Re: [kvm-devel] [PATCH 27/50] KVM: Support assigning userspace memory to the guest

Avi Kivity wrote:

From: Izik Eidus <[email protected]>

Instead of having the kernel allocate memory to the guest, let userspace
allocate it and pass the address to the kernel.

This is required for s390 support, but also enables features like memory
sharing and using hugetlbfs backed memory.

[...]

@@ -728,11 +752,27 @@ static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,

memset(new.phys_mem, 0, npages * sizeof(struct page *));

 		memset(new.rmap, 0, npages * sizeof(*new.rmap));
-		for (i = 0; i < npages; ++i) {
-			new.phys_mem[i] = alloc_page(GFP_HIGHUSER
-						     | __GFP_ZERO);
-			if (!new.phys_mem[i])
+		if (user_alloc) {
+			unsigned long pages_num;
+
+			new.user_alloc = 1;
+			down_read(&current->mm->mmap_sem);
+
+			pages_num = get_user_pages(current, current->mm,
+						   mem->userspace_addr,
+						   npages, 1, 0, new.phys_mem,
+						   NULL);
+

I just combined a patch that changes the 'force' parameter to get_user_pages from 0 to 1, into this patch, to avoid introducing a bug and its fix in the same patchset. I won't be resending this patch since the change is too trivial. Same change applies to patch 48, "KVM: MMU: Partial swapping of guest memory".

--
error compiling committee.c: too many arguments to function

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---

• References:
  • [PATCH 00/50] KVM patch queue review for 2.6.25 merge window (part I)
    • From: Avi Kivity <[email protected]>
  • [PATCH 27/50] KVM: Support assigning userspace memory to the guest
    • From: Avi Kivity <[email protected]>

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