would normally run only on ARM64.

It used to work quite well but now qcom-venus fails to probe on:
    if (WARN_ON(iaext || paddr >> cfg->oas))
(I added some debug prints for clarity.)

    qcom-venus 1d00000.video-codec: Adding to iommu group 0
    arm-lpae io-pgtable: quirks: 0x0
    arm-lpae io-pgtable: arm_lpae_map: iova: 0xdd800000, paddr: 0xebe3f000, iaext: 0xffffffff, paddr >> oas: 0x0
    ------------[ cut here ]------------
    WARNING: CPU: 0 PID: 954 at drivers/iommu/io-pgtable-arm.c:487 arm_lpae_map+0xe4/0x510
    Hardware name: Generic DT based system
    ...
    [<c04bafb0>] (arm_lpae_map) from [<c04bcd6c>] (qcom_iommu_map+0x50/0x78)
    [<c04bcd6c>] (qcom_iommu_map) from [<c04b7290>] (__iommu_map+0xe8/0x1cc)
    [<c04b7290>] (__iommu_map) from [<c04b7bbc>] (__iommu_map_sg+0xa8/0x118)
    [<c04b7bbc>] (__iommu_map_sg) from [<c04b7c64>] (iommu_map_sg_atomic+0x18/0x20)
    [<c04b7c64>] (iommu_map_sg_atomic) from [<c04b94f8>] (iommu_dma_alloc+0x4dc/0x5a0)
    [<c04b94f8>] (iommu_dma_alloc) from [<c0196a50>] (dma_alloc_attrs+0x104/0x114)
    [<c0196a50>] (dma_alloc_attrs) from [<bf302c60>] (venus_hfi_create+0xa4/0x260 [venus_core])
    [<bf302c60>] (venus_hfi_create [venus_core]) from [<bf2fe6cc>] (venus_probe+0x1e4/0x328 [venus_core])
    [<bf2fe6cc>] (venus_probe [venus_core]) from [<c04c8eb4>] (platform_drv_probe+0x48/0x98)
    ...
    Exception stack(0xc2587fa8 to 0xc2587ff0)
    7fa0:                   b6f3dc70 b5051010 b5051010 0017388c b6e645b0 b6e645b0
    7fc0: b6f3dc70 b5051010 00020000 00000080 b6e30790 be84ea54 0046ac91 00000000
    7fe0: b6e75f1c be84e940 b6e5fb51 b6eec8a4
    ---[ end trace 2a0ed284f6d82f16 ]---
    qcom-venus: probe of 1d00000.video-codec failed with error -12

Note that iaext = 0xffffffff != 0.
It seems to be some int/long size problem that only happens with larger
iova addresses on 32-bit systems.

Without the (long) cast for iova everything is working correctly again:

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 983b08477e64..f7ecc763c706 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -468,7 +468,7 @@ static int arm_lpae_map(struct io_pgtable_ops *ops, unsigned long iova,
 	arm_lpae_iopte *ptep = data->pgd;
 	int ret, lvl = data->start_level;
 	arm_lpae_iopte prot;
-	long iaext = (long)iova >> cfg->ias;
+	long iaext = iova >> cfg->ias;
 
 	/* If no access, then nothing to do */
 	if (!(iommu_prot & (IOMMU_READ | IOMMU_WRITE)))
@@ -645,7 +645,7 @@ static size_t arm_lpae_unmap(struct io_pgtable_ops *ops, unsigned long iova,
 	struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops);
 	struct io_pgtable_cfg *cfg = &data->iop.cfg;
 	arm_lpae_iopte *ptep = data->pgd;
-	long iaext = (long)iova >> cfg->ias;
+	long iaext = iova >> cfg->ias;
 
 	if (WARN_ON(!size || (size & cfg->pgsize_bitmap) != size))
 		return 0;

But I'm not sure if this is really the correct "fix"...

This problem can be also easily reproduced by enabling
IOMMU_IO_PGTABLE_LPAE_SELFTEST on ARM32.
(Shouldn't there be some system that runs these automatically? ;))

Without this patch all of them are passing:

    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x40201000, IAS 32
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x40201000, IAS 36
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x40201000, IAS 40
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x40201000, IAS 42
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x40201000, IAS 44
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x40201000, IAS 48
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x02004000, IAS 32
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x02004000, IAS 36
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x02004000, IAS 40
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x02004000, IAS 42
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x02004000, IAS 44
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x02004000, IAS 48
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x20010000, IAS 32
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x20010000, IAS 36
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x20010000, IAS 40
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x20010000, IAS 42
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x20010000, IAS 44
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x20010000, IAS 48
    arm-lpae io-pgtable: selftest: completed with 18 PASS 0 FAIL

But with this patch 6 of them are failing (with a similar warning as
I posted above):

