Commit 33608aaf authored by Isaku Yamahata's avatar Isaku Yamahata Committed by Paolo Bonzini
Browse files

KVM: TDX: Handle TDX PV port I/O hypercall 



Emulate port I/O requested by TDX guest via TDVMCALL with leaf
Instruction.IO (same value as EXIT_REASON_IO_INSTRUCTION) according to
TDX Guest Host Communication Interface (GHCI).

All port I/O instructions inside the TDX guest trigger the #VE exception.
On #VE triggered by I/O instructions, TDX guest can call TDVMCALL with
leaf Instruction.IO to request VMM to emulate I/O instructions.

Similar to normal port I/O emulation, try to handle the port I/O in kernel
first, if kernel can't support it, forward the request to userspace.

Note string I/O operations are not supported in TDX.  Guest should unroll
them before calling the TDVMCALL.

Suggested-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarIsaku Yamahata <isaku.yamahata@intel.com>
Co-developed-by: default avatarBinbin Wu <binbin.wu@linux.intel.com>
Signed-off-by: default avatarBinbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Message-ID: <20250222014225.897298-9-binbin.wu@linux.intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 79462faa

arch/x86/kvm/vmx/tdx.c

+62 −0
Original line number Diff line number Diff line
@@ -808,6 +808,8 @@ int tdx_vcpu_pre_run(struct kvm_vcpu *vcpu) 
static __always_inline u32 tdcall_to_vmx_exit_reason(struct kvm_vcpu *vcpu)

{

	switch (tdvmcall_leaf(vcpu)) {

	case EXIT_REASON_IO_INSTRUCTION:

		return tdvmcall_leaf(vcpu);

	default:

		break;

	}
@@ -1130,6 +1132,64 @@ static int tdx_report_fatal_error(struct kvm_vcpu *vcpu) 
	return 0;

}



static int tdx_complete_pio_out(struct kvm_vcpu *vcpu)

{

	vcpu->arch.pio.count = 0;

	return 1;

}



static int tdx_complete_pio_in(struct kvm_vcpu *vcpu)

{

	struct x86_emulate_ctxt *ctxt = vcpu->arch.emulate_ctxt;

	unsigned long val = 0;

	int ret;



	ret = ctxt->ops->pio_in_emulated(ctxt, vcpu->arch.pio.size,

					 vcpu->arch.pio.port, &val, 1);



	WARN_ON_ONCE(!ret);



	tdvmcall_set_return_val(vcpu, val);



	return 1;

}



static int tdx_emulate_io(struct kvm_vcpu *vcpu)

{

	struct vcpu_tdx *tdx = to_tdx(vcpu);

	struct x86_emulate_ctxt *ctxt = vcpu->arch.emulate_ctxt;

	unsigned long val = 0;

	unsigned int port;

	u64 size, write;

	int ret;



	++vcpu->stat.io_exits;



	size = tdx->vp_enter_args.r12;

	write = tdx->vp_enter_args.r13;

	port = tdx->vp_enter_args.r14;



	if ((write != 0 && write != 1) || (size != 1 && size != 2 && size != 4)) {

		tdvmcall_set_return_code(vcpu, TDVMCALL_STATUS_INVALID_OPERAND);

		return 1;

	}



	if (write) {

		val = tdx->vp_enter_args.r15;

		ret = ctxt->ops->pio_out_emulated(ctxt, size, port, &val, 1);

	} else {

		ret = ctxt->ops->pio_in_emulated(ctxt, size, port, &val, 1);

	}



	if (!ret)

		vcpu->arch.complete_userspace_io = write ? tdx_complete_pio_out :

							   tdx_complete_pio_in;

	else if (!write)

		tdvmcall_set_return_val(vcpu, val);



	return ret;

}



static int handle_tdvmcall(struct kvm_vcpu *vcpu)

{

	switch (tdvmcall_leaf(vcpu)) {
@@ -1507,6 +1567,8 @@ int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath) 
		return handle_tdvmcall(vcpu);

	case EXIT_REASON_VMCALL:

		return tdx_emulate_vmcall(vcpu);

	case EXIT_REASON_IO_INSTRUCTION:

		return tdx_emulate_io(vcpu);

	default:

		break;

	}