x86/tdx: Remove 'struct tdx_hypercall_args'

Now 'struct tdx_hypercall_args' is basically 'struct tdx_module_args'
minus RCX.  Although from __tdx_hypercall()'s perspective RCX isn't
used as shared register thus not part of input/output registers, it's
not worth to have a separate structure just due to one register.

Remove the 'struct tdx_hypercall_args' and use 'struct tdx_module_args'
instead in __tdx_hypercall() related code.  This also saves the memory
copy between the two structures within __tdx_hypercall().

Suggested-by: Peter Zijlstra <[email protected]>
Signed-off-by: Kai Huang <[email protected]>
Signed-off-by: Dave Hansen <[email protected]>
Reviewed-by: Kirill A. Shutemov <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/all/798dad5ce24e9d745cf0e16825b75ccc433ad065.1692096753.git.kai.huang%40intel.com

1 files changed, 7 insertions, 30 deletions

diff --git a/arch/x86/coco/tdx/tdx-shared.c b/arch/x86/coco/tdx/tdx-shared.c
index 344b3818f4c3..78e413269791 100644
--- a/arch/x86/coco/tdx/tdx-shared.c
+++ b/arch/x86/coco/tdx/tdx-shared.c
@@ -70,45 +70,22 @@ bool tdx_accept_memory(phys_addr_t start, phys_addr_t end)
 	return true;
 }
 
-noinstr u64 __tdx_hypercall(struct tdx_hypercall_args *args)
+noinstr u64 __tdx_hypercall(struct tdx_module_args *args)
 {
-	struct tdx_module_args margs = {
-		.rcx = TDVMCALL_EXPOSE_REGS_MASK,
-		.rdx = args->rdx,
-		.r8  = args->r8,
-		.r9  = args->r9,
-		.r10 = args->r10,
-		.r11 = args->r11,
-		.r12 = args->r12,
-		.r13 = args->r13,
-		.r14 = args->r14,
-		.r15 = args->r15,
-		.rbx = args->rbx,
-		.rdi = args->rdi,
-		.rsi = args->rsi,
-	};
+	/*
+	 * For TDVMCALL explicitly set RCX to the bitmap of shared registers.
+	 * The caller isn't expected to set @args->rcx anyway.
+	 */
+	args->rcx = TDVMCALL_EXPOSE_REGS_MASK;
 
 	/*
 	 * Failure of __tdcall_saved_ret() indicates a failure of the TDVMCALL
 	 * mechanism itself and that something has gone horribly wrong with
 	 * the TDX module.  __tdx_hypercall_failed() never returns.
 	 */
-	if (__tdcall_saved_ret(TDG_VP_VMCALL, &margs))
+	if (__tdcall_saved_ret(TDG_VP_VMCALL, args))
 		__tdx_hypercall_failed();
 
-	args->r8  = margs.r8;
-	args->r9  = margs.r9;
-	args->r10 = margs.r10;
-	args->r11 = margs.r11;
-	args->r12 = margs.r12;
-	args->r13 = margs.r13;
-	args->r14 = margs.r14;
-	args->r15 = margs.r15;
-	args->rdi = margs.rdi;
-	args->rsi = margs.rsi;
-	args->rbx = margs.rbx;
-	args->rdx = margs.rdx;
-
 	/* TDVMCALL leaf return code is in R10 */
 	return args->r10;
 }