From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
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@xxxxxxx>
Reviewed-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
---
arch/arm/kvm/mmu.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++------
1 file changed, 69 insertions(+), 8 deletions(-)
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index a7eabd1..6038027 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -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);
}
--
2.1.1
--
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