linux-kernel - [PATCH 07/20] x86/tdx: Convert CPUID handling to use new TDVMCALL

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Date: Fri, 17 May 2024 17:19:25 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Sean Christopherson <seanjc@...gle.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	"K. Y. Srinivasan" <kys@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	Wei Liu <wei.liu@...nel.org>,
	Dexuan Cui <decui@...rosoft.com>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>
Cc: linux-coco@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	linux-hyperv@...r.kernel.org,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCH 07/20] x86/tdx: Convert CPUID handling to use new TDVMCALL_4()

Use newly introduced TDVMCALL_4() instead of __tdx_hypercall() to handle
CPUID instruction emulation.

It cuts code bloat substantially:

Function                                     old     new   delta
tdx_handle_virt_exception                   1819    1747     -72

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
 arch/x86/coco/tdx/tdx.c | 20 ++------------------
 1 file changed, 2 insertions(+), 18 deletions(-)

diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
index f59a2b3500db..c436cab355e0 100644
--- a/arch/x86/coco/tdx/tdx.c
+++ b/arch/x86/coco/tdx/tdx.c
@@ -414,13 +414,6 @@ static int write_msr(struct pt_regs *regs, struct ve_info *ve)
 
 static int handle_cpuid(struct pt_regs *regs, struct ve_info *ve)
 {
-	struct tdx_module_args args = {
-		.r10 = TDX_HYPERCALL_STANDARD,
-		.r11 = hcall_func(EXIT_REASON_CPUID),
-		.r12 = regs->ax,
-		.r13 = regs->cx,
-	};
-
 	/*
 	 * Only allow VMM to control range reserved for hypervisor
 	 * communication.
@@ -438,19 +431,10 @@ static int handle_cpuid(struct pt_regs *regs, struct ve_info *ve)
 	 * ABI can be found in TDX Guest-Host-Communication Interface
 	 * (GHCI), section titled "VP.VMCALL<Instruction.CPUID>".
 	 */
-	if (__tdx_hypercall(&args))
+	if (TDVMCALL_4(EXIT_REASON_CPUID, regs->ax, regs->cx, 0, 0,
+		       regs->ax, regs->bx, regs->cx, regs->dx))
 		return -EIO;
 
-	/*
-	 * As per TDX GHCI CPUID ABI, r12-r15 registers contain contents of
-	 * EAX, EBX, ECX, EDX registers after the CPUID instruction execution.
-	 * So copy the register contents back to pt_regs.
-	 */
-	regs->ax = args.r12;
-	regs->bx = args.r13;
-	regs->cx = args.r14;
-	regs->dx = args.r15;
-
 	return ve_instr_len(ve);
 }
 
-- 
2.43.0