On 09/23/2014 11:56 PM, Alex Williamson wrote:
> On Tue, 2014-09-23 at 13:01 +1000, Alexey Kardashevskiy wrote:
>> This defines and implements VFIO IOMMU API which lets the userspace
>> create and remove DMA windows.
>>
>> This updates VFIO_IOMMU_SPAPR_TCE_GET_INFO to return the number of
>> available windows and page mask.
>>
>> This adds VFIO_IOMMU_SPAPR_TCE_CREATE and VFIO_IOMMU_SPAPR_TCE_REMOVE
>> to allow the user space to create and remove window(s).
>>
>> The VFIO IOMMU driver does basic sanity checks and calls corresponding
>> SPAPR TCE functions. At the moment only IODA2 (POWER8 PCI host bridge)
>> implements them.
>>
>> This advertises VFIO_IOMMU_SPAPR_TCE_FLAG_DDW capability via
>> VFIO_IOMMU_SPAPR_TCE_GET_INFO.
>>
>> This calls platform DDW reset() callback when IOMMU is being disabled
>> to reset the DMA configuration to its original state.
>>
>> Signed-off-by: Alexey Kardashevskiy <[email protected]>
>> ---
>> drivers/vfio/vfio_iommu_spapr_tce.c | 135 ++++++++++++++++++++++++++++++++++--
>> include/uapi/linux/vfio.h | 25 ++++++-
>> 2 files changed, 153 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
>> index 0dccbc4..b518891 100644
>> --- a/drivers/vfio/vfio_iommu_spapr_tce.c
>> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
>> @@ -190,18 +190,25 @@ static void tce_iommu_disable(struct tce_container *container)
>>
>> container->enabled = false;
>>
>> - if (!container->grp || !current->mm)
>> + if (!container->grp)
>> return;
>>
>> data = iommu_group_get_iommudata(container->grp);
>> if (!data || !data->iommu_owner || !data->ops->get_table)
>> return;
>>
>> - tbl = data->ops->get_table(data, 0);
>> - if (!tbl)
>> - return;
>> + if (current->mm) {
>> + tbl = data->ops->get_table(data, 0);
>> + if (tbl)
>> + decrement_locked_vm(tbl);
>>
>> - decrement_locked_vm(tbl);
>> + tbl = data->ops->get_table(data, 1);
>> + if (tbl)
>> + decrement_locked_vm(tbl);
>> + }
>> +
>> + if (data->ops->reset)
>> + data->ops->reset(data);
>> }
>>
>> static void *tce_iommu_open(unsigned long arg)
>> @@ -243,7 +250,7 @@ static long tce_iommu_ioctl(void *iommu_data,
>> unsigned int cmd, unsigned long arg)
>> {
>> struct tce_container *container = iommu_data;
>> - unsigned long minsz;
>> + unsigned long minsz, ddwsz;
>> long ret;
>>
>> switch (cmd) {
>> @@ -288,6 +295,28 @@ static long tce_iommu_ioctl(void *iommu_data,
>> info.dma32_window_size = tbl->it_size << tbl->it_page_shift;
>> info.flags = 0;
>>
>> + ddwsz = offsetofend(struct vfio_iommu_spapr_tce_info,
>> + page_size_mask);
>> +
>> + if (info.argsz == ddwsz) {
>
>> =
>
>> + if (data->ops->query && data->ops->create &&
>> + data->ops->remove) {
>> + info.flags |= VFIO_IOMMU_SPAPR_TCE_FLAG_DDW;
>
> I think you want to set this flag regardless of whether the user has
> provided space for it. A valid use model is to call with the minimum
> size and look at the flags to determine if it needs to be called again
> with a larger size.
>
>> +
>> + ret = data->ops->query(data,
>> + &info.current_windows,
>> + &info.windows_available,
>> + &info.page_size_mask);
>> + if (ret)
>> + return ret;
>> + } else {
>> + info.current_windows = 0;
>> + info.windows_available = 0;
>> + info.page_size_mask = 0;
>> + }
>> + minsz = ddwsz;
>
> It's not really any longer the min size, is it?
>
>> + }
>> +
>> if (copy_to_user((void __user *)arg, &info, minsz))
>> return -EFAULT;
>>
>> @@ -412,12 +441,106 @@ static long tce_iommu_ioctl(void *iommu_data,
>> tce_iommu_disable(container);
>> mutex_unlock(&container->lock);
>> return 0;
>> +
>> case VFIO_EEH_PE_OP:
>> if (!container->grp)
>> return -ENODEV;
>>
>> return vfio_spapr_iommu_eeh_ioctl(container->grp,
>> cmd, arg);
>> +
>> + case VFIO_IOMMU_SPAPR_TCE_CREATE: {
>> + struct vfio_iommu_spapr_tce_create create;
>> + struct spapr_tce_iommu_group *data;
>> + struct iommu_table *tbl;
>> +
>> + if (WARN_ON(!container->grp))
>
> redux previous comment on this warning
>
>> + return -ENXIO;
>> +
>> + data = iommu_group_get_iommudata(container->grp);
>> +
>> + minsz = offsetofend(struct vfio_iommu_spapr_tce_create,
>> + start_addr);
>> +
>> + if (copy_from_user(&create, (void __user *)arg, minsz))
>> + return -EFAULT;
>> +
>> + if (create.argsz < minsz)
>> + return -EINVAL;
>> +
>> + if (create.flags)
>> + return -EINVAL;
>> +
>> + if (!data->ops->create || !data->iommu_owner)
>> + return -ENOSYS;
>> +
>> + BUG_ON(!data || !data->ops || !data->ops->remove);
>
> Little late for this test since we'll oops on the previous test. Why is
> this a BUG_ON? A user could exploit this on a system with only a
> partial set of callbacks.
