linux-kernel - [PATCH v3 08/13] x86/hyperv/vtl: Set real_mode_header in hv_vtl_init

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Message-Id: <20250503191515.24041-9-ricardo.neri-calderon@linux.intel.com>
Date: Sat,  3 May 2025 12:15:10 -0700
From: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
To: x86@...nel.org,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Rob Herring <robh@...nel.org>,
	"K. Y. Srinivasan" <kys@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	Wei Liu <wei.liu@...nel.org>,
	Dexuan Cui <decui@...rosoft.com>,
	Michael Kelley <mhklinux@...look.com>
Cc: devicetree@...r.kernel.org,
	Saurabh Sengar <ssengar@...ux.microsoft.com>,
	Chris Oo <cho@...rosoft.com>,
	linux-hyperv@...r.kernel.org,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	linux-acpi@...r.kernel.org ,
	linux-kernel@...r.kernel.org,
	"Ravi V. Shankar" <ravi.v.shankar@...el.com>,
	Ricardo Neri <ricardo.neri@...el.com>
Subject: [PATCH v3 08/13] x86/hyperv/vtl: Set real_mode_header in hv_vtl_init_platform()

From: Yunhong Jiang <yunhong.jiang@...ux.intel.com>

Hyper-V VTL clears x86_platform.realmode_{init(), reserve()} in
hv_vtl_platform_init() whereas it sets real_mode_header later in
hv_vtl_early_init(). There is no need to deal with the real mode memory
in two places: x86_platform.realmode_init() is invoked much later via an
early_initcall.

Set real_mode_header in hv_vtl_init_platform() to keep all code dealing
with memory for the real mode trampoline in one place. Besides making the
code more readable, it prepares it for a subsequent changeset in which the
behavior needs to change to support Hyper-V VTL guests in TDX environment.

Suggested-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Yunhong Jiang <yunhong.jiang@...ux.intel.com>
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
---
Changes since v2:
 - Edited the commit message for clarity.

Changes since v1:
 - Introduced this patch.
---
 arch/x86/hyperv/hv_vtl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/hyperv/hv_vtl.c b/arch/x86/hyperv/hv_vtl.c
index 4580936dcb03..6bd183ee484f 100644
--- a/arch/x86/hyperv/hv_vtl.c
+++ b/arch/x86/hyperv/hv_vtl.c
@@ -60,6 +60,7 @@ void __init hv_vtl_init_platform(void)
 
 	x86_platform.realmode_reserve = x86_init_noop;
 	x86_platform.realmode_init = x86_init_noop;
+	real_mode_header = &hv_vtl_real_mode_header;
 	x86_init.irqs.pre_vector_init = x86_init_noop;
 	x86_init.timers.timer_init = x86_init_noop;
 	x86_init.resources.probe_roms = x86_init_noop;
@@ -279,7 +280,6 @@ int __init hv_vtl_early_init(void)
 		panic("XSAVE has to be disabled as it is not supported by this module.\n"
 			  "Please add 'noxsave' to the kernel command line.\n");
 
-	real_mode_header = &hv_vtl_real_mode_header;
 	apic_update_callback(wakeup_secondary_cpu_64, hv_vtl_wakeup_secondary_cpu);
 
 	return 0;
-- 
2.43.0