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Diffstat (limited to 'Documentation/virtual')
| -rw-r--r-- | Documentation/virtual/kvm/api.txt | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index a67fb35993fa..7ca696227d3a 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -1771,6 +1771,29 @@ developer registration required to access it). /* Fix the size of the union. */ char padding[256]; }; + + /* + * shared registers between kvm and userspace. + * kvm_valid_regs specifies the register classes set by the host + * kvm_dirty_regs specified the register classes dirtied by userspace + * struct kvm_sync_regs is architecture specific, as well as the + * bits for kvm_valid_regs and kvm_dirty_regs + */ + __u64 kvm_valid_regs; + __u64 kvm_dirty_regs; + union { + struct kvm_sync_regs regs; + char padding[1024]; + } s; + +If KVM_CAP_SYNC_REGS is defined, these fields allow userspace to access +certain guest registers without having to call SET/GET_*REGS. Thus we can +avoid some system call overhead if userspace has to handle the exit. +Userspace can query the validity of the structure by checking +kvm_valid_regs for specific bits. These bits are architecture specific +and usually define the validity of a groups of registers. (e.g. one bit + for general purpose registers) + }; 6. Capabilities that can be enabled |