>
>> +
>> + ret = data->ops->create(data, create.page_shift,
>> + create.window_shift, &tbl);
>> + if (ret)
>> + return ret;
>> +
>> + ret = try_increment_locked_vm(tbl);
>> + if (ret) {
>> + data->ops->remove(data, tbl);
>> + return ret;
>> + }
>> +
>> + create.start_addr = tbl->it_offset << tbl->it_page_shift;
>> +
>> + if (copy_to_user((void __user *)arg, &create, minsz)) {
>> + data->ops->remove(data, tbl);
>> + decrement_locked_vm(tbl);
>> + return -EFAULT;
>> + }
>> + mutex_lock(&container->lock);
>> + ++container->windows_num;
>> + mutex_unlock(&container->lock);
>> +
>> + return ret;
>> + }
>> + case VFIO_IOMMU_SPAPR_TCE_REMOVE: {
>> + struct vfio_iommu_spapr_tce_remove remove;
>> + struct spapr_tce_iommu_group *data;
>> + struct iommu_table *tbl;
>> +
>> + if (WARN_ON(!container->grp))
>> + return -ENXIO;
>> +
>> + data = iommu_group_get_iommudata(container->grp);
>> +
>> + minsz = offsetofend(struct vfio_iommu_spapr_tce_remove,
>> + start_addr);
>> +
>> + if (copy_from_user(&remove, (void __user *)arg, minsz))
>> + return -EFAULT;
>> +
>> + if (remove.argsz < minsz)
>> + return -EINVAL;
>> +
>> + if (remove.flags)
>> + return -EINVAL;
>> +
>> + if (!data->ops->remove || !data->iommu_owner)
>
> On this one we don't both to get data/data->ops. Is there also an
> exploit where the user can call these CREATE/REMOVE interfaces even
> though INFO doesn't expose them if only a partial set of callbacks are
> present?
if (!data || !data->ops || !data->ops->remove || !data->iommu_owner)
should do it, right?
And I am not going to add create() without remove(), may be it is worth
adding a compile time check for that.
>
>> + return -ENOSYS;
>> +
>> + tbl = spapr_tce_find_table(container, data, remove.start_addr);
>
> What happens if this returns the 0 index rather than the expected 1
> index table? Why doesn't this call ops->find_table()?
Why ops->find_table()? They are different (->find_table() searches for the
window by number, spapr_tce_find_table() searches by address), I do not
understand this comment.
And removing window#0 is supported.
>
>> + if (!tbl)
>> + return -EINVAL;
>> +
>> + ret = data->ops->remove(data, tbl);
>> + if (ret)
>> + return ret;
>> +
>> + decrement_locked_vm(tbl);
>> +
>> + mutex_lock(&container->lock);
>> + --container->windows_num;
>> + mutex_unlock(&container->lock);
>> +
>> + return 0;
>> + }
>> }
>>
>> return -ENOTTY;
>> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
>> index 6612974..e71a6ef 100644
>> --- a/include/uapi/linux/vfio.h
>> +++ b/include/uapi/linux/vfio.h
>> @@ -451,9 +451,13 @@ struct vfio_iommu_type1_dma_unmap {
>> */
>> struct vfio_iommu_spapr_tce_info {
>> __u32 argsz;
>> - __u32 flags; /* reserved for future use */
>> + __u32 flags;
>> +#define VFIO_IOMMU_SPAPR_TCE_FLAG_DDW 1 /* Support dynamic windows */
>> __u32 dma32_window_start; /* 32 bit window start (bytes) */
>> __u32 dma32_window_size; /* 32 bit window size (bytes) */
>> + __u32 current_windows;
>> + __u32 windows_available;
>> + __u32 page_size_mask;
>> };
>>
>> #define VFIO_IOMMU_SPAPR_TCE_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12)
>> @@ -489,6 +493,25 @@ struct vfio_eeh_pe_op {
>>
>> #define VFIO_EEH_PE_OP _IO(VFIO_TYPE, VFIO_BASE + 21)
>>
>> +struct vfio_iommu_spapr_tce_create {
>> + __u32 argsz;
>> + __u32 flags;
>> + /* in */
>> + __u32 page_shift;
>> + __u32 window_shift;
>> + /* out */
>> + __u64 start_addr;
>> +};
>> +#define VFIO_IOMMU_SPAPR_TCE_CREATE _IO(VFIO_TYPE, VFIO_BASE + 18)
>> +
>> +struct vfio_iommu_spapr_tce_remove {
>> + __u32 argsz;
>> + __u32 flags;
>> + /* in */
>> + __u64 start_addr;
>> +};
>> +#define VFIO_IOMMU_SPAPR_TCE_REMOVE _IO(VFIO_TYPE, VFIO_BASE + 19)
>> +
>
> Zero comments, no good.
Right. I'll fix it. Thanks for the review.
>
>> /* ***************************************************************** */
>>
>> #endif /* _UAPIVFIO_H */
>
>
>
--
Alexey