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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/9/24 21:02, Sean Christopherson wrote: > Disallow read-only memory for all VMs with protected state, i.e. for > upcoming TDX VMs as well as ES/SNP VMs. For TDX, it's actually possible > to support read-only memory, as TDX uses EPT Violation #VE to reflect the > fault into the guest, e.g. KVM could configure read-only SPTEs with RX > protections and SUPPRESS_VE=0. But there is no strong use case for > supporting read-only memslots on TDX, e.g. the main historical usage is > to emulate option ROMs, but TDX disallows executing from shared memory. > And if someone comes along with a legitimate, strong use case, the > restriction can always be lifted for TDX. > > Don't bother trying to retroactively apply the restriction to SEV-ES > VMs that are created as type KVM_X86_DEFAULT_VM. Read-only memslots can't > possibly work for SEV-ES, i.e. disallowing such memslots is really just > means reporting an error to userspace instead of silently hanging vCPUs. > Trying to deal with the ordering between KVM_SEV_INIT and memslot creation > isn't worth the marginal benefit it would provide userspace. Queuing this one for 6.11, thanks. Paolo