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arm/arm64: KVM: map MMIO regions at creation time

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There is really no point in faulting in memory regions page by page
if they are not backed by demand paged system RAM but by a linear
passthrough mapping of a host MMIO region. So instead, detect such
regions at setup time and install the mappings for the backing all
at once.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
This commit is contained in:
Ard Biesheuvel 2014-10-10 17:00:32 +02:00 committed by Christoffer Dall
parent 4a513fb009
commit 8eef91239e
1 changed files with 69 additions and 8 deletions
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77
arch/arm/kvm/mmu.c
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@ -1134,13 +1134,6 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
const struct kvm_memory_slot *old,
enum kvm_mr_change change)
{
gpa_t gpa = old->base_gfn << PAGE_SHIFT;
phys_addr_t size = old->npages << PAGE_SHIFT;
if (change == KVM_MR_DELETE || change == KVM_MR_MOVE) {
spin_lock(&kvm->mmu_lock);
unmap_stage2_range(kvm, gpa, size);
spin_unlock(&kvm->mmu_lock);
}
}
int kvm_arch_prepare_memory_region(struct kvm *kvm,
@ -1148,7 +1141,69 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
struct kvm_userspace_memory_region *mem,
enum kvm_mr_change change)
{
return 0;
hva_t hva = mem->userspace_addr;
hva_t reg_end = hva + mem->memory_size;
bool writable = !(mem->flags & KVM_MEM_READONLY);
int ret = 0;
if (change != KVM_MR_CREATE && change != KVM_MR_MOVE)
return 0;
/*
* A memory region could potentially cover multiple VMAs, and any holes
* between them, so iterate over all of them to find out if we can map
* any of them right now.
*
* +--------------------------------------------+
* +---------------+----------------+ +----------------+
* | : 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;
/*
* Mapping a read-only VMA is only allowed if the
* memory region is configured as read-only.
*/
if (writable && !(vma->vm_flags & VM_WRITE)) {
ret = -EPERM;
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 = mem->guest_phys_addr +
(vm_start - mem->userspace_addr);
phys_addr_t pa = (vma->vm_pgoff << PAGE_SHIFT) +
vm_start - vma->vm_start;
ret = kvm_phys_addr_ioremap(kvm, gpa, pa,
vm_end - vm_start,
writable);
if (ret)
break;
}
hva = vm_end;
} while (hva < reg_end);
if (ret) {
spin_lock(&kvm->mmu_lock);
unmap_stage2_range(kvm, mem->guest_phys_addr, mem->memory_size);
spin_unlock(&kvm->mmu_lock);
}
return ret;
}
void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
@ -1173,4 +1228,10 @@ void kvm_arch_flush_shadow_all(struct kvm *kvm)
void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
struct kvm_memory_slot *slot)
{
gpa_t gpa = slot->base_gfn << PAGE_SHIFT;
phys_addr_t size = slot->npages << PAGE_SHIFT;
spin_lock(&kvm->mmu_lock);
unmap_stage2_range(kvm, gpa, size);
spin_unlock(&kvm->mmu_lock);
}