linux-kernel - [RFC PATCH v2 13/34] x86/xen/msr: Remove the error pointer argument from set

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Message-ID: <20250422082216.1954310-14-xin@zytor.com>
Date: Tue, 22 Apr 2025 01:21:54 -0700
From: "Xin Li (Intel)" <xin@...or.com>
To: linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-perf-users@...r.kernel.org, linux-hyperv@...r.kernel.org,
        virtualization@...ts.linux.dev, linux-pm@...r.kernel.org,
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Subject: [RFC PATCH v2 13/34] x86/xen/msr: Remove the error pointer argument from set_reg()

set_reg() 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_reg() 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>
---
 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 b5a8bceb5f56..9a89cb29fa35 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);
 }
 
@@ -1138,15 +1132,15 @@ 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:
-- 
2.49.0