From e920de8507c6c8760c775cd718627e7cbf57c3b7 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Mon, 23 Jul 2018 12:32:46 -0700 Subject: [PATCH] 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 Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx.c | 18 +++++------------- 1 file changed, 5 insertions(+), 13 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index a135c91..c8a583f 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -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)) { -- 2.7.4