iommu: Use refcount for fault data access

The per-device fault data structure stores information about faults
occurring on a device. Its lifetime spans from IOPF enablement to
disablement. Multiple paths, including IOPF reporting, handling, and
responding, may access it concurrently.

Previously, a mutex protected the fault data from use after free. But
this is not performance friendly due to the critical nature of IOPF
handling paths.

Refine this with a refcount-based approach. The fault data pointer is
obtained within an RCU read region with a refcount. The fault data
pointer is returned for usage only when the pointer is valid and a
refcount is successfully obtained. The fault data is freed with
kfree_rcu(), ensuring data is only freed after all RCU critical regions
complete.

An iopf handling work starts once an iopf group is created. The handling
work continues until iommu_page_response() is called to respond to the
iopf and the iopf group is freed. During this time, the device fault
parameter should always be available. Add a pointer to the device fault
parameter in the iopf_group structure and hold the reference until the
iopf_group is freed.

Make iommu_page_response() static as it is only used in io-pgfault.c.

Co-developed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Tested-by: Yan Zhao <yan.y.zhao@intel.com>
Link: https://lore.kernel.org/r/20240212012227.119381-13-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

iommu: Separate SVA and IOPF

Add CONFIG_IOMMU_IOPF for page fault handling framework and select it
from its real consumer. Move iopf function declaration from iommu-sva.h
to iommu.h and remove iommu-sva.h as it's empty now.

Consolidate all SVA related code into iommu-sva.c:
- Move iommu_sva_domain_alloc() from iommu.c to iommu-sva.c.
- Move sva iopf handling code from io-pgfault.c to iommu-sva.c.

Consolidate iommu_report_device_fault() and iommu_page_response() into
io-pgfault.c.

Export iopf_free_group() and iopf_group_response() for iopf handlers
implemented in modules. Some functions are renamed with more meaningful
names. No other intentional functionality changes.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Tested-by: Yan Zhao <yan.y.zhao@intel.com>
Tested-by: Longfang Liu <liulongfang@huawei.com>
Link: https://lore.kernel.org/r/20240212012227.119381-11-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

iommu: Make iommu_queue_iopf() more generic

Make iommu_queue_iopf() more generic by making the iopf_group a minimal
set of iopf's that an iopf handler of domain should handle and respond
to. Add domain parameter to struct iopf_group so that the handler can
retrieve and use it directly.

Change iommu_queue_iopf() to forward groups of iopf's to the domain's
iopf handler. This is also a necessary step to decouple the sva iopf
handling code from this interface.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Yi Liu <yi.l.liu@intel.com>
Tested-by: Yan Zhao <yan.y.zhao@intel.com>
Tested-by: Longfang Liu <liulongfang@huawei.com>
Link: https://lore.kernel.org/r/20240212012227.119381-10-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

iommu/sva: Fix SVA handle sharing in multi device case

iommu_sva_bind_device will directly goto out in multi-device
case when found existing domain, ignoring list_add handle,
which causes the handle to fail to be shared.

Fixes: 65d4418c5002 ("iommu/sva: Restore SVA handle sharing")
Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20240227064821.128-1-zhangfei.gao@linaro.org
Signed-off-by: Joerg Roedel <jroedel@suse.de>

iommu/sva: Restore SVA handle sharing

Prior to commit 092edaddb660 ("iommu: Support mm PASID 1:n with sva
domains") the code allowed a SVA handle to be bound multiple times to the
same (mm, device) pair. This was alluded to in the kdoc comment, but we
had understood this to be more a remark about allowing multiple devices,
not a literal same-driver re-opening the same SVA.

It turns out uacce and idxd were both relying on the core code to handle
reference counting for same-device same-mm scenarios. As this looks hard
to resolve in the drivers bring it back to the core code.

The new design has changed the meaning of the domain->users refcount to
refer to the number of devices that are sharing that domain for the same
mm. This is part of the design to lift the SVA domain de-duplication out
of the drivers.

