From mboxrd@z Thu Jan 1 00:00:00 1970 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 55C7AC433EF for ; Thu, 28 Apr 2022 07:36:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245550AbiD1Hj1 (ORCPT ); Thu, 28 Apr 2022 03:39:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43062 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245649AbiD1HjH (ORCPT ); Thu, 28 Apr 2022 03:39:07 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 6E1ED9AE40 for ; Thu, 28 Apr 2022 00:35:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1651131352; 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=OqfdA0bLR2lU6dIJnTIPrt1WfOytY9LJKfbf8xcOP6k=; b=FO1GvlVd1+aMjqhen1N9epQo10xJSrCv8s5XDvEpl3pOVI9FsU7R1HIJ3I6h2OyjipOnDK 0hQmjPx4RZHwAhyxQZHAVkKj9is4kWdAt/ttArYqaisqTcPFmu4KfiQn4WlTDjju5swPv3 KWHKrvygs3g9LbxFZFP13P0F0ATYB08= 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-225-mvpQepD2MrqNQ2MYjfAh-A-1; Thu, 28 Apr 2022 03:35:48 -0400 X-MC-Unique: mvpQepD2MrqNQ2MYjfAh-A-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 42F39811E75; Thu, 28 Apr 2022 07:35:48 +0000 (UTC) Received: from starship (unknown [10.40.192.41]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2F0C7407E240; Thu, 28 Apr 2022 07:35:45 +0000 (UTC) Message-ID: <61ad22d6de1f6a51148d2538f992700cac5540d4.camel@redhat.com> Subject: Re: [PATCH v2 02/11] KVM: SVM: Don't BUG if userspace injects a soft interrupt with GIF=0 From: Maxim Levitsky To: Sean Christopherson , Paolo Bonzini Cc: Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, "Maciej S . Szmigiero" Date: Thu, 28 Apr 2022 10:35:45 +0300 In-Reply-To: <20220423021411.784383-3-seanjc@google.com> References: <20220423021411.784383-1-seanjc@google.com> <20220423021411.784383-3-seanjc@google.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2022-04-23 at 02:14 +0000, Sean Christopherson wrote: > From: Maciej S. Szmigiero > > Don't BUG/WARN on interrupt injection due to GIF being cleared if the > injected event is a soft interrupt, which are not actually IRQs and thus Are any injected events subject to GIF set? I think that EVENTINJ just injects unconditionaly whatever hypervisor puts in it. Best regards, Maxim Levitsky > not subject to IRQ blocking conditions. KVM doesn't currently use event > injection to handle incomplete soft interrupts, but it's trivial for > userspace to force the situation via KVM_SET_VCPU_EVENTS. > > Opportunistically downgrade the BUG_ON() to WARN_ON(), there's no need to > bring down the whole host just because there might be some issue with > respect to guest GIF handling in KVM, or as evidenced here, an egregious > oversight with respect to KVM's uAPI. > > kernel BUG at arch/x86/kvm/svm/svm.c:3386! > invalid opcode: 0000 [#1] SMP > CPU: 15 PID: 926 Comm: smm_test Not tainted 5.17.0-rc3+ #264 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 > RIP: 0010:svm_inject_irq+0xab/0xb0 [kvm_amd] > Code: <0f> 0b 0f 1f 00 0f 1f 44 00 00 80 3d ac b3 01 00 00 55 48 89 f5 53 > RSP: 0018:ffffc90000b37d88 EFLAGS: 00010246 > RAX: 0000000000000000 RBX: ffff88810a234ac0 RCX: 0000000000000006 > RDX: 0000000000000000 RSI: ffffc90000b37df7 RDI: ffff88810a234ac0 > RBP: ffffc90000b37df7 R08: ffff88810a1fa410 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > R13: ffff888109571000 R14: ffff88810a234ac0 R15: 0000000000000000 > FS: 0000000001821380(0000) GS:ffff88846fdc0000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007f74fc550008 CR3: 000000010a6fe000 CR4: 0000000000350ea0 > Call Trace: > > inject_pending_event+0x2f7/0x4c0 [kvm] > kvm_arch_vcpu_ioctl_run+0x791/0x17a0 [kvm] > kvm_vcpu_ioctl+0x26d/0x650 [kvm] > __x64_sys_ioctl+0x82/0xb0 > do_syscall_64+0x3b/0xc0 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > > Fixes: 219b65dcf6c0 ("KVM: SVM: Improve nested interrupt injection") > Cc: stable@vger.kernel.org > Signed-off-by: Maciej S. Szmigiero > Co-developed-by: Sean Christopherson > Signed-off-by: Sean Christopherson > --- > arch/x86/kvm/svm/svm.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index 75b4f3ac8b1a..151fba0b405f 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -3384,7 +3384,7 @@ static void svm_inject_irq(struct kvm_vcpu *vcpu) > { > struct vcpu_svm *svm = to_svm(vcpu); > > - BUG_ON(!(gif_set(svm))); > + WARN_ON(!vcpu->arch.interrupt.soft && !gif_set(svm)); > > trace_kvm_inj_virq(vcpu->arch.interrupt.nr); > ++vcpu->stat.irq_injections;