On 4/1/2019 6:30 PM, Jerin Jacob Kollanukkaran wrote: > On Tue, 2018-10-02 at 18:05 +0100, Ferruh Yigit wrote: >> On 9/27/2018 11:49 AM, Kiran Kumar wrote: >>> With current KNI implementation kernel module will work only in >>> IOVA=PA mode. This patch will add support for kernel module to work >>> with IOVA=VA mode. >>> >>> The idea is to maintain a mapping in KNI module between user pages >>> and >>> kernel pages and in fast path perform a lookup in this table and >>> get >>> the kernel virtual address for corresponding user virtual address. >>> >>> In IOVA=VA mode, the memory allocated to the pool is physically >>> and virtually contiguous. We will take advantage of this and create >>> a >>> mapping in the kernel.In kernel we need mapping for queues >>> (tx_q, rx_q,... slow path) and mbuf memory (fast path). >>> >>> At the KNI init time, in slow path we will create a mapping for the >>> queues and mbuf using get_user_pages similar to af_xdp. Using pool >>> memory base address, we will create a page map table for the mbuf, >>> which we will use in the fast path for kernel page translation. >>> >>> At KNI init time, we will pass the base address of the pool and >>> size of >>> the pool to kernel. In kernel, using get_user_pages API, we will >>> get >>> the pages with size PAGE_SIZE and store the mapping and start >>> address >>> of user space in a table. >>> >>> In fast path for any user address perform PAGE_SHIFT >>> (user_addr >> PAGE_SHIFT) and subtract the start address from this >>> value, >>> we will get the index of the kernel page with in the page map >>> table. >>> Adding offset to this kernel page address, we will get the kernel >>> address >>> for this user virtual address. >>> >>> For example user pool base address is X, and size is S that we >>> passed to >>> kernel. In kernel we will create a mapping for this using >>> get_user_pages. >>> Our page map table will look like [Y, Y+PAGE_SIZE, Y+(PAGE_SIZE*2) >>> ....] >>> and user start page will be U (we will get it from X >> >>> PAGE_SHIFT). >>> >>> For any user address Z we will get the index of the page map table >>> using >>> ((Z >> PAGE_SHIFT) - U). Adding offset (Z & (PAGE_SIZE - 1)) to >>> this >>> address will give kernel virtual address. >>> >>> Signed-off-by: Kiran Kumar <kkokkilaga...@caviumnetworks.com> >> >> Hi Kiran, >> >> Thanks for the patch but it was later for this release, missed >> proposal deadline >> etc.. Taking the time remaining for integration deadline, this patch >> will be >> considered for next release. > > Hi Ferruh, > > This patch submitted in Oct last year. Could you please review this? > This feature was added based on community request to support IOVA for > KNI as Initial IOVA support doesn;t have KNI support. >
Hi Jerin, I will check it, I remember the request, thanks for the patch.
