On Wed, Apr 01, 2020 at 10:29:32PM +0800, Jason Wang wrote:

On 2020/4/1 下午10:13, Michael S. Tsirkin wrote:

quoted

On Wed, Apr 01, 2020 at 10:08:59PM +0800, Jason Wang wrote:

quoted

On 2020/4/1 下午9:22, Michael S. Tsirkin wrote:

quoted

On Thu, Mar 26, 2020 at 10:01:17PM +0800, Jason Wang wrote:

quoted

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@redhat.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.

How about stubs for IOTLB so VHOST_RING does not depend on VHOST_IOTLB?

That could work.

quoted

I'm pretty sure neither user of vringh can actually use IOTLB, it's a
software only thing.

Right.

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quoted

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Given the impact it had I'd like to defer it till next release if
possible.

quoted

---
   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.

Can we just bring it back and select it?

Right, so if bring it back, we don't even need the stub.

How about something like attached?

Thanks

quoted

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For VHOST_RING, it was selected by CAIF, VOP and VDPASIM.

Thanks

quoted

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   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

In fact this is similar to VIRTIO, and I wonder whether VIRTIO has also
been broken by
	commit 7b95fec6d2ffa53f4a8d637b0f223644d458ea4e
	Author: Vincent Legoll [off-list ref]
	Date:   Sun Jan 7 12:33:56 2018 +0100

	    virtio: make VIRTIO a menuconfig to ease disabling it all

I see lots of defconfigs set VIRTIO_PCI but not VIRTIO_MENU ...



-- 
MST