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[213.175.37.10]) by smtp.gmail.com with ESMTPSA id a70sm14012856wme.28.2020.03.06.06.42.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 06 Mar 2020 06:42:47 -0800 (PST) From: Vitaly Kuznetsov To: Paolo Bonzini Cc: cavery@redhat.com, jan.kiszka@siemens.com, wei.huang2@amd.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH 1/4] KVM: nSVM: do not change host intercepts while nested VM is running In-Reply-To: <1583403227-11432-2-git-send-email-pbonzini@redhat.com> References: <1583403227-11432-1-git-send-email-pbonzini@redhat.com> <1583403227-11432-2-git-send-email-pbonzini@redhat.com> Date: Fri, 06 Mar 2020 15:42:46 +0100 Message-ID: <87a74tee8p.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Paolo Bonzini writes: > Instead of touching the host intercepts so that the bitwise OR in > recalc_intercepts just works, mask away uninteresting intercepts > directly in recalc_intercepts. > > This is cleaner and keeps the logic in one place even for intercepts > that can change even while L2 is running. > > Signed-off-by: Paolo Bonzini > --- > arch/x86/kvm/svm.c | 31 ++++++++++++++++++------------- > 1 file changed, 18 insertions(+), 13 deletions(-) > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 247e31d21b96..14cb5c194008 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -519,10 +519,24 @@ static void recalc_intercepts(struct vcpu_svm *svm) > h = &svm->nested.hsave->control; > g = &svm->nested; > > - c->intercept_cr = h->intercept_cr | g->intercept_cr; > - c->intercept_dr = h->intercept_dr | g->intercept_dr; > - c->intercept_exceptions = h->intercept_exceptions | g->intercept_exceptions; > - c->intercept = h->intercept | g->intercept; > + c->intercept_cr = h->intercept_cr; > + c->intercept_dr = h->intercept_dr; > + c->intercept_exceptions = h->intercept_exceptions; > + c->intercept = h->intercept; > + > + if (svm->vcpu.arch.hflags & HF_VINTR_MASK) { > + /* We only want the cr8 intercept bits of L1 */ > + c->intercept_cr &= ~(1U << INTERCEPT_CR8_READ); > + c->intercept_cr &= ~(1U << INTERCEPT_CR8_WRITE); > + } > + > + /* We don't want to see VMMCALLs from a nested guest */ > + c->intercept &= ~(1ULL << INTERCEPT_VMMCALL); > + > + c->intercept_cr |= g->intercept_cr; > + c->intercept_dr |= g->intercept_dr; > + c->intercept_exceptions |= g->intercept_exceptions; > + c->intercept |= g->intercept; > } > > static inline struct vmcb *get_host_vmcb(struct vcpu_svm *svm) > @@ -3590,15 +3604,6 @@ static void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa, > else > svm->vcpu.arch.hflags &= ~HF_VINTR_MASK; > > - if (svm->vcpu.arch.hflags & HF_VINTR_MASK) { > - /* We only want the cr8 intercept bits of the guest */ > - clr_cr_intercept(svm, INTERCEPT_CR8_READ); > - clr_cr_intercept(svm, INTERCEPT_CR8_WRITE); > - } > - > - /* We don't want to see VMMCALLs from a nested guest */ > - clr_intercept(svm, INTERCEPT_VMMCALL); > - > svm->vcpu.arch.tsc_offset += nested_vmcb->control.tsc_offset; > svm->vmcb->control.tsc_offset = svm->vcpu.arch.tsc_offset; FWIW, Reviewed-by: Vitaly Kuznetsov -- Vitaly