From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756066AbZELUVk (ORCPT ); Tue, 12 May 2009 16:21:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753880AbZELUVN (ORCPT ); Tue, 12 May 2009 16:21:13 -0400 Received: from mx2.redhat.com ([66.187.237.31]:36184 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751772AbZELUVH (ORCPT ); Tue, 12 May 2009 16:21:07 -0400 From: Glauber Costa To: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, avi@redhat.com, "H. Peter Anvin" , Gleb Natapov Subject: [PATCH 2/2] deal with interrupt shadow state for emulated instruction Date: Tue, 12 May 2009 16:21:06 -0400 Message-Id: <1242159666-27492-3-git-send-email-glommer@redhat.com> In-Reply-To: <1242159666-27492-2-git-send-email-glommer@redhat.com> References: <1242159666-27492-1-git-send-email-glommer@redhat.com> <1242159666-27492-2-git-send-email-glommer@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org we currently unblock shadow interrupt state when we skip an instruction, but failing to do so when we actually emulate one. This blocks interrupts in key instruction blocks, in particular sti; hlt; sequences If the instruction emulated is an sti, we have to block shadow interrupts. The same goes for mov ss. pop ss also needs it, but we don't currently emulate it. Without this patch, I cannot boot gpxe option roms at vmx machines. This is described at https://bugzilla.redhat.com/show_bug.cgi?id=494469 Signed-off-by: Glauber Costa CC: H. Peter Anvin CC: Avi Kivity CC: Gleb Natapov --- arch/x86/include/asm/kvm_x86_emulate.h | 3 +++ arch/x86/kvm/x86.c | 6 +++++- arch/x86/kvm/x86_emulate.c | 20 ++++++++++++++++++++ 3 files changed, 28 insertions(+), 1 deletions(-) diff --git a/arch/x86/include/asm/kvm_x86_emulate.h b/arch/x86/include/asm/kvm_x86_emulate.h index be40d6e..b7ed2c4 100644 --- a/arch/x86/include/asm/kvm_x86_emulate.h +++ b/arch/x86/include/asm/kvm_x86_emulate.h @@ -155,6 +155,9 @@ struct x86_emulate_ctxt { int mode; u32 cs_base; + /* interruptibility state, as a result of execution of STI or MOV SS */ + int interruptibility; + /* decode cache */ struct decode_cache decode; }; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 3d8fcc5..b45baff 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2362,7 +2362,7 @@ int emulate_instruction(struct kvm_vcpu *vcpu, u16 error_code, int emulation_type) { - int r; + int r, shadow_mask; struct decode_cache *c; kvm_clear_exception_queue(vcpu); @@ -2416,6 +2416,10 @@ int emulate_instruction(struct kvm_vcpu *vcpu, } r = x86_emulate_insn(&vcpu->arch.emulate_ctxt, &emulate_ops); + shadow_mask = vcpu->arch.emulate_ctxt.interruptibility; + + if (r == 0) + kvm_x86_ops->set_interrupt_shadow(vcpu, shadow_mask); if (vcpu->arch.pio.string) return EMULATE_DO_MMIO; diff --git a/arch/x86/kvm/x86_emulate.c b/arch/x86/kvm/x86_emulate.c index d2664fc..c1b6c23 100644 --- a/arch/x86/kvm/x86_emulate.c +++ b/arch/x86/kvm/x86_emulate.c @@ -1361,6 +1361,20 @@ static inline int writeback(struct x86_emulate_ctxt *ctxt, return 0; } +void toggle_interruptibility(struct x86_emulate_ctxt *ctxt, u32 mask) +{ + u32 int_shadow = kvm_x86_ops->get_interrupt_shadow(ctxt->vcpu, mask); + /* + * an sti; sti; sequence only disable interrupts for the first + * instruction. So, if the last instruction, be it emulated or + * not, left the system with the INT_STI flag enabled, it + * means that the last instruction is an sti. We should not + * leave the flag on in this case. The same goes for mov ss + */ + if (!(int_shadow & mask)) + ctxt->interruptibility = mask; +} + int x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) { @@ -1372,6 +1386,8 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) int io_dir_in; int rc = 0; + ctxt->interruptibility = 0; + /* Shadow copy of register state. Committed on successful emulation. * NOTE: we can copy them from vcpu as x86_decode_insn() doesn't * modify them. @@ -1618,6 +1634,9 @@ special_insn: int err; sel = c->src.val; + if (c->modrm_reg == VCPU_SREG_SS) + toggle_interruptibility(ctxt, X86_SHADOW_INT_MOV_SS); + if (c->modrm_reg <= 5) { type_bits = (c->modrm_reg == 1) ? 9 : 1; err = kvm_load_segment_descriptor(ctxt->vcpu, sel, @@ -1847,6 +1866,7 @@ special_insn: c->dst.type = OP_NONE; /* Disable writeback. */ break; case 0xfb: /* sti */ + toggle_interruptibility(ctxt, X86_SHADOW_INT_STI); ctxt->eflags |= X86_EFLAGS_IF; c->dst.type = OP_NONE; /* Disable writeback. */ break; -- 1.5.6.6