Re: IOMMU breakage on arm64
From: Robin Murphy
Date: Tue Nov 06 2018 - 15:20:43 EST
Hi Geert,
On 2018-11-06 7:44 pm, Geert Uytterhoeven wrote:
Hi Christoph et al,
On Tue, Oct 23, 2018 at 1:40 AM Linux Kernel Mailing List
<linux-kernel@xxxxxxxxxxxxxxx> wrote:
Commit: b4ebe6063204da58e48600b810a97c29ae9e5d12
Parent: 7d21ee4c719f00896767ce19c4c01a56374c2ced
Refname: refs/heads/master
Web: https://git.kernel.org/torvalds/c/b4ebe6063204da58e48600b810a97c29ae9e5d12
Author: Christoph Hellwig <hch@xxxxxx>
AuthorDate: Thu Sep 20 14:04:08 2018 +0200
Committer: Christoph Hellwig <hch@xxxxxx>
CommitDate: Mon Oct 1 07:28:03 2018 -0700
dma-direct: implement complete bus_dma_mask handling
Instead of rejecting devices with a too small bus_dma_mask we can handle
by taking the bus dma_mask into account for allocations and bounce
buffering decisions.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
I have bisected the following crash to the above commit:
I think that commit mostly just changes the presentation of my
underlying cockup - see here for what should fix it:
https://patchwork.kernel.org/patch/10670177/
I have a feeling we've ironed out crash-on-early-domain-free bugs in the
SMMU drivers already - arm-smmu certainly has an early return in
arm_smmu_destroy_domain_context() which should behave exactly like your
diff below, while I think arm-smmu-v3 gets away with it by virtue of
smmu_domain->cfg being unset, but I'll double-check that when I'm fresh
tomorrow (Jean-Philippe reported SMMUv3 hitting the DMA thing to me
internally, but didn't mention any crash).
Thanks for the report,
Robin.
ipmmu-vmsa e67b0000.mmu: Cannot accommodate DMA translation for
IOMMU page tables
sata_rcar ee300000.sata: Unable to initialize IPMMU context
iommu: Failed to add device ee300000.sata to group 0: -22
Unable to handle kernel NULL pointer dereference at virtual
address 0000000000000038
Mem abort info:
ESR = 0x96000004
Exception class = DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
Data abort info:
ISV = 0, ISS = 0x00000004
CM = 0, WnR = 0
[0000000000000038] user address but active_mm is swapper
Internal error: Oops: 96000004 [#1] PREEMPT SMP
CPU: 2 PID: 51 Comm: kworker/2:1 Not tainted
4.20.0-rc1-arm64-renesas-dirty #74
Hardware name: Renesas Salvator-X 2nd version board based on
r8a7795 ES2.0+ (DT)
Workqueue: events deferred_probe_work_func
pstate: 60000005 (nZCv daif -PAN -UAO)
pc : ipmmu_domain_free+0x1c/0xa0
lr : ipmmu_domain_free+0x14/0xa0
sp : ffff000009c9b990
x29: ffff000009c9b990 x28: 0000000000000000
x27: ffff000008dff000 x26: 0000000000000000
x25: ffff000008dd9000 x24: 0000000000000014
x23: ffff8006fffdbb20 x22: ffff000008dff000
x21: ffff8006f898e680 x20: ffff8006f8fa6c00
x19: ffff8006f8fa6c08 x18: 0000000000000037
x17: 0000000000000020 x16: ffff000008a8f780
x15: ffff8006fb096f10 x14: ffff8006f93731c8
x13: 0000000000000000 x12: ffff8006fb096f10
x11: ffff8006f9372fe8 x10: ffff000008dff708
x9 : ffff8006fb096f50 x8 : ffff000008dff708
x7 : ffff0000089f1858 x6 : 0000000000000000
