linux-kernel - [PATCH v18 098/121] KVM: TDX: Handle TDX PV port io hypercall

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Message-Id: <06a142259ea1d80ae54161e18e8d4983d4d11210.1705965635.git.isaku.yamahata@intel.com>
Date: Mon, 22 Jan 2024 15:54:14 -0800
From: isaku.yamahata@...el.com
To: kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: isaku.yamahata@...el.com,
	isaku.yamahata@...il.com,
	Paolo Bonzini <pbonzini@...hat.com>,
	erdemaktas@...gle.com,
	Sean Christopherson <seanjc@...gle.com>,
	Sagi Shahar <sagis@...gle.com>,
	Kai Huang <kai.huang@...el.com>,
	chen.bo@...el.com,
	hang.yuan@...el.com,
	tina.zhang@...el.com
Subject: [PATCH v18 098/121] KVM: TDX: Handle TDX PV port io hypercall

From: Isaku Yamahata <isaku.yamahata@...el.com>

Wire up TDX PV port IO hypercall to the KVM backend function.

Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>
---
v18:
- Fix out case to set R10 and R11 correctly when user space handled port
  out.
---
 arch/x86/kvm/vmx/tdx.c | 67 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)

diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 4628c7eb3002..71c444cfbc9e 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -1202,6 +1202,71 @@ static int tdx_emulate_hlt(struct kvm_vcpu *vcpu)
 	return kvm_emulate_halt_noskip(vcpu);
 }
 
+static int tdx_complete_pio_out(struct kvm_vcpu *vcpu)
+{
+	tdvmcall_set_return_code(vcpu, TDG_VP_VMCALL_SUCCESS);
+	tdvmcall_set_return_val(vcpu, 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;
+
+	WARN_ON_ONCE(vcpu->arch.pio.count != 1);
+
+	ret = ctxt->ops->pio_in_emulated(ctxt, vcpu->arch.pio.size,
+					 vcpu->arch.pio.port, &val, 1);
+	WARN_ON_ONCE(!ret);
+
+	tdvmcall_set_return_code(vcpu, TDG_VP_VMCALL_SUCCESS);
+	tdvmcall_set_return_val(vcpu, val);
+
+	return 1;
+}
+
+static int tdx_emulate_io(struct kvm_vcpu *vcpu)
+{
+	struct x86_emulate_ctxt *ctxt = vcpu->arch.emulate_ctxt;
+	unsigned long val = 0;
+	unsigned int port;
+	int size, ret;
+	bool write;
+
+	++vcpu->stat.io_exits;
+
+	size = tdvmcall_a0_read(vcpu);
+	write = tdvmcall_a1_read(vcpu);
+	port = tdvmcall_a2_read(vcpu);
+
+	if (size != 1 && size != 2 && size != 4) {
+		tdvmcall_set_return_code(vcpu, TDG_VP_VMCALL_INVALID_OPERAND);
+		return 1;
+	}
+
+	if (write) {
+		val = tdvmcall_a3_read(vcpu);
+		ret = ctxt->ops->pio_out_emulated(ctxt, size, port, &val, 1);
+
+		/* No need for a complete_userspace_io callback. */
+		vcpu->arch.pio.count = 0;
+	} else
+		ret = ctxt->ops->pio_in_emulated(ctxt, size, port, &val, 1);
+
+	if (ret)
+		tdvmcall_set_return_val(vcpu, val);
+	else {
+		if (write)
+			vcpu->arch.complete_userspace_io = tdx_complete_pio_out;
+		else
+			vcpu->arch.complete_userspace_io = tdx_complete_pio_in;
+	}
+
+	return ret;
+}
+
 static int handle_tdvmcall(struct kvm_vcpu *vcpu)
 {
 	if (tdvmcall_exit_type(vcpu))
@@ -1212,6 +1277,8 @@ static int handle_tdvmcall(struct kvm_vcpu *vcpu)
 		return tdx_emulate_cpuid(vcpu);
 	case EXIT_REASON_HLT:
 		return tdx_emulate_hlt(vcpu);
+	case EXIT_REASON_IO_INSTRUCTION:
+		return tdx_emulate_io(vcpu);
 	default:
 		break;
 	}
-- 
2.25.1