Will Deacon <will@xxxxxxxxxx> writes:
> On Sun, May 25, 2025 at 01:19:15PM +0530, Aneesh Kumar K.V (Arm) wrote:
>> This also allocates a stage1 bypass and stage2 translate table.
>
> Please write your commit messages as per Linux kernel guidelines.
>
>> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@xxxxxxxxxx>
>> ---
>> builtin-run.c | 2 +
>> include/kvm/kvm-config.h | 1 +
>> vfio/core.c | 4 +-
>> vfio/iommufd.c | 115 ++++++++++++++++++++++++++++++++++++++-
>
> [...]
>
>> 4 files changed, 119 insertions(+), 3 deletions(-)
>> diff --git a/vfio/iommufd.c b/vfio/iommufd.c
>> index 742550705746..39870320e4ac 100644
>> --- a/vfio/iommufd.c
>> +++ b/vfio/iommufd.c
>> @@ -108,6 +108,116 @@ err_out:
>> return ret;
>> }
>>
>> +static int iommufd_alloc_s1bypass_hwpt(struct vfio_device *vdev)
>> +{
>> + int ret;
>> + unsigned long dev_num;
>> + unsigned long guest_bdf;
>> + struct vfio_device_bind_iommufd bind;
>> + struct vfio_device_attach_iommufd_pt attach_data;
>> + struct iommu_hwpt_alloc alloc_hwpt;
>> + struct iommu_viommu_alloc alloc_viommu;
>> + struct iommu_hwpt_arm_smmuv3 bypass_ste;
>> + struct iommu_vdevice_alloc alloc_vdev;
>> +
>> + bind.argsz = sizeof(bind);
>> + bind.flags = 0;
>> + bind.iommufd = iommu_fd;
>> +
>> + /* now bind the iommufd */
>> + if (ioctl(vdev->fd, VFIO_DEVICE_BIND_IOMMUFD, &bind)) {
>> + ret = -errno;
>> + vfio_dev_err(vdev, "failed to get info");
>> + goto err_out;
>> + }
>> +
>> + alloc_hwpt.size = sizeof(struct iommu_hwpt_alloc);
>> + alloc_hwpt.flags = IOMMU_HWPT_ALLOC_NEST_PARENT;
>> + alloc_hwpt.dev_id = bind.out_devid;
>> + alloc_hwpt.pt_id = ioas_id;
>> + alloc_hwpt.data_type = IOMMU_HWPT_DATA_NONE;
>> + alloc_hwpt.data_len = 0;
>> + alloc_hwpt.data_uptr = 0;
>> +
>> + if (ioctl(iommu_fd, IOMMU_HWPT_ALLOC, &alloc_hwpt)) {
>> + ret = -errno;
>> + pr_err("Failed to allocate HWPT");
>> + goto err_out;
>> + }
>> +
>> + attach_data.argsz = sizeof(attach_data);
>> + attach_data.flags = 0;
>> + attach_data.pt_id = alloc_hwpt.out_hwpt_id;
>> +
>> + if (ioctl(vdev->fd, VFIO_DEVICE_ATTACH_IOMMUFD_PT, &attach_data)) {
>> + ret = -errno;
>> + vfio_dev_err(vdev, "failed to attach to IOAS ");
>> + goto err_out;
>> + }
>> +
>> + alloc_viommu.size = sizeof(alloc_viommu);
>> + alloc_viommu.flags = 0;
>> + alloc_viommu.type = IOMMU_VIOMMU_TYPE_ARM_SMMUV3;
>> + alloc_viommu.dev_id = bind.out_devid;
>> + alloc_viommu.hwpt_id = alloc_hwpt.out_hwpt_id;
>> +
>> + if (ioctl(iommu_fd, IOMMU_VIOMMU_ALLOC, &alloc_viommu)) {
>> + ret = -errno;
>> + vfio_dev_err(vdev, "failed to allocate VIOMMU %d", ret);
>> + goto err_out;
>> + }
>> +#define STRTAB_STE_0_V (1UL << 0)
>> +#define STRTAB_STE_0_CFG_S2_TRANS 6
>> +#define STRTAB_STE_0_CFG_S1_TRANS 5
>> +#define STRTAB_STE_0_CFG_BYPASS 4
>> +
>> + /* set up virtual ste as bypass ste */
>> + bypass_ste.ste[0] = STRTAB_STE_0_V | (STRTAB_STE_0_CFG_BYPASS << 1);
>> + bypass_ste.ste[1] = 0x0UL;
>> +
>> + alloc_hwpt.size = sizeof(struct iommu_hwpt_alloc);
>> + alloc_hwpt.flags = 0;
>> + alloc_hwpt.dev_id = bind.out_devid;
>> + alloc_hwpt.pt_id = alloc_viommu.out_viommu_id;
>> + alloc_hwpt.data_type = IOMMU_HWPT_DATA_ARM_SMMUV3;
>> + alloc_hwpt.data_len = sizeof(bypass_ste);
>> + alloc_hwpt.data_uptr = (unsigned long)&bypass_ste;
>> +
>> + if (ioctl(iommu_fd, IOMMU_HWPT_ALLOC, &alloc_hwpt)) {
>> + ret = -errno;
>> + pr_err("Failed to allocate S1 bypass HWPT %d", ret);
>> + goto err_out;
>> + }
>> +
>> + alloc_vdev.size = sizeof(alloc_vdev),
>> + alloc_vdev.viommu_id = alloc_viommu.out_viommu_id;
>> + alloc_vdev.dev_id = bind.out_devid;
>> +
>> + dev_num = vdev->dev_hdr.dev_num;
>> + /* kvmtool only do 0 domain, 0 bus and 0 function devices. */
>> + guest_bdf = (0ULL << 32) | (0 << 16) | dev_num << 11 | (0 << 8);
>
> I don't understand this. Shouldn't the BDF correspond to the virtual
> configuration space? That's not allocated until later, but just going
> with 0 isn't going to work.
>
> What am I missing?
>
As I understand it, kvmtool supports only bus 0 and does not allow
multifunction devices. Based on that, I derived the guest BDF as follows
(correcting what was wrong in the original patch):
guest_bdf = (0ULL << 16) | (0 << 8) | dev_num << 3 | (0 << 0);
Are you suggesting that this approach is incorrect, and that we can use
a bus number other than 0?
