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torvaldstorvalds
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Merge branch 'kvm-updates/2.6.36' of git://git.kernel.org/pub/scm/virt/kvm/kvm
* 'kvm-updates/2.6.36' of git://git.kernel.org/pub/scm/virt/kvm/kvm: KVM: Fix fs/gs reload oops with invalid ldt
2 parents 51ea8a8 + 9581d44 commit ef2533d

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3 files changed

+19
-44
lines changed

3 files changed

+19
-44
lines changed

‎arch/x86/include/asm/kvm_host.h

Lines changed: 0 additions & 24 deletions
Original file line numberDiff line numberDiff line change
@@ -652,37 +652,13 @@ static inline struct kvm_mmu_page *page_header(hpa_t shadow_page)
652652
return (struct kvm_mmu_page *)page_private(page);
653653
}
654654

655-
static inline u16 kvm_read_fs(void)
656-
{
657-
u16 seg;
658-
asm("mov %%fs, %0" : "=g"(seg));
659-
return seg;
660-
}
661-
662-
static inline u16 kvm_read_gs(void)
663-
{
664-
u16 seg;
665-
asm("mov %%gs, %0" : "=g"(seg));
666-
return seg;
667-
}
668-
669655
static inline u16 kvm_read_ldt(void)
670656
{
671657
u16 ldt;
672658
asm("sldt %0" : "=g"(ldt));
673659
return ldt;
674660
}
675661

676-
static inline void kvm_load_fs(u16 sel)
677-
{
678-
asm("mov %0, %%fs" : : "rm"(sel));
679-
}
680-
681-
static inline void kvm_load_gs(u16 sel)
682-
{
683-
asm("mov %0, %%gs" : : "rm"(sel));
684-
}
685-
686662
static inline void kvm_load_ldt(u16 sel)
687663
{
688664
asm("lldt %0" : : "rm"(sel));

‎arch/x86/kvm/svm.c

Lines changed: 10 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -3163,8 +3163,8 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
31633163
sync_lapic_to_cr8(vcpu);
31643164

31653165
save_host_msrs(vcpu);
3166-
fs_selector = kvm_read_fs();
3167-
gs_selector = kvm_read_gs();
3166+
savesegment(fs, fs_selector);
3167+
savesegment(gs, gs_selector);
31683168
ldt_selector = kvm_read_ldt();
31693169
svm->vmcb->save.cr2 = vcpu->arch.cr2;
31703170
/* required for live migration with NPT */
@@ -3251,10 +3251,15 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
32513251
vcpu->arch.regs[VCPU_REGS_RSP] = svm->vmcb->save.rsp;
32523252
vcpu->arch.regs[VCPU_REGS_RIP] = svm->vmcb->save.rip;
32533253

3254-
kvm_load_fs(fs_selector);
3255-
kvm_load_gs(gs_selector);
3256-
kvm_load_ldt(ldt_selector);
32573254
load_host_msrs(vcpu);
3255+
loadsegment(fs, fs_selector);
3256+
#ifdef CONFIG_X86_64
3257+
load_gs_index(gs_selector);
3258+
wrmsrl(MSR_KERNEL_GS_BASE, current->thread.gs);
3259+
#else
3260+
loadsegment(gs, gs_selector);
3261+
#endif
3262+
kvm_load_ldt(ldt_selector);
32583263

32593264
reload_tss(vcpu);
32603265

‎arch/x86/kvm/vmx.c

Lines changed: 9 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -803,15 +803,15 @@ static void vmx_save_host_state(struct kvm_vcpu *vcpu)
803803
*/
804804
vmx->host_state.ldt_sel = kvm_read_ldt();
805805
vmx->host_state.gs_ldt_reload_needed = vmx->host_state.ldt_sel;
806-
vmx->host_state.fs_sel = kvm_read_fs();
806+
savesegment(fs, vmx->host_state.fs_sel);
807807
if (!(vmx->host_state.fs_sel & 7)) {
808808
vmcs_write16(HOST_FS_SELECTOR, vmx->host_state.fs_sel);
809809
vmx->host_state.fs_reload_needed = 0;
810810
} else {
811811
vmcs_write16(HOST_FS_SELECTOR, 0);
812812
vmx->host_state.fs_reload_needed = 1;
813813
}
814-
vmx->host_state.gs_sel = kvm_read_gs();
814+
savesegment(gs, vmx->host_state.gs_sel);
815815
if (!(vmx->host_state.gs_sel & 7))
816816
vmcs_write16(HOST_GS_SELECTOR, vmx->host_state.gs_sel);
817817
else {
@@ -841,27 +841,21 @@ static void vmx_save_host_state(struct kvm_vcpu *vcpu)
841841

842842
static void __vmx_load_host_state(struct vcpu_vmx *vmx)
843843
{
844-
unsigned long flags;
845-
846844
if (!vmx->host_state.loaded)
847845
return;
848846

849847
++vmx->vcpu.stat.host_state_reload;
850848
vmx->host_state.loaded = 0;
851849
if (vmx->host_state.fs_reload_needed)
852-
kvm_load_fs(vmx->host_state.fs_sel);
850+
loadsegment(fs, vmx->host_state.fs_sel);
853851
if (vmx->host_state.gs_ldt_reload_needed) {
854852
kvm_load_ldt(vmx->host_state.ldt_sel);
855-
/*
856-
* If we have to reload gs, we must take care to
857-
* preserve our gs base.
858-
*/
859-
local_irq_save(flags);
860-
kvm_load_gs(vmx->host_state.gs_sel);
861853
#ifdef CONFIG_X86_64
862-
wrmsrl(MSR_GS_BASE, vmcs_readl(HOST_GS_BASE));
854+
load_gs_index(vmx->host_state.gs_sel);
855+
wrmsrl(MSR_KERNEL_GS_BASE, current->thread.gs);
856+
#else
857+
loadsegment(gs, vmx->host_state.gs_sel);
863858
#endif
864-
local_irq_restore(flags);
865859
}
866860
reload_tss();
867861
#ifdef CONFIG_X86_64
@@ -2589,8 +2583,8 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
25892583
vmcs_write16(HOST_CS_SELECTOR, __KERNEL_CS); /* 22.2.4 */
25902584
vmcs_write16(HOST_DS_SELECTOR, __KERNEL_DS); /* 22.2.4 */
25912585
vmcs_write16(HOST_ES_SELECTOR, __KERNEL_DS); /* 22.2.4 */
2592-
vmcs_write16(HOST_FS_SELECTOR, kvm_read_fs()); /* 22.2.4 */
2593-
vmcs_write16(HOST_GS_SELECTOR, kvm_read_gs()); /* 22.2.4 */
2586+
vmcs_write16(HOST_FS_SELECTOR, 0); /* 22.2.4 */
2587+
vmcs_write16(HOST_GS_SELECTOR, 0); /* 22.2.4 */
25942588
vmcs_write16(HOST_SS_SELECTOR, __KERNEL_DS); /* 22.2.4 */
25952589
#ifdef CONFIG_X86_64
25962590
rdmsrl(MSR_FS_BASE, a);

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