The generic KVM_PRE_FAULT_MEMORY ioctl lets userspace populate KVM page tables before running a vCPU over a GPA range. x86 already supports the ioctl, but RISC-V does not expose the capability and has no arch hook.
Add the RISC-V arch hook and reuse the existing G-stage fault mapping path with a read access. Report progress using the G-stage mapping returned by the map path, so the ioctl can advance by the actual leaf size that covers the requested GPA. Retry until a mapping is installed or a signal, VM-dead request, or real error is observed. Signed-off-by: Jinyu Tang <[email protected]> --- arch/riscv/kvm/Kconfig | 1 + arch/riscv/kvm/gstage.c | 3 +++ arch/riscv/kvm/mmu.c | 45 ++++++++++++++++++++++++++++++++++++++++- arch/riscv/kvm/vm.c | 1 + 4 files changed, 49 insertions(+), 1 deletion(-) diff --git a/arch/riscv/kvm/Kconfig b/arch/riscv/kvm/Kconfig index ec2cee0a39e0..8ac209e8ac87 100644 --- a/arch/riscv/kvm/Kconfig +++ b/arch/riscv/kvm/Kconfig @@ -28,6 +28,7 @@ config KVM select KVM_COMMON select KVM_GENERIC_DIRTYLOG_READ_PROTECT select KVM_GENERIC_HARDWARE_ENABLING + select KVM_GENERIC_PRE_FAULT_MEMORY select KVM_MMIO select VIRT_XFER_TO_GUEST_WORK select SCHED_INFO diff --git a/arch/riscv/kvm/gstage.c b/arch/riscv/kvm/gstage.c index 54d45addf18f..dff315dfd24e 100644 --- a/arch/riscv/kvm/gstage.c +++ b/arch/riscv/kvm/gstage.c @@ -286,6 +286,9 @@ int kvm_riscv_gstage_map_page(struct kvm_gstage *gstage, out_map->level, true); } else if (ALIGN_DOWN(PFN_PHYS(pte_pfn(ptep_get(ptep))), page_size) == hpa) { kvm_riscv_gstage_update_pte_prot(gstage, ptep_level, gpa, ptep, prot); + out_map->addr = ALIGN_DOWN(gpa, page_size); + out_map->level = ptep_level; + out_map->pte = ptep_get(ptep); return 0; } } diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c index 2fabcd409991..f6ca86da53eb 100644 --- a/arch/riscv/kvm/mmu.c +++ b/arch/riscv/kvm/mmu.c @@ -717,7 +717,7 @@ int kvm_riscv_mmu_map(struct kvm_vcpu *vcpu, struct kvm_memory_slot *memslot, if (hfn == KVM_PFN_ERR_HWPOISON) { send_sig_mceerr(BUS_MCEERR_AR, (void __user *)hva, vma_pageshift, current); - return 0; + return -EFAULT; } if (is_error_noslot_pfn(hfn)) return -EFAULT; @@ -782,6 +782,49 @@ int kvm_riscv_mmu_map(struct kvm_vcpu *vcpu, struct kvm_memory_slot *memslot, return ret; } +long kvm_arch_vcpu_pre_fault_memory(struct kvm_vcpu *vcpu, + struct kvm_pre_fault_memory *range) +{ + struct kvm_gstage_mapping out_map = { 0 }; + struct kvm_memory_slot *memslot; + unsigned long map_size; + unsigned long hva; + gpa_t end; + gfn_t gfn; + int ret; + + gfn = gpa_to_gfn(range->gpa); + memslot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); + if (!memslot) + return -ENOENT; + + hva = gfn_to_hva_memslot_prot(memslot, gfn, NULL); + if (kvm_is_error_hva(hva)) + return -ENOENT; + + for (;;) { + if (signal_pending(current)) + return -EINTR; + + if (kvm_check_request(KVM_REQ_VM_DEAD, vcpu)) + return -EIO; + + cond_resched(); + ret = kvm_riscv_mmu_map(vcpu, memslot, range->gpa, hva, false, &out_map); + if (ret) + return ret; + + if (!pte_val(out_map.pte)) + continue; + + map_size = PAGE_SIZE << (out_map.level * kvm_riscv_gstage_index_bits); + end = out_map.addr + map_size; + break; + } + + return min_t(u64, range->size, end - range->gpa); +} + int kvm_riscv_mmu_alloc_pgd(struct kvm *kvm) { struct page *pgd_page; diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c index a9f083feeb76..58500a19b33b 100644 --- a/arch/riscv/kvm/vm.c +++ b/arch/riscv/kvm/vm.c @@ -187,6 +187,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_MP_STATE: case KVM_CAP_IMMEDIATE_EXIT: case KVM_CAP_SET_GUEST_DEBUG: + case KVM_CAP_PRE_FAULT_MEMORY: r = 1; break; case KVM_CAP_NR_VCPUS: -- 2.43.0
