On Thu, Oct 27, 2022, Peter Gonda wrote: > On Wed, Oct 19, 2022 at 10:34 AM Sean Christopherson <seanjc@xxxxxxxxxx> wrote: > > > > On Tue, Oct 18, 2022, Peter Gonda wrote: > > > On Mon, Oct 17, 2022 at 2:34 PM Sean Christopherson <seanjc@xxxxxxxxxx> wrote: > > > > > > > > On Mon, Oct 17, 2022, Peter Gonda wrote: > > > > > I think this means we don't need to add VM_MODE_PXXV48_4K_SEV since we > > > > > can set up the c-bit from inside of vm_sev_create_*(), thoughts? > > > > > > > > Configuring the C-bit inside vm_sev_create_*() won't work (at least not well). > > > > The C-bit needs to be known before kvm_vm_elf_load(), i.e. can't be handled after > > > > __vm_create(), and needs to be tracked inside the VM, i.e. can't be handled before > > > > __vm_create(). > > > > > > > > The proposed kvm_init_vm_address_properties() seems like the best fit since the > > > > C-bit (and TDX's S-bit) is stolen from GPA space, i.e. directly affects the other > > > > values computed in that path. > > > > > > > > As for the kvm_vm_arch allocation ugliness, when we talked off-list I didn't > > > > consider the need to allocate in kvm_init_vm_address_properties(). That's quite > > > > gross, especially since the pointer will be larger than the thing being allocated. > > > > > > > > With that in mind, adding .../include/<arch>/kvm_util.h so that "struct kvm_vm_arch" > > > > can be defined and referenced directly doesn't seem so bad. Having to stub in the > > > > struct for the other architectures is annoying, but not the end of the world. > > > > > > I'll make "struct kvm_vm_arch" a non pointer member, so adding > > > /include/<arch>/kvm_util.h files. > > > > > > But I think we do not need VM_MODE_PXXV48_4K_SEV, see: > > > > I really don't want to open code __vm_create() with a slight tweak. E.g. the > > below code will be broken by Ricardo's series to add memslot0 is moved out of > > ____vm_create()[1], and kinda sorta be broken again by Vishal's series to add an > > arch hook to __vm_create()[2]. > > > > AFAICT, there is no requirement that KVM_SEV_INIT be called before computing the > > C-Bit, the only requirement is that KVM_SEV_INIT is called before adding vCPUs. > > > > [1] https://lore.kernel.org/all/20221017195834.2295901-8-ricarkol@xxxxxxxxxx > > [2] https://lore.kernel.org/all/YzsC4ibDqGh5qaP9@xxxxxxxxxx > > Oh I misunderstood your suggestion above. > > I should make KVM_SEV_INIT happen from kvm_arch_vm_post_create(). Add > VM_MODE_PXXV48_4K_SEV for c-bit setting inside of > kvm_init_vm_address_properties(). > > Inside of vm_sev_create_with_one_vcpu() I use > __vm_create_with_vcpus(), then call KVM_SEV_LAUNCH_FINISH. > > Is that correct? Yep, I'm pretty sure that was what I was thinking.
