From nobody Wed Apr 8 17:28:55 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D54E5FA3740 for ; Thu, 27 Oct 2022 16:20:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236776AbiJ0QUR (ORCPT ); Thu, 27 Oct 2022 12:20:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54128 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236606AbiJ0QTE (ORCPT ); Thu, 27 Oct 2022 12:19:04 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0F85F18DD75 for ; Thu, 27 Oct 2022 09:19:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1666887539; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=pXzajH97NHl0gEvAvhaePvRNuVty75RFHBFDXcj4E30=; b=argqq2J+nea1SfUcxbd9D0xZkcNnzUKIOytwlYeXh3+LJV4H/bKsFgsUv3KHPT/NI1DdGh LHYGgeD1mX474FGu0257ypPaqq9GFVS6nnTHn6IOXmjlr6yy4yC3FfRBHFW/b573vA60jG oacDEGh+l7S1AVjLbBh0CMQBKhu43mQ= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-332-NzG0FtqCNMWX5O91G12vAA-1; Thu, 27 Oct 2022 12:18:53 -0400 X-MC-Unique: NzG0FtqCNMWX5O91G12vAA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id B993D811E81; Thu, 27 Oct 2022 16:18:52 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id 98CEE39DB3; Thu, 27 Oct 2022 16:18:52 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: mhal@rbox.co, seanjc@google.com Subject: [PATCH 13/16] KVM: Drop @gpa from exported gfn=>pfn cache check() and refresh() helpers Date: Thu, 27 Oct 2022 12:18:46 -0400 Message-Id: <20221027161849.2989332-14-pbonzini@redhat.com> In-Reply-To: <20221027161849.2989332-1-pbonzini@redhat.com> References: <20221027161849.2989332-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Sean Christopherson Drop the @gpa param from the exported check()+refresh() helpers and limit changing the cache's GPA to the activate path. All external users just feed in gpc->gpa, i.e. this is a fancy nop. Allowing users to change the GPA at check()+refresh() is dangerous as those helpers explicitly allow concurrent calls, e.g. KVM could get into a livelock scenario. It's also unclear as to what the expected behavior should be if multiple tasks attempt to refresh with different GPAs. Signed-off-by: Sean Christopherson Message-Id: <20221013211234.1318131-14-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/x86.c | 4 ++-- arch/x86/kvm/xen.c | 20 ++++++++++---------- include/linux/kvm_host.h | 6 ++---- virt/kvm/pfncache.c | 11 ++++------- 4 files changed, 18 insertions(+), 23 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index bdc3110650d3..f7ee5ee58990 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3034,10 +3034,10 @@ static void kvm_setup_guest_pvclock(struct kvm_vcpu= *v, WARN_ON_ONCE(gpc->len !=3D offset + sizeof(*guest_hv_clock)); =20 read_lock_irqsave(&gpc->lock, flags); - while (!kvm_gpc_check(gpc, gpc->gpa)) { + while (!kvm_gpc_check(gpc)) { read_unlock_irqrestore(&gpc->lock, flags); =20 - if (kvm_gpc_refresh(gpc, gpc->gpa)) + if (kvm_gpc_refresh(gpc)) return; =20 read_lock_irqsave(&gpc->lock, flags); diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index 545ecbd0ca36..7b7b1eb88a0b 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -241,14 +241,14 @@ void kvm_xen_update_runstate_guest(struct kvm_vcpu *v= , int state) return; =20 read_lock_irqsave(&gpc->lock, flags); - while (!kvm_gpc_check(gpc, gpc->gpa)) { + while (!kvm_gpc_check(gpc)) { read_unlock_irqrestore(&gpc->lock, flags); =20 /* When invoked from kvm_sched_out() we cannot sleep */ if (state =3D=3D RUNSTATE_runnable) return; =20 - if (kvm_gpc_refresh(gpc, gpc->gpa)) + if (kvm_gpc_refresh(gpc)) return; =20 read_lock_irqsave(&gpc->lock, flags); @@ -374,10 +374,10 @@ void kvm_xen_inject_pending_events(struct kvm_vcpu *v) * little more honest about it. */ read_lock_irqsave(&gpc->lock, flags); - while (!kvm_gpc_check(gpc, gpc->gpa)) { + while (!kvm_gpc_check(gpc)) { read_unlock_irqrestore(&gpc->lock, flags); =20 - if (kvm_gpc_refresh(gpc, gpc->gpa)) + if (kvm_gpc_refresh(gpc)) return; =20 read_lock_irqsave(&gpc->lock, flags); @@ -437,7 +437,7 @@ int __kvm_xen_has_interrupt(struct kvm_vcpu *v) sizeof_field(struct compat_vcpu_info, evtchn_upcall_pending)); =20 read_lock_irqsave(&gpc->lock, flags); - while (!kvm_gpc_check(gpc, gpc->gpa)) { + while (!kvm_gpc_check(gpc)) { read_unlock_irqrestore(&gpc->lock, flags); =20 /* @@ -451,7 +451,7 @@ int __kvm_xen_has_interrupt(struct kvm_vcpu *v) if (in_atomic() || !task_is_running(current)) return 1; =20 - if (kvm_gpc_refresh(gpc, gpc->gpa)) { + if (kvm_gpc_refresh(gpc)) { /* * If this failed, userspace has screwed up the * vcpu_info mapping. No interrupts for you. @@ -981,7 +981,7 @@ static bool wait_pending_event(struct kvm_vcpu *vcpu, i= nt nr_ports, =20 read_lock_irqsave(&gpc->lock, flags); idx =3D srcu_read_lock(&kvm->srcu); - if (!kvm_gpc_check(gpc, gpc->gpa)) + if (!kvm_gpc_check(gpc)) goto out_rcu; =20 ret =3D false; @@ -1372,7 +1372,7 @@ int kvm_xen_set_evtchn_fast(struct kvm_xen_evtchn *xe= , struct kvm *kvm) idx =3D srcu_read_lock(&kvm->srcu); =20 read_lock_irqsave(&gpc->lock, flags); - if (!kvm_gpc_check(gpc, gpc->gpa)) + if (!kvm_gpc_check(gpc)) goto out_rcu; =20 if (IS_ENABLED(CONFIG_64BIT) && kvm->arch.xen.long_mode) { @@ -1406,7 +1406,7 @@ int kvm_xen_set_evtchn_fast(struct kvm_xen_evtchn *xe= , struct kvm *kvm) gpc =3D &vcpu->arch.xen.vcpu_info_cache; =20 read_lock_irqsave(&gpc->lock, flags); - if (!kvm_gpc_check(gpc, gpc->gpa)) { + if (!kvm_gpc_check(gpc)) { /* * Could not access the vcpu_info. Set the bit in-kernel * and prod the vCPU to deliver it for itself. @@ -1504,7 +1504,7 @@ static int kvm_xen_set_evtchn(struct kvm_xen_evtchn *= xe, struct kvm *kvm) break; =20 idx =3D srcu_read_lock(&kvm->srcu); - rc =3D kvm_gpc_refresh(gpc, gpc->gpa); + rc =3D kvm_gpc_refresh(gpc); srcu_read_unlock(&kvm->srcu, idx); } while(!rc); =20 diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 3847b721e753..fd6b58c870cf 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1282,7 +1282,6 @@ int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gp= a_t gpa, unsigned long len) * kvm_gpc_check - check validity of a gfn_to_pfn_cache. * * @gpc: struct gfn_to_pfn_cache object. - * @gpa: current guest physical address to map. * * @return: %true if the cache is still valid and the address matches. * %false if the cache is not valid. @@ -1294,13 +1293,12 @@ int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, = gpa_t gpa, unsigned long len) * Callers in IN_GUEST_MODE may do so without locking, although they should * still hold a read lock on kvm->scru for the memslot checks. */ -bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, gpa_t gpa); +bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc); =20 /** * kvm_gpc_refresh - update a previously initialized cache. * * @gpc: struct gfn_to_pfn_cache object. - * @gpa: updated guest physical address to map. * * @return: 0 for success. * -EINVAL for a mapping which would cross a page boundary. @@ -1312,7 +1310,7 @@ bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, gpa_= t gpa); * still lock and check the cache status, as this function does not return * with the lock still held to permit access. */ -int kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa); +int kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc); =20 /** * kvm_gpc_deactivate - deactivate and unlink a gfn_to_pfn_cache. diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c index 06fcf03c2da6..68e2e53eac8a 100644 --- a/virt/kvm/pfncache.c +++ b/virt/kvm/pfncache.c @@ -76,17 +76,14 @@ void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm,= unsigned long start, } } =20 -bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, gpa_t gpa) +bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc) { struct kvm_memslots *slots =3D kvm_memslots(gpc->kvm); =20 if (!gpc->active) return false; =20 - if ((gpa & ~PAGE_MASK) + gpc->len > PAGE_SIZE) - return false; - - if (gpc->gpa !=3D gpa || gpc->generation !=3D slots->generation || + if (gpc->generation !=3D slots->generation || kvm_is_error_hva(gpc->uhva)) return false; =20 @@ -329,9 +326,9 @@ static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *g= pc, gpa_t gpa, unsigned l return ret; } =20 -int kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa) +int kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc) { - return __kvm_gpc_refresh(gpc, gpa, gpc->len); + return __kvm_gpc_refresh(gpc, gpc->gpa, gpc->len); } EXPORT_SYMBOL_GPL(kvm_gpc_refresh); =20 --=20 2.31.1