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Message-ID: <6b4d169a-9962-6014-5423-1507059343e9@redhat.com>
Date: Wed, 1 Apr 2020 22:08:59 +0800
From: Jason Wang <jasowang@...hat.com>
To: "Michael S. Tsirkin" <mst@...hat.com>
Cc: linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
jgg@...lanox.com, maxime.coquelin@...hat.com,
cunming.liang@...el.com, zhihong.wang@...el.com,
rob.miller@...adcom.com, xiao.w.wang@...el.com,
lingshan.zhu@...el.com, eperezma@...hat.com, lulu@...hat.com,
parav@...lanox.com, kevin.tian@...el.com, stefanha@...hat.com,
rdunlap@...radead.org, hch@...radead.org, aadam@...hat.com,
jiri@...lanox.com, shahafs@...lanox.com, hanand@...inx.com,
mhabets@...arflare.com, gdawar@...inx.com, saugatm@...inx.com,
vmireyno@...vell.com, zhangweining@...jie.com.cn
Subject: Re: [PATCH V9 1/9] vhost: refine vhost and vringh kconfig
On 2020/4/1 下午9:22, Michael S. Tsirkin wrote:
> On Thu, Mar 26, 2020 at 10:01:17PM +0800, 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.
>>
>> While at it, also squash Kconfig.vringh into vhost Kconfig file. This
>> avoids the trick of conditional inclusion from VOP or CAIF. Then it
>> will be easier to introduce new vringh users and common dependency for
>> both vringh and vhost.
>>
>> Signed-off-by: Jason Wang <jasowang@...hat.com>
> Is this just so we can drop the dependency on CONFIG_VIRTUALIZATION?
> If yes what happens if we drop this patch?
The problem is that then VHOST_RING must depend on CONFIG_VIRTUALIZATION
(which enable VHOST_IOTLB) to work.
But it looks to me CAIF and VOP doesn't requires CONFIG_VIRTUALIZATION.
> Given the impact it had I'd like to defer it till next release if
> possible.
>
>
>> ---
>> arch/arm/kvm/Kconfig | 2 --
>> arch/arm64/kvm/Kconfig | 2 --
>> arch/mips/kvm/Kconfig | 2 --
>> arch/powerpc/kvm/Kconfig | 2 --
>> arch/s390/kvm/Kconfig | 4 ----
>> arch/x86/kvm/Kconfig | 4 ----
>> drivers/Kconfig | 2 ++
>> drivers/misc/mic/Kconfig | 4 ----
>> drivers/net/caif/Kconfig | 4 ----
>> drivers/vhost/Kconfig | 23 ++++++++++++++---------
>> drivers/vhost/Kconfig.vringh | 6 ------
>> 11 files changed, 16 insertions(+), 39 deletions(-)
>> delete mode 100644 drivers/vhost/Kconfig.vringh
>>
>> diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig
>> index f591026347a5..be97393761bf 100644
>> --- a/arch/arm/kvm/Kconfig
>> +++ b/arch/arm/kvm/Kconfig
>> @@ -54,6 +54,4 @@ config KVM_ARM_HOST
>> ---help---
>> Provides host support for ARM processors.
>>
>> -source "drivers/vhost/Kconfig"
>> -
>> endif # VIRTUALIZATION
>> diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
>> index a475c68cbfec..449386d76441 100644
>> --- a/arch/arm64/kvm/Kconfig
>> +++ b/arch/arm64/kvm/Kconfig
>> @@ -64,6 +64,4 @@ config KVM_ARM_PMU
>> config KVM_INDIRECT_VECTORS
>> def_bool KVM && (HARDEN_BRANCH_PREDICTOR || HARDEN_EL2_VECTORS)
>>
>> -source "drivers/vhost/Kconfig"
>> -
>> endif # VIRTUALIZATION
>> diff --git a/arch/mips/kvm/Kconfig b/arch/mips/kvm/Kconfig
>> index eac25aef21e0..b91d145aa2d5 100644
>> --- a/arch/mips/kvm/Kconfig
>> +++ b/arch/mips/kvm/Kconfig
>> @@ -72,6 +72,4 @@ config KVM_MIPS_DEBUG_COP0_COUNTERS
>>
>> If unsure, say N.
>>
>> -source "drivers/vhost/Kconfig"
>> -
>> endif # VIRTUALIZATION
>> diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig
>> index 711fca9bc6f0..12885eda324e 100644
>> --- a/arch/powerpc/kvm/Kconfig
>> +++ b/arch/powerpc/kvm/Kconfig
>> @@ -204,6 +204,4 @@ config KVM_XIVE
>> default y
>> depends on KVM_XICS && PPC_XIVE_NATIVE && KVM_BOOK3S_HV_POSSIBLE
>>
>> -source "drivers/vhost/Kconfig"
>> -
>> endif # VIRTUALIZATION
>> diff --git a/arch/s390/kvm/Kconfig b/arch/s390/kvm/Kconfig
>> index d3db3d7ed077..def3b60f1fe8 100644
>> --- a/arch/s390/kvm/Kconfig
>> +++ b/arch/s390/kvm/Kconfig
>> @@ -55,8 +55,4 @@ config KVM_S390_UCONTROL
>>
>> If unsure, say N.
