On 2022/8/8 6:00, isaku.yamahata@xxxxxxxxx wrote:
From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
KVM accesses Virtual Machine Control Structure (VMCS) with VMX instructions
to operate on VM. TDX defines its data structure and TDX SEAMCALL APIs for
VMM to operate on Trust Domain (TD) instead.
Trust Domain Virtual Processor State (TDVPS) is the root control structure
of a TD VCPU. It helps the TDX module control the operation of the VCPU,
and holds the VCPU state while the VCPU is not running. TDVPS is opaque to
software and DMA access, accessible only by using the TDX module interface
functions (such as TDH.VP.RD, TDH.VP.WR ,..). TDVPS includes TD VMCS, and
TD VMCS auxiliary structures, such as virtual APIC page, virtualization
exception information, etc. TDVPS is composed of Trust Domain Virtual
Processor Root (TDVPR) which is the root page of TDVPS and Trust Domain
Virtual Processor eXtension (TDVPX) pages which extend TDVPR to help
provide enough physical space for the logical TDVPS structure.
Also, we have a new structure, Trust Domain Control Structure (TDCS) is the
main control structure of a guest TD, and encrypted (using the guest TD's
ephemeral private key). At a high level, TDCS holds information for
controlling TD operation as a whole, execution, EPTP, MSR bitmaps, etc. KVM
needs to set it up. Note that MSR bitmaps are held as part of TDCS (unlike
VMX) because they are meant to have the same value for all VCPUs of the
same TD. TDCS is a multi-page logical structure composed of multiple Trust
Domain Control Extension (TDCX) physical pages. Trust Domain Root (TDR) is
the root control structure of a guest TD and is encrypted using the TDX
global private key. It holds a minimal set of state variables that enable
guest TD control even during times when the TD's private key is not known,
or when the TD's key management state does not permit access to memory
encrypted using the TD's private key.
The following shows the relationship between those structures.
TDR--> TDCS per-TD
| \--> TDCX
\
\--> TDVPS per-TD VCPU
\--> TDVPR and TDVPX
The existing global struct kvm_x86_ops already defines an interface which
fits with TDX. But kvm_x86_ops is system-wide, not per-VM structure. To
allow VMX to coexist with TDs, the kvm_x86_ops callbacks will have wrappers
"if (tdx) tdx_op() else vmx_op()" to switch VMX or TDX at run time.
To split the runtime switch, the VMX implementation, and the TDX
implementation, add main.c, and move out the vmx_x86_ops hooks in
preparation for adding TDX, which can coexist with VMX, i.e. KVM can run
both VMs and TDs. Use 'vt' for the naming scheme as a nod to VT-x and as a
concatenation of VmxTdx.
The current code looks as follows.
In vmx.c
static vmx_op() { ... }
static struct kvm_x86_ops vmx_x86_ops = {
.op = vmx_op,
initialization code
The eventually converted code will look like
In vmx.c, keep the VMX operations.
vmx_op() { ... }
VMX initialization
In tdx.c, define the TDX operations.
tdx_op() { ... }
TDX initialization
In x86_ops.h, declare the VMX and TDX operations.
vmx_op();
tdx_op();
In main.c, define common wrappers for VMX and VMX.
LGTM.
One typo here, VMX and TDX.
static vt_ops() { if (tdx) tdx_ops() else vmx_ops() }
static struct kvm_x86_ops vt_x86_ops = {
.op = vt_op,
initialization to call VMX and TDX initialization
Opportunistically, fix the name inconsistency from vmx_create_vcpu() and
vmx_free_vcpu() to vmx_vcpu_create() and vxm_vcpu_free().
Co-developed-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
