Typical hardware devices require a driver stack to translate application
buffers to hardware addresses, and a kernel-user transition to notify the
hardware of new work. What if both the translation and transition overhead
could be eliminated? This is what Shared Virtual Address (SVA) and ENQCMD
enabled hardware like Data Streaming Accelerator (DSA) aims to achieve.
Applications map portals in their local-address-space and directly submit
work to them using a new instruction.
This series enables ENQCMD and associated management of the new MSR
(MSR_IA32_PASID). This new MSR allows an application address space to be
associated with what the PCIe spec calls a Process Address Space ID (PASID).
This PASID tag is carried along with all requests between applications and
devices and allows devices to interact with the process address space.
SVA and ENQCMD enabled device drivers need this series. The phase 2 DSA
patches with SVA and ENQCMD support was released on the top of this series:
https://lore.kernel.org/patchwork/cover/1244060/
This series only provides simple and basic support for ENQCMD and the MSR:
1. Clean up type definitions (patch 1-2). These patches can be in a
separate series.
- Define "pasid" as "u32" consistently
- Define "flags" as "unsigned int"
2. Explain different various technical terms used in the series (patch 3).
3. Enumerate support for ENQCMD in the processor (patch 4).
4. Handle FPU PASID state and the MSR during context switch (patches 5-6).
5. Define "pasid" in mm_struct (patch 7).
6. Disable ENQCMD when configured out (patch 8).
7. Allocate and free PASID for a process (patch 9).
This patch series and the DSA phase 2 series are in
https://github.com/intel/idxd-driver/tree/idxd-stage2
References:
1. Detailed information on the ENQCMD/ENQCMDS instructions and the
IA32_PASID MSR can be found in Intel Architecture Instruction Set
Extensions and Future Features Programming Reference:
https://software.intel.com/sites/default/files/managed/c5/15/architecture-instruction-set-extensions-programming-reference.pdf
2. Detailed information on DSA can be found in DSA specification:
https://software.intel.com/en-us/download/intel-data-streaming-accelerator-preliminary-architecture-specification
Chang log:
v8:
- Change subject to "drm, iommu:" in patch 1 (Boris).
- Address all comments on patch 3 from Boris and Randy.
- Re-write commit message for patch 8 (Boris)
- Re-write commit message, remove "#ifdef CONFIG_IOMMU_SUPPORT", remove
the "if (!ppasid_state)" check in patch 9 (Boris).
v7:
- Don't fix up PASID in #GP. Instead, update the PASID MSR by IPI and
context switch after PASID allocation and free. Inherit PASID from
parent. (Andy)
v6:
- Change return type to u32 for kfd_pasid_alloc() in patch 1 (Felix)
v5:
- Mark ENQCMD disabled when configured out and use cpu_feature_enabled()
to simplify the feature checking code in patch 10 and 12 (PeterZ and
Dave Hansen)
- Add Reviewed-by: Lu Baolu to patch 1, 2, 10, and 12.
v4:
- Define PASID as "u32" instead of "unsigned int" in patch 1, 7, 10, 12.
(Christoph)
- Drop v3 patch 2 which changes PASID type in ocxl because it's not related
to x86 and was rejected by ocxl maintainer Frederic Barrat
- A split patch which changes PASID type to u32 in crypto/hisilicon/qm.c
was released separately to linux-crypto mailing list because it's not
related to x86 and is a standalone patch:
v3:
- Change names of bind_mm() and unbind_mm() to match to new APIs in
patch 4 (Baolu)
- Change CONFIG_PCI_PASID to CONFIG_IOMMU_SUPPORT because non-PCI device
can have PASID in ARM in patch 8 (Jean)
- Add a few sanity checks in __free_pasid() and alloc_pasid() in
patch 11 (Baolu)
- Add patch 12 to define a new flag "has_valid_pasid" for a task and
use the flag to identify if the task has a valid PASID MSR (PeterZ)
- Add fpu__pasid_write() to update the MSR in fixup() in patch 13
- Check if mm->pasid can be found in fixup() in patch 13
v2:
- Add patches 1-3 to define "pasid" and "flags" as "unsigned int"
consistently (Thomas)
(these 3 patches could be in a separate patch set)
- Add patch 8 to move "pasid" to generic mm_struct (Christoph).
Jean-Philippe Brucker released a virtually same patch. Upstream only
needs one of the two.
- Add patch 9 to initialize PASID in a new mm.
- Plus other changes described in each patch (Thomas)
Ashok Raj (1):
Documentation/x86: Add documentation for SVA (Shared Virtual
Addressing)
Fenghua Yu (7):
drm, iommu: Change type of pasid to u32
iommu/vt-d: Change flags type to unsigned int in binding mm
x86/cpufeatures: Enumerate ENQCMD and ENQCMDS instructions
x86/msr-index: Define IA32_PASID MSR
mm: Define pasid in mm
x86/cpufeatures: Mark ENQCMD as disabled when configured out
x86/mmu: Allocate/free PASID
Yu-cheng Yu (1):
x86/fpu/xstate: Add supervisor PASID state for ENQCMD feature
Documentation/x86/index.rst | 1 +
Documentation/x86/sva.rst
