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KVM: vmx: compute need to reload FS/GS/LDT on demand 

Remove fs_reload_needed and gs_ldt_reload_needed from host_state
and instead compute whether we need to reload various state at
the time we actually do the reload.  The state that is tracked
by the *_reload_needed variables is not any more volatile than
the trackers themselves.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2018-07-23 12:32:46 -07:00 committed by Paolo Bonzini
parent fd1ec7723f
commit e920de8507
1 changed files with 5 additions and 13 deletions
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18
arch/x86/kvm/vmx.c
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@ -824,8 +824,6 @@ struct vcpu_vmx {
#ifdef CONFIG_X86_64
u16 ds_sel, es_sel;
#endif
int gs_ldt_reload_needed;
int fs_reload_needed;
} host_state;
struct {
int vm86_active;
@ -2681,7 +2679,6 @@ static void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
* allow segment selectors with cpl > 0 or ti == 1.
*/
vmx->host_state.ldt_sel = kvm_read_ldt();
vmx->host_state.gs_ldt_reload_needed = vmx->host_state.ldt_sel;
#ifdef CONFIG_X86_64
savesegment(ds, vmx->host_state.ds_sel);
@ -2711,20 +2708,15 @@ static void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
#endif
vmx->host_state.fs_sel = fs_sel;
if (!(fs_sel & 7)) {
if (!(fs_sel & 7))
vmcs_write16(HOST_FS_SELECTOR, fs_sel);
vmx->host_state.fs_reload_needed = 0;
} else {
else
vmcs_write16(HOST_FS_SELECTOR, 0);
vmx->host_state.fs_reload_needed = 1;
}
vmx->host_state.gs_sel = gs_sel;
if (!(gs_sel & 7))
vmcs_write16(HOST_GS_SELECTOR, gs_sel);
else {
else
vmcs_write16(HOST_GS_SELECTOR, 0);
vmx->host_state.gs_ldt_reload_needed = 1;
}
vmcs_writel(HOST_FS_BASE, fs_base);
vmcs_writel(HOST_GS_BASE, gs_base);
@ -2749,7 +2741,7 @@ static void vmx_prepare_switch_to_host(struct vcpu_vmx *vmx)
if (is_long_mode(&vmx->vcpu))
rdmsrl(MSR_KERNEL_GS_BASE, vmx->msr_guest_kernel_gs_base);
#endif
if (vmx->host_state.gs_ldt_reload_needed) {
if (vmx->host_state.ldt_sel || (vmx->host_state.gs_sel & 7)) {
kvm_load_ldt(vmx->host_state.ldt_sel);
#ifdef CONFIG_X86_64
load_gs_index(vmx->host_state.gs_sel);
@ -2757,7 +2749,7 @@ static void vmx_prepare_switch_to_host(struct vcpu_vmx *vmx)
loadsegment(gs, vmx->host_state.gs_sel);
#endif
}
if (vmx->host_state.fs_reload_needed)
if (vmx->host_state.fs_sel & 7)
loadsegment(fs, vmx->host_state.fs_sel);
#ifdef CONFIG_X86_64
if (unlikely(vmx->host_state.ds_sel | vmx->host_state.es_sel)) {