On 03/12/14 21:18, Christoffer Dall wrote:
> Introduce a new function to unmap user RAM regions in the stage2 page
> tables. This is needed on reboot (or when the guest turns off the MMU)
> to ensure we fault in pages again and make the dcache, RAM, and icache
> coherent.
>
> Using unmap_stage2_range for the whole guest physical range does not
> work, because that unmaps IO regions (such as the GIC) which will not be
> recreated or in the best case faulted in on a page-by-page basis.
>
> Call this function on secondary and subsequent calls to the
> KVM_ARM_VCPU_INIT ioctl so that a reset VCPU will detect the guest
> Stage-1 MMU is off when faulting in pages and make the caches coherent.
>
> Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
> ---
> arch/arm/include/asm/kvm_mmu.h | 1 +
> arch/arm/kvm/arm.c | 7 +++++
> arch/arm/kvm/mmu.c | 65 ++++++++++++++++++++++++++++++++++++++++
> arch/arm64/include/asm/kvm_mmu.h | 1 +
> 4 files changed, 74 insertions(+)
>
> diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
> index acb0d57..4654c42 100644
> --- a/arch/arm/include/asm/kvm_mmu.h
> +++ b/arch/arm/include/asm/kvm_mmu.h
> @@ -52,6 +52,7 @@ int create_hyp_io_mappings(void *from, void *to, phys_addr_t);
> void free_boot_hyp_pgd(void);
> void free_hyp_pgds(void);
>
> +void stage2_unmap_vm(struct kvm *kvm);
> int kvm_alloc_stage2_pgd(struct kvm *kvm);
> void kvm_free_stage2_pgd(struct kvm *kvm);
> int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
> index 4043769..da87c07 100644
> --- a/arch/arm/kvm/arm.c
> +++ b/arch/arm/kvm/arm.c
> @@ -701,6 +701,13 @@ static int kvm_arch_vcpu_ioctl_vcpu_init(struct kvm_vcpu *vcpu,
> if (ret)
> return ret;
>
> + /*
> + * Ensure a rebooted VM will fault in RAM pages and detect if the
> + * guest MMU is turned off and flush the caches as needed.
> + */
> + if (vcpu->arch.has_run_once)
> + stage2_unmap_vm(vcpu->kvm);
> +
> vcpu_reset_hcr(vcpu);
>
> /*
> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
> index 57a403a..b1f3c9a 100644
> --- a/arch/arm/kvm/mmu.c
> +++ b/arch/arm/kvm/mmu.c
> @@ -611,6 +611,71 @@ static void unmap_stage2_range(struct kvm *kvm, phys_addr_t start, u64 size)
> unmap_range(kvm, kvm->arch.pgd, start, size);
> }
>
> +static void stage2_unmap_memslot(struct kvm *kvm,
> + struct kvm_memory_slot *memslot)
> +{
> + hva_t hva = memslot->userspace_addr;
> + phys_addr_t addr = memslot->base_gfn << PAGE_SHIFT;
> + phys_addr_t size = PAGE_SIZE * memslot->npages;
> + hva_t reg_end = hva + size;
> +
> + /*
> + * A memory region could potentially cover multiple VMAs, and any holes
> + * between them, so iterate over all of them to find out if we should
> + * unmap any of them.
> + *
> + * +--------------------------------------------+
> + * +---------------+----------------+ +----------------+
> + * | : VMA 1 | VMA 2 | | VMA 3 : |
> + * +---------------+----------------+ +----------------+
> + * | memory region |
> + * +--------------------------------------------+
> + */
> + do {
> + struct vm_area_struct *vma = find_vma(current->mm, hva);
> + hva_t vm_start, vm_end;
> +
> + if (!vma || vma->vm_start >= reg_end)
> + break;
> +
> + /*
> + * Take the intersection of this VMA with the memory region
> + */
> + vm_start = max(hva, vma->vm_start);
> + vm_end = min(reg_end, vma->vm_end);
> +
> + if (!(vma->vm_flags & VM_PFNMAP)) {
> + gpa_t gpa = addr + (vm_start - memslot->userspace_addr);
> + unmap_stage2_range(kvm, gpa, vm_end - vm_start);
> + }
> + hva = vm_end;
> + } while (hva < reg_end);
> +}
> +
> +/**
> + * stage2_unmap_vm - Unmap Stage-2 RAM mappings
> + * @kvm: The struct kvm pointer
> + *
> + * Go through the memregions and unmap any reguler RAM
> + * backing memory already mapped to the VM.
> + */
> +void stage2_unmap_vm(struct kvm *kvm)
> +{
> + struct kvm_memslots *slots;
> + struct kvm_memory_slot *memslot;
> + int idx;
> +
> + idx = srcu_read_lock(&kvm->srcu);
> + spin_lock(&kvm->mmu_lock);
> +
> + slots = kvm_memslots(kvm);
> + kvm_for_each_memslot(memslot, slots)
> + stage2_unmap_memslot(kvm, memslot);
> +
> + spin_unlock(&kvm->mmu_lock);
> + srcu_read_unlock(&kvm->srcu, idx);
> +}
> +
> /**
> * kvm_free_stage2_pgd - free all stage-2 tables
> * @kvm: The KVM struct pointer for the VM.
> diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
> index 0caf7a5..061fed7 100644
> --- a/arch/arm64/include/asm/kvm_mmu.h
> +++ b/arch/arm64/include/asm/kvm_mmu.h
> @@ -83,6 +83,7 @@ int create_hyp_io_mappings(void *from, void *to, phys_addr_t);
> void free_boot_hyp_pgd(void);
> void free_hyp_pgds(void);
>
> +void stage2_unmap_vm(struct kvm *kvm);
> int kvm_alloc_stage2_pgd(struct kvm *kvm);
> void kvm_free_stage2_pgd(struct kvm *kvm);
> int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
>
Acked-by: Marc Zyngier <marc.zyngier@xxxxxxx>
M.
--
Jazz is not dead. It just smells funny...
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