Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753072AbaFRQnd (ORCPT ); Wed, 18 Jun 2014 12:43:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42759 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751701AbaFRQnb (ORCPT ); Wed, 18 Jun 2014 12:43:31 -0400 From: Bandan Das To: Nadav Amit Cc: pbonzini@redhat.com, gleb@kernel.org, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, joro@8bytes.org Subject: Re: [PATCH 3/3] KVM: x86: correct mwait and monitor emulation References: <1403101176-23664-1-git-send-email-namit@cs.technion.ac.il> <1403101176-23664-4-git-send-email-namit@cs.technion.ac.il> Date: Wed, 18 Jun 2014 12:43:13 -0400 In-Reply-To: <1403101176-23664-4-git-send-email-namit@cs.technion.ac.il> (Nadav Amit's message of "Wed, 18 Jun 2014 17:19:36 +0300") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Nadav Amit writes: > mwait and monitor are currently handled as nop. Considering this behavior, they > should still be handled correctly, i.e., check execution conditions and generate > exceptions when required. mwait and monitor may also be executed in real-mode Is this necessary ? They are NOPs and kvm prints that out (correctly so) to dmesg. Implementing them correctly is a different thing, but adding extra checks for NOPs just seems like adding extra cycles. > and are not handled in that case. This patch performs the emulation of > monitor-mwait according to Intel SDM (other than checking whether interrupt can > be used as a break event). > > Signed-off-by: Nadav Amit > --- > arch/x86/kvm/emulate.c | 41 +++++++++++++++++++++++++++++++++++++++-- > arch/x86/kvm/svm.c | 22 ++-------------------- > arch/x86/kvm/vmx.c | 27 +++++++++++---------------- > 3 files changed, 52 insertions(+), 38 deletions(-) > > diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c > index ef7a5a0..424b58d 100644 > --- a/arch/x86/kvm/emulate.c > +++ b/arch/x86/kvm/emulate.c > @@ -3344,6 +3344,43 @@ static int em_bswap(struct x86_emulate_ctxt *ctxt) > return X86EMUL_CONTINUE; > } > > +static int em_monitor(struct x86_emulate_ctxt *ctxt) > +{ > + int rc; > + struct segmented_address addr; > + u64 rcx = reg_read(ctxt, VCPU_REGS_RCX); > + u64 rax = reg_read(ctxt, VCPU_REGS_RAX); > + u8 byte; > + > + if (ctxt->mode != X86EMUL_MODE_PROT64) > + rcx = (u32)rcx; > + if (rcx != 0) > + return emulate_gp(ctxt, 0); > + > + addr.seg = seg_override(ctxt); > + addr.ea = ctxt->ad_bytes == 8 ? rax : (u32)rax; > + rc = segmented_read(ctxt, addr, &byte, 1); > + if (rc != X86EMUL_CONTINUE) > + return rc; > + > + printk_once(KERN_WARNING "kvm: MONITOR instruction emulated as NOP!\n"); > + return X86EMUL_CONTINUE; > +} > + > +static int em_mwait(struct x86_emulate_ctxt *ctxt) > +{ > + u64 rcx = reg_read(ctxt, VCPU_REGS_RCX); > + > + if (ctxt->mode != X86EMUL_MODE_PROT64) > + rcx = (u32)rcx; > + if ((rcx & ~1UL) != 0) > + return emulate_gp(ctxt, 0); > + > + /* Accepting interrupt as break event regardless to cpuid */ > + printk_once(KERN_WARNING "kvm: MWAIT instruction emulated as NOP!\n"); > + return X86EMUL_CONTINUE; > +} > + > static bool valid_cr(int nr) > { > switch (nr) { > @@ -3557,8 +3594,8 @@ static int check_perm_out(struct x86_emulate_ctxt *ctxt) > F2bv(((_f) & ~Lock) | DstAcc | SrcImm, _e) > > static const struct opcode group7_rm1[] = { > - DI(SrcNone | Priv, monitor), > - DI(SrcNone | Priv, mwait), > + II(SrcNone | Priv | NoBigReal | UDOnPriv, em_monitor, monitor), > + II(SrcNone | Priv | NoBigReal | UDOnPriv, em_mwait, mwait), > N, N, N, N, N, N, > }; > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index ec8366c..a524e04 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -3274,24 +3274,6 @@ static int pause_interception(struct vcpu_svm *svm) > return 1; > } > > -static int nop_interception(struct vcpu_svm *svm) > -{ > - skip_emulated_instruction(&(svm->vcpu)); > - return 1; > -} > - > -static int monitor_interception(struct vcpu_svm *svm) > -{ > - printk_once(KERN_WARNING "kvm: MONITOR instruction emulated as NOP!\n"); > - return nop_interception(svm); > -} > - > -static int mwait_interception(struct vcpu_svm *svm) > -{ > - printk_once(KERN_WARNING "kvm: MWAIT instruction emulated as NOP!\n"); > - return nop_interception(svm); > -} > - > static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = { > [SVM_EXIT_READ_CR0] = cr_interception, > [SVM_EXIT_READ_CR3] = cr_interception, > @@ -3349,8 +3331,8 @@ static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = { > [SVM_EXIT_CLGI] = clgi_interception, > [SVM_EXIT_SKINIT] = skinit_interception, > [SVM_EXIT_WBINVD] = emulate_on_interception, > - [SVM_EXIT_MONITOR] = monitor_interception, > - [SVM_EXIT_MWAIT] = mwait_interception, > + [SVM_EXIT_MONITOR] = emulate_on_interception, > + [SVM_EXIT_MWAIT] = emulate_on_interception, > [SVM_EXIT_XSETBV] = xsetbv_interception, > [SVM_EXIT_NPF] = pf_interception, > }; > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 801332e..7023e71 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -5672,22 +5672,17 @@ static int handle_pause(struct kvm_vcpu *vcpu) > return 1; > } > > -static int handle_nop(struct kvm_vcpu *vcpu) > +static int handle_emulate(struct kvm_vcpu *vcpu) > { > - skip_emulated_instruction(vcpu); > - return 1; > -} > + int err = emulate_instruction(vcpu, 0); > > -static int handle_mwait(struct kvm_vcpu *vcpu) > -{ > - printk_once(KERN_WARNING "kvm: MWAIT instruction emulated as NOP!\n"); > - return handle_nop(vcpu); > -} > - > -static int handle_monitor(struct kvm_vcpu *vcpu) > -{ > - printk_once(KERN_WARNING "kvm: MONITOR instruction emulated as NOP!\n"); > - return handle_nop(vcpu); > + if (err != EMULATE_DONE) { > + vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR; > + vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION; > + vcpu->run->internal.ndata = 0; > + return 0; > + } > + return 1; > } > > /* > @@ -6651,8 +6646,8 @@ static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = { > [EXIT_REASON_EPT_VIOLATION] = handle_ept_violation, > [EXIT_REASON_EPT_MISCONFIG] = handle_ept_misconfig, > [EXIT_REASON_PAUSE_INSTRUCTION] = handle_pause, > - [EXIT_REASON_MWAIT_INSTRUCTION] = handle_mwait, > - [EXIT_REASON_MONITOR_INSTRUCTION] = handle_monitor, > + [EXIT_REASON_MWAIT_INSTRUCTION] = handle_emulate, > + [EXIT_REASON_MONITOR_INSTRUCTION] = handle_emulate, > [EXIT_REASON_INVEPT] = handle_invept, > }; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/