x86/hyperv: Support hypercalls for fully enlightened TDX guests

A fully enlightened TDX guest on Hyper-V (i.e. without the paravisor) only
uses the GHCI call rather than hv_hypercall_pg. Do not initialize
hypercall_pg for such a guest.

In hv_common_cpu_init(), the hyperv_pcpu_input_arg page needs to be
decrypted in such a guest.

Reviewed-by: Kuppuswamy Sathyanarayanan <[email protected]>
Reviewed-by: Michael Kelley <[email protected]>
Reviewed-by: Tianyu Lan <[email protected]>
Signed-off-by: Dexuan Cui <[email protected]>
Signed-off-by: Wei Liu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

1 files changed, 17 insertions, 0 deletions

diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index afdae1a8a117..6c7598d9e68a 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -571,3 +571,20 @@ bool hv_isolation_type_tdx(void)
 {
 	return static_branch_unlikely(&isolation_type_tdx);
 }
+
+#ifdef CONFIG_INTEL_TDX_GUEST
+
+u64 hv_tdx_hypercall(u64 control, u64 param1, u64 param2)
+{
+	struct tdx_hypercall_args args = { };
+
+	args.r10 = control;
+	args.rdx = param1;
+	args.r8  = param2;
+
+	(void)__tdx_hypercall_ret(&args);
+
+	return args.r11;
+}
+
+#endif