On Mon, Jun 22, 2026 at 03:53:33PM +0400, Marc-André Lureau wrote: > Hi Peter > > On Fri, Jun 19, 2026 at 7:13 PM Peter Xu <[email protected]> wrote: > > > > On Fri, Jun 19, 2026 at 12:11:48AM +0400, Marc-André Lureau wrote: > > > Hi > > > > > > On Thu, Jun 4, 2026 at 5:46 PM Marc-André Lureau > > > <[email protected]> wrote: > > > > > > > > Hi, > > > > > > > > This is an attempt to fix the incompatibility of virtio-mem with > > > > confidential > > > > VMs. The solution implements what was discussed earlier with D. > > > > Hildenbrand: > > > > https://patchwork.ozlabs.org/project/qemu-devel/patch/[email protected]/#3502238 > > > > > > > > The first patches are misc cleanups. Then some code refactoring to have > > > > split a > > > > manager/source. And finally, the manager learns to deal with multiple > > > > sources. > > > > > > > > This has been tested together with the Linux kernel series from > > > > Zhenzhong Duan [1] for TDX guests. > > > > > > > > (help fix https://issues.redhat.com/browse/RHEL-131968) > > > > > > Can the patch 1-11 be queued or are we missing something? > > > (RFC patch 12 can be dropped for now) > > > > Likely yes.. one thing to double check with you before I do: We don't need > > the kernel series, do we? Since when unplug, I expect with the truncation > > approach that this series proposed, KVM will emit TDH.MEM.PAGE.REMOVE then > > unaccept is done (?). > > > Say, what happens if we run QEMU with this series applied, but without the > > kernel series? > > The kernel series is needed at least for PAGE.ACCEPT. Without it, QEMU > will have KVM_RUN return EIO, and finish into assert (while tearing > down ioeventfd).
Could you elaborate a bit more on why ACCEPT would fail? I used to ask the event flow here: https://lore.kernel.org/qemu-devel/[email protected]/ If AUG existed, then why ACCEPT would fail? PS: I didn't read a lot of what a Linux guest would do; I know there're some lazy accept approach, but IIUC it's only a matter of time to ACCEPT, not correctness. My understanding is if we properly notify these new slots with AUG, then it should be able to ACCEPT? > > > What confused me a bit is the dependency of this series v.s. the kernel > > one. It seems to use different approaches, but then I don't understand why > > this series was tested with the kernel change. > > My understanding is that the kernel may perform TDG.MEM.PAGE.RELEASE. > That depends on TDX config TDCS_CONFIG_PAGE_RELEASE which qemu/kvm > doesnt currently control. I don't know whether this is then > redundant/needless with qemu doing discard on the guest_memfd.. The problem is if this series depends on the kernel series, should we then wait for the kernel solution be accepted first in case it'll change? But obviously I still don't yet fully understand how this whole thing works.. :( Thanks, -- Peter Xu
