[PATCH] i386: Convert i386 PDA code to use %fs
Convert the PDA code to use %fs rather than %gs as the segment for
per-processor data. This is because some processors show a small but
measurable performance gain for reloading a NULL segment selector (as %fs
generally is in user-space) versus a non-NULL one (as %gs generally is).
On modern processors the difference is very small, perhaps undetectable.
Some old AMD "K6 3D+" processors are noticably slower when %fs is used
rather than %gs; I have no idea why this might be, but I think they're
sufficiently rare that it doesn't matter much.
This patch also fixes the math emulator, which had not been adjusted to
match the changed struct pt_regs.
[frederik.deweerdt@gmail.com: fixit with gdb]
[mingo@elte.hu: Fix KVM too]
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Ian Campbell <Ian.Campbell@XenSource.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Zachary Amsden <zach@vmware.com>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Frederik Deweerdt <frederik.deweerdt@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 1e640b8..fd4e9173 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1879,12 +1879,6 @@
asm ("mov %0, %%ds; mov %0, %%es" : : "r"(__USER_DS));
- /*
- * Profile KVM exit RIPs:
- */
- if (unlikely(prof_on == KVM_PROFILING))
- profile_hit(KVM_PROFILING, (void *)vmcs_readl(GUEST_RIP));
-
kvm_run->exit_type = 0;
if (fail) {
kvm_run->exit_type = KVM_EXIT_TYPE_FAIL_ENTRY;
@@ -1907,6 +1901,12 @@
reload_tss();
}
+ /*
+ * Profile KVM exit RIPs:
+ */
+ if (unlikely(prof_on == KVM_PROFILING))
+ profile_hit(KVM_PROFILING, (void *)vmcs_readl(GUEST_RIP));
+
vcpu->launched = 1;
kvm_run->exit_type = KVM_EXIT_TYPE_VM_EXIT;
r = kvm_handle_exit(kvm_run, vcpu);