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KVM: VMX: Split segments reload in vmx_load_host_state() 

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 due to fs being used by threads.

Unbundle the reloads so reduce expensive gs reloads.

Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Laurent Vivier 2007-08-23 16:33:11 +02:00 committed by Avi Kivity
parent d39dba54ce
commit 152d3f2f24
1 changed files with 12 additions and 10 deletions
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22
drivers/kvm/vmx.c
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@ -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 vcpu_vmx *vmx)
* 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 vcpu_vmx *vmx)
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 vcpu_vmx *vmx)
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))