[PATCH 9/9] Documentation/virt/kvm/api.rst: Add protvirt dump/info api descriptions

Janosch Frank
2022-02-23T09:20:39Z

Time to add the dump API changes to the api documentation file.
Also some minor cleanup.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
Documentation/virt/kvm/api.rst | 129 ++++++++++++++++++++++++++++++++-
1 file changed, 127 insertions(+), 2 deletions(-)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 622667cc87ef..f73a5d774191 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -5062,7 +5062,7 @@ into ESA mode. This reset is a superset of the initial reset.
__u32 reserved[3];
};

-cmd values:
+**cmd values:**

KVM_PV_ENABLE
Allocate memory and register the VM with the Ultravisor, thereby
@@ -5078,7 +5078,6 @@ KVM_PV_ENABLE
===== =============================

KVM_PV_DISABLE
-
Deregister the VM from the Ultravisor and reclaim the memory that
had been donated to the Ultravisor, making it usable by the kernel
again. All registered VCPUs are converted back to non-protected
@@ -5095,6 +5094,93 @@ KVM_PV_VM_VERIFY
Verify the integrity of the unpacked image. Only if this succeeds,
KVM is allowed to start protected VCPUs.

+KVM_PV_INFO
+ :Capability: KVM_CAP_S390_PROTECTED_DUMP
+
+ Presents an API that provides Ultravisor related data to userspace
+ like the size of buffers needed for other commands, the UV feature
+ indications and the installed UV calls.
+
+**subcommands:**
+
+ KVM_PV_INFO_VM
+ This subcommand provides basic Ultravisor information for PV
+ hosts. These values are likely also exported as files in the sysfs
+ firmware UV query interface but they are more easily available to
+ programs in this API.
+
+ The installed calls and feature_indication members provide the
+ installed UV calls and the UV's other feature indications.
+
+ The max_* members provide information about the maximum number of PV
+ vcpus, PV guests and PV guest memory size.
+
+ ::
+
+ struct kvm_s390_pv_info_vm {
+ __u64 inst_calls_list[4];
+ __u64 max_cpus;
+ __u64 max_guests;
+ __u64 max_guest_addr;
+ __u64 feature_indication;
+ };
+
+
+ KVM_PV_INFO_DUMP
+ This subcommand provides information related to dumping PV guests.
+
+ ::
+
+ struct kvm_s390_pv_info_dump {
+ __u64 dump_cpu_buffer_len;
+ __u64 dump_config_mem_buffer_per_1m;
+ __u64 dump_config_finalize_len;
+ };
+
+KVM_PV_DUMP
+ :Capability: KVM_CAP_S390_PROTECTED_DUMP
+
+ Presents an API that provides calls which facilitate dumping a
+ protected VM.
+
+ ::
+
+ struct kvm_s390_pv_dmp {
+ __u64 subcmd;
+ __u64 buff_addr;
+ __u64 buff_len;
+ __u64 gaddr; /* For dump storage state */
+ };
+
+ **subcommands:**
+
+ KVM_PV_DUMP_INIT
+ Initializes the dump process of a protected VM. If this call does
+ not succeed all other subcommands will fail with -EINVAL. This
+ subcommand will return -EINVAL if a dump process has not yet been
+ completed.
+
+ Not all PV vms can be dumped, the owner needs to set `dump
+ allowed` PCF bit 34 in the SE header to allow dumping.
+
+ KVM_PV_DUMP_CONFIG_STOR_STATE
+ Stores `buff_len` bytes of tweak component values starting with
+ the 1MB block specified by the absolute guest address
+ (`gaddr`). `buff_len` needs to be `conf_dump_storage_state_len`
+ aligned and at least >= the `conf_dump_storage_state_len` value
+ provided by the dump uv_info data.
+
+ KVM_PV_DUMP_COMPLETE
+ If the subcommand succeeds it completes the dump process and lets
+ KVM_PV_DUMP_INIT be called again.
+
+ On success `conf_dump_finalize_len` bytes of completion data will be
+ stored to the `buff_addr`. The completion data contains a key
+ derivation seed, IV, tweak nonce and encryption keys as well as an
+ authentication tag all of which are needed to decrypt the dump at a
+ later time.
+
+
4.126 KVM_X86_SET_MSR_FILTER
----------------------------

@@ -5643,6 +5729,32 @@ The offsets of the state save areas in struct kvm_xsave follow the contents
of CPUID leaf 0xD on the host.

+4.135 KVM_S390_PV_CPU_COMMAND
+-----------------------------
+
+:Capability: KVM_CAP_S390_PROTECTED_DUMP
+:Architectures: s390
+:Type: vcpu ioctl
+:Parameters: none
+:Returns: 0 on success, < 0 on error
+
+This ioctl closely mirrors `KVM_S390_PV_COMMAND` but handles requests
+for vcpus. It re-uses the kvm_s390_pv_dmp struct and hence also shares
+the command ids.
+
+**command:**
+
+KVM_PV_DUMP
+ Presents an API that provides calls which facilitate dumping a vcpu
+ of a protected VM.
+
+**subcommand:**
+
+KVM_PV_DUMP_CPU
+ Provides encrypted dump data like register values.
+ The length of the returned data is provided by uv_info.guest_cpu_stor_len.
+
+
5. The kvm_run structure
========================

@@ -7629,3 +7741,16 @@ The argument to KVM_ENABLE_CAP is also a bitmask, and must be a subset
of the result of KVM_CHECK_EXTENSION. KVM will forward to userspace
the hypercalls whose corresponding bit is in the argument, and return
ENOSYS for the others.
+
+8.35 KVM_CAP_S390_PROTECTED_DUMP
+--------------------------------
+
+:Capability: KVM_CAP_S390_PROTECTED_DUMP
+:Architectures: s390
+:Type: vm
+
+This capability indicates that KVM and the Ultravisor support dumping
+PV guests. The `KVM_PV_DUMP` command is available for the
+`KVM_S390_PV_COMMAND` ioctl and the `KVM_PV_INFO` command provides
+dump related UV data. Also the vcpu ioctl `KVM_S390_PV_CPU_COMMAND` is
+available and supports the `KVM_PV_DUMP_CPU` subcommand.
--
2.32.0