Userspace can use ioctl KVM_SET_MSRS to update a set of MSRs of guest. This ioctl set specified MSRs one by one. If it fails to set an MSR, e.g., due to setting reserved bits, the MSR is not supported/emulated by KVM, etc..., it stops processing the MSR list and returns the number of MSRs have been set successfully. Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx> --- v3: refine the description based on Sean's comment. v2: elaborate the changelog and description of ioctl KVM_SET_MSRS based on Sean's comments. --- Documentation/virt/kvm/api.txt | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/Documentation/virt/kvm/api.txt b/Documentation/virt/kvm/api.txt index 2d067767b617..24541e52e96e 100644 --- a/Documentation/virt/kvm/api.txt +++ b/Documentation/virt/kvm/api.txt @@ -586,7 +586,7 @@ Capability: basic Architectures: x86 Type: vcpu ioctl Parameters: struct kvm_msrs (in) -Returns: 0 on success, -1 on error +Returns: number of msrs successfully set (see below), -1 on error Writes model-specific registers to the vcpu. See KVM_GET_MSRS for the data structures. @@ -595,6 +595,11 @@ Application code should set the 'nmsrs' member (which indicates the size of the entries array), and the 'index' and 'data' members of each array entry. +It tries to set the MSRs in array entries[] one by one. If setting an MSR +fails, e.g., due to setting reserved bits, the MSR isn't supported/emulated +by KVM, etc..., it stops processing the MSR list and returns the number of +MSRs that have been set successfully. + 4.20 KVM_SET_CPUID -- 2.19.1
