From 520116f7b14e19668cfbc660cd42e8cdc09193cd Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Fri, 17 Aug 2018 13:51:27 +0200 Subject: [PATCH] x86: make arch_set_info_guest() match comments in load_segments() For both fs_base and gs_base_user, there are comments saying "This can only be non-zero if selector is NULL." While save_segments() ensures this, so far arch_set_info_guest() didn't. Make behavior consistent (attaching comments identical to those in save_segments()). Signed-off-by: Jan Beulich Reviewed-by: Andrew Cooper --- xen/arch/x86/domain.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c index b5bb0f3b22..5bb900edec 100644 --- a/xen/arch/x86/domain.c +++ b/xen/arch/x86/domain.c @@ -931,9 +931,13 @@ int arch_set_info_guest( if ( !compat ) { v->arch.pv_vcpu.syscall_callback_eip = c.nat->syscall_callback_eip; - v->arch.pv_vcpu.fs_base = c.nat->fs_base; + /* non-nul selector kills fs_base */ + v->arch.pv_vcpu.fs_base = + !(v->arch.user_regs.fs & ~3) ? c.nat->fs_base : 0; v->arch.pv_vcpu.gs_base_kernel = c.nat->gs_base_kernel; - v->arch.pv_vcpu.gs_base_user = c.nat->gs_base_user; + /* non-nul selector kills gs_base_user */ + v->arch.pv_vcpu.gs_base_user = + !(v->arch.user_regs.gs & ~3) ? c.nat->gs_base_user : 0; } else { -- 2.30.2