Hi Eric,
>-----Original Message-----
>From: Eric Auger <eric.au...@redhat.com>
>Sent: Tuesday, June 3, 2025 8:21 PM
>To: Duan, Zhenzhong <zhenzhong.d...@intel.com>; qemu-devel@nongnu.org
>Cc: alex.william...@redhat.com; c...@redhat.com; m...@redhat.com;
>jasow...@redhat.com; pet...@redhat.com; ddut...@redhat.com;
>j...@nvidia.com; nicol...@nvidia.com; shameerali.kolothum.th...@huawei.com;
>joao.m.mart...@oracle.com; clement.mathieu--d...@eviden.com; Tian, Kevin
><kevin.t...@intel.com>; Liu, Yi L <yi.l....@intel.com>; Peng, Chao P
><chao.p.p...@intel.com>
>Subject: Re: [PATCH v2 1/4] backends/iommufd: Add a helper to invalidate user-
>managed HWPT
>
>Hi Zhenzhong,
>
>On 5/30/25 11:35 AM, Zhenzhong Duan wrote:
>> This helper passes cache invalidation request from guest to invalidate
>> stage-1 page table cache in host hardware.
>>
>> Signed-off-by: Nicolin Chen <nicol...@nvidia.com>
>> Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
>> ---
>> include/system/iommufd.h | 4 ++++
>> backends/iommufd.c | 36 ++++++++++++++++++++++++++++++++++++
>> backends/trace-events | 1 +
>> 3 files changed, 41 insertions(+)
>>
>> diff --git a/include/system/iommufd.h b/include/system/iommufd.h
>> index cbab75bfbf..83ab8e1e4c 100644
>> --- a/include/system/iommufd.h
>> +++ b/include/system/iommufd.h
>> @@ -61,6 +61,10 @@ bool
>iommufd_backend_get_dirty_bitmap(IOMMUFDBackend *be, uint32_t hwpt_id,
>> uint64_t iova, ram_addr_t size,
>> uint64_t page_size, uint64_t *data,
>> Error **errp);
>> +bool iommufd_backend_invalidate_cache(IOMMUFDBackend *be, uint32_t id,
>> + uint32_t data_type, uint32_t
>> entry_len,
>> + uint32_t *entry_num, void *data,
>> + Error **errp);
>>
>> #define TYPE_HOST_IOMMU_DEVICE_IOMMUFD
>TYPE_HOST_IOMMU_DEVICE "-iommufd"
>> #endif
>> diff --git a/backends/iommufd.c b/backends/iommufd.c
>> index b73f75cd0b..8bcdb60fe7 100644
>> --- a/backends/iommufd.c
>> +++ b/backends/iommufd.c
>> @@ -311,6 +311,42 @@ bool
>iommufd_backend_get_device_info(IOMMUFDBackend *be, uint32_t devid,
>> return true;
>> }
>>
>> +bool iommufd_backend_invalidate_cache(IOMMUFDBackend *be, uint32_t id,
>> + uint32_t data_type, uint32_t
>> entry_len,
>> + uint32_t *entry_num, void *data,
>> + Error **errp)
>> +{
>> + int ret, fd = be->fd;
>> + uint32_t total_entries = *entry_num;
>> + struct iommu_hwpt_invalidate cache = {
>> + .size = sizeof(cache),
>> + .hwpt_id = id,
>> + .data_type = data_type,
>> + .entry_len = entry_len,
>> + .entry_num = total_entries,
>> + .data_uptr = (uintptr_t)data,
>> + };
>> +
>> + ret = ioctl(fd, IOMMU_HWPT_INVALIDATE, &cache);
>> + trace_iommufd_backend_invalidate_cache(fd, id, data_type, entry_len,
>> + total_entries, cache.entry_num,
>> + (uintptr_t)data, ret ? errno :
>> 0);
>> + *entry_num = cache.entry_num;
>> +
>> + if (ret) {
>> + error_setg_errno(errp, errno, "IOMMU_HWPT_INVALIDATE failed:"
>> + " total %d entries, processed %d entries",
>> + total_entries, cache.entry_num);
>> + } else if (total_entries != cache.entry_num) {
>> + error_setg(errp, "IOMMU_HWPT_INVALIDATE succeed but with
>unprocessed"
>> + " entries: total %d entries, processed %d entries."
>> + " Kernel BUG?!", total_entries, cache.entry_num);
>Can this happen? Isn't it a failure case?
It shouldn't happen except kernel has a bug. It's a failure case, so false is
returned.
Thanks
Zhenzhong
>
>Besides
>Reviewed-by: Eric Auger <eric.au...@redhat.com>
>
>
>Eric
>> + return false;
>> + }
>> +
>> + return !ret;
>> +}
>> +
>> static int hiod_iommufd_get_cap(HostIOMMUDevice *hiod, int cap, Error
>**errp)
>> {
>> HostIOMMUDeviceCaps *caps = &hiod->caps;
>> diff --git a/backends/trace-events b/backends/trace-events
>> index 40811a3162..7278214ea5 100644
>> --- a/backends/trace-events
>> +++ b/backends/trace-events
>> @@ -18,3 +18,4 @@ iommufd_backend_alloc_hwpt(int iommufd, uint32_t
>dev_id, uint32_t pt_id, uint32_
>> iommufd_backend_free_id(int iommufd, uint32_t id, int ret) " iommufd=%d
>id=%d (%d)"
>> iommufd_backend_set_dirty(int iommufd, uint32_t hwpt_id, bool start, int
>> ret)
>" iommufd=%d hwpt=%u enable=%d (%d)"
>> iommufd_backend_get_dirty_bitmap(int iommufd, uint32_t hwpt_id, uint64_t
>iova, uint64_t size, uint64_t page_size, int ret) " iommufd=%d hwpt=%u
>iova=0x%"PRIx64" size=0x%"PRIx64" page_size=0x%"PRIx64" (%d)"
>> +iommufd_backend_invalidate_cache(int iommufd, uint32_t id, uint32_t
>data_type, uint32_t entry_len, uint32_t entry_num, uint32_t done_num, uint64_t
>data_ptr, int ret) " iommufd=%d id=%u data_type=%u entry_len=%u
>entry_num=%u done_num=%u data_ptr=0x%"PRIx64" (%d)"
