From c8770e7ba63bb5dd8fe5f9d251275a8fa717fb78 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Thu, 11 Nov 2010 12:37:26 +0200 Subject: KVM: VMX: Fix host userspace gsbase corruption We now use load_gs_index() to load gs safely; unfortunately this also changes MSR_KERNEL_GS_BASE, which we managed separately. This resulted in confusion and breakage running 32-bit host userspace on a 64-bit kernel. Fix by - saving guest MSR_KERNEL_GS_BASE before we we reload the host's gs - doing the host save/load unconditionally, instead of only when in guest long mode Things can be cleaned up further, but this is the minmal fix for now. Signed-off-by: Avi Kivity Signed-off-by: Marcelo Tosatti --- arch/x86/kvm/vmx.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 6fe7df75bfd4..ff21fdda0c53 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -821,10 +821,9 @@ static void vmx_save_host_state(struct kvm_vcpu *vcpu) #endif #ifdef CONFIG_X86_64 - if (is_long_mode(&vmx->vcpu)) { - rdmsrl(MSR_KERNEL_GS_BASE, vmx->msr_host_kernel_gs_base); + rdmsrl(MSR_KERNEL_GS_BASE, vmx->msr_host_kernel_gs_base); + if (is_long_mode(&vmx->vcpu)) wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_guest_kernel_gs_base); - } #endif for (i = 0; i < vmx->save_nmsrs; ++i) kvm_set_shared_msr(vmx->guest_msrs[i].index, @@ -839,11 +838,14 @@ static void __vmx_load_host_state(struct vcpu_vmx *vmx) ++vmx->vcpu.stat.host_state_reload; vmx->host_state.loaded = 0; +#ifdef CONFIG_X86_64 + 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) { kvm_load_ldt(vmx->host_state.ldt_sel); #ifdef CONFIG_X86_64 load_gs_index(vmx->host_state.gs_sel); - wrmsrl(MSR_KERNEL_GS_BASE, current->thread.gs); #else loadsegment(gs, vmx->host_state.gs_sel); #endif @@ -852,10 +854,7 @@ static void __vmx_load_host_state(struct vcpu_vmx *vmx) loadsegment(fs, vmx->host_state.fs_sel); reload_tss(); #ifdef CONFIG_X86_64 - if (is_long_mode(&vmx->vcpu)) { - rdmsrl(MSR_KERNEL_GS_BASE, vmx->msr_guest_kernel_gs_base); - wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_host_kernel_gs_base); - } + wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_host_kernel_gs_base); #endif if (current_thread_info()->status & TS_USEDFPU) clts(); -- cgit v1.2.3