[PATCH v7 7/7] x86/vmware: Add TDX hypercall support

From: Alexey Makhalov
Date: Thu Mar 07 2024 - 16:32:34 EST

From: Alexey Makhalov <amakhalov@xxxxxxxxxx>

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@xxxxxxxxxx>
Signed-off-by: Tim Merrifield <timothym@xxxxxxxxxx>
Signed-off-by: Alexey Makhalov <amakhalov@xxxxxxxxxx>
Reviewed-by: Nadav Amit <namit@xxxxxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
---
arch/x86/include/asm/vmware.h | 46 +++++++++++++++++++++++++++++++
arch/x86/kernel/cpu/vmware.c | 52 +++++++++++++++++++++++++++++++++++
2 files changed, 98 insertions(+)

diff --git a/arch/x86/include/asm/vmware.h b/arch/x86/include/asm/vmware.h
index 84a31f579a30..cc79c14d1ac2 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 +60,28 @@
#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,
+ 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);
+
/*
* 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 +109,10 @@ 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,
+ NULL, NULL, NULL, NULL, NULL);
+
asm_inline volatile (VMWARE_HYPERCALL
: "=a" (out0)
: [port] "i" (VMWARE_HYPERVISOR_PORT),
@@ -105,6 +131,10 @@ 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,
+ out1, out2, NULL, NULL, NULL);
+
asm_inline volatile (VMWARE_HYPERCALL
: "=a" (out0), "=b" (*out1), "=c" (*out2)
: [port] "i" (VMWARE_HYPERVISOR_PORT),
@@ -124,6 +154,10 @@ 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,
+ 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 +177,10 @@ 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,
+ NULL, out2, NULL, NULL, NULL);
+
asm_inline volatile (VMWARE_HYPERCALL
: "=a" (out0), "=c" (*out2)
: [port] "i" (VMWARE_HYPERVISOR_PORT),
@@ -165,6 +203,10 @@ 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,
+ NULL, out2, out3, out4, out5);
+
asm_inline volatile (VMWARE_HYPERCALL
: "=a" (out0), "=c" (*out2), "=d" (*out3), "=S" (*out4),
"=D" (*out5)
@@ -186,6 +228,10 @@ 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,
+ 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..41309f03cb94 100644
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -428,6 +428,58 @@ static bool __init vmware_legacy_x2apic_available(void)
(eax & BIT(VCPU_LEGACY_X2APIC));
}

+#ifdef CONFIG_INTEL_TDX_GUEST
+/*
+ * TDCALL[TDG.VP.VMCALL] uses %rax (arg0) and %rcx (arg2). Therefore,
+ * we remap those registers to %r12 and %r13, respectively.
+ */
+unsigned long vmware_tdx_hypercall(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)
+{
+ struct tdx_module_args args;
+
+ if (!hypervisor_is_type(X86_HYPER_VMWARE)) {
+ pr_warn_once("Incorrect usage\n");
+ return ULONG_MAX;
+ }
+
+ if (cmd & ~VMWARE_CMD_MASK) {
+ pr_warn_once("Out of range command %lx\n", cmd);
+ return ULONG_MAX;
+ }
+
+ args.rbx = in1;
+ args.rdx = in3;
+ args.rsi = in4;
+ args.rdi = in5;
+ 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);
+
+ 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 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