From 6d9658df07789a124e5c1f8677afcd7773439f3e Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Sun, 11 Mar 2007 13:52:33 +0100 Subject: [PATCH] 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 --- drivers/kvm/vmx.c | 37 +++++++++++++++++++++---------------- 1 file changed, 21 insertions(+), 16 deletions(-) diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c index 25b2471..fbbf9d6 100644 --- a/drivers/kvm/vmx.c +++ b/drivers/kvm/vmx.c @@ -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: */ -- 2.7.4