* [PATCH] iommu/vt-d: Do not dump pasid table entries in kdump kernel
@ 2022-01-19 9:07 Zelin Deng
2022-01-20 2:58 ` Lu Baolu
0 siblings, 1 reply; 3+ messages in thread
From: Zelin Deng @ 2022-01-19 9:07 UTC (permalink / raw)
To: David Woodhouse, Lu Baolu; +Cc: iommu, Kyung Min Park, linux-kernel
In kdump kernel PASID translations won't be copied from previous kernel
even if scalable-mode is enabled, so pages of PASID translations are
non-present in kdump kernel. Attempt to access those address will cause
PF fault:
[ 13.396476] DMAR: DRHD: handling fault status reg 3
[ 13.396478] DMAR: [DMA Read NO_PASID] Request device [81:00.0] fault addr 0xffffd000 [fault reason 0x59] SM: Present bit in PA$
[ 13.396480] DMAR: Dump dmar5 table entries for IOVA 0xffffd000
[ 13.396481] DMAR: scalable mode root entry: hi 0x0000000000000000, low 0x00000000460d1001
[ 13.396482] DMAR: context entry: hi 0x0000000000000008, low 0x00000010c4237401
[ 13.396485] BUG: unable to handle page fault for address: ff110010c4237000
[ 13.396486] #PF: supervisor read access in kernel mode
[ 13.396487] #PF: error_code(0x0000) - not-present page
[ 13.396488] PGD 5d201067 P4D 5d202067 PUD 0
[ 13.396490] Oops: 0000 [#1] PREEMPT SMP NOPTI
[ 13.396491] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.16.0-rc6-next-20211224+ #6
[ 13.396493] Hardware name: Intel Corporation EAGLESTREAM/EAGLESTREAM, BIOS EGSDCRB1.86B.0067.D12.2110190950 10/19/2021
[ 13.396494] RIP: 0010:dmar_fault_dump_ptes+0x13b/0x295
Hence skip dumping pasid table entries if in kdump kernel.
Fixes: 914ff7719e8a (“iommu/vt-d: Dump DMAR translation structure when DMA fault occurs”)
Signed-off-by: Zelin Deng <zelin.deng@linux.alibaba.com>
---
drivers/iommu/intel/iommu.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 92fea3fb..f0134cf 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -1074,6 +1074,12 @@ void dmar_fault_dump_ptes(struct intel_iommu *iommu, u16 source_id,
if (!sm_supported(iommu))
goto pgtable_walk;
+ /* PASID translations is not copied, skip dumping pasid table entries
+ * otherwise non-present page will be accessed.
+ */
+ if (is_kdump_kernel())
+ goto pgtable_walk;
+
/* get the pointer to pasid directory entry */
dir = phys_to_virt(ctx_entry->lo & VTD_PAGE_MASK);
if (!dir) {
--
1.8.3.1
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https://lists.linuxfoundation.org/mailman/listinfo/iommu
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] iommu/vt-d: Do not dump pasid table entries in kdump kernel
2022-01-19 9:07 [PATCH] iommu/vt-d: Do not dump pasid table entries in kdump kernel Zelin Deng
@ 2022-01-20 2:58 ` Lu Baolu
2022-01-20 3:13 ` zelin deng
0 siblings, 1 reply; 3+ messages in thread
From: Lu Baolu @ 2022-01-20 2:58 UTC (permalink / raw)
To: Zelin Deng, David Woodhouse; +Cc: iommu, linux-kernel
On 1/19/22 5:07 PM, Zelin Deng wrote:
> In kdump kernel PASID translations won't be copied from previous kernel
> even if scalable-mode is enabled, so pages of PASID translations are
Yes. The copy table support for scalable mode is still in my task list.
