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From:   Alexey Makhalov <alexey.makhalov@broadcom.com>
To:     linux-kernel@vger.kernel.org, virtualization@lists.linux.dev,
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Subject: [PATCH] x86/vmware: Add TDX hypercall support
Date:   Thu,  7 Dec 2023 18:32:33 -0800
Message-Id: <20231208023233.71170-1-alexey.makhalov@broadcom.com>
In-Reply-To: <64074f04-fd72-488b-831a-ad744bbcd950@broadcom.com>
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From: 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 | 83 +++++++++++++++++++++++++++++++++++
 arch/x86/kernel/cpu/vmware.c  | 22 ++++++++++
 2 files changed, 105 insertions(+)

diff --git a/arch/x86/include/asm/vmware.h b/arch/x86/include/asm/vmware.h
index 719e41260ece..04c698b905ab 100644
--- a/arch/x86/include/asm/vmware.h
+++ b/arch/x86/include/asm/vmware.h
@@ -34,12 +34,65 @@
 #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			0xf007fULL
 
 #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(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_args(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)
+{
+	unsigned long ret;
+
+	struct tdx_module_args args = {
+		.r13 = cmd,
+		.rbx = in1,
+		.rdx = in3,
+		.rsi = in4,
+		.rdi = in5,
+		.r14 = in6,
+	};
+
+	ret = vmware_tdx_hypercall(&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 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.
@@ -67,6 +120,11 @@ 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, 0,
+						 NULL, NULL, NULL,
+						 NULL, NULL, NULL);
+
 	asm_inline volatile (VMWARE_HYPERCALL
 		: "=a" (out0)
 		: [port] "i" (VMWARE_HYPERVISOR_PORT),
@@ -85,6 +143,11 @@ 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, 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 +167,11 @@ 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, 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 +191,11 @@ 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, 0,
+						 NULL, out2, NULL,
+						 NULL, NULL, NULL);
+
 	asm_inline volatile (VMWARE_HYPERCALL
 		: "=a" (out0), "=c" (*out2)
 		: [port] "i" (VMWARE_HYPERVISOR_PORT),
@@ -145,6 +218,11 @@ 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, 0,
+						 NULL, out2, out3,
+						 out4, out5, NULL);
+
 	asm_inline volatile (VMWARE_HYPERCALL
 		: "=a" (out0), "=c" (*out2), "=d" (*out3), "=S" (*out4),
 		  "=D" (*out5)
@@ -166,6 +244,11 @@ 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, 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..bcf1d0fb3e89 100644
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -428,6 +428,28 @@ static bool __init vmware_legacy_x2apic_available(void)
 		(eax & BIT(VCPU_LEGACY_X2APIC));
 }
 
+#ifdef CONFIG_INTEL_TDX_GUEST
+unsigned long vmware_tdx_hypercall(struct tdx_module_args *args)
+{
+	if (!hypervisor_is_type(X86_HYPER_VMWARE))
+		return 0;
+
+	if (args->r13 & ~VMWARE_CMD_MASK) {
+		pr_warn("Out of range command %llx\n", args->r13);
+		return 0;
+	}
+
+	args->r10 = VMWARE_TDX_VENDOR_LEAF;
+	args->r11 = VMWARE_TDX_HCALL_FUNC;
+	args->r12 = VMWARE_HYPERVISOR_MAGIC;
+
+	__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