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Wed, 06 Dec 2023 05:41:26 -0800 (PST) MIME-Version: 1.0 References: <20231205222816.1152720-1-michael.roth@amd.com> In-Reply-To: <20231205222816.1152720-1-michael.roth@amd.com> From: Paolo Bonzini Date: Wed, 6 Dec 2023 14:41:13 +0100 Message-ID: Subject: Re: [PATCH v2 for-8.2?] i386/sev: Avoid SEV-ES crash due to missing MSR_EFER_LMA bit To: Michael Roth Cc: qemu-devel@nongnu.org, Marcelo Tosatti , Tom Lendacky , Akihiko Odaki , kvm@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=170.10.129.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Tue, Dec 5, 2023 at 11:28=E2=80=AFPM Michael Roth = wrote: > @@ -3637,12 +3638,18 @@ static int kvm_get_sregs(X86CPU *cpu) > env->gdt.limit =3D sregs.gdt.limit; > env->gdt.base =3D sregs.gdt.base; > > + cr0_old =3D env->cr[0]; > env->cr[0] =3D sregs.cr0; > env->cr[2] =3D sregs.cr2; > env->cr[3] =3D sregs.cr3; > env->cr[4] =3D sregs.cr4; > > env->efer =3D sregs.efer; > + if (sev_es_enabled() && env->efer & MSR_EFER_LME) { > + if (!(cr0_old & CR0_PG_MASK) && env->cr[0] & CR0_PG_MASK) { > + env->efer |=3D MSR_EFER_LMA; > + } > + } There is no need to check cr0_old or sev_es_enabled(); EFER.LMA is simply EFER.LME && CR0.PG. Alternatively, sev_es_enabled() could be an assertion, that is: if ((env->efer & MSR_EFER_LME) && (env->cr[0] & CR0_PG_MASK) && !(env->efer & MSR_EFER_LMA)) { /* Workaround for... */ assert(sev_es_enabled()); env->efer |=3D MSR_EFER_LMA; } What do you think? Thanks, Paolo > /* changes to apic base and cr8/tpr are read back via kvm_arch_post_= run */ > x86_update_hflags(env); > @@ -3654,6 +3661,7 @@ static int kvm_get_sregs2(X86CPU *cpu) > { > CPUX86State *env =3D &cpu->env; > struct kvm_sregs2 sregs; > + target_ulong cr0_old; > int i, ret; > > ret =3D kvm_vcpu_ioctl(CPU(cpu), KVM_GET_SREGS2, &sregs); > @@ -3676,12 +3684,18 @@ static int kvm_get_sregs2(X86CPU *cpu) > env->gdt.limit =3D sregs.gdt.limit; > env->gdt.base =3D sregs.gdt.base; > > + cr0_old =3D env->cr[0]; > env->cr[0] =3D sregs.cr0; > env->cr[2] =3D sregs.cr2; > env->cr[3] =3D sregs.cr3; > env->cr[4] =3D sregs.cr4; > > env->efer =3D sregs.efer; > + if (sev_es_enabled() && env->efer & MSR_EFER_LME) { > + if (!(cr0_old & CR0_PG_MASK) && env->cr[0] & CR0_PG_MASK) { > + env->efer |=3D MSR_EFER_LMA; > + } > + } > > env->pdptrs_valid =3D sregs.flags & KVM_SREGS2_FLAGS_PDPTRS_VALID; > > -- > 2.25.1 >