> non-present in kdump kernel. Attempt to access those address will cause
> PF fault:
>
> [ 13.396476] DMAR: DRHD: handling fault status reg 3
> [ 13.396478] DMAR: [DMA Read NO_PASID] Request device [81:00.0] fault addr 0xffffd000 [fault reason 0x59] SM: Present bit in PA$
> [ 13.396480] DMAR: Dump dmar5 table entries for IOVA 0xffffd000
> [ 13.396481] DMAR: scalable mode root entry: hi 0x0000000000000000, low 0x00000000460d1001
> [ 13.396482] DMAR: context entry: hi 0x0000000000000008, low 0x00000010c4237401
> [ 13.396485] BUG: unable to handle page fault for address: ff110010c4237000
> [ 13.396486] #PF: supervisor read access in kernel mode
> [ 13.396487] #PF: error_code(0x0000) - not-present page
> [ 13.396488] PGD 5d201067 P4D 5d202067 PUD 0
> [ 13.396490] Oops: 0000 [#1] PREEMPT SMP NOPTI
> [ 13.396491] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.16.0-rc6-next-20211224+ #6
> [ 13.396493] Hardware name: Intel Corporation EAGLESTREAM/EAGLESTREAM, BIOS EGSDCRB1.86B.0067.D12.2110190950 10/19/2021
> [ 13.396494] RIP: 0010:dmar_fault_dump_ptes+0x13b/0x295
>
> Hence skip dumping pasid table entries if in kdump kernel.
This just asks dmar_fault_dump_ptes() to keep silent. The problem is
that the context entry is mis-configured. Perhaps we should disable
copy table for scalable mode for now. How about below change?
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -3337,10 +3337,11 @@ static int __init init_dmars(void)
init_translation_status(iommu);
- if (translation_pre_enabled(iommu) && !is_kdump_kernel()) {
+ if (translation_pre_enabled(iommu) &&
+ (!is_kdump_kernel() || sm_supported(iommu))) {
iommu_disable_translation(iommu);
clear_translation_pre_enabled(iommu);
- pr_warn("Translation was enabled for %s but we
are not in kdump mode\n",
+ pr_warn("Translation was enabled for %s but we
are not in kdump mode or copy table not supported\n",
iommu->name);
}
>
> Fixes: 914ff7719e8a (“iommu/vt-d: Dump DMAR translation structure when DMA fault occurs”)
> Signed-off-by: Zelin Deng <zelin.deng@linux.alibaba.com>
> ---
> drivers/iommu/intel/iommu.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 92fea3fb..f0134cf 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -1074,6 +1074,12 @@ void dmar_fault_dump_ptes(struct intel_iommu *iommu, u16 source_id,
> if (!sm_supported(iommu))
> goto pgtable_walk;
>
> + /* PASID translations is not copied, skip dumping pasid table entries
> + * otherwise non-present page will be accessed.
> + */
> + if (is_kdump_kernel())
> + goto pgtable_walk;
> +
> /* get the pointer to pasid directory entry */
> dir = phys_to_virt(ctx_entry->lo & VTD_PAGE_MASK);
> if (!dir) {
>
Best regards,
baolu
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iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] iommu/vt-d: Do not dump pasid table entries in kdump kernel
2022-01-20 2:58 ` Lu Baolu
@ 2022-01-20 3:13 ` zelin deng
0 siblings, 0 replies; 3+ messages in thread
From: zelin deng @ 2022-01-20 3:13 UTC (permalink / raw)
To: Lu Baolu, David Woodhouse; +Cc: iommu, linux-kernel
在 2022/1/20 上午10:58, Lu Baolu 写道:
> On 1/19/22 5:07 PM, Zelin Deng wrote:
>> In kdump kernel PASID translations won't be copied from previous kernel
>> even if scalable-mode is enabled, so pages of PASID translations are
>
> Yes. The copy table support for scalable mode is still in my task list.
