From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60660) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dmbYz-000053-QL for qemu-devel@nongnu.org; Tue, 29 Aug 2017 04:07:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dmbYu-0004pe-Rk for qemu-devel@nongnu.org; Tue, 29 Aug 2017 04:07:57 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35228) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dmbYu-0004pM-Ie for qemu-devel@nongnu.org; Tue, 29 Aug 2017 04:07:52 -0400 Date: Tue, 29 Aug 2017 10:07:46 +0200 From: Cornelia Huck Message-ID: <20170829100746.66c47fd8.cohuck@redhat.com> In-Reply-To: <498a00ca-ea1a-ae09-0772-4a25c729841e@linux.vnet.ibm.com> References: <1503907487-2764-1-git-send-email-zyimin@linux.vnet.ibm.com> <1503907487-2764-5-git-send-email-zyimin@linux.vnet.ibm.com> <20170828175722.0b54b59a.cohuck@redhat.com> <498a00ca-ea1a-ae09-0772-4a25c729841e@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH 4/4] s390x/pci: add iommu replay callback List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Yi Min Zhao Cc: qemu-devel@nongnu.org, borntraeger@de.ibm.com, pasic@linux.vnet.ibm.com, pmorel@linux.vnet.ibm.com, agraf@suse.de, richard.henderson@linaro.org [Restored cc:s. Please remember to do reply-all.] On Tue, 29 Aug 2017 12:46:51 +0800 Yi Min Zhao wrote: > =E5=9C=A8 2017/8/28 =E4=B8=8B=E5=8D=8811:57, Cornelia Huck =E5=86=99=E9= =81=93: > > On Mon, 28 Aug 2017 10:04:47 +0200 > > Yi Min Zhao wrote: > > > >> Let's introduce iommu replay callback for s390 pci iommu memory region. > >> Currently we don't need any dma mapping replay. So let it return > >> directly. This implementation will avoid meaningless loops calling > >> translation callback. > >> > >> Reviewed-by: Pierre Morel > >> Reviewed-by: Halil Pasic > >> Signed-off-by: Yi Min Zhao > >> --- > >> hw/s390x/s390-pci-bus.c | 8 ++++++++ > >> 1 file changed, 8 insertions(+) > >> > >> diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c > >> index 9e1f7ff5c5..359509ccea 100644 > >> --- a/hw/s390x/s390-pci-bus.c > >> +++ b/hw/s390x/s390-pci-bus.c > >> @@ -407,6 +407,13 @@ static IOMMUTLBEntry s390_translate_iommu(IOMMUMe= moryRegion *mr, hwaddr addr, > >> return ret; > >> } > >> =20 > >> +static void s390_pci_iommu_replay(IOMMUMemoryRegion *iommu, > >> + IOMMUNotifier *notifier) > >> +{ > >> + /* we don't need iommu replay currently */ > > This really needs to be heavier on the _why_. My guess is that anything > > which would require replay goes through the rpcit instruction? > My understanding is: > Our arch is different from others. Each pci device has its own iommu, not > like other archs' implementation. So currently there must be no existing > mappings belonging to any newly plugged pci device whose iommu doesn't > have any mapping at the time. So please put that explanation into the function. (Also, "currently"? Are we expecting it to change?) > In addition, it's also due to vfio blocking migration. If vfio-pci suppor= ts > migration in future, we could implement iommu replay by that time. That's not an argument: This is the base zpci support, it should not depend on the supported devices and what they do. (What's the status of virtio-pci, btw? Does it work with your patches applied, or is there still more to be done?)