From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752283AbdKZQlm (ORCPT ); Sun, 26 Nov 2017 11:41:42 -0500 Received: from smtp-fw-6001.amazon.com ([52.95.48.154]:40343 "EHLO smtp-fw-6001.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751969AbdKZQlj (ORCPT ); Sun, 26 Nov 2017 11:41:39 -0500 X-IronPort-AV: E=Sophos;i="5.44,459,1505779200"; d="scan'208";a="320851156" From: Filippo Sironi To: pbonzini@redhat.com, rkrcmar@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Filippo Sironi Subject: [PATCH 2/2] KVM: x86: Allow userspace to define what's the microcode version Date: Sun, 26 Nov 2017 17:41:22 +0100 Message-Id: <1511714482-3273-2-git-send-email-sironi@amazon.de> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1511714482-3273-1-git-send-email-sironi@amazon.de> References: <1511714482-3273-1-git-send-email-sironi@amazon.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ... that the guest should see. Guest operating systems may check the microcode version to decide whether to disable certain features that are known to be buggy up to certain microcode versions. Address the issue by making the microcode version that the guest should see settable. The rationale for having userspace specifying the microcode version, rather than having the kernel picking it, is to ensure consistency for live-migrated instances; we don't want them to see a microcode version increase without a reset. Signed-off-by: Filippo Sironi --- arch/x86/kvm/x86.c | 23 +++++++++++++++++++++++ include/uapi/linux/kvm.h | 3 +++ 2 files changed, 26 insertions(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 925c3e29cad3..741588f27ebc 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4033,6 +4033,29 @@ long kvm_arch_vm_ioctl(struct file *filp, } u; switch (ioctl) { + case KVM_GET_MICROCODE_VERSION: { + r = -EFAULT; + if (copy_to_user(argp, + &kvm->arch.microcode_version, + sizeof(kvm->arch.microcode_version))) + goto out; + break; + } + case KVM_SET_MICROCODE_VERSION: { + u32 microcode_version; + + r = -EFAULT; + if (copy_from_user(µcode_version, + argp, + sizeof(microcode_version))) + goto out; + r = -EINVAL; + if (!microcode_version) + goto out; + kvm->arch.microcode_version = microcode_version; + r = 0; + break; + } case KVM_SET_TSS_ADDR: r = kvm_vm_ioctl_set_tss_addr(kvm, arg); break; diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 282d7613fce8..e11887758e29 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1192,6 +1192,9 @@ struct kvm_s390_ucas_mapping { #define KVM_S390_UCAS_UNMAP _IOW(KVMIO, 0x51, struct kvm_s390_ucas_mapping) #define KVM_S390_VCPU_FAULT _IOW(KVMIO, 0x52, unsigned long) +#define KVM_GET_MICROCODE_VERSION _IOR(KVMIO, 0x5e, __u32) +#define KVM_SET_MICROCODE_VERSION _IOW(KVMIO, 0x5f, __u32) + /* Device model IOC */ #define KVM_CREATE_IRQCHIP _IO(KVMIO, 0x60) #define KVM_IRQ_LINE _IOW(KVMIO, 0x61, struct kvm_irq_level) -- 2.7.4