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From: Alexey Makhalov <alexey.makhalov@broadcom.com>
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Subject: [PATCH v6 7/7] x86/vmware: Add TDX hypercall support
Date: Tue,  9 Jan 2024 00:40:52 -0800
Message-Id: <20240109084052.58661-8-amakhalov@vmware.com>
In-Reply-To: <20240109084052.58661-1-amakhalov@vmware.com>
References: <20240109084052.58661-1-amakhalov@vmware.com>
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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>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 arch/x86/include/asm/vmware.h | 79 +++++++++++++++++++++++++++++++++++
 arch/x86/kernel/cpu/vmware.c  | 25 +++++++++++
 2 files changed, 104 insertions(+)

diff --git a/arch/x86/include/asm/vmware.h b/arch/x86/include/asm/vmware.h
index 84a31f579a30..3bd593c6591d 100644
--- a/arch/x86/include/asm/vmware.h
+++ b/arch/x86/include/asm/vmware.h
@@ -18,6 +18,12 @@
  * arg2 - Hypercall command
  * arg3 bits [15:0] - Port number, LB and direction flags
  *
+ * - Low bandwidth TDX hypercalls (x86_64 only) are similar to LB
+ * hypercalls. They also have up to 6 input and 6 output on registers
+ * arguments, with different argument to register mapping:
+ * %r12 (arg0), %rbx (arg1), %r13 (arg2), %rdx (arg3),
+ * %rsi (arg4), %rdi (arg5).
+ *
  * - High bandwidth (HB) hypercalls are I/O port based only. They have
  * up to 7 input and 7 output arguments passed and returned using
  * registers: %eax (arg0), %ebx (arg1), %ecx (arg2), %edx (arg3),
@@ -54,12 +60,61 @@
 #define VMWARE_CMD_GETHZ		45
 #define VMWARE_CMD_GETVCPU_INFO		68
 #define VMWARE_CMD_STEALCLOCK		91
+/*
+ * Hypercall command mask:
+ *   bits [6:0] command, range [0, 127]
+ *   bits [19:16] sub-command, range [0, 15]
+ */
+#define VMWARE_CMD_MASK			0xf007fU
 
 #define CPUID_VMWARE_FEATURES_ECX_VMMCALL	BIT(0)
 #define CPUID_VMWARE_FEATURES_ECX_VMCALL	BIT(1)
 
 extern u8 vmware_hypercall_mode;
 
+#define VMWARE_TDX_VENDOR_LEAF 0x1af7e4909ULL
+#define VMWARE_TDX_HCALL_FUNC  1
+
+extern unsigned long vmware_tdx_hypercall(unsigned long cmd,
+					  struct tdx_module_args *args);
+
+/*
+ * TDCALL[TDG.VP.VMCALL] uses %rax (arg0) and %rcx (arg2). Therefore,
+ * we remap those registers to %r12 and %r13, respectively.
+ */
+static inline
+unsigned long vmware_tdx_hypercall_args(unsigned long cmd, unsigned long in1,
+					unsigned long in3, unsigned long in4,
+					unsigned long in5,
+					uint32_t *out1, uint32_t *out2,
+					uint32_t *out3, uint32_t *out4,
+					uint32_t *out5)
+{
+	unsigned long ret;
+
+	struct tdx_module_args args = {
+		.rbx = in1,
+		.rdx = in3,
+		.rsi = in4,
+		.rdi = in5,
+	};
+
+	ret = vmware_tdx_hypercall(cmd, &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;
+
+	return ret;
+}
+
 /*
  * 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.
@@ -87,6 +142,10 @@ 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_args(cmd, in1, 0, 0, 0,
+						 NULL, NULL, NULL, NULL, NULL);
+
 	asm_inline volatile (VMWARE_HYPERCALL
 		: "=a" (out0)
 		: [port] "i" (VMWARE_HYPERVISOR_PORT),
@@ -105,6 +164,10 @@ 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_args(cmd, in1, 0, 0, 0,
+						 out1, out2, NULL, NULL, NULL);
+
 	asm_inline volatile (VMWARE_HYPERCALL
 		: "=a" (out0), "=b" (*out1), "=c" (*out2)
 		: [port] "i" (VMWARE_HYPERVISOR_PORT),
@@ -124,6 +187,10 @@ 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_args(cmd, in1, 0, 0, 0,
+						 out1, out2, out3, NULL, NULL);
+
 	asm_inline volatile (VMWARE_HYPERCALL
 		: "=a" (out0), "=b" (*out1), "=c" (*out2), "=d" (*out3)
 		: [port] "i" (VMWARE_HYPERVISOR_PORT),
@@ -143,6 +210,10 @@ 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_args(cmd, in1, in3, in4, in5,
+						 NULL, out2, NULL, NULL, NULL);
+
 	asm_inline volatile (VMWARE_HYPERCALL
 		: "=a" (out0), "=c" (*out2)
 		: [port] "i" (VMWARE_HYPERVISOR_PORT),
@@ -165,6 +236,10 @@ 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_args(cmd, in1, in3, 0, 0,
+						 NULL, out2, out3, out4, out5);
+
 	asm_inline volatile (VMWARE_HYPERCALL
 		: "=a" (out0), "=c" (*out2), "=d" (*out3), "=S" (*out4),
 		  "=D" (*out5)
@@ -186,6 +261,10 @@ 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_args(cmd, in1, in3, in4, in5,
+						 out1, out2, out3, 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..84caa67d4820 100644
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -428,6 +428,31 @@ static bool __init vmware_legacy_x2apic_available(void)
 		(eax & BIT(VCPU_LEGACY_X2APIC));
 }
 
+#ifdef CONFIG_INTEL_TDX_GUEST
+unsigned long vmware_tdx_hypercall(unsigned long cmd,
+				   struct tdx_module_args *args)
+{
+	if (!hypervisor_is_type(X86_HYPER_VMWARE))
+		return ULONG_MAX;
+
+	if (cmd & ~VMWARE_CMD_MASK) {
+		pr_warn_once("Out of range command %lx\n", cmd);
+		return ULONG_MAX;
+	}
+
+	args->r10 = VMWARE_TDX_VENDOR_LEAF;
+	args->r11 = VMWARE_TDX_HCALL_FUNC;
+	args->r12 = VMWARE_HYPERVISOR_MAGIC;
+	args->r13 = cmd;
+	args->r15 = 0; /* CPL */
+
+	__tdx_hypercall(args);
+
+	return args->r12;
+}
+EXPORT_SYMBOL_GPL(vmware_tdx_hypercall);
+#endif
+
 #ifdef CONFIG_AMD_MEM_ENCRYPT
 static void vmware_sev_es_hcall_prepare(struct ghcb *ghcb,
 					struct pt_regs *regs)
-- 
2.39.0