Hi Keqian,
On 4/16/21 12:03 AM, Keqian Zhu wrote:
The MMIO regions may be unmapped for many reasons and can be remapped
by stage2 fault path. Map MMIO regions at creation time becomes a
minor optimization and makes these two mapping path hard to sync.
Remove the mapping code while keep the useful sanity check.
Signed-off-by: Keqian Zhu <zhukeqian1@xxxxxxxxxx>
---
arch/arm64/kvm/mmu.c | 38 +++-----------------------------------
1 file changed, 3 insertions(+), 35 deletions(-)
After removing the logic to create stage2 mapping for VM_PFNMAP region,
I think the "do { } while" loop becomes unnecessary and can be dropped
completely. It means the only sanity check is to see if the memory slot
overflows IPA space or not. In that case, KVM_MR_FLAGS_ONLY can be
ignored because the memory slot's base address and length aren't changed
when we have KVM_MR_FLAGS_ONLY.
It seems the patch isn't based on "next" branch because find_vma() was
replaced by find_vma_intersection() by one of my patches :)
Thanks,
Gavin
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 8711894db8c2..c59af5ca01b0 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1301,7 +1301,6 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
{
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 &&
@@ -1318,8 +1317,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
mmap_read_lock(current->mm);
/*
* 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.
+ * between them, so iterate over all of them.
*
* +--------------------------------------------+
* +---------------+----------------+ +----------------+
@@ -1330,50 +1328,20 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
*/
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 = mem->guest_phys_addr +
- (vm_start - mem->userspace_addr);
- phys_addr_t pa;
-
- pa = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT;
- pa += vm_start - vma->vm_start;
-
/* IO region dirty page logging not allowed */
if (memslot->flags & KVM_MEM_LOG_DIRTY_PAGES) {
ret = -EINVAL;
- goto out;
- }
-
- ret = kvm_phys_addr_ioremap(kvm, gpa, pa,
- vm_end - vm_start,
- writable);
- if (ret)
break;
+ }
}
- hva = vm_end;
+ hva = min(reg_end, vma->vm_end);
} while (hva < reg_end);
- if (change == KVM_MR_FLAGS_ONLY)
- goto out;
-
- spin_lock(&kvm->mmu_lock);
- if (ret)
- unmap_stage2_range(&kvm->arch.mmu, mem->guest_phys_addr, mem->memory_size);
- else if (!cpus_have_final_cap(ARM64_HAS_STAGE2_FWB))
- stage2_flush_memslot(kvm, memslot);
- spin_unlock(&kvm->mmu_lock);
-out:
mmap_read_unlock(current->mm);
return ret;
}
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