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Wed, 23 Mar 2022 10:53:52 -0700 (PDT) Received: from localhost ([192.55.54.52]) by smtp.gmail.com with ESMTPSA id s30-20020a056a001c5e00b004f73f27aa40sm515081pfw.161.2022.03.23.10.53.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Mar 2022 10:53:51 -0700 (PDT) Date: Wed, 23 Mar 2022 10:53:49 -0700 From: Isaku Yamahata To: Sagi Shahar Cc: "Yamahata, Isaku" , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, isaku.yamahata@gmail.com, Paolo Bonzini , Jim Mattson , Erdem Aktas , Connor Kuehl , Sean Christopherson Subject: Re: [RFC PATCH v5 083/104] KVM: x86: Split core of hypercall emulation to helper function Message-ID: <20220323175349.GF1964605@ls.amr.corp.intel.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, Mar 21, 2022 at 11:32:21AM -0700, Sagi Shahar wrote: > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > index 314ae43e07bf..9acb33a17445 100644 > > --- a/arch/x86/kvm/x86.c > > +++ b/arch/x86/kvm/x86.c > > @@ -9090,26 +9090,15 @@ static int complete_hypercall_exit(struct kvm_vcpu *vcpu) > > return kvm_skip_emulated_instruction(vcpu); > > } > > > > -int kvm_emulate_hypercall(struct kvm_vcpu *vcpu) > > +unsigned long __kvm_emulate_hypercall(struct kvm_vcpu *vcpu, unsigned long nr, > > + unsigned long a0, unsigned long a1, > > + unsigned long a2, unsigned long a3, > > + int op_64_bit) > > { > > - unsigned long nr, a0, a1, a2, a3, ret; > > - int op_64_bit; > > - > > - if (kvm_xen_hypercall_enabled(vcpu->kvm)) > > - return kvm_xen_hypercall(vcpu); > > - > > - if (kvm_hv_hypercall_enabled(vcpu)) > > - return kvm_hv_hypercall(vcpu); > > - > > - nr = kvm_rax_read(vcpu); > > - a0 = kvm_rbx_read(vcpu); > > - a1 = kvm_rcx_read(vcpu); > > - a2 = kvm_rdx_read(vcpu); > > - a3 = kvm_rsi_read(vcpu); > > + unsigned long ret; > > > > trace_kvm_hypercall(nr, a0, a1, a2, a3); > > > > - op_64_bit = is_64_bit_hypercall(vcpu); > > if (!op_64_bit) { > > nr &= 0xFFFFFFFF; > > a0 &= 0xFFFFFFFF; > > @@ -9118,11 +9107,6 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu) > > a3 &= 0xFFFFFFFF; > > } > > > > - if (static_call(kvm_x86_get_cpl)(vcpu) != 0) { > > - ret = -KVM_EPERM; > > - goto out; > > - } > > - > > ret = -KVM_ENOSYS; > > > > switch (nr) { > > @@ -9181,6 +9165,34 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu) > > ret = -KVM_ENOSYS; > > break; > > } > > + return ret; > > +} > > +EXPORT_SYMBOL_GPL(__kvm_emulate_hypercall); > > + > > +int kvm_emulate_hypercall(struct kvm_vcpu *vcpu) > > +{ > > + unsigned long nr, a0, a1, a2, a3, ret; > > + int op_64_bit; > > + > > + if (kvm_xen_hypercall_enabled(vcpu->kvm)) > > + return kvm_xen_hypercall(vcpu); > > + > > + if (kvm_hv_hypercall_enabled(vcpu)) > > + return kvm_hv_hypercall(vcpu); > > + > > + nr = kvm_rax_read(vcpu); > > + a0 = kvm_rbx_read(vcpu); > > + a1 = kvm_rcx_read(vcpu); > > + a2 = kvm_rdx_read(vcpu); > > + a3 = kvm_rsi_read(vcpu); > > + op_64_bit = is_64_bit_mode(vcpu); > > I think this should be "op_64_bit = is_64_bit_hypercall(vcpu);" > is_64_bit_mode was replaced with is_64_bit_hypercall to support > protected guests here: > https://lore.kernel.org/all/87cztf8h43.fsf@vitty.brq.redhat.com/T/ > > Without it, op_64_bit will be set to 0 for TD VMs which will cause the > upper 32 bit of the registers to be cleared in __kvm_emulate_hypercall Oops, thanks for pointing it out. I'll fix it up with next respin. -- Isaku Yamahata