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KVM: always reload segment selectors 

failed VM entry on VMX might still change %fs or %gs, thus make sure
that KVM always reloads the segment selectors. This is crutial on both
x86 and x86_64: x86 has __KERNEL_PDA in %fs on which things like
'current' depends and x86_64 has 0 there and needs MSR_GS_BASE to work.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar 2007-03-11 13:52:33 +01:00 committed by Avi Kivity
parent 6af11b9e82
commit 6d9658df07
1 changed files with 21 additions and 16 deletions
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37
drivers/kvm/vmx.c
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@ -1888,6 +1888,27 @@ again:
[cr2]"i"(offsetof(struct kvm_vcpu, cr2))
: "cc", "memory" );
/*
* Reload segment selectors ASAP. (it's needed for a functional
* kernel: x86 relies on having __KERNEL_PDA in %fs and x86_64
* relies on having 0 in %gs for the CPU PDA to work.)
*/
if (fs_gs_ldt_reload_needed) {
load_ldt(ldt_sel);
load_fs(fs_sel);
/*
* If we have to reload gs, we must take care to
* preserve our gs base.
*/
local_irq_disable();
load_gs(gs_sel);
#ifdef CONFIG_X86_64
wrmsrl(MSR_GS_BASE, vmcs_readl(HOST_GS_BASE));
#endif
local_irq_enable();
reload_tss();
}
++kvm_stat.exits;
save_msrs(vcpu->guest_msrs, NR_BAD_MSRS);
@ -1905,22 +1926,6 @@ again:
kvm_run->exit_reason = vmcs_read32(VM_INSTRUCTION_ERROR);
r = 0;
} else {
if (fs_gs_ldt_reload_needed) {
load_ldt(ldt_sel);
load_fs(fs_sel);
/*
* If we have to reload gs, we must take care to
* preserve our gs base.
*/
local_irq_disable();
load_gs(gs_sel);
#ifdef CONFIG_X86_64
wrmsrl(MSR_GS_BASE, vmcs_readl(HOST_GS_BASE));
#endif
local_irq_enable();
reload_tss();
}
/*
* Profile KVM exit RIPs:
*/