2.6.32-stable review patch. If anyone has any objections, please let us know.
------------------ From: Ben Hutchings <[email protected]> commit c8770e7ba63bb5dd8fe5f9d251275a8fa717fb78 upstream. 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 <[email protected]> Signed-off-by: Marcelo Tosatti <[email protected]> [bwh: Backport to 2.6.32] Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/x86/kvm/vmx.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -654,10 +654,7 @@ static void vmx_save_host_state(struct k #endif #ifdef CONFIG_X86_64 - if (is_long_mode(&vmx->vcpu)) - save_msrs(vmx->host_msrs + - vmx->msr_offset_kernel_gs_base, 1); - + save_msrs(vmx->host_msrs + vmx->msr_offset_kernel_gs_base, 1); #endif load_msrs(vmx->guest_msrs, vmx->save_nmsrs); load_transition_efer(vmx); @@ -672,17 +669,26 @@ static void __vmx_load_host_state(struct vmx->host_state.loaded = 0; if (vmx->host_state.fs_reload_needed) loadsegment(fs, vmx->host_state.fs_sel); +#ifdef CONFIG_X86_64 + if (is_long_mode(&vmx->vcpu)) + save_msrs(vmx->guest_msrs + vmx->msr_offset_kernel_gs_base, 1); +#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 } reload_tss(); +#ifdef CONFIG_X86_64 + save_msrs(vmx->guest_msrs, vmx->msr_offset_kernel_gs_base); + save_msrs(vmx->guest_msrs + vmx->msr_offset_kernel_gs_base + 1, + vmx->save_nmsrs - vmx->msr_offset_kernel_gs_base - 1); +#else save_msrs(vmx->guest_msrs, vmx->save_nmsrs); +#endif load_msrs(vmx->host_msrs, vmx->save_nmsrs); reload_host_efer(vmx); load_gdt(&__get_cpu_var(host_gdt)); _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
