On 01.04.20 17:57, Michael S. Tsirkin wrote: > On Wed, Apr 01, 2020 at 10:50:50PM +0800, Jason Wang wrote: >> >> On 2020/4/1 下午10:27, Michael S. Tsirkin wrote: >>> On Wed, Apr 01, 2020 at 10:13:29PM +0800, Jason Wang wrote: >>>> On 2020/4/1 下午9:02, Christian Borntraeger wrote: >>>>> On 01.04.20 14:56, Christian Borntraeger wrote: >>>>>> On 01.04.20 14:50, Jason Wang wrote: >>>>>>> On 2020/4/1 下午7:21, Christian Borntraeger wrote: >>>>>>>> On 26.03.20 15:01, Jason Wang wrote: >>>>>>>>> Currently, CONFIG_VHOST depends on CONFIG_VIRTUALIZATION. But vhost is >>>>>>>>> not necessarily for VM since it's a generic userspace and kernel >>>>>>>>> communication protocol. Such dependency may prevent archs without >>>>>>>>> virtualization support from using vhost. >>>>>>>>> >>>>>>>>> To solve this, a dedicated vhost menu is created under drivers so >>>>>>>>> CONIFG_VHOST can be decoupled out of CONFIG_VIRTUALIZATION. >>>>>>>> FWIW, this now results in vhost not being build with defconfig kernels (in todays >>>>>>>> linux-next). >>>>>>>> >>>>>>> Hi Christian: >>>>>>> >>>>>>> Did you meet it even with this commit https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=a4be40cbcedba9b5b714f3c95182e8a45176e42d? >>>>>> I simply used linux-next. The defconfig does NOT contain CONFIG_VHOST and therefore CONFIG_VHOST_NET and friends >>>>>> can not be selected. >>>>>> >>>>>> $ git checkout next-20200401 >>>>>> $ make defconfig >>>>>> HOSTCC scripts/basic/fixdep >>>>>> HOSTCC scripts/kconfig/conf.o >>>>>> HOSTCC scripts/kconfig/confdata.o >>>>>> HOSTCC scripts/kconfig/expr.o >>>>>> LEX scripts/kconfig/lexer.lex.c >>>>>> YACC scripts/kconfig/parser.tab.[ch] >>>>>> HOSTCC scripts/kconfig/lexer.lex.o >>>>>> HOSTCC scripts/kconfig/parser.tab.o >>>>>> HOSTCC scripts/kconfig/preprocess.o >>>>>> HOSTCC scripts/kconfig/symbol.o >>>>>> HOSTCC scripts/kconfig/util.o >>>>>> HOSTLD scripts/kconfig/conf >>>>>> *** Default configuration is based on 'x86_64_defconfig' >>>>>> # >>>>>> # configuration written to .config >>>>>> # >>>>>> >>>>>> $ grep VHOST .config >>>>>> # CONFIG_VHOST is not set >>>>>> >>>>>>> If yes, what's your build config looks like? >>>>>>> >>>>>>> Thanks >>>>> This was x86. Not sure if that did work before. >>>>> On s390 this is definitely a regression as the defconfig files >>>>> for s390 do select VHOST_NET >>>>> >>>>> grep VHOST arch/s390/configs/* >>>>> arch/s390/configs/debug_defconfig:CONFIG_VHOST_NET=m >>>>> arch/s390/configs/debug_defconfig:CONFIG_VHOST_VSOCK=m >>>>> arch/s390/configs/defconfig:CONFIG_VHOST_NET=m >>>>> arch/s390/configs/defconfig:CONFIG_VHOST_VSOCK=m >>>>> >>>>> and this worked with 5.6, but does not work with next. Just adding >>>>> CONFIG_VHOST=m to the defconfig solves the issue, something like >>>> >>>> Right, I think we probably need >>>> >>>> 1) add CONFIG_VHOST=m to all defconfigs that enables >>>> CONFIG_VHOST_NET/VSOCK/SCSI. >>>> >>>> or >>>> >>>> 2) don't use menuconfig for CONFIG_VHOST, let NET/SCSI/VDPA just select it. >>>> >>>> Thanks >>> OK I tried this: >>> >>> diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig >>> index 2523a1d4290a..a314b900d479 100644 >>> --- a/drivers/vhost/Kconfig >>> +++ b/drivers/vhost/Kconfig >>> @@ -19,11 +19,10 @@ menuconfig VHOST >>> This option is selected by any driver which needs to access >>> the core of vhost. >>> -if VHOST >>> - >>> config VHOST_NET >>> tristate "Host kernel accelerator for virtio net" >>> depends on NET && EVENTFD && (TUN || !TUN) && (TAP || !TAP) >>> + select VHOST >>> ---help--- >>> This kernel module can be loaded in host kernel to accelerate >>> guest networking with virtio_net. Not to be confused with virtio_net >>> @@ -35,6 +34,7 @@ config VHOST_NET >>> config VHOST_SCSI >>> tristate "VHOST_SCSI TCM fabric driver" >>> depends on TARGET_CORE && EVENTFD >>> + select VHOST >>> default n >>> ---help--- >>> Say M here to enable the vhost_scsi TCM fabric module >>> @@ -44,6 +44,7 @@ config VHOST_VSOCK >>> tristate "vhost virtio-vsock driver" >>> depends on VSOCKETS && EVENTFD >>> select VIRTIO_VSOCKETS_COMMON >>> + select VHOST >>> default n >>> ---help--- >>> This kernel module can be loaded in the host kernel to provide AF_VSOCK >>> @@ -57,6 +58,7 @@ config VHOST_VDPA >>> tristate "Vhost driver for vDPA-based backend" >>> depends on EVENTFD >>> select VDPA >>> + select VHOST >>> help >>> This kernel module can be loaded in host kernel to accelerate >>> guest virtio devices with the vDPA-based backends. >>> @@ -78,5 +80,3 @@ config VHOST_CROSS_ENDIAN_LEGACY >>> adds some overhead, it is disabled by default. >>> If unsure, say "N". >>> - >>> -endif >>> >>> >>> But now CONFIG_VHOST is always "y", never "m". >>> Which I think will make it a built-in. >>> Didn't figure out why yet. >> >> >> Is it because the dependency of EVENTFD for CONFIG_VHOST? > > Oh no, it's because I forgot to change menuconfig to config. > > >> Remove that one for this patch, I can get CONFIG_VHOST=m. FWIW, the current vhost/linux-next branch seems to work again.