    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x40201000, IAS 32
    ------------[ cut here ]------------
    WARNING: CPU: 3 PID: 1 at drivers/iommu/io-pgtable-arm.c:482 arm_lpae_map+0xa4/0x4e4
    Hardware name: Generic DT based system
    [<c01104ac>] (unwind_backtrace) from [<c010c0b4>] (show_stack+0x10/0x14)
    [<c010c0b4>] (show_stack) from [<c06cfb34>] (dump_stack+0x90/0xa4)
    [<c06cfb34>] (dump_stack) from [<c012d76c>] (__warn+0xb8/0xd4)
    [<c012d76c>] (__warn) from [<c012d7ec>] (warn_slowpath_fmt+0x64/0xbc)
    [<c012d7ec>] (warn_slowpath_fmt) from [<c04baf70>] (arm_lpae_map+0xa4/0x4e4)
    [<c04baf70>] (arm_lpae_map) from [<c0a1de3c>] (arm_lpae_do_selftests+0x234/0x688)
    [<c0a1de3c>] (arm_lpae_do_selftests) from [<c0102788>] (do_one_initcall+0x50/0x1b8)
    [<c0102788>] (do_one_initcall) from [<c0a0148c>] (kernel_init_freeable+0x1ec/0x25c)
    [<c0a0148c>] (kernel_init_freeable) from [<c06e6dc4>] (kernel_init+0x8/0x110)
    [<c06e6dc4>] (kernel_init) from [<c01010e8>] (ret_from_fork+0x14/0x2c)
    Exception stack(0xee867fb0 to 0xee867ff8)
    7fa0:                                     00000000 00000000 00000000 00000000
    7fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
    7fe0: 00000000 00000000 00000000 00000000 00000013 00000000
    ---[ end trace 89e831c50a111e7c ]---
    ------------[ cut here ]------------
    WARNING: CPU: 3 PID: 1 at drivers/iommu/io-pgtable-arm.c:1182 arm_lpae_do_selftests+0x4b8/0x688
    selftest: test failed for fmt idx 0
    Hardware name: Generic DT based system
    [<c01104ac>] (unwind_backtrace) from [<c010c0b4>] (show_stack+0x10/0x14)
    [<c010c0b4>] (show_stack) from [<c06cfb34>] (dump_stack+0x90/0xa4)
    [<c06cfb34>] (dump_stack) from [<c012d76c>] (__warn+0xb8/0xd4)
    [<c012d76c>] (__warn) from [<c012d820>] (warn_slowpath_fmt+0x98/0xbc)
    [<c012d820>] (warn_slowpath_fmt) from [<c0a1e0c0>] (arm_lpae_do_selftests+0x4b8/0x688)
    [<c0a1e0c0>] (arm_lpae_do_selftests) from [<c0102788>] (do_one_initcall+0x50/0x1b8)
    [<c0102788>] (do_one_initcall) from [<c0a0148c>] (kernel_init_freeable+0x1ec/0x25c)
    [<c0a0148c>] (kernel_init_freeable) from [<c06e6dc4>] (kernel_init+0x8/0x110)
    [<c06e6dc4>] (kernel_init) from [<c01010e8>] (ret_from_fork+0x14/0x2c)
    Exception stack(0xee867fb0 to 0xee867ff8)
    7fa0:                                     00000000 00000000 00000000 00000000
    7fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
    7fe0: 00000000 00000000 00000000 00000000 00000013 00000000
    ---[ end trace 89e831c50a111e7d ]---
    arm-lpae io-pgtable: cfg: pgsize_bitmap 0x40201000, ias 32-bit
    arm-lpae io-pgtable: data: 3 levels, 0x20 pgd_size, 12 pg_shift, 9 bits_per_level, pgd @ (ptrval)
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x40201000, IAS 36
    [warning as above]
    arm-lpae io-pgtable: cfg: pgsize_bitmap 0x40201000, ias 36-bit
    arm-lpae io-pgtable: data: 3 levels, 0x200 pgd_size, 12 pg_shift, 9 bits_per_level, pgd @ (ptrval)
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x40201000, IAS 40
    [warning as above]
    arm-lpae io-pgtable: cfg: pgsize_bitmap 0x40201000, ias 40-bit
    arm-lpae io-pgtable: data: 4 levels, 0x10 pgd_size, 12 pg_shift, 9 bits_per_level, pgd @ (ptrval)
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x40201000, IAS 42
    [warning as above]
    arm-lpae io-pgtable: cfg: pgsize_bitmap 0x40201000, ias 42-bit
    arm-lpae io-pgtable: data: 4 levels, 0x40 pgd_size, 12 pg_shift, 9 bits_per_level, pgd @ (ptrval)
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x40201000, IAS 44
    [warning as above]
    arm-lpae io-pgtable: cfg: pgsize_bitmap 0x40201000, ias 44-bit
    arm-lpae io-pgtable: data: 4 levels, 0x100 pgd_size, 12 pg_shift, 9 bits_per_level, pgd @ (ptrval)
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x40201000, IAS 48
    [warning as above]
    arm-lpae io-pgtable: cfg: pgsize_bitmap 0x40201000, ias 48-bit
    arm-lpae io-pgtable: data: 4 levels, 0x1000 pgd_size, 12 pg_shift, 9 bits_per_level, pgd @ (ptrval)
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x02004000, IAS 32
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x02004000, IAS 36
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x02004000, IAS 40
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x02004000, IAS 42
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x02004000, IAS 44
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x02004000, IAS 48
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x20010000, IAS 32
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x20010000, IAS 36
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x20010000, IAS 40
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x20010000, IAS 42
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x20010000, IAS 44
    arm-lpae io-pgtable: selftest: pgsize_bitmap 0x20010000, IAS 48
    arm-lpae io-pgtable: selftest: completed with 12 PASS 6 FAIL

Any suggestions how to fix this properly?

Thanks,
Stephan

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