>>
>> -# OK, it's a little counter-intuitive to do this, but it puts it neatly under
>> -# the virtualization menu.
>> -source "drivers/vhost/Kconfig"
>> -
>> endif # VIRTUALIZATION
>> diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
>> index 991019d5eee1..0dfe70e17af9 100644
>> --- a/arch/x86/kvm/Kconfig
>> +++ b/arch/x86/kvm/Kconfig
>> @@ -94,8 +94,4 @@ config KVM_MMU_AUDIT
>> This option adds a R/W kVM module parameter 'mmu_audit', which allows
>> auditing of KVM MMU events at runtime.
>>
>> -# OK, it's a little counter-intuitive to do this, but it puts it neatly under
>> -# the virtualization menu.
>> -source "drivers/vhost/Kconfig"
>> -
>> endif # VIRTUALIZATION
>> diff --git a/drivers/Kconfig b/drivers/Kconfig
>> index 8befa53f43be..7a6d8b2b68b4 100644
>> --- a/drivers/Kconfig
>> +++ b/drivers/Kconfig
>> @@ -138,6 +138,8 @@ source "drivers/virt/Kconfig"
>>
>> source "drivers/virtio/Kconfig"
>>
>> +source "drivers/vhost/Kconfig"
>> +
>> source "drivers/hv/Kconfig"
>>
>> source "drivers/xen/Kconfig"
>> diff --git a/drivers/misc/mic/Kconfig b/drivers/misc/mic/Kconfig
>> index b6841ba6d922..8f201d019f5a 100644
>> --- a/drivers/misc/mic/Kconfig
>> +++ b/drivers/misc/mic/Kconfig
>> @@ -133,8 +133,4 @@ config VOP
>> OS and tools for MIC to use with this driver are available from
>> <http://software.intel.com/en-us/mic-developer>.
>>
>> -if VOP
>> -source "drivers/vhost/Kconfig.vringh"
>> -endif
>> -
>> endmenu
>> diff --git a/drivers/net/caif/Kconfig b/drivers/net/caif/Kconfig
>> index e74e2bb61236..9db0570c5beb 100644
>> --- a/drivers/net/caif/Kconfig
>> +++ b/drivers/net/caif/Kconfig
>> @@ -58,8 +58,4 @@ config CAIF_VIRTIO
>> ---help---
>> The CAIF driver for CAIF over Virtio.
>>
>> -if CAIF_VIRTIO
>> -source "drivers/vhost/Kconfig.vringh"
>> -endif
>> -
>> endif # CAIF_DRIVERS
>> diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
>> index 3d03ccbd1adc..4aef10a54cd1 100644
>> --- a/drivers/vhost/Kconfig
>> +++ b/drivers/vhost/Kconfig
>> @@ -1,8 +1,20 @@
>> # SPDX-License-Identifier: GPL-2.0-only
>> +config VHOST_RING
>> + tristate
>> + help
>> + This option is selected by any driver which needs to access
>> + the host side of a virtio ring.
>> +
>> +menuconfig VHOST
>> + tristate "Host kernel accelerator for virtio (VHOST)"
>> + help
>> + This option is selected by any driver which needs to access
>> + the core of vhost.
>> +if VHOST
>> +
> The description here is wrong, isn't it?
> VHOST and VHOST_RING are no longer selected, right?
For VHOST not currently.
For VHOST_RING, it was selected by CAIF, VOP and VDPASIM.
Thanks
>
>
>> 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
>> @@ -14,7 +26,6 @@ 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
>> @@ -24,7 +35,6 @@ 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
>> @@ -34,12 +44,6 @@ config VHOST_VSOCK
>> To compile this driver as a module, choose M here: the module will be called
>> vhost_vsock.
>>
>> -config VHOST
>> - tristate
>> - ---help---
>> - This option is selected by any driver which needs to access
>> - the core of vhost.
>> -
>> config VHOST_CROSS_ENDIAN_LEGACY
>> bool "Cross-endian support for vhost"
>> default n
>> @@ -54,3 +58,4 @@ config VHOST_CROSS_ENDIAN_LEGACY
>> adds some overhead, it is disabled by default.
>>
>> If unsure, say "N".
>> +endif
>> diff --git a/drivers/vhost/Kconfig.vringh b/drivers/vhost/Kconfig.vringh
>> deleted file mode 100644
>> index c1fe36a9b8d4..000000000000
>> --- a/drivers/vhost/Kconfig.vringh
>> +++ /dev/null
>> @@ -1,6 +0,0 @@
>> -# SPDX-License-Identifier: GPL-2.0-only
>> -config VHOST_RING
>> - tristate
>> - ---help---
>> - This option is selected by any driver which needs to access
>> - the host side of a virtio ring.
>> --
>> 2.20.1
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