[PATCH v2 6/6] x86/vmware: Add TDX hypercall support

[Alexey Makhalov <amakhalov@vmware.com>]

VMware hypercalls use I/O port, VMCALL or VMMCALL instructions.
Add __tdx_hypercall path to support TDX guests.

No change in high bandwidth hypercalls, as only low bandwidth
ones are supported for TDX guests.

Co-developed-by: Tim Merrifield <timothym@vmware.com>
Signed-off-by: Tim Merrifield <timothym@vmware.com>
Signed-off-by: Alexey Makhalov <amakhalov@vmware.com>
Reviewed-by: Nadav Amit <namit@vmware.com>
---
 arch/x86/include/asm/vmware.h | 72 +++++++++++++++++++++++++++++++++++
 arch/x86/kernel/cpu/vmware.c  |  9 +++++
 2 files changed, 81 insertions(+)

diff --git a/arch/x86/include/asm/vmware.h b/arch/x86/include/asm/vmware.h
index 17091eba68cb..cd58ff8ef1af 100644
--- a/arch/x86/include/asm/vmware.h
+++ b/arch/x86/include/asm/vmware.h
@@ -40,6 +40,54 @@
 
 extern u8 vmware_hypercall_mode;
 
+#define VMWARE_TDX_VENDOR_LEAF 0x1AF7E4909ULL
+#define VMWARE_TDX_HCALL_FUNC  1
+
+extern void vmware_tdx_hypercall_args(struct tdx_module_args *args);
+
+/*
+ * TDCALL[TDG.VP.VMCALL] uses rax (arg0) and rcx (arg2), while the use of
+ * rbp (arg6) is discouraged by the TDX specification. Therefore, we
+ * remap those registers to r12, r13 and r14, respectively.
+ */
+static inline
+unsigned long vmware_tdx_hypercall(unsigned long cmd, unsigned long in1,
+				   unsigned long in3, unsigned long in4,
+				   unsigned long in5, unsigned long in6,
+				   uint32_t *out1, uint32_t *out2,
+				   uint32_t *out3, uint32_t *out4,
+				   uint32_t *out5, uint32_t *out6)
+{
+	struct tdx_module_args args = {
+		.r10 = VMWARE_TDX_VENDOR_LEAF,
+		.r11 = VMWARE_TDX_HCALL_FUNC,
+		.r12 = VMWARE_HYPERVISOR_MAGIC,
+		.r13 = cmd,
+		.rbx = in1,
+		.rdx = in3,
+		.rsi = in4,
+		.rdi = in5,
+		.r14 = in6,
+	};
+
+	vmware_tdx_hypercall_args(&args);
+
+	if (out1)
+		*out1 = args.rbx;
+	if (out2)
+		*out2 = args.r13;
+	if (out3)
+		*out3 = args.rdx;
+	if (out4)
+		*out4 = args.rsi;
+	if (out5)
+		*out5 = args.rdi;
+	if (out6)
+		*out6 = args.r14;
+
+	return args.r12;
+}
+
 /*
  * The low bandwidth call. The low word of edx is presumed to have OUT bit
  * set. The high word of edx may contain input data from the caller.
@@ -67,6 +115,10 @@ unsigned long vmware_hypercall1(unsigned long cmd, unsigned long in1)
 {
 	unsigned long out0;
 
+	if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST))
+		return vmware_tdx_hypercall(cmd, in1, 0, 0, 0, 0, NULL, NULL,
+					    NULL, NULL, NULL, NULL);
+
 	asm_inline volatile (VMWARE_HYPERCALL
 		: "=a" (out0)
 		: [port] "i" (VMWARE_HYPERVISOR_PORT),
@@ -85,6 +137,10 @@ unsigned long vmware_hypercall3(unsigned long cmd, unsigned long in1,
 {
 	unsigned long out0;
 
+	if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST))
+		return vmware_tdx_hypercall(cmd, in1, 0, 0, 0, 0, out1, out2,
+					    NULL, NULL, NULL, NULL);
+
 	asm_inline volatile (VMWARE_HYPERCALL
 		: "=a" (out0), "=b" (*out1), "=c" (*out2)
 		: [port] "i" (VMWARE_HYPERVISOR_PORT),
@@ -104,6 +160,10 @@ unsigned long vmware_hypercall4(unsigned long cmd, unsigned long in1,
 {
 	unsigned long out0;
 
+	if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST))
+		return vmware_tdx_hypercall(cmd, in1, 0, 0, 0, 0, out1, out2,
+					    out3, NULL, NULL, NULL);
+
 	asm_inline volatile (VMWARE_HYPERCALL
 		: "=a" (out0), "=b" (*out1), "=c" (*out2), "=d" (*out3)
 		: [port] "i" (VMWARE_HYPERVISOR_PORT),
@@ -123,6 +183,10 @@ unsigned long vmware_hypercall5(unsigned long cmd, unsigned long in1,
 {
 	unsigned long out0;
 
+	if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST))
+		return vmware_tdx_hypercall(cmd, in1, in3, in4, in5, 0, NULL,
+					    out2, NULL, NULL, NULL, NULL);
+
 	asm_inline volatile (VMWARE_HYPERCALL
 		: "=a" (out0), "=c" (*out2)
 		: [port] "i" (VMWARE_HYPERVISOR_PORT),
@@ -145,6 +209,10 @@ unsigned long vmware_hypercall6(unsigned long cmd, unsigned long in1,
 {
 	unsigned long out0;
 
+	if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST))
+		return vmware_tdx_hypercall(cmd, in1, in3, 0, 0, 0, NULL, out2,
+					    out3, out4, out5, NULL);
+
 	asm_inline volatile (VMWARE_HYPERCALL
 		: "=a" (out0), "=c" (*out2), "=d" (*out3), "=S" (*out4),
 		  "=D" (*out5)
@@ -166,6 +234,10 @@ unsigned long vmware_hypercall7(unsigned long cmd, unsigned long in1,
 {
 	unsigned long out0;
 
+	if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST))
+		return vmware_tdx_hypercall(cmd, in1, in3, in4, in5, 0, out1,
+					    out2, out3, NULL, NULL, NULL);
+
 	asm_inline volatile (VMWARE_HYPERCALL
 		: "=a" (out0), "=b" (*out1), "=c" (*out2), "=d" (*out3)
 		: [port] "i" (VMWARE_HYPERVISOR_PORT),
diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
index 3aa1adaed18f..0207e8ced92c 100644
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -428,6 +428,15 @@ static bool __init vmware_legacy_x2apic_available(void)
 		(eax & BIT(VCPU_LEGACY_X2APIC));
 }
 
+#ifdef CONFIG_INTEL_TDX_GUEST
+/* __tdx_hypercall() is not exported. So, export the wrapper */
+void vmware_tdx_hypercall_args(struct tdx_module_args *args)
+{
+	__tdx_hypercall(args);
+}
+EXPORT_SYMBOL_GPL(vmware_tdx_hypercall_args);
+#endif
+
 #ifdef CONFIG_AMD_MEM_ENCRYPT
 static void vmware_sev_es_hcall_prepare(struct ghcb *ghcb,
 					struct pt_regs *regs)
-- 
2.39.0