[PATCH v11 8/8] x86/vmware: Add TDX hypercall support

Alexey Makhalov
2024-06-13T19:17:53Z

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 <tim.merrifield@broadcom.com>
Signed-off-by: Tim Merrifield <tim.merrifield@broadcom.com>
Signed-off-by: Alexey Makhalov <alexey.makhalov@broadcom.com>
---
arch/x86/include/asm/vmware.h | 45 +++++++++++++++++++++++++++++++
arch/x86/kernel/cpu/vmware.c | 51 +++++++++++++++++++++++++++++++++++
2 files changed, 96 insertions(+)

diff --git a/arch/x86/include/asm/vmware.h b/arch/x86/include/asm/vmware.h
index d83444f03969..c9cf43d5ef23 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),
@@ -54,6 +60,12 @@
#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)
@@ -64,6 +76,15 @@ extern unsigned long vmware_hypercall_slow(unsigned long cmd,
u32 *out1, u32 *out2, u32 *out3,
u32 *out4, u32 *out5);

+#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,
+ u32 *out1, u32 *out2, u32 *out3,
+ u32 *out4, u32 *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.
@@ -79,6 +100,10 @@ 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);
+
if (unlikely(!alternatives_patched) && !__is_defined(MODULE))
return vmware_hypercall_slow(cmd, in1, 0, 0, 0,
NULL, NULL, NULL, NULL, NULL);
@@ -100,6 +125,10 @@ 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);
+
if (unlikely(!alternatives_patched) && !__is_defined(MODULE))
return vmware_hypercall_slow(cmd, in1, 0, 0, 0,
out1, out2, NULL, NULL, NULL);
@@ -121,6 +150,10 @@ 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);
+
if (unlikely(!alternatives_patched) && !__is_defined(MODULE))
return vmware_hypercall_slow(cmd, in1, 0, 0, 0,
out1, out2, out3, NULL, NULL);
@@ -143,6 +176,10 @@ 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);
+
if (unlikely(!alternatives_patched) && !__is_defined(MODULE))
return vmware_hypercall_slow(cmd, in1, in3, in4, in5,
NULL, out2, NULL, NULL, NULL);
@@ -167,6 +204,10 @@ 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);
+
if (unlikely(!alternatives_patched) && !__is_defined(MODULE))
return vmware_hypercall_slow(cmd, in1, in3, 0, 0,
NULL, out2, out3, out4, out5);
@@ -191,6 +232,10 @@ 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);
+
if (unlikely(!alternatives_patched) && !__is_defined(MODULE))
return vmware_hypercall_slow(cmd, in1, in3, in4, in5,
out1, out2, out3, NULL, NULL);
diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
index d24ba03b30b8..708048b8a095 100644
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -477,6 +477,57 @@ static bool __init vmware_legacy_x2apic_available(void)
(eax & GETVCPU_INFO_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,
+ u32 *out1, u32 *out2, u32 *out3,
+ u32 *out4, u32 *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)
--
2.39.4