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@zytor.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Uros Bizjak <ubizjak@gmail.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20250427092027.1598740-13-xin@zytor.com

diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 719370d366226c6f6d5ce8c51f507d57cf6ca0a9..97f7894d31362cb41ae29bbbea45c4ad5ba4f42d 100644 (file)
--- 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: