On Wed, Jul 24, 2024 at 06:16:37PM +0100, David Woodhouse wrote: > From: David Woodhouse <dwmw@xxxxxxxxxxxx> > > The vmclock "device" provides a shared memory region with precision clock > information. By using shared memory, it is safe across Live Migration. > > Like the KVM PTP clock, this can convert TSC-based cross timestamps into > KVM clock values. Unlike the KVM PTP clock, it does so only when such is > actually helpful. > > The memory region of the device is also exposed to userspace so it can be > read or memory mapped by application which need reliable notification of > clock disruptions. > > Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx> one other thing worth mentioning is that this design can't work with confidential computing setups. By comparison, mapping e.g. a range in a PCI BAR would work for these setups. Is there a reason this functionality is not interesting for confidential VMs? -- MST
