diff mbox series

[RFC,12/42] iommufd: Introduce allocation data info and flag for KVM managed HWPT

Message ID 20231202092113.14141-1-yan.y.zhao@intel.com
State New
Headers
Series Sharing KVM TDP to IOMMU |

Commit Message

Yan Zhao Dec. 2, 2023, 9:21 a.m. UTC 
  Add allocation data info iommu_hwpt_kvm_info to allow IOMMUFD to create a
KVM managed HWPT via ioctl IOMMU_HWPT_ALLOC.

As KVM managed HWPT serves as stage-2 page tables whose paging structure
and page mapping/unmapping are managed by KVM, there's no need to connect
KVM managed HWPT to IOAS or parent HWPT.

Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
---
 include/uapi/linux/iommufd.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

Comments

Jason Gunthorpe Dec. 4, 2023, 6:29 p.m. UTC | #1 
On Sat, Dec 02, 2023 at 05:21:13PM +0800, Yan Zhao wrote:

> @@ -413,11 +422,13 @@ struct iommu_hwpt_arm_smmuv3 {
>   * @IOMMU_HWPT_DATA_NONE: no data
>   * @IOMMU_HWPT_DATA_VTD_S1: Intel VT-d stage-1 page table
>   * @IOMMU_HWPT_DATA_ARM_SMMUV3: ARM SMMUv3 Context Descriptor Table
> + * @IOMMU_HWPT_DATA_KVM: KVM managed stage-2 page table
>   */
>  enum iommu_hwpt_data_type {
>  	IOMMU_HWPT_DATA_NONE,
>  	IOMMU_HWPT_DATA_VTD_S1,
>  	IOMMU_HWPT_DATA_ARM_SMMUV3,
> +	IOMMU_HWPT_DATA_KVM,
>  };

Definately no, the HWPT_DATA is for the *driver* - it should not be
"kvm".

Add the kvm fd to the main structure

Jason
Yan Zhao Dec. 5, 2023, 7:08 a.m. UTC | #2 
On Mon, Dec 04, 2023 at 02:29:28PM -0400, Jason Gunthorpe wrote:
> On Sat, Dec 02, 2023 at 05:21:13PM +0800, Yan Zhao wrote:
> 
> > @@ -413,11 +422,13 @@ struct iommu_hwpt_arm_smmuv3 {
> >   * @IOMMU_HWPT_DATA_NONE: no data
> >   * @IOMMU_HWPT_DATA_VTD_S1: Intel VT-d stage-1 page table
> >   * @IOMMU_HWPT_DATA_ARM_SMMUV3: ARM SMMUv3 Context Descriptor Table
> > + * @IOMMU_HWPT_DATA_KVM: KVM managed stage-2 page table
> >   */
> >  enum iommu_hwpt_data_type {
> >  	IOMMU_HWPT_DATA_NONE,
> >  	IOMMU_HWPT_DATA_VTD_S1,
> >  	IOMMU_HWPT_DATA_ARM_SMMUV3,
> > +	IOMMU_HWPT_DATA_KVM,
> >  };
> 
> Definately no, the HWPT_DATA is for the *driver* - it should not be
> "kvm".
> 
> Add the kvm fd to the main structure
>
Do you mean add a "int kvm_fd" to "struct iommu_hwpt_alloc" ?
struct iommu_hwpt_alloc {
        __u32 size;
        __u32 flags;
        __u32 dev_id;
        __u32 pt_id;
        __u32 out_hwpt_id;
        __u32 __reserved;
        __u32 data_type;
        __u32 data_len;
        __aligned_u64 data_uptr;
};

Then always create the HWPT as IOMMUFD_OBJ_HWPT_KVM as long as kvm_fd > 0 ?
Jason Gunthorpe Dec. 5, 2023, 2:53 p.m. UTC | #3 
On Tue, Dec 05, 2023 at 03:08:03PM +0800, Yan Zhao wrote:
> On Mon, Dec 04, 2023 at 02:29:28PM -0400, Jason Gunthorpe wrote:
> > On Sat, Dec 02, 2023 at 05:21:13PM +0800, Yan Zhao wrote:
> > 
> > > @@ -413,11 +422,13 @@ struct iommu_hwpt_arm_smmuv3 {
> > >   * @IOMMU_HWPT_DATA_NONE: no data
> > >   * @IOMMU_HWPT_DATA_VTD_S1: Intel VT-d stage-1 page table
> > >   * @IOMMU_HWPT_DATA_ARM_SMMUV3: ARM SMMUv3 Context Descriptor Table
> > > + * @IOMMU_HWPT_DATA_KVM: KVM managed stage-2 page table
> > >   */
> > >  enum iommu_hwpt_data_type {
> > >  	IOMMU_HWPT_DATA_NONE,
> > >  	IOMMU_HWPT_DATA_VTD_S1,
> > >  	IOMMU_HWPT_DATA_ARM_SMMUV3,
> > > +	IOMMU_HWPT_DATA_KVM,
> > >  };
> > 
> > Definately no, the HWPT_DATA is for the *driver* - it should not be
> > "kvm".
> > 
> > Add the kvm fd to the main structure
> >
> Do you mean add a "int kvm_fd" to "struct iommu_hwpt_alloc" ?
> struct iommu_hwpt_alloc {
>         __u32 size;
>         __u32 flags;
>         __u32 dev_id;
>         __u32 pt_id;
>         __u32 out_hwpt_id;
>         __u32 __reserved;
>         __u32 data_type;
>         __u32 data_len;
>         __aligned_u64 data_uptr;
> };
> 
> Then always create the HWPT as IOMMUFD_OBJ_HWPT_KVM as long as kvm_fd > 0 ?

