linux-kernel - [PATCH 2/3] x86/hyperv: Use savesegment() instead of inline asm() to save segment registers

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Message-ID: <20251120134105.189753-2-ubizjak@gmail.com>
Date: Thu, 20 Nov 2025 14:40:23 +0100
From: Uros Bizjak <ubizjak@...il.com>
To: linux-hyperv@...r.kernel.org,
	x86@...nel.org,
	linux-kernel@...r.kernel.org
Cc: Uros Bizjak <ubizjak@...il.com>,
	"K. Y. Srinivasan" <kys@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	Wei Liu <wei.liu@...nel.org>,
	Dexuan Cui <decui@...rosoft.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH 2/3] x86/hyperv: Use savesegment() instead of inline asm() to save segment registers

Use standard savesegment() utility macro to save segment registers.

Signed-off-by: Uros Bizjak <ubizjak@...il.com>
Cc: "K. Y. Srinivasan" <kys@...rosoft.com>
Cc: Haiyang Zhang <haiyangz@...rosoft.com>
Cc: Wei Liu <wei.liu@...nel.org>
Cc: Dexuan Cui <decui@...rosoft.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
---
 arch/x86/hyperv/ivm.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index 651771534cae..7365d8f43181 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -25,6 +25,7 @@
 #include <asm/e820/api.h>
 #include <asm/desc.h>
 #include <asm/msr.h>
+#include <asm/segment.h>
 #include <uapi/asm/vmx.h>
 
 #ifdef CONFIG_AMD_MEM_ENCRYPT
@@ -315,16 +316,16 @@ int hv_snp_boot_ap(u32 apic_id, unsigned long start_ip, unsigned int cpu)
 	vmsa->gdtr.base = gdtr.address;
 	vmsa->gdtr.limit = gdtr.size;
 
-	asm volatile("movl %%es, %%eax;" : "=a" (vmsa->es.selector));
+	savesegment(es, vmsa->es.selector);
 	hv_populate_vmcb_seg(vmsa->es, vmsa->gdtr.base);
 
-	asm volatile("movl %%cs, %%eax;" : "=a" (vmsa->cs.selector));
+	savesegment(cs, vmsa->cs.selector);
 	hv_populate_vmcb_seg(vmsa->cs, vmsa->gdtr.base);
 
-	asm volatile("movl %%ss, %%eax;" : "=a" (vmsa->ss.selector));
+	savesegment(ss, vmsa->ss.selector);
 	hv_populate_vmcb_seg(vmsa->ss, vmsa->gdtr.base);
 
-	asm volatile("movl %%ds, %%eax;" : "=a" (vmsa->ds.selector));
+	savesegment(ds, vmsa->ds.selector);
 	hv_populate_vmcb_seg(vmsa->ds, vmsa->gdtr.base);
 
 	vmsa->efer = native_read_msr(MSR_EFER);
-- 
2.51.1