x5 : 0000000000000000 x4 : ffff8006f89a3000
x3 : 00008006f7131000 x2 : ffff8006fb2b5700
x1 : 0000000000000000 x0 : 0000000000000028
Process kworker/2:1 (pid: 51, stack limit = 0x(____ptrval____))
Call trace:
ipmmu_domain_free+0x1c/0xa0
iommu_group_release+0x48/0x68
kobject_put+0x74/0xe8
kobject_del.part.0+0x3c/0x50
kobject_put+0x60/0xe8
iommu_group_get_for_dev+0xa8/0x1f0
ipmmu_add_device+0x1c/0x40
of_iommu_configure+0x118/0x190
of_dma_configure+0xcc/0x1f0
platform_dma_configure+0x18/0x28
really_probe+0x94/0x2a8
driver_probe_device+0x58/0x100
__device_attach_driver+0x90/0xd0
bus_for_each_drv+0x64/0xc8
__device_attach+0xd8/0x130
device_initial_probe+0x10/0x18
bus_probe_device+0x98/0xa0
deferred_probe_work_func+0x74/0xb0
process_one_work+0x294/0x6f0
worker_thread+0x238/0x460
kthread+0x120/0x128
ret_from_fork+0x10/0x1c
Code: aa0003f3 97ffeb1a d1002274 f85f8261 (f9401c20)
---[ end trace 4c46c7fd7cd07245 ]---
Reproducing on v4.20-rc1 requires CONFIG_IPMMU_VMSA=y, and whitelisting
SATA for IOMMU use (https://patchwork.kernel.org/patch/10544059/).
For older versions you also have to backport commit 3a0832d093693ede ("arm64:
dts: renesas: salvator-xs: enable SATA").
Actually there are two issues at hand:
1) drivers/iommu/io-pgtable-arm.c:__arm_lpae_alloc_pages() allocates
memory (above 4 GiB) and maps it for DMA use, but it is rejected due
to:
dma_map_single(dev, pages, size, DMA_TO_DEVICE) != virt_to_phys(pages)
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -27,7 +27,8 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
if (!dev->dma_mask)
return false;
- return addr + size - 1 <= *dev->dma_mask;
+ return addr + size - 1 <=
+ min_not_zero(*dev->dma_mask, dev->bus_dma_mask);
*dev->dma_mask = 0xffffffffff (40-bit)
dev->bus_dma_mask = 0xffffffff (32-bit)
Hence before, we had (in __arm_lpae_alloc_pages()):
arm-lpae io-pgtable: pages = ffff8006f88f3000
arm-lpae io-pgtable: dma = 0x00000007388f3000
arm-lpae io-pgtable: virt_to_phys(pages) = 0x00000007388f3000
After this change, we have:
arm-lpae io-pgtable: pages = ffff8006f882b000
arm-lpae io-pgtable: dma = 0x0000000074009000
arm-lpae io-pgtable: virt_to_phys(pages) = 0x000000073882b000
And SATA runs without using the IOMMU.
2) The Renesas IPMMU driver doesn't handle the above failure well,
leading to a NULL pointer dereference.
This can be fixed using the (gmail-whitespace-damaged) patch below:
--- a/drivers/iommu/ipmmu-vmsa.c
+++ b/drivers/iommu/ipmmu-vmsa.c
@@ -635,7 +635,8 @@ static void ipmmu_domain_free(struct iommu_domain
*io_domain)
* been detached.
*/
iommu_put_dma_cookie(io_domain);
- ipmmu_domain_destroy_context(domain);
+ if (domain->mmu)
+ ipmmu_domain_destroy_context(domain);
free_io_pgtable_ops(domain->iop);
kfree(domain);
}
I expect drivers/iommu/arm-smmu-v3.c and drivers/iommu/arm-smmu.c
need similar fixes.
I didn't check all drivers, but e.g. drivers/iommu/amd_iommu.c has
a similar check.
Does the IOMMU work on other arm64 platforms in v4.20-rc1?
Thanks for your comments!
Gr{oetje,eeting}s,
Geert