From patchwork Thu Feb 27 01:25:34 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 13993477 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E00E415E5C2 for ; Thu, 27 Feb 2025 01:25:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740619551; cv=none; b=jHsH2OtcTYPIF93yK6A1ZPdAtsscRd7lrpKWnbqhcJFsybHei+/tCX5GhJuNer1mZ6pbqX8rIaSsOhXsFjDno0vJpxkKhjA8qWJeBrCUBUZQjElnDrWq1J0PLnXFTnewP1e+kTKNq90l7oSQP84cSI9NmJm37KJ5YUkSmB9994c= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740619551; c=relaxed/simple; bh=Bd2jcIIVus5KKhQQxvEgLThZpvhnEnb0Zp6oqmiDeNc=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=NZ9tEiR4j+UbI5qp9a8z9pEORBygkQElcz4Mv//45ly2bKHES1yZt4ToaMe7lE3mWtqUgQliNcnjIdLgWugy0e1FB5hn2m3jXBxNz9C+oSXS89sP3QunDLcSfOJTPvbuRiviQqWVnAr7EO++OAZ4xq4EHCBTMRZka5/x27Me5Do= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=sX+ytRaW; arc=none smtp.client-ip=209.85.214.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="sX+ytRaW" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-22350e4b7baso4602925ad.3 for ; Wed, 26 Feb 2025 17:25:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1740619549; x=1741224349; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=SpiV/7IGUVGhPtuzMA7ncb1Ov7eVPXJdzTw8o7Y+oeM=; b=sX+ytRaWgmh8rx/g4QSbKm4lQHPMSzGHtVbJ1Wy1V6TnQmybyQVt3YbiYQhlmKEX0Z 2RvmjqrzNyGl1bsd5mzPU7rwEeFVPEPS8T41yUQ1RZrVmKtT+iOFxaGPqrpUCbNNm7n+ LZISBDJVVeYa4d5Bpr+qs0+IJgciD7wVX1EAyacNOYGjZGLsTHQ8VW8+BpMigcz9pZ9y j3pSFDXvf66VcAD0827ALYTduV2zO3kFm83FcgeJJviRyb4klyIM6g4WXvrr0f1n3/jP 23kpn4GtmZBTYmm3Td5KnZHXpuR2HgwP2Km/tOfevX4u6ymLvrFBl5P+GSywf7IcofXT f+tQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1740619549; x=1741224349; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=SpiV/7IGUVGhPtuzMA7ncb1Ov7eVPXJdzTw8o7Y+oeM=; b=Ov4pMlLOWuls4B2kN8/vvthZIHZc5fCNjEHNutbnlkUbRxu106VDVLfaGI9o4LB6B+ 6sa8+9n1GiK/dHuEqx829ZpMBIKsqKlEnOr7o9T7/JTGGaPyzon+RtvkqY1INPnkvlwy rh3kOfpVUukrSDW0LFjrLsW423SIdKrpBS3WR8mXqThaed4P++S0dWLGRYCKp7nNInKf jkTISDJ6LwGHZTSmOUKvtQHUh/JocPtjVf/M8X2KgG7BfPxdLIB8Uay2NUdGTqVUkQW6 S46STNDY6jE+wrcnSxarIAyf5+E3bMe2FmzZHHLfv2MXTl0VcgkBznIV7ybm+JhDeacD nYQg== X-Gm-Message-State: AOJu0Ywaxzw4xS2Df7fXde2OFd4Y8q00olyKgo4ACr5c2f/0pP3NM/RB 7JXXKzr6CIl2ZC6Zf1gzkhjBMAuRBiGOGSXpu9Atjs4wUnKNuH6IivRasYz03TOTJAlfEGSHKA1 VFw== X-Google-Smtp-Source: AGHT+IEBhn1N/oyrrmPhXLjz3V/jBJme9qVZVIFVvFpCt+5P1PKn2MbmobZJwvu3dN1sDK4eJAez625G97g= X-Received: from pfcg22.prod.google.com ([2002:a05:6a00:23d6:b0:730:880d:7ed5]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:1310:b0:730:9567:c3d5 with SMTP id d2e1a72fcca58-7347909fee5mr15105470b3a.4.1740619549128; Wed, 26 Feb 2025 17:25:49 -0800 (PST) Reply-To: Sean Christopherson Date: Wed, 26 Feb 2025 17:25:34 -0800 In-Reply-To: <20250227012541.3234589-1-seanjc@google.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250227012541.3234589-1-seanjc@google.com> X-Mailer: git-send-email 2.48.1.711.g2feabab25a-goog Message-ID: <20250227012541.3234589-4-seanjc@google.com> Subject: [PATCH v2 03/10] KVM: SVM: Refuse to attempt VRMUN if an SEV-ES+ guest has an invalid VMSA From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Naveen N Rao , Kim Phillips , Tom Lendacky , Alexey Kardashevskiy , Pankaj Gupta Explicitly reject KVM_RUN with KVM_EXIT_FAIL_ENTRY if userspace "coerces" KVM into running an SEV-ES+ guest with an invalid VMSA, e.g. by modifying a vCPU's mp_state to be RUNNABLE after an SNP vCPU has undergone a Destroy event. On Destroy