From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-69569-1517507577-2-17904558372282236773 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no ("Email failed DMARC policy for domain") X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.001, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES enro, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='com', MailFrom='org' X-Spam-charsets: from='UTF-8', plain='UTF-8' X-IgnoreVacation: yes ("Email failed DMARC policy for domain") X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1517507576; b=EipdceXsrg9PdgXsoP3D6pAx1O0rHJdUyxjIKSbbBab5ekB GcT7VcCtCQTy3kiw9sgT/KZ9LRE78a7eblkFf4a4p8KoVFRjBtUv3jUzfYib+jGk K9mBwfSEYFuOAgGqVY9uKUaqQ+dbCVxvVij/50Y1E9bYJLNtGo8GlYwWhlsKH8Gl x1DqFuUpxtxex9ea3K3MgTpX5Nj0L8wSn6TxEvMTYKiMetBRCAns1MPijROK1ejB mKR5PtfB0jCVkro7YcZzCEhNsOqvJEYQFUCAnWUi5hf8NV9pfl7uAEYR+hdyYPuE MZ20mnx8eaTJZWoI7GOAhg8E96KAuGgscwXrJew== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :mime-version:content-type:content-transfer-encoding:sender :list-id; s=arctest; t=1517507576; bh=orTdt3p1JxSrG8339uyZtoHYrE SVsdIt2h3VKNNuXRo=; b=MOZ32wtmmiZkX0KQVW0nmnYNHqH39ElKKZRQOb7efN DRWDEnptlE0p4XOPcusJtTb3zBeIc55OC0zW4pZH4fU8kOhmgyy16DSW4ni+Z4rV vJGCHS7ZKSrJtVvxjyM+OQ0T498A83hpHMaPRj2NHcRanyJBNyJiCzaUKxa331sM XD+VMzJwhLT58B/JjJTf6q1L/GREskv6Koen787neFBZg6c3HmT/kQZ49khCiwvp Fa1k4UgF48+HUW8YWyfrxEWnK42igMGriZkNnRAQS9GUDWjxSafAPSulWOVXHNlc JX41znpqAOPI1bGSUJofLv4nUBP3CDMTrP0fxtMlMehg== ARC-Authentication-Results: i=1; mx6.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=fail (p=none,has-list-id=yes,d=none) header.from=redhat.com; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=redhat.com header.result=pass header_is_org_domain=yes Authentication-Results: mx6.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=fail (p=none,has-list-id=yes,d=none) header.from=redhat.com; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=redhat.com header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751988AbeBARwx (ORCPT ); Thu, 1 Feb 2018 12:52:53 -0500 Received: from mx1.redhat.com ([209.132.183.28]:51698 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751913AbeBARww (ORCPT ); Thu, 1 Feb 2018 12:52:52 -0500 From: =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Paolo Bonzini , Wanpeng Li , stable@vger.kernel.org Subject: [PATCH] KVM: x86: fix backward migration with async_PF Date: Thu, 1 Feb 2018 18:50:22 +0100 Message-Id: <20180201175022.25011-1-rkrcmar@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Guests on new hypersiors might set KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT bit when enabling async_PF, but this bit is reserved on old hypervisors, which results in a failure upon migration. Guests at least expect that KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT might not be present when booting, so we allow userspace to handle migration compatibility by adding a KVM CPUID flag that determines the presence of KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT. Fixes: 52a5c155cf79 ("KVM: async_pf: Let guest support delivery of async_pf from guest mode") Cc: Signed-off-by: Radim Krčmář --- arch/x86/include/uapi/asm/kvm_para.h | 1 + arch/x86/kernel/kvm.c | 8 ++++---- arch/x86/kvm/cpuid.c | 3 ++- arch/x86/kvm/cpuid.h | 11 +++++++++++ arch/x86/kvm/x86.c | 6 ++++-- 5 files changed, 22 insertions(+), 7 deletions(-) diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h index 7a2ade4aa235..6cfa9c8cb7d6 100644 --- a/arch/x86/include/uapi/asm/kvm_para.h +++ b/arch/x86/include/uapi/asm/kvm_para.h @@ -26,6 +26,7 @@ #define KVM_FEATURE_PV_EOI 6 #define KVM_FEATURE_PV_UNHALT 7 #define KVM_FEATURE_PV_TLB_FLUSH 9 +#define KVM_FEATURE_ASYNC_PF_VMEXIT 10 /* The last 8 bits are used to indicate how to interpret the flags field * in pvclock structure. If no bits are set, all flags are ignored. diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index 4e37d1a851a6..971babe964d2 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -341,10 +341,10 @@ static void kvm_guest_cpu_init(void) #endif pa |= KVM_ASYNC_PF_ENABLED; - /* Async page fault support for L1 hypervisor is optional */ - if (wrmsr_safe(MSR_KVM_ASYNC_PF_EN, - (pa | KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT) & 0xffffffff, pa >> 32) < 0) - wrmsrl(MSR_KVM_ASYNC_PF_EN, pa); + if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT)) + pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT; + + wrmsrl(MSR_KVM_ASYNC_PF_EN, pa); __this_cpu_write(apf_reason.enabled, 1); printk(KERN_INFO"KVM setup async PF for cpu %d\n", smp_processor_id()); diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 20e491b94f44..7fc04a176c57 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -604,7 +604,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, (1 << KVM_FEATURE_PV_EOI) | (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) | (1 << KVM_FEATURE_PV_UNHALT) | - (1 << KVM_FEATURE_PV_TLB_FLUSH); + (1 << KVM_FEATURE_PV_TLB_FLUSH) | + (1 << KVM_FEATURE_ASYNC_PF_VMEXIT); if (sched_info_on()) entry->eax |= (1 << KVM_FEATURE_STEAL_TIME); diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h index c2cea6651279..f20731dfe28e 100644 --- a/arch/x86/kvm/cpuid.h +++ b/arch/x86/kvm/cpuid.h @@ -105,6 +105,17 @@ static __always_inline bool guest_cpuid_has(struct kvm_vcpu *vcpu, unsigned x86_ return *reg & bit(x86_feature); } +static inline bool guest_kvm_cpuid_has(struct kvm_vcpu *vcpu, unsigned kvm_feature) +{ + struct kvm_cpuid_entry2 *entry; + + entry = kvm_find_cpuid_entry(vcpu, KVM_CPUID_FEATURES, 0); + if (!entry) + return false; + + return entry->eax & bit(kvm_feature); +} + static __always_inline void guest_cpuid_clear(struct kvm_vcpu *vcpu, unsigned x86_feature) { int *reg; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 4c3103f449a3..c16740a06f0c 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2139,8 +2139,10 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data) { gpa_t gpa = data & ~0x3f; - /* Bits 3:5 are reserved, Should be zero */ - if (data & 0x38) + /* Bits 3:5 are reserved, Should be zero. */ + if (data & 0x38 || + (data & KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT && + !guest_kvm_cpuid_has(vcpu, KVM_FEATURE_ASYNC_PF_VMEXIT))) return 1; vcpu->arch.apf.msr_val = data; -- 2.15.1