From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH V9 9/9] virtio: Intel IFC VF driver for VDPA Date: Thu, 9 Apr 2020 16:25:15 -0400 Message-ID: <20200409162427-mutt-send-email-mst@kernel.org> References: <20200326140125.19794-1-jasowang@redhat.com> <20200326140125.19794-10-jasowang@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Arnd Bergmann Cc: Jason Wang , "linux-kernel@vger.kernel.org" , kvm list , virtualization@lists.linux-foundation.org, Networking , Jason Gunthorpe , maxime.coquelin@redhat.com, cunming.liang@intel.com, zhihong.wang@intel.com, rob.miller@broadcom.com, xiao.w.wang@intel.com, lingshan.zhu@intel.com, eperezma@redhat.com, lulu@redhat.com, Parav Pandit , kevin.tian@intel.com, Stefan Hajnoczi , Randy Dunlap , Christoph Hellwig , aadam@redhat.com, Jiri Pirko , shahafs@mellanox.com, hanand@xilinx.com, mhabets@solarflare.com, gdawar@xilinx.com, saugatm@xilinx.com, vmireyno@marvell. List-Id: virtualization@lists.linuxfoundation.org On Thu, Apr 09, 2020 at 12:41:13PM +0200, Arnd Bergmann wrote: > On Thu, Mar 26, 2020 at 3:08 PM Jason Wang wrote: > > > > From: Zhu Lingshan > > > > This commit introduced two layers to drive IFC VF: > > > > (1) ifcvf_base layer, which handles IFC VF NIC hardware operations and > > configurations. > > > > (2) ifcvf_main layer, which complies to VDPA bus framework, > > implemented device operations for VDPA bus, handles device probe, > > bus attaching, vring operations, etc. > > > > Signed-off-by: Zhu Lingshan > > Signed-off-by: Bie Tiwei > > Signed-off-by: Wang Xiao > > Signed-off-by: Jason Wang > > > + > > +#define IFCVF_QUEUE_ALIGNMENT PAGE_SIZE > > +#define IFCVF_QUEUE_MAX 32768 > > +static u16 ifcvf_vdpa_get_vq_align(struct vdpa_device *vdpa_dev) > > +{ > > + return IFCVF_QUEUE_ALIGNMENT; > > +} > > This fails to build on arm64 with 64kb page size (found in linux-next): > > /drivers/vdpa/ifcvf/ifcvf_main.c: In function 'ifcvf_vdpa_get_vq_align': > arch/arm64/include/asm/page-def.h:17:20: error: conversion from 'long > unsigned int' to 'u16' {aka 'short unsigned int'} changes value from > '65536' to '0' [-Werror=overflow] > 17 | #define PAGE_SIZE (_AC(1, UL) << PAGE_SHIFT) > | ^ > drivers/vdpa/ifcvf/ifcvf_base.h:37:31: note: in expansion of macro 'PAGE_SIZE' > 37 | #define IFCVF_QUEUE_ALIGNMENT PAGE_SIZE > | ^~~~~~~~~ > drivers/vdpa/ifcvf/ifcvf_main.c:231:9: note: in expansion of macro > 'IFCVF_QUEUE_ALIGNMENT' > 231 | return IFCVF_QUEUE_ALIGNMENT; > | ^~~~~~~~~~~~~~~~~~~~~ > > It's probably good enough to just not allow the driver to be built in that > configuration as it's fairly rare but unfortunately there is no simple Kconfig > symbol for it. > > In a similar driver, we did > > config VMXNET3 > tristate "VMware VMXNET3 ethernet driver" > depends on PCI && INET > depends on !(PAGE_SIZE_64KB || ARM64_64K_PAGES || \ > IA64_PAGE_SIZE_64KB || MICROBLAZE_64K_PAGES || \ > PARISC_PAGE_SIZE_64KB || PPC_64K_PAGES) > > I think we should probably make PAGE_SIZE_64KB a global symbol > in arch/Kconfig and have it selected by the other symbols so drivers > like yours can add a dependency for it. > > Arnd It's probably easier to make the alignment u32 - I don't really know why it's u16, all callers seem to assign the result to a u32 value.