From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELvzyiqH0tMhsP9OW7BA5/lB0kE6diQ8Cefnumnpd4cPPPA/FLGjgdGEx5TnzeNO3gHACstM ARC-Seal: i=1; a=rsa-sha256; t=1520451813; cv=none; d=google.com; s=arc-20160816; b=zIsO1fgUkftVMZUmT4jbboHAsvIp0NMAFU6u7OBn+YqtHOUUzw22NBB4IlXi/XV4pZ lIwcBZSQ+pjH5C1HX8N7IYLUZ4v14V5ORaKazb5egawZA+pPetWgSSDoYLRJgjVAzFt/ dYYy1+yHqK++TnJD+rSE2b6AMq8B2L5WsYlQeHv1MSiA49HZZWwTDH7MYxr8pmUs9x4X 49l7MlRH96Kti3pXUorpKOZKTGhE6FHG8m2hRRi3RTdTD6iZ9f7gxWsrXIQsPD6ZgPKf MeHneS4IwFqNeAMbJ03Otv6PGknh7LJzRKmiTbbCD2CuAEdmY7UqlNqvjEqv+BEj0LLy tBOQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=YJjD67KlFJqH218hfgYusGtwVsdAskYiIfyMyLdlk4k=; b=cw3Fd3X7eGjWvwLtfy11jtMjwFTrdSODCeb4L0yiM8/LvsNjz0fg1ce2ysS8r7aLvE Lch1cibDGqMfwUJtosDnZiu4Cc06MFfoFnjzVjFFdsWCd1oG0LwXwDbm7ZuYqTw87TOM 32ttcLvhvwmvJ+jE6KgjZup1WWFhkXv3rUm8tA8BSUp4TqFGqrx7s997QMhb4p52EzTe MlHhIDZ/CS/+Opaqsxg+xwFnehLrjmFBze3qfaxx9JOdwBqwS50Papf6koFQz2ZLyMOm 6IRkTUGlz2hMP7bjX9uk0vnH7eys2tEv4KMKXA9N3a41iaDB4FjTZKDUlWuN3jubiZ7w pU0Q== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 185.236.200.248 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 185.236.200.248 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, David Hildenbrand , Christian Borntraeger Subject: [PATCH 4.15 104/122] KVM: s390: consider epoch index on TOD clock syncs Date: Wed, 7 Mar 2018 11:38:36 -0800 Message-Id: <20180307191744.549054908@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180307191729.190879024@linuxfoundation.org> References: <20180307191729.190879024@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1594309280290613110?= X-GMAIL-MSGID: =?utf-8?q?1594309280290613110?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Hildenbrand commit 1575767ef3cf5326701d2ae3075b7732cbc855e4 upstream. For now, we don't take care of over/underflows. Especially underflows are critical: Assume the epoch is currently 0 and we get a sync request for delta=1, meaning the TOD is moved forward by 1 and we have to fix it up by subtracting 1 from the epoch. Right now, this will leave the epoch index untouched, resulting in epoch=-1, epoch_idx=0, which is wrong. We have to take care of over and underflows, also for the VSIE case. So let's factor out calculation into a separate function. Signed-off-by: David Hildenbrand Message-Id: <20180207114647.6220-5-david@redhat.com> Reviewed-by: Christian Borntraeger Fixes: 8fa1696ea781 ("KVM: s390: Multiple Epoch Facility support") Cc: stable@vger.kernel.org Signed-off-by: Christian Borntraeger [use u8 for idx] Signed-off-by: Greg Kroah-Hartman --- arch/s390/kvm/kvm-s390.c | 32 +++++++++++++++++++++++++++++--- 1 file changed, 29 insertions(+), 3 deletions(-) --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -166,6 +166,28 @@ int kvm_arch_hardware_enable(void) static void kvm_gmap_notifier(struct gmap *gmap, unsigned long start, unsigned long end); +static void kvm_clock_sync_scb(struct kvm_s390_sie_block *scb, u64 delta) +{ + u8 delta_idx = 0; + + /* + * The TOD jumps by delta, we have to compensate this by adding + * -delta to the epoch. + */ + delta = -delta; + + /* sign-extension - we're adding to signed values below */ + if ((s64)delta < 0) + delta_idx = -1; + + scb->epoch += delta; + if (scb->ecd & ECD_MEF) { + scb->epdx += delta_idx; + if (scb->epoch < delta) + scb->epdx += 1; + } +} + /* * This callback is executed during stop_machine(). All CPUs are therefore * temporarily stopped. In order not to change guest behavior, we have to @@ -181,13 +203,17 @@ static int kvm_clock_sync(struct notifie unsigned long long *delta = v; list_for_each_entry(kvm, &vm_list, vm_list) { - kvm->arch.epoch -= *delta; kvm_for_each_vcpu(i, vcpu, kvm) { - vcpu->arch.sie_block->epoch -= *delta; + kvm_clock_sync_scb(vcpu->arch.sie_block, *delta); + if (i == 0) { + kvm->arch.epoch = vcpu->arch.sie_block->epoch; + kvm->arch.epdx = vcpu->arch.sie_block->epdx; + } if (vcpu->arch.cputm_enabled) vcpu->arch.cputm_start += *delta; if (vcpu->arch.vsie_block) - vcpu->arch.vsie_block->epoch -= *delta; + kvm_clock_sync_scb(vcpu->arch.vsie_block, + *delta); } } return NOTIFY_OK;