Izik Eidus wrote:
> we are working on swapping support for the guests in kvm.
> we want to allow management of the memory swapping of the guests from kvm.
This is excellent, thank you!
> this is request for comment, so any idea you have please write to me.
I ran into a few while reading the code:
+static void kvm_free_userspace_physmem(struct kvm_memory_slot *free)
+{
+ int i;
+
+ for (i = 0; i < free->npages; ++i) {
+ if (free->phys_mem[i]) {
+ if (!PageReserved(free->phys_mem[i]))
+ SetPageDirty(free->phys_mem[i]);
+ page_cache_release(free->phys_mem[i]);
+ }
+ }
+}
I don't see why we would want to dirty a page we release in general.
We do only need to dirty it, if the corresponding page table entry
indicates so (dirty bit). Did I miss something?
@@ -670,7 +692,8 @@ EXPORT_SYMBOL_GPL(fx_init);
* Discontiguous memory is allowed, mostly for framebuffers.
*/
static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
- struct kvm_memory_region *mem)
+ struct kvm_memory_region *mem,
+ unsigned long guest_host_addr)
{
int r;
gfn_t base_gfn;
@@ -748,12 +771,26 @@ raced:
goto out_free;
memset(new.phys_mem, 0, npages * sizeof(struct page *));
- for (i = 0; i < npages; ++i) {
- new.phys_mem[i] = alloc_page(GFP_HIGHUSER
- | __GFP_ZERO);
- if (!new.phys_mem[i])
+
+ if (guest_host_addr) {
+ unsigned long pages_num;
+
+ new.user_alloc = 1;
+ down_read(¤t->mm->mmap_sem);
+ pages_num = get_user_pages(current, current->mm,
guest_host_addr,
+ npages, 1, 0,
new.phys_mem, NULL);
+ up_read(¤t->mm->mmap_sem);
+ if (pages_num != npages)
goto out_free;
- set_page_private(new.phys_mem[i],0);
+ } else {
+ new.user_alloc = 0;
+ for (i = 0; i < npages; ++i) {
+ new.phys_mem[i] = alloc_page(GFP_HIGHUSER
+ | __GFP_ZERO);
+ if (!new.phys_mem[i])
+ goto out_free;
+ set_page_private(new.phys_mem[i],0);
+ }
}
}
Do we intend to maintain both pathes in the long run, or wait until we
don't care about ancient userland anymore that does'nt do the
allocation on its own?
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