added support to query caps on kvm fd + few caps

4 files changed, 84 insertions, 2 deletions

diff --git a/src/cap.rs b/src/cap.rs
new file mode 100644
index 0000000..672ca75
--- /dev/null
+++ b/src/cap.rs
@@ -0,0 +1,34 @@
+//! Definitions of KVM capabilities.
+
+use crate::kvm_sys;
+use std::convert::Into;
+
+/// Definition of capabilities that return a bool value indicating whether the capability is
+/// supported or not.
+#[repr(u64)]
+pub enum CapBool {
+    /// Check if capabilities can be queried on VM fds (`KVM_CAP_CHECK_EXTENSION_VM`).
+    CheckExtensionVm = kvm_sys::KVM_CAP_CHECK_EXTENSION_VM,
+}
+
+impl Into<u64> for CapBool {
+    fn into(self) -> u64 {
+        self as u64
+    }
+}
+
+/// Definition of capabilities that return an integer value indicating the amount of the queried
+/// capability.
+#[repr(u64)]
+pub enum CapInt {
+    /// Get the recommended max VPCUs (`KVM_CAP_NR_VCPUS`).
+    NrVcpus = kvm_sys::KVM_CAP_NR_VCPUS,
+    /// Get the possible max VPCUs (`KVM_CAP_MAX_VCPUS`).
+    MaxVcpus = kvm_sys::KVM_CAP_MAX_VCPUS,
+}
+
+impl Into<u64> for CapInt {
+    fn into(self) -> u64 {
+        self as u64
+    }
+}
diff --git a/src/kvm.rs b/src/kvm.rs
index 23112aa..30a00bb 100644
--- a/src/kvm.rs
+++ b/src/kvm.rs
@@ -4,8 +4,9 @@ use std::fs;
 use std::io;
 use std::os::unix::io::FromRawFd;
 
-use crate::{libcret, ioctl, kvm_sys};
+use crate::cap::{CapBool, CapInt};
 use crate::vm::Vm;
+use crate::{ioctl, kvm_sys, libcret};
 
 /// Wrapper for `/dev/kvm` ioctls.
 ///
@@ -49,4 +50,24 @@ impl Kvm {
 
         Ok(Vm::new(vm, vcpu_mmap_size))
     }
+
+    /// Check availability of an extension with the [`KVM_CHECK_EXTENSION`][kvm-check-extension]
+    /// ioctl.
+    ///
+    /// [kvm-check-extension]: https://www.kernel.org/doc/html/latest/virt/kvm/api.html#kvm-check-extension
+    pub fn check_extenstion(&self, cap: CapBool) -> bool {
+        let ret = ioctl(&self.kvm, kvm_sys::KVM_CHECK_EXTENSION, cap.into());
+
+        matches!(ret, Ok(ret) if ret > 0)
+    }
+
+    /// Check availability of an extension with the [`KVM_CHECK_EXTENSION`][kvm-check-extension]
+    /// ioctl.
+    ///
+    /// [kvm-check-extension]: https://www.kernel.org/doc/html/latest/virt/kvm/api.html#kvm-check-extension
+    pub fn check_extenstion_int(&self, cap: CapInt) -> i32 {
+        let ret = ioctl(&self.kvm, kvm_sys::KVM_CHECK_EXTENSION, cap.into());
+
+        ret.unwrap_or(0)
+    }
 }
diff --git a/src/lib.rs b/src/lib.rs
index 1833890..372255c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -3,6 +3,7 @@ use std::io;
 use std::ops;
 use std::os::unix::io::AsRawFd;
 
+pub mod cap;
 mod fmt;
 pub mod kvm;
 pub mod kvm_sys;
@@ -154,7 +155,7 @@ impl ops::Drop for KvmRun {
 
 impl AsRef<kvm_sys::kvm_run> for KvmRun {
     fn as_ref(&self) -> &kvm_sys::kvm_run {
-        unsafe { & *(self.ptr as *const kvm_sys::kvm_run) }
+        unsafe { &*(self.ptr as *const kvm_sys::kvm_run) }
     }
 }
 
diff --git a/sysdeps/kvm.c b/sysdeps/kvm.c
index 1665349..f7ff1a4 100644
--- a/sysdeps/kvm.c
+++ b/sysdeps/kvm.c
@@ -56,6 +56,32 @@ int main() {
     printf("pub(crate) const KVM_EXIT_IO_OUT : u64 = 0x%x;\n", KVM_EXIT_IO_OUT);
     printf("pub(crate) const KVM_EXIT_MMIO : u64 = 0x%x;\n", KVM_EXIT_MMIO);
 
+    /* Capabilities */
+
+    // Can be used on /dev/kvm fd and VM fd (if KVM_CAP_CHECK_EXTENSION_VM is available).
+    //
+    // param: capability to query KVM_CAP_*
+    // ret  : 0 unsupported, 1 supported (some return >=1 returning number for cap)
+    printf("pub(crate) const KVM_CHECK_EXTENSION : u64 = 0x%x;\n", KVM_CHECK_EXTENSION);
+
+    /* Bool Capabilities */
+
+    // Check if capabilities can be checked in VM fd.
+    //
+    // ret: 0 unsupported, 1 supported
+    printf("pub(crate) const KVM_CAP_CHECK_EXTENSION_VM : u64 = 0x%x;\n", KVM_CAP_CHECK_EXTENSION_VM);
+
+    /* Int Capabilities */
+
+    // Check the recommended max amount of VCPUs.
+    //
+    // ret: 0 unsupported, >0 #vcpus
+    printf("pub(crate) const KVM_CAP_NR_VCPUS : u64 = 0x%x;\n", KVM_CAP_NR_VCPUS);
+    // Check the possible max amount of VCPUs.
+    //
+    // ret: 0 unsupported, >0 #vcpus
+    printf("pub(crate) const KVM_CAP_MAX_VCPUS : u64 = 0x%x;\n", KVM_CAP_MAX_VCPUS);
+
     /* Testing constants */
 
     printf("#[cfg(test)] const TEST_KVM_REGS_SIZE : usize = %ld;\n", sizeof(struct kvm_regs));