x86/kvm/vmx: Get rid of segment_base() on 64-bit kernels

amluto · bonzini · commit e28baeadcf0d · 2017-02-21T11:48:46.000+01:00
It was a bit buggy (it didn't list all segment types that needed
64-bit fixups), but the bug was irrelevant because it wasn't called
in any interesting context on 64-bit kernels and was only used for
data segents on 32-bit kernels.

To avoid confusion, make it explicitly 32-bit only.

Cc: Thomas Garnier &lt;thgarnie@google.com&gt;
Cc: Jim Mattson &lt;jmattson@google.com&gt;
Cc: Radim Krčmář &lt;rkrcmar@redhat.com&gt;
Cc: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
Signed-off-by: Andy Lutomirski &lt;luto@kernel.org&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
@@ -2057,6 +2057,12 @@ static bool update_transition_efer(struct vcpu_vmx *vmx, int efer_offset)
 	}
 }
 
+#ifdef CONFIG_X86_32
+/*
+ * On 32-bit kernels, VM exits still load the FS and GS bases from the
+ * VMCS rather than the segment table.  KVM uses this helper to figure
+ * out the current bases to poke them into the VMCS before entry.
+ */
 static unsigned long segment_base(u16 selector)
 {
 	struct desc_ptr *gdt = this_cpu_ptr(&host_gdt);
@@ -2079,12 +2085,9 @@ static unsigned long segment_base(u16 selector)
 	}
 	d = (struct desc_struct *)(table_base + (selector & ~7));
 	v = get_desc_base(d);
-#ifdef CONFIG_X86_64
-       if (d->s == 0 && (d->type == 2 || d->type == 9 || d->type == 11))
-               v |= ((unsigned long)((struct ldttss_desc64 *)d)->base3) << 32;
-#endif
 	return v;
 }
+#endif
 
 static void vmx_save_host_state(struct kvm_vcpu *vcpu)
 {

Original file line number	Diff line number	Diff line change
`@@ -2057,6 +2057,12 @@ static bool update_transition_efer(struct vcpu_vmx *vmx, int efer_offset)`
`2057`	`2057`	`}`
`2058`	`2058`	`}`
`2059`	`2059`
	`2060`	`+#ifdef CONFIG_X86_32`
	`2061`	`+/*`
	`2062`	`+ * On 32-bit kernels, VM exits still load the FS and GS bases from the`
	`2063`	`+ * VMCS rather than the segment table. KVM uses this helper to figure`
	`2064`	`+ * out the current bases to poke them into the VMCS before entry.`
	`2065`	`+ */`
`2060`	`2066`	`static unsigned long segment_base(u16 selector)`
`2061`	`2067`	`{`
`2062`	`2068`	`struct desc_ptr *gdt = this_cpu_ptr(&host_gdt);`
`@@ -2079,12 +2085,9 @@ static unsigned long segment_base(u16 selector)`
`2079`	`2085`	`}`
`2080`	`2086`	`d = (struct desc_struct *)(table_base + (selector & ~7));`
`2081`	`2087`	`v = get_desc_base(d);`
`2082`		`-#ifdef CONFIG_X86_64`
`2083`		`- if (d->s == 0 && (d->type == 2 \|\| d->type == 9 \|\| d->type == 11))`
`2084`		`- v \|= ((unsigned long)((struct ldttss_desc64 *)d)->base3) << 32;`
`2085`		`-#endif`
`2086`	`2088`	`return v;`
`2087`	`2089`	`}`
	`2090`	`+#endif`
`2088`	`2091`
`2089`	`2092`	`static void vmx_save_host_state(struct kvm_vcpu *vcpu)`
`2090`	`2093`	`{`