Return the old behavior by explicitly de-duplicating the struct iommu_sva
handle. The same (mm, device) will return the same handle pointer and the
core code will handle tracking this. The last unbind of the handle will
destroy it.

Fixes: 092edaddb660 ("iommu: Support mm PASID 1:n with sva domains")
Reported-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Closes: https://lore.kernel.org/all/20240221110658.529-1-zhangfei.gao@linaro.org/
Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/0-v1-9455fc497a6f+3b4-iommu_sva_sharing_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

iommu/sva: Fix memory leak in iommu_sva_bind_device()

Free the handle when the domain allocation fails before unlocking and
returning.

Fixes: 092edaddb660 ("iommu: Support mm PASID 1:n with sva domains")
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20231213111450.2487861-1-harshit.m.mogalapalli@oracle.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

iommu: Support mm PASID 1:n with sva domains

Each mm bound to devices gets a PASID and corresponding sva domains
allocated in iommu_sva_bind_device(), which are referenced by iommu_mm
field of the mm. The PASID is released in __mmdrop(), while a sva domain
is released when no one is using it (the reference count is decremented
in iommu_sva_unbind_device()). However, although sva domains and their
PASID are separate objects such that their own life cycles could be
handled independently, an enqcmd use case may require releasing the
PASID in releasing the mm (i.e., once a PASID is allocated for a mm, it
will be permanently used by the mm and won't be released until the end
of mm) and only allows to drop the PASID after the sva domains are
released. To this end, mmgrab() is called in iommu_sva_domain_alloc() to
increment the mm reference count and mmdrop() is invoked in
iommu_domain_free() to decrement the mm reference count.

Since the required info of PASID and sva domains is kept in struct
iommu_mm_data of a mm, use mm->iommu_mm field instead of the old pasid
field in mm struct. The sva domain list is protected by iommu_sva_lock.

Besides, this patch removes mm_pasid_init(), as with the introduced
iommu_mm structure, initializing mm pasid in mm_init() is unnecessary.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Tina Zhang <tina.zhang@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20231027000525.1278806-6-tina.zhang@intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

iommu: Add mm_get_enqcmd_pasid() helper function

mm_get_enqcmd_pasid() should be used by architecture code and closely
related to learn the PASID value that the x86 ENQCMD operation should
use for the mm.

For the moment SMMUv3 uses this without any connection to ENQCMD, it
will be cleaned up similar to how the prior patch made VT-d use the
PASID argument of set_dev_pasid().

The motivation is to replace mm->pasid with an iommu private data
structure that is introduced in a later patch.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Tina Zhang <tina.zhang@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20231027000525.1278806-4-tina.zhang@intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

iommu: Move global PASID allocation from SVA to core

Intel ENQCMD requires a single PASID to be shared between multiple
devices, as the PASID is stored in a single MSR register per-process
and userspace can use only that one PASID.

This means that the PASID allocation for any ENQCMD using device driver
must always come from a shared global pool, regardless of what kind of
domain the PASID will be used with.

Split the code for the global PASID allocator into
iommu_alloc/free_global_pasid() so that drivers can attach non-SVA
domains to PASIDs as well.

This patch moves global PASID allocation APIs from SVA to IOMMU APIs.
Reserved PASIDs, currently only RID_PASID, are excluded from the global
PASID allocation.

It is expected that device drivers will use the allocated PASIDs to
attach to appropriate IOMMU domains for use.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Link: https://lore.kernel.org/r/20230802212427.1497170-3-jacob.jun.pan@linux.intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

iommu/sva: Fix signedness bug in iommu_sva_alloc_pasid()

The ida_alloc_range() function returns negative error codes on error.
On success it returns values in the min to max range (inclusive). It
never returns more then INT_MAX even if "max" is higher. It never
returns values in the 0 to (min - 1) range.

The bug is that "min" is an unsigned int so negative error codes will
be promoted to high positive values errors treated as success.