Yes, but 0 is a valid FD so you need to add a flag 'kvm_fd valid'

Jason
Yan Zhao Dec. 6, 2023, 12:58 a.m. UTC | #4 
On Tue, Dec 05, 2023 at 10:53:04AM -0400, Jason Gunthorpe wrote:
> On Tue, Dec 05, 2023 at 03:08:03PM +0800, Yan Zhao wrote:
> > On Mon, Dec 04, 2023 at 02:29:28PM -0400, Jason Gunthorpe wrote:
> > > On Sat, Dec 02, 2023 at 05:21:13PM +0800, Yan Zhao wrote:
> > > 
> > > > @@ -413,11 +422,13 @@ struct iommu_hwpt_arm_smmuv3 {
> > > >   * @IOMMU_HWPT_DATA_NONE: no data
> > > >   * @IOMMU_HWPT_DATA_VTD_S1: Intel VT-d stage-1 page table
> > > >   * @IOMMU_HWPT_DATA_ARM_SMMUV3: ARM SMMUv3 Context Descriptor Table
> > > > + * @IOMMU_HWPT_DATA_KVM: KVM managed stage-2 page table
> > > >   */
> > > >  enum iommu_hwpt_data_type {
> > > >  	IOMMU_HWPT_DATA_NONE,
> > > >  	IOMMU_HWPT_DATA_VTD_S1,
> > > >  	IOMMU_HWPT_DATA_ARM_SMMUV3,
> > > > +	IOMMU_HWPT_DATA_KVM,
> > > >  };
> > > 
> > > Definately no, the HWPT_DATA is for the *driver* - it should not be
> > > "kvm".
> > > 
> > > Add the kvm fd to the main structure
> > >
> > Do you mean add a "int kvm_fd" to "struct iommu_hwpt_alloc" ?
> > struct iommu_hwpt_alloc {
> >         __u32 size;
> >         __u32 flags;
> >         __u32 dev_id;
> >         __u32 pt_id;
> >         __u32 out_hwpt_id;
> >         __u32 __reserved;
> >         __u32 data_type;
> >         __u32 data_len;
> >         __aligned_u64 data_uptr;
> > };
> > 
> > Then always create the HWPT as IOMMUFD_OBJ_HWPT_KVM as long as kvm_fd > 0 ?
> 
> Yes, but 0 is a valid FD so you need to add a flag 'kvm_fd valid'

Got it, thanks!
diff mbox series

Patch

diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 71c009cc614a4..08570f3a751fc 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -390,6 +390,15 @@  struct iommu_hwpt_vtd_s1 {
 	__u32 __reserved;
 };
 
+/**
+ * struct iommu_hwpt_kvm_info - KVM managed stage-2 page table info
+ *                              (IOMMU_HWPT_DATA_KVM)
+ * @fd: The fd of the page table shared from KVM
+ */
+struct iommu_hwpt_kvm_info {
+	__aligned_u64 fd;
+};
+
 /**
  * struct iommu_hwpt_arm_smmuv3 - ARM SMMUv3 Context Descriptor Table info
  *                                (IOMMU_HWPT_DATA_ARM_SMMUV3)
@@ -413,11 +422,13 @@  struct iommu_hwpt_arm_smmuv3 {
  * @IOMMU_HWPT_DATA_NONE: no data
  * @IOMMU_HWPT_DATA_VTD_S1: Intel VT-d stage-1 page table
  * @IOMMU_HWPT_DATA_ARM_SMMUV3: ARM SMMUv3 Context Descriptor Table
+ * @IOMMU_HWPT_DATA_KVM: KVM managed stage-2 page table
  */
 enum iommu_hwpt_data_type {
 	IOMMU_HWPT_DATA_NONE,
 	IOMMU_HWPT_DATA_VTD_S1,
 	IOMMU_HWPT_DATA_ARM_SMMUV3,
+	IOMMU_HWPT_DATA_KVM,
 };
 
 /**
@@ -447,6 +458,10 @@  enum iommu_hwpt_data_type {
  * must be set to a pre-defined type corresponding to an I/O page table
  * type supported by the underlying IOMMU hardware.
  *
+ * A KVM-managed HWPT will be created if @data_type is IOMMU_HWPT_DATA_KVM.
+ * @pt_id is not queried if data_type is IOMMU_HWPT_DATA_KVM because KVM-managed
+ * HWPT doesn't have any IOAS or parent HWPT associated.
+ *
  * If the @data_type is set to IOMMU_HWPT_DATA_NONE, @data_len and
  * @data_uptr should be zero. Otherwise, both @data_len and @data_uptr
  * must be given.