On Wed, 2024-04-10 at 15:07 -0700, isaku.yamahata@xxxxxxxxx wrote:
> From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
>
> Wire KVM_MAP_MEMORY ioctl to kvm_mmu_map_tdp_page() to populate guest
> memory. When KVM_CREATE_VCPU creates vCPU, it initializes the x86
> KVM MMU part by kvm_mmu_create() and kvm_init_mmu(). vCPU is ready to
> invoke the KVM page fault handler.
>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> ---
> v2:
> - Catch up the change of struct kvm_memory_mapping. (Sean)
> - Removed mapping level check. Push it down into vendor code. (David, Sean)
> - Rename goal_level to level. (Sean)
> - Drop kvm_arch_pre_vcpu_map_memory(), directly call kvm_mmu_reload().
> (David, Sean)
> - Fixed the update of mapping.
> ---
> arch/x86/kvm/x86.c | 30 ++++++++++++++++++++++++++++++
> 1 file changed, 30 insertions(+)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 2d2619d3eee4..2c765de3531e 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -4713,6 +4713,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long
> ext)
> case KVM_CAP_VM_DISABLE_NX_HUGE_PAGES:
> case KVM_CAP_IRQFD_RESAMPLE:
> case KVM_CAP_MEMORY_FAULT_INFO:
> + case KVM_CAP_MAP_MEMORY:
> r = 1;
> break;
Should we add this after all of the pieces are in place?
> case KVM_CAP_EXIT_HYPERCALL:
> @@ -5867,6 +5868,35 @@ static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu
> *vcpu,
> }
> }
>
> +int kvm_arch_vcpu_map_memory(struct kvm_vcpu *vcpu,
> + struct kvm_memory_mapping *mapping)
> +{
> + u64 end, error_code = 0;
> + u8 level = PG_LEVEL_4K;
> + int r;
> +
> + /*
> + * Shadow paging uses GVA for kvm page fault. The first
> implementation
> + * supports GPA only to avoid confusion.
> + */
> + if (!tdp_enabled)
> + return -EOPNOTSUPP;
It's not confusion, it's that you can't pre-map GPAs for legacy shadow paging.
Or you are saying why not to support pre-mapping GVAs? I think that discussion
belongs more in the commit log. The code should just say it's not possible to
pre-map GPAs in shadow paging.
> +
> + /* reload is optimized for repeated call. */
> + kvm_mmu_reload(vcpu);
> +
> + r = kvm_tdp_map_page(vcpu, mapping->base_address, error_code, &level);
> + if (r)
> + return r;
> +
> + /* mapping->base_address is not necessarily aligned to level-hugepage.
> */
> + end = (mapping->base_address & KVM_HPAGE_MASK(level)) +
> + KVM_HPAGE_SIZE(level);
> + mapping->size -= end - mapping->base_address;
> + mapping->base_address = end;
> + return r;
> +}
> +
> long kvm_arch_vcpu_ioctl(struct file *filp,
> unsigned int ioctl, unsigned long arg)
> {