or failed Create, KVM marks the vCPU HALTED so that *KVM* doesn't run the vCPU, but nothing prevents a misbehaving VMM from manually making the vCPU RUNNABLE via KVM_SET_MP_STATE. Attempting VMRUN with an invalid VMSA should be harmless, but knowingly executing VMRUN with bad control state is at best dodgy. Fixes: e366f92ea99e ("KVM: SEV: Support SEV-SNP AP Creation NAE event") Signed-off-by: Sean Christopherson Reviewed-by: Tom Lendacky Reviewed-by: Pankaj Gupta --- arch/x86/kvm/svm/sev.c | 16 +++++++++++++--- arch/x86/kvm/svm/svm.c | 11 +++++++++-- arch/x86/kvm/svm/svm.h | 2 +- 3 files changed, 23 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 719cd48330f1..218738a360ba 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -3452,10 +3452,19 @@ void sev_es_unmap_ghcb(struct vcpu_svm *svm) svm->sev_es.ghcb = NULL; } -void pre_sev_run(struct vcpu_svm *svm, int cpu) +int pre_sev_run(struct vcpu_svm *svm, int cpu) { struct svm_cpu_data *sd = per_cpu_ptr(&svm_data, cpu); - unsigned int asid = sev_get_asid(svm->vcpu.kvm); + struct kvm *kvm = svm->vcpu.kvm; + unsigned int asid = sev_get_asid(kvm); + + /* + * Reject KVM_RUN if userspace attempts to run the vCPU with an invalid + * VMSA, e.g. if userspace forces the vCPU to be RUNNABLE after an SNP + * AP Destroy event. + */ + if (sev_es_guest(kvm) && !VALID_PAGE(svm->vmcb->control.vmsa_pa)) + return -EINVAL; /* Assign the asid allocated with this SEV guest */ svm->asid = asid; @@ -3468,11 +3477,12 @@ void pre_sev_run(struct vcpu_svm *svm, int cpu) */ if (sd->sev_vmcbs[asid] == svm->vmcb && svm->vcpu.arch.last_vmentry_cpu == cpu) - return; + return 0; sd->sev_vmcbs[asid] = svm->vmcb; svm->vmcb->control.tlb_ctl = TLB_CONTROL_FLUSH_ASID; vmcb_mark_dirty(svm->vmcb, VMCB_ASID); + return 0; } #define GHCB_SCRATCH_AREA_LIMIT (16ULL * PAGE_SIZE) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index b8aa0f36850f..f72bcf2e590e 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -3587,7 +3587,7 @@ static int svm_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath) return svm_invoke_exit_handler(vcpu, exit_code); } -static void pre_svm_run(struct kvm_vcpu *vcpu) +static int pre_svm_run(struct kvm_vcpu *vcpu) { struct svm_cpu_data *sd = per_cpu_ptr(&svm_data, vcpu->cpu); struct vcpu_svm *svm = to_svm(vcpu); @@ -3609,6 +3609,8 @@ static void pre_svm_run(struct kvm_vcpu *vcpu) /* FIXME: handle wraparound of asid_generation */ if (svm->current_vmcb->asid_generation != sd->asid_generation) new_asid(svm, sd); + + return 0; } static void svm_inject_nmi(struct kvm_vcpu *vcpu) @@ -4231,7 +4233,12 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu, if (force_immediate_exit) smp_send_reschedule(vcpu->cpu); - pre_svm_run(vcpu); + if (pre_svm_run(vcpu)) { + vcpu->run->exit_reason = KVM_EXIT_FAIL_ENTRY; + vcpu->run->fail_entry.hardware_entry_failure_reason = SVM_EXIT_ERR; + vcpu->run->fail_entry.cpu = vcpu->cpu; + return EXIT_FASTPATH_EXIT_USERSPACE; + } sync_lapic_to_cr8(vcpu); diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 5b159f017055..e51852977b70 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -713,7 +713,7 @@ void avic_refresh_virtual_apic_mode(struct kvm_vcpu *vcpu); /* sev.c */ -void pre_sev_run(struct vcpu_svm *svm, int cpu); +int pre_sev_run(struct vcpu_svm *svm, int cpu); void sev_init_vmcb(struct vcpu_svm *svm); void sev_vcpu_after_set_cpuid(struct vcpu_svm *svm); int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in);