[PATCH][RESEND] Split segments reload in vmx_load_host_state()

Laurent Vivier
2007-08-23T14:33:11Z

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From KVM/TODO:
vmx_load_host_state() bundles fs, gs, ldt, and tss reloading into
one in the hope that it is infrequent. With smp guests, fs reloading is
frequent and the separate reloads should be unbundled.

Signed-off-by: Laurent Vivier <Laurent.Vivier-6ktuUTfB/bM@public.gmane.org>

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Index: kvm/drivers/kvm/vmx.c
===================================================================
--- kvm.orig/drivers/kvm/vmx.c 2007-08-23 14:41:48.000000000 +0200
+++ kvm/drivers/kvm/vmx.c 2007-08-23 16:20:23.000000000 +0200
@@ -54,7 +54,8 @@ struct vcpu_vmx {
struct {
int loaded;
u16 fs_sel, gs_sel, ldt_sel;
- int fs_gs_ldt_reload_needed;
+ int gs_ldt_reload_needed;
+ int fs_reload_needed;
}host_state;

};
@@ -353,20 +354,21 @@ static void vmx_save_host_state(struct v
* allow segment selectors with cpl > 0 or ti == 1.
*/
vmx->host_state.ldt_sel = read_ldt();
- vmx->host_state.fs_gs_ldt_reload_needed = vmx->host_state.ldt_sel;
+ vmx->host_state.gs_ldt_reload_needed = vmx->host_state.ldt_sel;
vmx->host_state.fs_sel = read_fs();
- if (!(vmx->host_state.fs_sel & 7))
+ if (!(vmx->host_state.fs_sel & 7)) {
vmcs_write16(HOST_FS_SELECTOR, vmx->host_state.fs_sel);
- else {
+ vmx->host_state.fs_reload_needed = 0;
+ } else {
vmcs_write16(HOST_FS_SELECTOR, 0);
- vmx->host_state.fs_gs_ldt_reload_needed = 1;
+ vmx->host_state.fs_reload_needed = 1;
}
vmx->host_state.gs_sel = read_gs();
if (!(vmx->host_state.gs_sel & 7))
vmcs_write16(HOST_GS_SELECTOR, vmx->host_state.gs_sel);
else {
vmcs_write16(HOST_GS_SELECTOR, 0);
- vmx->host_state.fs_gs_ldt_reload_needed = 1;
+ vmx->host_state.gs_ldt_reload_needed = 1;
}

#ifdef CONFIG_X86_64
@@ -396,9 +398,10 @@ static void vmx_load_host_state(struct v
return;

vmx->host_state.loaded = 0;
- if (vmx->host_state.fs_gs_ldt_reload_needed) {
- load_ldt(vmx->host_state.ldt_sel);
+ if (vmx->host_state.fs_reload_needed)
load_fs(vmx->host_state.fs_sel);
+ if (vmx->host_state.gs_ldt_reload_needed) {
+ load_ldt(vmx->host_state.ldt_sel);
/*
* If we have to reload gs, we must take care to
* preserve our gs base.
@@ -409,9 +412,8 @@ static void vmx_load_host_state(struct v
wrmsrl(MSR_GS_BASE, vmcs_readl(HOST_GS_BASE));
#endif
local_irq_restore(flags);
-
- reload_tss();
}
+ reload_tss();
save_msrs(vmx->guest_msrs, vmx->save_nmsrs);
load_msrs(vmx->host_msrs, vmx->save_nmsrs);
if (msr_efer_need_save_restore(vmx))

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