| Message ID | 20200416221902.5801-1-mst@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] vhost: disable for OABI | expand |
On Thu, Apr 16, 2020 at 06:20:20PM -0400, Michael S. Tsirkin wrote: > vhost is currently broken on the some ARM configs. > > The reason is that that uses apcs-gnu which is the ancient OABI that is been > deprecated for a long time. > > Given that virtio support on such ancient systems is not needed in the > first place, let's just add something along the lines of > > depends on !ARM || AEABI > > to the virtio Kconfig declaration, and add a comment that it has to do > with struct member alignment. > > Note: we can't make VHOST and VHOST_RING themselves have > a dependency since these are selected. Add a new symbol for that. This description is horrible. The only interesting thing for ARM OABI is that it has some strange padding rules, but that isn't something that can't be handled. Please spend some time looking into the issue and add te proper __padded annotations, we've done that elsewhere in the kernel and it isn't too bad - in fact it helps understanding issues with implicit alignment. And even if you have a good reason not to fix vhost (which I think you don't have) this changelog is just utter crap, as it fails to mention what the problem with ARM OABI even is.
On Mon, Apr 20, 2020 at 01:29:09AM -0700, Christoph Hellwig wrote: > On Thu, Apr 16, 2020 at 06:20:20PM -0400, Michael S. Tsirkin wrote: > > vhost is currently broken on the some ARM configs. > > > > The reason is that that uses apcs-gnu which is the ancient OABI that is been > > deprecated for a long time. > > > > Given that virtio support on such ancient systems is not needed in the > > first place, let's just add something along the lines of > > > > depends on !ARM || AEABI > > > > to the virtio Kconfig declaration, and add a comment that it has to do > > with struct member alignment. > > > > Note: we can't make VHOST and VHOST_RING themselves have > > a dependency since these are selected. Add a new symbol for that. > > This description is horrible. The only interesting thing for ARM OABI > is that it has some strange padding rules, but that isn't something > that can't be handled. Please spend some time looking into the issue > and add te proper __padded annotations, we've done that elsewhere in > the kernel and it isn't too bad - in fact it helps understanding issues > with implicit alignment. Yes I have a patch queued to fix it. I wanted a minimal patch for this release though. > And even if you have a good reason not to fix vhost (which I think you > don't have) this changelog is just utter crap, as it fails to mention > what the problem with ARM OABI even is. I'll tweak that, thanks!
diff --git a/drivers/misc/mic/Kconfig b/drivers/misc/mic/Kconfig index 8f201d019f5a..3bfe72c59864 100644 --- a/drivers/misc/mic/Kconfig +++ b/drivers/misc/mic/Kconfig @@ -116,7 +116,7 @@ config MIC_COSM config VOP tristate "VOP Driver" - depends on VOP_BUS + depends on VOP_BUS && VHOST_DPN select VHOST_RING select VIRTIO help diff --git a/drivers/net/caif/Kconfig b/drivers/net/caif/Kconfig index 9db0570c5beb..661c25eb1c46 100644 --- a/drivers/net/caif/Kconfig +++ b/drivers/net/caif/Kconfig @@ -50,7 +50,7 @@ config CAIF_HSI config CAIF_VIRTIO tristate "CAIF virtio transport driver" - depends on CAIF && HAS_DMA + depends on CAIF && HAS_DMA && VHOST_DPN select VHOST_RING select VIRTIO select GENERIC_ALLOCATOR diff --git a/drivers/vdpa/Kconfig b/drivers/vdpa/Kconfig index 71d9a64f2c7d..ee35f8261a88 100644 --- a/drivers/vdpa/Kconfig +++ b/drivers/vdpa/Kconfig @@ -10,7 +10,7 @@ if VDPA config VDPA_SIM tristate "vDPA device simulator" - depends on RUNTIME_TESTING_MENU && HAS_DMA + depends on RUNTIME_TESTING_MENU && HAS_DMA && VHOST_DPN select VHOST_RING select VHOST_IOTLB default n diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig index e79cbbdfea45..d9b3a3ec765a 100644 --- a/drivers/vhost/Kconfig +++ b/drivers/vhost/Kconfig @@ -12,6 +12,15 @@ config VHOST_RING This option is selected by any driver which needs to access the host side of a virtio ring. +config VHOST_DPN + bool + depends on !ARM || AEABI + default y + help + Anything selecting VHOST or VHOST_RING must depend on VHOST_DPN. + This excludes the deprecated ARM ABI since that forces a 4 byte + alignment on all structs - incompatible with virtio spec requirements. + config VHOST tristate select VHOST_IOTLB @@ -27,7 +36,7 @@ if VHOST_MENU config VHOST_NET tristate "Host kernel accelerator for virtio net" - depends on NET && EVENTFD && (TUN || !TUN) && (TAP || !TAP) + depends on NET && EVENTFD && (TUN || !TUN) && (TAP || !TAP) && VHOST_DPN select VHOST ---help--- This kernel module can be loaded in host kernel to accelerate @@ -39,7 +48,7 @@ config VHOST_NET config VHOST_SCSI tristate "VHOST_SCSI TCM fabric driver" - depends on TARGET_CORE && EVENTFD + depends on TARGET_CORE && EVENTFD && VHOST_DPN select VHOST default n ---help--- @@ -48,7 +57,7 @@ config VHOST_SCSI config VHOST_VSOCK tristate "vhost virtio-vsock driver" - depends on VSOCKETS && EVENTFD + depends on VSOCKETS && EVENTFD && VHOST_DPN select VHOST select VIRTIO_VSOCKETS_COMMON default n @@ -62,7 +71,7 @@ config VHOST_VSOCK config VHOST_VDPA tristate "Vhost driver for vDPA-based backend" - depends on EVENTFD + depends on EVENTFD && VHOST_DPN select VHOST depends on VDPA help
vhost is currently broken on the some ARM configs. The reason is that that uses apcs-gnu which is the ancient OABI that is been deprecated for a long time. Given that virtio support on such ancient systems is not needed in the first place, let's just add something along the lines of depends on !ARM || AEABI to the virtio Kconfig declaration, and add a comment that it has to do with struct member alignment. Note: we can't make VHOST and VHOST_RING themselves have a dependency since these are selected. Add a new symbol for that. Link: https://lore.kernel.org/r/20200406121233.109889-3-mst@redhat.com Suggested-by: Ard Biesheuvel <ardb@kernel.org> Suggested-by: Richard Earnshaw <Richard.Earnshaw@arm.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- Changes from v2: - drop prompt from VHOST_DPN - typo fix in commit log - OABI is a possible ARM config but not the default one drivers/misc/mic/Kconfig | 2 +- drivers/net/caif/Kconfig | 2 +- drivers/vdpa/Kconfig | 2 +- drivers/vhost/Kconfig | 17 +++++++++++++---- 4 files changed, 16 insertions(+), 7 deletions(-)