From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47629) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XMZWJ-0003mH-Ef for qemu-devel@nongnu.org; Wed, 27 Aug 2014 05:28:05 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XMZWD-0001KD-6s for qemu-devel@nongnu.org; Wed, 27 Aug 2014 05:27:59 -0400 Message-ID: <53FDA495.6040303@suse.de> Date: Wed, 27 Aug 2014 11:27:49 +0200 From: Alexander Graf MIME-Version: 1.0 References: <1408097555-28126-1-git-send-email-aik@ozlabs.ru> <1408097555-28126-3-git-send-email-aik@ozlabs.ru> In-Reply-To: <1408097555-28126-3-git-send-email-aik@ozlabs.ru> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC PATCH v2 02/13] spapr_iommu: Disable in-kernel IOMMU tables for >4GB windows List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexey Kardashevskiy , qemu-devel@nongnu.org Cc: Alex Williamson , qemu-ppc@nongnu.org, Gavin Shan , David Gibson On 15.08.14 12:12, Alexey Kardashevskiy wrote: > The existing KVM_CREATE_SPAPR_TCE ioctl only support 4G windows max. > We are going to add huge DMA windows support so this will create small > window and unexpectedly fail later. > > This disables KVM_CREATE_SPAPR_TCE for windows bigger that 4GB. Since > those windows are normally mapped at the boot time, there will be no > performance impact. > > Signed-off-by: Alexey Kardashevskiy > --- > hw/ppc/spapr_iommu.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/hw/ppc/spapr_iommu.c b/hw/ppc/spapr_iommu.c > index f6e32a4..36f5d27 100644 > --- a/hw/ppc/spapr_iommu.c > +++ b/hw/ppc/spapr_iommu.c > @@ -113,11 +113,11 @@ static MemoryRegionIOMMUOps spapr_iommu_ops = { > static int spapr_tce_table_realize(DeviceState *dev) > { > sPAPRTCETable *tcet = SPAPR_TCE_TABLE(dev); > + uint64_t window_size = tcet->nb_table << tcet->page_shift; > > - if (kvm_enabled()) { > + if (kvm_enabled() && !(window_size >> 32)) { Please add a comment here that explains the reasoning. Alex