linux-kernel - [tip: x86/merge] x86/xen/msr: Remove the error pointer argument from set

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Message-ID: <174617665930.22196.4454428302490229307.tip-bot2@tip-bot2>
Date: Fri, 02 May 2025 09:04:19 -0000
From: "tip-bot2 for Xin Li (Intel)" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: "Xin Li (Intel)" <xin@...or.com>, Ingo Molnar <mingo@...nel.org>,
 Juergen Gross <jgross@...e.com>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>,
 Andy Lutomirski <luto@...nel.org>, Brian Gerst <brgerst@...il.com>,
 David Woodhouse <dwmw2@...radead.org>, "H. Peter Anvin" <hpa@...or.com>,
 Josh Poimboeuf <jpoimboe@...hat.com>, Kees Cook <keescook@...omium.org>,
 Linus Torvalds <torvalds@...ux-foundation.org>,
 Paolo Bonzini <pbonzini@...hat.com>, Sean Christopherson <seanjc@...gle.com>,
 Stefano Stabellini <sstabellini@...nel.org>, Uros Bizjak <ubizjak@...il.com>,
 Vitaly Kuznetsov <vkuznets@...hat.com>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: x86/merge] x86/xen/msr: Remove the error pointer argument from
 set_seg()

The following commit has been merged into the x86/merge branch of tip:

Commit-ID:     2b7e25301c5418059b013c14af9022d892466398
Gitweb:        https://git.kernel.org/tip/2b7e25301c5418059b013c14af9022d892466398
Author:        Xin Li (Intel) <xin@...or.com>
AuthorDate:    Sun, 27 Apr 2025 02:20:24 -07:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Fri, 02 May 2025 10:36:36 +02:00

x86/xen/msr: Remove the error pointer argument from set_seg()

set_seg() is used to write the following MSRs on Xen:

    MSR_FS_BASE
    MSR_KERNEL_GS_BASE
    MSR_GS_BASE

But none of these MSRs are written using any MSR write safe API.
Therefore there is no need to pass an error pointer argument to
set_seg() for returning an error code to be used in MSR safe APIs.

Remove the error pointer argument.

Signed-off-by: Xin Li (Intel) <xin@...or.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Reviewed-by: Juergen Gross <jgross@...e.com>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Brian Gerst <brgerst@...il.com>
Cc: David Woodhouse <dwmw2@...radead.org>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Sean Christopherson <seanjc@...gle.com>
Cc: Stefano Stabellini <sstabellini@...nel.org>
Cc: Uros Bizjak <ubizjak@...il.com>
Cc: Vitaly Kuznetsov <vkuznets@...hat.com>
Link: https://lore.kernel.org/r/20250427092027.1598740-13-xin@zytor.com
---
 arch/x86/xen/enlighten_pv.c | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 719370d..97f7894 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -1111,17 +1111,11 @@ static u64 xen_do_read_msr(unsigned int msr, int *err)
 	return val;
 }

-static void set_seg(unsigned int which, unsigned int low, unsigned int high,
-		    int *err)
+static void set_seg(u32 which, u32 low, u32 high)
 {
 	u64 base = ((u64)high << 32) | low;

-	if (HYPERVISOR_set_segment_base(which, base) == 0)
-		return;
-
-	if (err)
-		*err = -EIO;
-	else
+	if (HYPERVISOR_set_segment_base(which, base))
 		WARN(1, "Xen set_segment_base(%u, %llx) failed\n", which, base);
 }

@@ -1137,15 +1131,15 @@ static void xen_do_write_msr(unsigned int msr, unsigned int low,

 	switch (msr) {
 	case MSR_FS_BASE:
-		set_seg(SEGBASE_FS, low, high, err);
+		set_seg(SEGBASE_FS, low, high);
 		break;

 	case MSR_KERNEL_GS_BASE:
-		set_seg(SEGBASE_GS_USER, low, high, err);
+		set_seg(SEGBASE_GS_USER, low, high);
 		break;

 	case MSR_GS_BASE:
-		set_seg(SEGBASE_GS_KERNEL, low, high, err);
+		set_seg(SEGBASE_GS_KERNEL, low, high);
 		break;

 	case MSR_STAR: