On 4/19/22 1:21 PM, Daniel P. Berrangé wrote: > On Tue, Apr 19, 2022 at 12:05:29PM -0400, Cole Robinson wrote: >> On 4/4/22 11:49 AM, Charles Arnold wrote: >>> >>> >>> On 4/4/22 6:50 AM, Daniel P. Berrangé wrote: >>>> On Fri, Apr 01, 2022 at 12:13:17PM -0600, Charles Arnold wrote: >>>>> From d700e8cee7cd525c0022b5a9a440f64c4ab149f0 Mon Sep 17 00:00:00 2001 >>>>> From: Charles Arnold <carnold@xxxxxxxx> >>>>> Date: Fri, 1 Apr 2022 12:01:21 -0600 >>>>> Subject: [PATCH 1/1] Add support for enabling Secure Encrypted >>>>> Virtualization >>>>> in the GUI >>>>> >>>>> Add an "Enable Launch Security" checkbox on the Details memory tab. >>>>> Do the minimal configuration required for libvirt to enable this feature >>>>> on compatible hardware. >>>>> >>>> Don't we need to turn on the 'iommu' option for all virtio devices >>>> too, and disable PXE on any NICs ? >>>> >>>> https://libvirt.org/kbase/launch_security_sev.html#virtio >>>> >>> >>> I used to enumerate through the virtio devices in an old version of this >>> patch >>> for virt-manager and enable iommu but it really wasn't reasonable for >>> virt-manager to track which virtio devices needed iommu enabled. >>> Additionally, >>> libvirt will sometimes add a device when a VM is created. This patch >>> leans on libvirt to do the right thing when sev is enabled similar to what >>> happens when launch security is specified on the virt-install command line. >>> >> >> Yeah, I would still like to see libvirt do this unless there's a good >> reason why it can't. From my July 2020 mail >> https://listman.redhat.com/archives/virt-tools-list/2020-July/017087.html >> >>> if sev >>> launchSecurity _requires_ every virtio device to have iommu='on' then >>> libvirt should be setting that itself. It doesn't need to hardcode it >>> into the XML, it can set it at VM startup time. If the user set an >>> explicit value in the XML then honor that but otherwise fill it in at >>> runtime when it is required. Trying to deal with this in an app where we >>> want to advertise turning the config off is basically an impossible >>> problem to know if we are going to undo any explicit user config or not. >> >> danpb does this sound reasonable? If so I can work on this. > > Something automagic sounds ok > >> Also, anyone know if TDX and SNP will require virtio iommu setting as well? > > I expect SNP will, but no idea about TDX. > So apparently qemu 6.0.0+ already does this for us: https://gitlab.com/qemu-project/qemu/-/commit/9f88a7a3df Which is strange because some of my sev testing definitely failed with an iommu sounding error in the guest kernel until I enabled iommu on virtio-blk, but I can't reproduce now. Maybe I was using an older qemu, I think the host was fedora 34 at the time I'll send a patch for libvirt docs I'll give this patch another look too Thanks, Cole
