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authorLinus Torvalds <torvalds@linux-foundation.org>2019-07-27 08:58:04 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-07-27 08:58:04 -0700
commit43e317c1bbdfe1d4d6d19d28f925f400898d41b9 (patch)
tree2a6be71740664317d31847d89d5e544f861d8823 /Documentation
parent5efbd93708df56e0fb92b4398960a5bb1ab62f02 (diff)
parent98abe0227827f45cddb21875b2ffa9aeca3848b3 (diff)
downloadlinux-43e317c1bbdfe1d4d6d19d28f925f400898d41b9.tar.bz2
Merge tag 's390-5.3-3' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull s390 updates from Heiko Carstens: - Add ABI to kernel image file which allows e.g. the file utility to figure out the kernel version. - Wire up clone3 system call. - Add support for kasan bitops instrumentation. - uapi header cleanup: use __u{16,32,64} instead of uint{16,32,64}_t. - Provide proper ARCH_ZONE_DMA_BITS so the s390 DMA zone is correctly defined with 2 GB instead of the default value of 1 MB. - Farhan Ali leaves the group of vfio-ccw maintainers. - Various small vfio-ccw fixes. - Add missing locking for airq_areas array in virtio code. - Minor qdio improvements. * tag 's390-5.3-3' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: MAINTAINERS: vfio-ccw: Remove myself as the maintainer s390/mm: use shared variables for sysctl range check virtio/s390: fix race on airq_areas[] s390/dma: provide proper ARCH_ZONE_DMA_BITS value s390/kasan: add bitops instrumentation s390/bitops: make test functions return bool s390: wire up clone3 system call kbuild: enable arch/s390/include/uapi/asm/zcrypt.h for uapi header test s390: use __u{16,32,64} instead of uint{16,32,64}_t in uapi header s390/hypfs: fix a typo in the name of a function s390/qdio: restrict QAOB usage to IQD unicast queues s390/qdio: add sanity checks to the fast-requeue path s390: enable detection of kernel version from bzImage Documentation: fix vfio-ccw doc vfio-ccw: Update documentation for csch/hsch vfio-ccw: Don't call cp_free if we are processing a channel program vfio-ccw: Set pa_nr to 0 if memory allocation fails for pa_iova_pfn vfio-ccw: Fix memory leak and don't call cp_free in cp_init vfio-ccw: Fix misleading comment when setting orb.cmd.c64
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/s390/vfio-ccw.rst31
1 files changed, 28 insertions, 3 deletions
diff --git a/Documentation/s390/vfio-ccw.rst b/Documentation/s390/vfio-ccw.rst
index 1e210c6afa88..fca9c4f5bd9c 100644
--- a/Documentation/s390/vfio-ccw.rst
+++ b/Documentation/s390/vfio-ccw.rst
@@ -180,6 +180,13 @@ The process of how these work together.
add it to an iommu_group and a vfio_group. Then we could pass through
the mdev to a guest.
+
+VFIO-CCW Regions
+----------------
+
+The vfio-ccw driver exposes MMIO regions to accept requests from and return
+results to userspace.
+
vfio-ccw I/O region
-------------------
@@ -205,6 +212,25 @@ irb_area stores the I/O result.
ret_code stores a return code for each access of the region.
+This region is always available.
+
+vfio-ccw cmd region
+-------------------
+
+The vfio-ccw cmd region is used to accept asynchronous instructions
+from userspace::
+
+ #define VFIO_CCW_ASYNC_CMD_HSCH (1 << 0)
+ #define VFIO_CCW_ASYNC_CMD_CSCH (1 << 1)
+ struct ccw_cmd_region {
+ __u32 command;
+ __u32 ret_code;
+ } __packed;
+
+This region is exposed via region type VFIO_REGION_SUBTYPE_CCW_ASYNC_CMD.
+
+Currently, CLEAR SUBCHANNEL and HALT SUBCHANNEL use this region.
+
vfio-ccw operation details
--------------------------
@@ -306,9 +332,8 @@ Together with the corresponding work in QEMU, we can bring the passed
through DASD/ECKD device online in a guest now and use it as a block
device.
-While the current code allows the guest to start channel programs via
-START SUBCHANNEL, support for HALT SUBCHANNEL or CLEAR SUBCHANNEL is
-not yet implemented.
+The current code allows the guest to start channel programs via
+START SUBCHANNEL, and to issue HALT SUBCHANNEL and CLEAR SUBCHANNEL.
vfio-ccw supports classic (command mode) channel I/O only. Transport
mode (HPF) is not supported.