lkml.org 
[lkml]   [2019]   [Mar]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v2 3/7] iommu/vt-d: Expose ISA direct mapping region via iommu_get_resv_regions
From
Date
Hi James,

On 3/22/19 5:57 PM, James Sewart wrote:
> Hey Lu,
>
>> On 15 Mar 2019, at 02:19, Lu Baolu <baolu.lu@linux.intel.com> wrote:
>>
>> Hi James,
>>
>> On 3/14/19 7:58 PM, James Sewart wrote:
>>> To support mapping ISA region via iommu_group_create_direct_mappings,
>>> make sure its exposed by iommu_get_resv_regions. This allows
>>> deduplication of reserved region mappings
>>> Signed-off-by: James Sewart <jamessewart@arista.com>
>>> ---
>>> drivers/iommu/intel-iommu.c | 42 +++++++++++++++++++++++++++++--------
>>> 1 file changed, 33 insertions(+), 9 deletions(-)
>>> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
>>> index 8e0a4e2ff77f..2e00e8708f06 100644
>>> --- a/drivers/iommu/intel-iommu.c
>>> +++ b/drivers/iommu/intel-iommu.c
>>> @@ -337,6 +337,8 @@ static LIST_HEAD(dmar_rmrr_units);
>>> #define for_each_rmrr_units(rmrr) \
>>> list_for_each_entry(rmrr, &dmar_rmrr_units, list)
>>> +static struct iommu_resv_region *isa_resv_region;
>>> +
>>> /* bitmap for indexing intel_iommus */
>>> static int g_num_of_iommus;
>>> @@ -2780,26 +2782,34 @@ static inline int iommu_prepare_rmrr_dev(struct dmar_rmrr_unit *rmrr,
>>> rmrr->end_address);
>>> }
>>> +static inline struct iommu_resv_region *iommu_get_isa_resv_region(void)
>>> +{
>>> + if (!isa_resv_region)
>>> + isa_resv_region = iommu_alloc_resv_region(0,
>>> + 16*1024*1024,
>>> + 0, IOMMU_RESV_DIRECT);
>>> +
>>> + return isa_resv_region;
>>> +}
>>> +
>>> #ifdef CONFIG_INTEL_IOMMU_FLOPPY_WA
>>> -static inline void iommu_prepare_isa(void)
>>> +static inline void iommu_prepare_isa(struct pci_dev *pdev)
>>> {
>>> - struct pci_dev *pdev;
>>> int ret;
>>> + struct iommu_resv_region *reg = iommu_get_isa_resv_region();
>>> - pdev = pci_get_class(PCI_CLASS_BRIDGE_ISA << 8, NULL);
>>> - if (!pdev)
>>> + if (!reg)
>>> return;
>>> pr_info("Prepare 0-16MiB unity mapping for LPC\n");
>>> - ret = iommu_prepare_identity_map(&pdev->dev, 0, 16*1024*1024 - 1);
>>> + ret = iommu_prepare_identity_map(&pdev->dev, reg->start,
>>> + reg->start + reg->length - 1);
>>> if (ret)
>>> pr_err("Failed to create 0-16MiB identity map - floppy might not work\n");
>>> -
>>> - pci_dev_put(pdev);
>>> }
>>> #else
>>> -static inline void iommu_prepare_isa(void)
>>> +static inline void iommu_prepare_isa(struct pci_dev *pdev)
>>> {
>>> return;
>>> }
>>> @@ -3289,6 +3299,7 @@ static int __init init_dmars(void)
>>> struct dmar_rmrr_unit *rmrr;
>>> bool copied_tables = false;
>>> struct device *dev;
>>> + struct pci_dev *pdev;
>>> struct intel_iommu *iommu;
>>> int i, ret;
>>> @@ -3469,7 +3480,11 @@ static int __init init_dmars(void)
>>> }
>>> }
>>> - iommu_prepare_isa();
>>> + pdev = pci_get_class(PCI_CLASS_BRIDGE_ISA << 8, NULL);
>>> + if (pdev) {
>>> + iommu_prepare_isa(pdev);
>>> + pci_dev_put(pdev);
>>> + }
>>> domains_done:
>>> @@ -5266,6 +5281,7 @@ static void intel_iommu_get_resv_regions(struct device *device,
>>> struct iommu_resv_region *reg;
>>> struct dmar_rmrr_unit *rmrr;
>>> struct device *i_dev;
>>> + struct pci_dev *pdev;
>>> int i;
>>> rcu_read_lock();
>>> @@ -5280,6 +5296,14 @@ static void intel_iommu_get_resv_regions(struct device *device,
>>> }
>>> rcu_read_unlock();
>>> + if (dev_is_pci(device)) {
>>> + pdev = to_pci_dev(device);
>>> + if ((pdev->class >> 8) == PCI_CLASS_BRIDGE_ISA) {
>>> + reg = iommu_get_isa_resv_region();
>>> + list_add_tail(&reg->list, head);
>>> + }
>>> + }
>>> +
>>
>> Just wondering why not just
>>
>> +#ifdef CONFIG_INTEL_IOMMU_FLOPPY_WA
>> + if (dev_is_pci(device)) {
>> + pdev = to_pci_dev(device);
>> + if ((pdev->class >> 8) == PCI_CLASS_BRIDGE_ISA) {
>> + reg = iommu_alloc_resv_region(0,
>> + 16*1024*1024,
>> + 0, IOMMU_RESV_DIRECT);
>> + if (reg)
>> + list_add_tail(&reg->list, head);
>> + }
>> + }
>> +#endif
>>
>> and, remove all other related code?
>
> At this point in the patchset if we remove iommu_prepare_isa then the ISA
> region won’t be mapped to the device. Only once the dma domain is allocable
> will the reserved regions be mapped by iommu_group_create_direct_mappings.

Yes. So if we put the allocation code here, it won't impact anything and
will take effect as soon as the dma domain is allocatable.

>
> Theres an issue that if we choose to alloc a new resv_region with type
> IOMMU_RESV_DIRECT, we will need to refactor intel_iommu_put_resv_regions
> to free this entry type which means refactoring the rmrr regions in
> get_resv_regions. Should this work be in this patchset?

Do you mean the rmrr regions are not allocated in get_resv_regions, but
are freed in put_resv_regions? I think we should fix this in this patch
set since this might impact the device passthrough if we don't do it.

Best regards,
Lu Baolu

\
 
 \ /
  Last update: 2019-03-25 03:10    [W:0.104 / U:38.700 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site