>
>> non-present in kdump kernel. Attempt to access those address will cause
>> PF fault:
>>
>> [ 13.396476] DMAR: DRHD: handling fault status reg 3
>> [ 13.396478] DMAR: [DMA Read NO_PASID] Request device [81:00.0]
>> fault addr 0xffffd000 [fault reason 0x59] SM: Present bit in PA$
>> [ 13.396480] DMAR: Dump dmar5 table entries for IOVA 0xffffd000
>> [ 13.396481] DMAR: scalable mode root entry: hi 0x0000000000000000,
>> low 0x00000000460d1001
>> [ 13.396482] DMAR: context entry: hi 0x0000000000000008, low
>> 0x00000010c4237401
>> [ 13.396485] BUG: unable to handle page fault for address:
>> ff110010c4237000
>> [ 13.396486] #PF: supervisor read access in kernel mode
>> [ 13.396487] #PF: error_code(0x0000) - not-present page
>> [ 13.396488] PGD 5d201067 P4D 5d202067 PUD 0
>> [ 13.396490] Oops: 0000 [#1] PREEMPT SMP NOPTI
>> [ 13.396491] CPU: 0 PID: 1 Comm: swapper/0 Not tainted
>> 5.16.0-rc6-next-20211224+ #6
>> [ 13.396493] Hardware name: Intel Corporation
>> EAGLESTREAM/EAGLESTREAM, BIOS EGSDCRB1.86B.0067.D12.2110190950
>> 10/19/2021
>> [ 13.396494] RIP: 0010:dmar_fault_dump_ptes+0x13b/0x295
>>
>> Hence skip dumping pasid table entries if in kdump kernel.
>
> This just asks dmar_fault_dump_ptes() to keep silent. The problem is
> that the context entry is mis-configured. Perhaps we should disable
> copy table for scalable mode for now. How about below change?
Yep. The change looks good to me.
Actually I had encountered another issue which had blocked virtio-net
device when scalable mode is enabled in kdump kernel so that I had made
the same change as yours -- 'to disable translation if sm_on in kdump
kernel' in our internal tree.
I only observe this issue on our dragonfly baremetal server with
virtio-net device inside, I did't send the fix to upstream as I am not
sure if it is reasonable to disable translation in kdump kernel.
>
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -3337,10 +3337,11 @@ static int __init init_dmars(void)
>
> init_translation_status(iommu);
>
> - if (translation_pre_enabled(iommu) &&
> !is_kdump_kernel()) {
> + if (translation_pre_enabled(iommu) &&
> + (!is_kdump_kernel() || sm_supported(iommu))) {
> iommu_disable_translation(iommu);
> clear_translation_pre_enabled(iommu);
> - pr_warn("Translation was enabled for %s but we
> are not in kdump mode\n",
> + pr_warn("Translation was enabled for %s but we
> are not in kdump mode or copy table not supported\n",
> iommu->name);
> }
>
>>
>> Fixes: 914ff7719e8a (“iommu/vt-d: Dump DMAR translation structure
>> when DMA fault occurs”)
>> Signed-off-by: Zelin Deng <zelin.deng@linux.alibaba.com>
>> ---
>> drivers/iommu/intel/iommu.c | 6 ++++++
>> 1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
>> index 92fea3fb..f0134cf 100644
>> --- a/drivers/iommu/intel/iommu.c
>> +++ b/drivers/iommu/intel/iommu.c
>> @@ -1074,6 +1074,12 @@ void dmar_fault_dump_ptes(struct intel_iommu
>> *iommu, u16 source_id,
>> if (!sm_supported(iommu))
>> goto pgtable_walk;
>> + /* PASID translations is not copied, skip dumping pasid table
>> entries
>> + * otherwise non-present page will be accessed.
>> + */
>> + if (is_kdump_kernel())
>> + goto pgtable_walk;
>> +
>> /* get the pointer to pasid directory entry */
>> dir = phys_to_virt(ctx_entry->lo & VTD_PAGE_MASK);
>> if (!dir) {
>>
>
> Best regards,
> baolu
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iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-01-19 9:07 [PATCH] iommu/vt-d: Do not dump pasid table entries in kdump kernel Zelin Deng
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