From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Paolo Bonzini Subject: [PATCH 4.2 39/54] KVM: x86: fix RSM into 64-bit protected mode Date: Fri, 23 Oct 2015 10:45:15 -0700 Message-Id: <20151023174520.260774934@linuxfoundation.org> In-Reply-To: <20151023174519.086915553@linuxfoundation.org> References: <20151023174519.086915553@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Paolo Bonzini commit b10d92a54dac25a6152f1aa1ffc95c12908035ce upstream. In order to get into 64-bit protected mode, you need to enable paging while EFER.LMA=1. For this to work, CS.L must be 0. Currently, we load the segments before CR0 and CR4, which means that if RSM returns into 64-bit protected mode CS.L is already 1 and everything breaks. Luckily, CS.L=0 is always the case when executing RSM, because it is forbidden to execute RSM from 64-bit protected mode. Hence it is enough to load CR0 and CR4 first, and only then the segments. Fixes: 660a5d517aaab9187f93854425c4c63f4a09195c Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/emulate.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -2418,7 +2418,7 @@ static int rsm_load_state_64(struct x86_ u64 val, cr0, cr4; u32 base3; u16 selector; - int i; + int i, r; for (i = 0; i < 16; i++) *reg_write(ctxt, i) = GET_SMSTATE(u64, smbase, 0x7ff8 - i * 8); @@ -2460,13 +2460,17 @@ static int rsm_load_state_64(struct x86_ dt.address = GET_SMSTATE(u64, smbase, 0x7e68); ctxt->ops->set_gdt(ctxt, &dt); + r = rsm_enter_protected_mode(ctxt, cr0, cr4); + if (r != X86EMUL_CONTINUE) + return r; + for (i = 0; i < 6; i++) { - int r = rsm_load_seg_64(ctxt, smbase, i); + r = rsm_load_seg_64(ctxt, smbase, i); if (r != X86EMUL_CONTINUE) return r; } - return rsm_enter_protected_mode(ctxt, cr0, cr4); + return X86EMUL_CONTINUE; } static int em_rsm(struct x86_emulate_ctxt *ctxt)