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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692115257; x=1692720057; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=XpJb+OJfG+8YyFrgPemLQHLQMcBP2sLxedbL+4WkyQI=; b=SRbjXEPtJuCNWyJydqLa3qzK/3iBHWGCWqLd+6h8Jjy7A9u51KbioHkT0oWGX5ubb1 OPMx+UoDL8mlt39anf9KOsK7XCSQFA5H8G3lo5FYsvTCoEMiJAFwDLxV70reZDLQi/Qo M0lJMVCUHzXdAe3UWmqdfnioMM4tIztbOY/wCGJ+Q/BKg3CM7g19DI+vukcWpb/YjwfS xf3S4HBDXoI5Uysuok9HRi+asQIAPHMvvLbVmLxJN/Pa1SRvpOqvd3mbE0edZzidA0XI icD6NAQWFUMvBc30AE0q5ROLYKK0dS40zN1UUf9X54plEGsshf+piiZHiQXT1ISI9NNZ cqQg== X-Gm-Message-State: AOJu0YygfxSlT2jXxAY19u3xjiaZzIXmplBfTeKSCNm+sdPkz1G14dDS hyoLcV7VV9fqIRPyx9GZhwegy9aEEp7SbbB5Cu7RpQ== X-Google-Smtp-Source: AGHT+IEdGhK9M3JtHIkjAkwh3xNQNLfzowgWF508z3Uj0qlA890h/RB4apOdF96xxD3sICYqpWEaeKcnTbjgLEFFWtk= X-Received: by 2002:a50:9fa4:0:b0:506:b280:4993 with SMTP id c33-20020a509fa4000000b00506b2804993mr363704edf.2.1692115256934; Tue, 15 Aug 2023 09:00:56 -0700 (PDT) MIME-Version: 1.0 References: <20230612042559.375660-1-michael.roth@amd.com> <20230612042559.375660-43-michael.roth@amd.com> In-Reply-To: <20230612042559.375660-43-michael.roth@amd.com> From: Peter Gonda Date: Tue, 15 Aug 2023 10:00:45 -0600 Message-ID: Subject: Re: [PATCH RFC v9 42/51] KVM: SVM: Support SEV-SNP AP Creation NAE event To: Michael Roth Cc: kvm@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, linux-crypto@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, jroedel@suse.de, thomas.lendacky@amd.com, hpa@zytor.com, ardb@kernel.org, pbonzini@redhat.com, seanjc@google.com, vkuznets@redhat.com, jmattson@google.com, luto@kernel.org, dave.hansen@linux.intel.com, slp@redhat.com, peterz@infradead.org, srinivas.pandruvada@linux.intel.com, rientjes@google.com, dovmurik@linux.ibm.com, tobin@ibm.com, bp@alien8.de, vbabka@suse.cz, kirill@shutemov.name, ak@linux.intel.com, tony.luck@intel.com, marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com, alpergun@google.com, dgilbert@redhat.com, jarkko@kernel.org, ashish.kalra@amd.com, nikunj.dadhania@amd.com, liam.merwick@oracle.com, zhi.a.wang@intel.com, Brijesh Singh Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Stat-Signature: scbmhccquamrif35meypxcmyzdto5o91 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: DE3474004A X-HE-Tag: 1692115258-391176 X-HE-Meta: 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 8sxoZ6bN xyjUJ4ZFoQiDdsoTAg9kgTQJp5B8OGd4rTYT23ugoPRHaqdGaTH2HrTeVppMsOkOOCgQhBBaJh6USEskLuwXLBjcXL+AQ6F2Hk7RK+DaCswyx85+yhEMp3x7ShSRX0pr0/ntKDtZGSMqYVD2TsOh3hCBONNGAplLA77/j+FMNNpHrp9YwJzNfvRSaiUMjlSFQiKArN7O1tH/K1sB7oOrZqtAQPqxFaDw7ppbN X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > + > + switch (request) { > + case SVM_VMGEXIT_AP_CREATE_ON_INIT: > + kick = false; > + fallthrough; > + case SVM_VMGEXIT_AP_CREATE: > + if (!page_address_valid(vcpu, svm->vmcb->control.exit_info_2)) { > + vcpu_unimpl(vcpu, "vmgexit: invalid AP VMSA address [%#llx] from guest\n", > + svm->vmcb->control.exit_info_2); > + ret = -EINVAL; > + goto out; > + } > + > + /* > + * Malicious guest can RMPADJUST a large page into VMSA which > + * will hit the SNP erratum where the CPU will incorrectly signal > + * an RMP violation #PF if a hugepage collides with the RMP entry > + * of VMSA page, reject the AP CREATE request if VMSA address from > + * guest is 2M aligned. > + */ > + if (IS_ALIGNED(svm->vmcb->control.exit_info_2, PMD_SIZE)) { > + vcpu_unimpl(vcpu, > + "vmgexit: AP VMSA address [%llx] from guest is unsafe as it is 2M aligned\n", > + svm->vmcb->control.exit_info_2); In this case and maybe the above case can we instead return an error to the guest instead of a #GP? I think Tom suggested: SW_EXITINFO1[31:0] to 2 (meaning there was an error with the VMGEXIT request) and SW_EXITINFO2 to 5 (The NAE event input was not valid (e.g., an invalid SW_EXITINFO1 value for the AP Jump Table NAE event). This way a non-malicious but buggy or naive guest gets a little more information and a chance to retry the request? > + ret = -EINVAL; > + goto out; > + } > + > + target_svm->sev_es.snp_vmsa_gpa = svm->vmcb->control.exit_info_2; > + break; > + case SVM_VMGEXIT_AP_DESTROY: > + break; > + default: > + vcpu_unimpl(vcpu, "vmgexit: invalid AP creation request [%#x] from guest\n", > + request); > + ret = -EINVAL; > + break; > + } > +