x86/kvm/vmx: Simplify segment_base()

Use actual pointer types for pointers (instead of unsigned long) and
replace hardcoded constants with the appropriate self-documenting
macros.

The function is still a bit messy, but this seems a lot better than
before to me.

This is mostly borrowed from a patch by Thomas Garnier.

Cc: Thomas Garnier <thgarnie@google.com>
Cc: Jim Mattson <jmattson@google.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 3ddd72303fe4a37afc7f513397de129d66e7fbf3..2dd94cf597ccdbbac1df4945050b3a11ee21b62d 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2067,24 +2067,23 @@ static unsigned long segment_base(u16 selector)
 {
        struct desc_ptr *gdt = this_cpu_ptr(&host_gdt);
        struct desc_struct *d;
-       unsigned long table_base;
+       struct desc_struct *table;
        unsigned long v;
 
-       if (!(selector & ~3))
+       if (!(selector & ~SEGMENT_RPL_MASK))
                return 0;
 
-       table_base = gdt->address;
+       table = (struct desc_struct *)gdt->address;
 
-       if (selector & 4) {           /* from ldt */
+       if ((selector & SEGMENT_TI_MASK) == SEGMENT_LDT) {
                u16 ldt_selector = kvm_read_ldt();
 
-               if (!(ldt_selector & ~3))
+               if (!(ldt_selector & ~SEGMENT_RPL_MASK))
                        return 0;
 
-               table_base = segment_base(ldt_selector);
+               table = (struct desc_struct *)segment_base(ldt_selector);
        }
-       d = (struct desc_struct *)(table_base + (selector & ~7));
-       v = get_desc_base(d);
+       v = get_desc_base(&table[selector >> 3]);
        return v;
 }
 #endif