Merge tag 'kvmarm-6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm...

[platform/kernel/linux-rpi.git] / Documentation / virt / kvm / api.rst

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 48fad65..e54fdfa 100644 (file)
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -6030,6 +6030,44 @@ delivery must be provided via the "reg_aen" struct.
 The "pad" and "reserved" fields may be used for future extensions and should be
 set to 0s by userspace.
 
+4.138 KVM_ARM_SET_COUNTER_OFFSET
+--------------------------------
+
+:Capability: KVM_CAP_COUNTER_OFFSET
+:Architectures: arm64
+:Type: vm ioctl
+:Parameters: struct kvm_arm_counter_offset (in)
+:Returns: 0 on success, < 0 on error
+
+This capability indicates that userspace is able to apply a single VM-wide
+offset to both the virtual and physical counters as viewed by the guest
+using the KVM_ARM_SET_CNT_OFFSET ioctl and the following data structure:
+
+::
+
+       struct kvm_arm_counter_offset {
+               __u64 counter_offset;
+               __u64 reserved;
+       };
+
+The offset describes a number of counter cycles that are subtracted from
+both virtual and physical counter views (similar to the effects of the
+CNTVOFF_EL2 and CNTPOFF_EL2 system registers, but only global). The offset
+always applies to all vcpus (already created or created after this ioctl)
+for this VM.
+
+It is userspace's responsibility to compute the offset based, for example,
+on previous values of the guest counters.
+
+Any value other than 0 for the "reserved" field may result in an error
+(-EINVAL) being returned. This ioctl can also return -EBUSY if any vcpu
+ioctl is issued concurrently.
+
+Note that using this ioctl results in KVM ignoring subsequent userspace
+writes to the CNTVCT_EL0 and CNTPCT_EL0 registers using the SET_ONE_REG
+interface. No error will be returned, but the resulting offset will not be
+applied.
+
 5. The kvm_run structure
 ========================
 
@@ -6219,15 +6257,40 @@ to the byte array.
                        __u64 nr;
                        __u64 args[6];
                        __u64 ret;
-                       __u32 longmode;
-                       __u32 pad;
+                       __u64 flags;
                } hypercall;
 
-Unused.  This was once used for 'hypercall to userspace'.  To implement
-such functionality, use KVM_EXIT_IO (x86) or KVM_EXIT_MMIO (all except s390).
+
+It is strongly recommended that userspace use ``KVM_EXIT_IO`` (x86) or
+``KVM_EXIT_MMIO`` (all except s390) to implement functionality that
+requires a guest to interact with host userpace.
 
 .. note:: KVM_EXIT_IO is significantly faster than KVM_EXIT_MMIO.
 
+For arm64:
+----------
+
+SMCCC exits can be enabled depending on the configuration of the SMCCC
+filter. See the Documentation/virt/kvm/devices/vm.rst
+``KVM_ARM_SMCCC_FILTER`` for more details.
+
+``nr`` contains the function ID of the guest's SMCCC call. Userspace is
+expected to use the ``KVM_GET_ONE_REG`` ioctl to retrieve the call
+parameters from the vCPU's GPRs.
+
+Definition of ``flags``:
+ - ``KVM_HYPERCALL_EXIT_SMC``: Indicates that the guest used the SMC
+   conduit to initiate the SMCCC call. If this bit is 0 then the guest
+   used the HVC conduit for the SMCCC call.
+
+ - ``KVM_HYPERCALL_EXIT_16BIT``: Indicates that the guest used a 16bit
+   instruction to initiate the SMCCC call. If this bit is 0 then the
+   guest used a 32bit instruction. An AArch64 guest always has this
+   bit set to 0.
+
+At the point of exit, PC points to the instruction immediately following
+the trapping instruction.
+
 ::
 
                /* KVM_EXIT_TPR_ACCESS */