Fixes: 1a14bf0fc7ed ("iommu/sva: Use GFP_KERNEL for pasid allocation")
Signed-off-by: Dan Carpenter <error27@gmail.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/6b32095d-7491-4ebb-a850-12e96209eaaf@kili.mountain
Signed-off-by: Joerg Roedel <jroedel@suse.de>

mm: always expand the stack with the mmap write lock held

This finishes the job of always holding the mmap write lock when
extending the user stack vma, and removes the 'write_locked' argument
from the vm helper functions again.

For some cases, we just avoid expanding the stack at all: drivers and
page pinning really shouldn't be extending any stacks. Let's see if any
strange users really wanted that.

It's worth noting that architectures that weren't converted to the new
lock_mm_and_find_vma() helper function are left using the legacy
"expand_stack()" function, but it has been changed to drop the mmap_lock
and take it for writing while expanding the vma. This makes it fairly
straightforward to convert the remaining architectures.

As a result of dropping and re-taking the lock, the calling conventions
for this function have also changed, since the old vma may no longer be
valid. So it will now return the new vma if successful, and NULL - and
the lock dropped - if the area could not be extended.

Tested-by: Vegard Nossum <vegard.nossum@oracle.com>
Tested-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> # ia64
Tested-by: Frank Scheiner <frank.scheiner@web.de> # ia64
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

iommu/sva: Use GFP_KERNEL for pasid allocation

We’re not using spinlock-protected IOASID allocation anymore, there’s
no need for GFP_ATOMIC.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Link: https://lore.kernel.org/r/20230322200803.869130-6-jacob.jun.pan@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

iommu/sva: Stop using ioasid_set for SVA

Instead SVA drivers can use a simple global IDA to allocate PASIDs for
each mm_struct.

Future work would be to allow drivers using the SVA APIs to reserve global
PASIDs from this IDA for their internal use, eg with the DMA API PASID
support.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20230322200803.869130-5-jacob.jun.pan@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

iommu/sva: Remove PASID to mm lookup function

There is no user of iommu_sva_find() function, remove it so that PASID
allocator can be a simple IDA. Device drivers are expected to store
and keep track of their own PASID metadata.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Jason Gunthorpe<jgg@nvidia.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20230322200803.869130-4-jacob.jun.pan@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

iommu/sva: Move PASID helpers to sva code

Preparing to remove IOASID infrastructure, PASID management will be
under SVA code. Decouple mm code from IOASID.

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20230322200803.869130-3-jacob.jun.pan@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

x86/mm/iommu/sva: Make LAM and SVA mutually exclusive

IOMMU and SVA-capable devices know nothing about LAM and only expect
canonical addresses. An attempt to pass down tagged pointer will lead
to address translation failure.

By default do not allow to enable both LAM and use SVA in the same
process.

The new ARCH_FORCE_TAGGED_SVA arch_prctl() overrides the limitation.
By using the arch_prctl() userspace takes responsibility to never pass
tagged address to the device.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Ashok Raj <ashok.raj@intel.com>
Reviewed-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20230312112612.31869-12-kirill.shutemov%40linux.intel.com

iommu/sva: Replace pasid_valid() helper with mm_valid_pasid()

Kernel has few users of pasid_valid() and all but one checks if the
process has PASID allocated. The helper takes ioasid_t as the input.

Replace the helper with mm_valid_pasid() that takes mm_struct as the
argument. The only call that checks PASID that is not tied to mm_struct
is open-codded now.

This is preparatory patch. It helps avoid ifdeffery: no need to
dereference mm->pasid in generic code to check if the process has PASID.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20230312112612.31869-11-kirill.shutemov%40linux.intel.com

iommu: Rename iommu-sva-lib.{c,h}

Rename iommu-sva-lib.c[h] to iommu-sva.c[h] as it contains all code
for SVA implementation in iommu core.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Tested-by: Tony Zhu <tony.zhu@intel.com>
Link: https://lore.kernel.org/r/20221031005917.45690-14-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>