On 9/15/20 1:30 PM, Suravee Suthikulpanit wrote:
> On 9/15/20 6:25 PM, Maxim Levitsky wrote:
>> On Mon, 2020-09-14 at 21:48 +0700, Suravee Suthikulpanit wrote:
>>> Could you please try with the following patch instead?
>>>
>>> --- a/drivers/iommu/amd/iommu.c
>>> +++ b/drivers/iommu/amd/iommu.c
>>> @@ -3840,14 +3840,18 @@ int amd_iommu_activate_guest_mode(void *data)
>>> {
>>> struct amd_ir_data *ir_data = (struct amd_ir_data *)data;
>>> struct irte_ga *entry = (struct irte_ga *) ir_data->entry;
>>> + u64 valid;
>>>
>>> if (!AMD_IOMMU_GUEST_IR_VAPIC(amd_iommu_guest_ir) ||
>>> !entry || entry->lo.fields_vapic.guest_mode)
>>> return 0;
>>>
>>> + valid = entry->lo.fields_vapic.valid;
>>> +
>>> entry->lo.val = 0;
>>> entry->hi.val = 0;
>>>
>>> + entry->lo.fields_vapic.valid = valid;
>>> entry->lo.fields_vapic.guest_mode = 1;
>>> entry->lo.fields_vapic.ga_log_intr = 1;
>>> entry->hi.fields.ga_root_ptr = ir_data->ga_root_ptr;
>>> @@ -3864,12 +3868,14 @@ int amd_iommu_deactivate_guest_mode(void *data)
>>> struct amd_ir_data *ir_data = (struct amd_ir_data *)data;
>>> struct irte_ga *entry = (struct irte_ga *) ir_data->entry;
>>> struct irq_cfg *cfg = ir_data->cfg;
>>> - u64 valid = entry->lo.fields_remap.valid;
>>> + u64 valid;
>>>
>>> if (!AMD_IOMMU_GUEST_IR_VAPIC(amd_iommu_guest_ir) ||
>>> !entry || !entry->lo.fields_vapic.guest_mode)
>>> return 0;
>>>
>>> + valid = entry->lo.fields_remap.valid;
>>> +
>>> entry->lo.val = 0;
>>> entry->hi.val = 0;
>> I see. I based my approach on the fact that valid bit was
>> set always to true anyway before, plus that amd_iommu_activate_guest_mode
>> should be really only called when someone activates a valid interrupt
>> remapping
>> entry, but IMHO the approach of preserving the valid bit is safer anyway.
>>
>> It works on my system (I applied the patch manually, since either your or my
>> email client,
>> seems to mangle the patch)
>>
>
> Sorry for the mangled patch. I'll submit the patch w/ your information.
> Thanks for your help reporting, debugging, and
> testing the patch.
>
I assume you're only doing the valid bit preservation in
amd_iommu_activate_guest_mode() ?
The null deref fix in amd_iommu_deactivate_guest_mode() was fixed elsewhere[0],
or are you
planning on merging both changes like the diff you attached?
Asking also because commit 26e495f341 ("iommu/amd: Restore IRTE.RemapEn bit
after
programming IRTE") was added in v5.4 and v5.8 stable trees but the v5.4
backport didn't
include e52d58d54a321 ("iommu/amd: Use cmpxchg_double() when updating 128-bit
IRTE").
Joao
[0]
https://lore.kernel.org/linux-iommu/20200910171621.12879-1-joao.m.mart...@oracle.com/
