From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756894AbaIEJrc (ORCPT ); Fri, 5 Sep 2014 05:47:32 -0400 Received: from mail-wg0-f52.google.com ([74.125.82.52]:61869 "EHLO mail-wg0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756579AbaIEJrQ (ORCPT ); Fri, 5 Sep 2014 05:47:16 -0400 Date: Fri, 5 Sep 2014 12:47:09 +0300 From: Gleb Natapov To: Paolo Bonzini Cc: Gleb Natapov , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, jroedel@suse.de, agraf@suse.de, valentine.sinitsyn@gmail.com, jan.kiszka@siemens.com, avi@cloudius-systems.com Subject: Re: [PATCH 3/4] KVM: x86: inject nested page faults on emulated instructions Message-ID: <20140905094709.GB26540@minantech.com> References: <1409670830-14544-1-git-send-email-pbonzini@redhat.com> <1409670830-14544-4-git-send-email-pbonzini@redhat.com> <20140904070220.GL9842@cloudius-systems.com> <54087343.5050409@redhat.com> <20140904150500.GA25317@minantech.com> <5408A513.6090603@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5408A513.6090603@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 04, 2014 at 07:44:51PM +0200, Paolo Bonzini wrote: > Il 04/09/2014 17:05, Gleb Natapov ha scritto: > >> > > >> > If you do that, KVM gets down to the "if (writeback)" and writes the > >> > ctxt->eip from L2 into the L1 EIP. > > Heh, that's a bummer. We should not write back if an instruction caused a vmexit. > > > > You're right, that works. Looks good! Reviewed-by: Gleb Natapov > > Paolo > > -------------- 8< ------------- > Subject: [PATCH] KVM: x86: skip writeback on injection of nested exception > > If a nested page fault happens during emulation, we will inject a vmexit, > not a page fault. However because writeback happens after the injection, > we will write ctxt->eip from L2 into the L1 EIP. We do not write back > if an instruction caused an interception vmexit---do the same for page > faults. > > Signed-off-by: Paolo Bonzini > --- > arch/x86/include/asm/kvm_host.h | 1 - > arch/x86/kvm/x86.c | 15 ++++++++++----- > 2 files changed, 10 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 08cc299..c989651 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -893,7 +893,6 @@ void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault); > int kvm_read_guest_page_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, > gfn_t gfn, void *data, int offset, int len, > u32 access); > -void kvm_propagate_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault); > bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl); > > static inline int __kvm_irq_line_state(unsigned long *irq_state, > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index e4ed85e..3541946 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -408,12 +408,14 @@ void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault) > } > EXPORT_SYMBOL_GPL(kvm_inject_page_fault); > > -void kvm_propagate_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault) > +static bool kvm_propagate_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault) > { > if (mmu_is_nested(vcpu) && !fault->nested_page_fault) > vcpu->arch.nested_mmu.inject_page_fault(vcpu, fault); > else > vcpu->arch.mmu.inject_page_fault(vcpu, fault); > + > + return fault->nested_page_fault; > } > > void kvm_inject_nmi(struct kvm_vcpu *vcpu) > @@ -4929,16 +4931,18 @@ static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask) > } > } > > -static void inject_emulated_exception(struct kvm_vcpu *vcpu) > +static bool inject_emulated_exception(struct kvm_vcpu *vcpu) > { > struct x86_emulate_ctxt *ctxt = &vcpu->arch.emulate_ctxt; > if (ctxt->exception.vector == PF_VECTOR) > - kvm_propagate_fault(vcpu, &ctxt->exception); > - else if (ctxt->exception.error_code_valid) > + return kvm_propagate_fault(vcpu, &ctxt->exception); > + > + if (ctxt->exception.error_code_valid) > kvm_queue_exception_e(vcpu, ctxt->exception.vector, > ctxt->exception.error_code); > else > kvm_queue_exception(vcpu, ctxt->exception.vector); > + return false; > } > > static void init_emulate_ctxt(struct kvm_vcpu *vcpu) > @@ -5300,8 +5304,9 @@ restart: > } > > if (ctxt->have_exception) { > - inject_emulated_exception(vcpu); > r = EMULATE_DONE; > + if (inject_emulated_exception(vcpu)) > + return r; > } else if (vcpu->arch.pio.count) { > if (!vcpu->arch.pio.in) { > /* FIXME: return into emulator if single-stepping. */ > -- > 1.9.3 > > -- Gleb.