x86_64: add initial support for protected VMs

Add support for running protected VMs with pKVM on Intel x86 [1].

The --protected-vm option is not workable yet, since loading pvmfw into
guest memory via pKVM is not implemented yet, but the developer options
--protected-vm-without-firmware and --protected-vm-with-firmware are
working.

Following the approach used for pKVM on arm64, the KVM uAPI used for
running protected VMs on x86 is a "stable temporary" uAPI: the
KVM_X86_PKVM_PROTECTED_VM value shall be updated when upstreaming pKVM
to the mainline kernel (see also [2]).

[1] https://android-review.git.corp.google.com/c/kernel/common/+/3351287
[2] https://android-review.git.corp.google.com/c/kernel/common/+/3351286

BUG=b:349990461
TEST=On an Intel device with kernel compiled with pKVM-IA patches [1]
and kvm-intel.pkvm=1 added to kernel command line, run a VM with
--protected-vm-without-firmware or with --protected-vm-with-firmware
with the same test pvmfw image as in TEST= in CL:5797353.

Change-Id: I625f5eb9a38eaef9312ba62308739efb66f163b0
Reviewed-on: https://chromium-review.googlesource.com/c/crosvm/crosvm/+/6022852
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
Commit-Queue: Dmytro Maluka <dmaluka@chromium.org>

hypervisor/src/kvm/x86_64.rs

@@ -156,11 +156,9 @@ impl Kvm {
         get_cpuid_with_initial_capacity(self, kind, KVM_MAX_ENTRIES)
     }
 
-    // The x86 machine type is always 0. Protected VMs are not supported.
     pub fn get_vm_type(&self, protection_type: ProtectionType) -> Result<u32> {
         if protection_type.isolates_memory() {
-            error!("Protected mode is not supported on x86_64.");
-            Err(Error::new(libc::EINVAL))
+            Ok(KVM_X86_PKVM_PROTECTED_VM)
         } else {
             Ok(0)
         }

kvm_sys/bindgen.sh

@@ -24,6 +24,7 @@ pub const KVM_CAP_ARM_PROTECTED_VM: u32 = 0xffbadab1;
 pub const KVM_CAP_ARM_PROTECTED_VM_FLAGS_SET_FW_IPA: u32 = 0;
 pub const KVM_CAP_ARM_PROTECTED_VM_FLAGS_INFO: u32 = 1;
 pub const KVM_VM_TYPE_ARM_PROTECTED: u32 = 0x80000000;
+pub const KVM_X86_PKVM_PROTECTED_VM: u32 = 28;
 pub const KVM_DEV_VFIO_PVIOMMU: u32 = 2;
 pub const KVM_DEV_VFIO_PVIOMMU_ATTACH: u32 = 1;
 #[repr(C)]

kvm_sys/src/aarch64/bindings.rs

@@ -22,6 +22,7 @@ pub const KVM_CAP_ARM_PROTECTED_VM: u32 = 0xffbadab1;
 pub const KVM_CAP_ARM_PROTECTED_VM_FLAGS_SET_FW_IPA: u32 = 0;
 pub const KVM_CAP_ARM_PROTECTED_VM_FLAGS_INFO: u32 = 1;
 pub const KVM_VM_TYPE_ARM_PROTECTED: u32 = 0x80000000;
+pub const KVM_X86_PKVM_PROTECTED_VM: u32 = 28;
 pub const KVM_DEV_VFIO_PVIOMMU: u32 = 2;
 pub const KVM_DEV_VFIO_PVIOMMU_ATTACH: u32 = 1;
 #[repr(C)]

kvm_sys/src/riscv64/bindings.rs

@@ -22,6 +22,7 @@ pub const KVM_CAP_ARM_PROTECTED_VM: u32 = 0xffbadab1;
 pub const KVM_CAP_ARM_PROTECTED_VM_FLAGS_SET_FW_IPA: u32 = 0;
 pub const KVM_CAP_ARM_PROTECTED_VM_FLAGS_INFO: u32 = 1;
 pub const KVM_VM_TYPE_ARM_PROTECTED: u32 = 0x80000000;
+pub const KVM_X86_PKVM_PROTECTED_VM: u32 = 28;
 pub const KVM_DEV_VFIO_PVIOMMU: u32 = 2;
 pub const KVM_DEV_VFIO_PVIOMMU_ATTACH: u32 = 1;
 #[repr(C)]

kvm_sys/src/x86/bindings.rs

@@ -22,6 +22,7 @@ pub const KVM_CAP_ARM_PROTECTED_VM: u32 = 0xffbadab1;
 pub const KVM_CAP_ARM_PROTECTED_VM_FLAGS_SET_FW_IPA: u32 = 0;
 pub const KVM_CAP_ARM_PROTECTED_VM_FLAGS_INFO: u32 = 1;
 pub const KVM_VM_TYPE_ARM_PROTECTED: u32 = 0x80000000;
+pub const KVM_X86_PKVM_PROTECTED_VM: u32 = 28;
 pub const KVM_DEV_VFIO_PVIOMMU: u32 = 2;
 pub const KVM_DEV_VFIO_PVIOMMU_ATTACH: u32 = 1;
 #[repr(C)]

src/crosvm/sys/linux.rs

@@ -1667,6 +1667,9 @@ fn run_kvm(device_path: Option<&Path>, cfg: Config, components: VmComponents) ->
     }
 
     // Check that the VM was actually created in protected mode as expected.
+    // This check is only needed on aarch64. On x86_64, protected VM creation will fail
+    // if protected mode is not supported.
+    #[cfg(not(target_arch = "x86_64"))]
     if cfg.protection_type.isolates_memory() && !vm.check_capability(VmCap::Protected) {
         bail!("Failed to create protected VM");
     }

x86_64/src/lib.rs

@@ -822,10 +822,6 @@ impl arch::LinuxArch for X8664arch {
         V: VmX86_64,
         Vcpu: VcpuX86_64,
     {
-        if components.hv_cfg.protection_type.isolates_memory() {
-            return Err(Error::UnsupportedProtectionType);
-        }
-
         let mem = vm.get_memory().clone();
 
         let vcpu_count = components.vcpu_count;