KVM: ensure that memslot userspace addresses are page-aligned

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From: Linux Kernel Mailing List
Date: Friday, January 2, 2009 - 2:00 pm

Gitweb:     http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=787498...
Commit:     78749809222be5083e21bfe697b44ab797e5c0a8
Parent:     0fdf8e59faa5c60e9d77c8e14abe3a0f8bfcf586
Author:     Hollis Blanchard <hollisb@us.ibm.com>
AuthorDate: Fri Nov 7 13:32:12 2008 -0600
Committer:  Avi Kivity <avi@redhat.com>
CommitDate: Wed Dec 31 16:52:24 2008 +0200

    KVM: ensure that memslot userspace addresses are page-aligned
    
    Bad page translation and silent guest failure ensue if the userspace address is
    not page-aligned.  I hit this problem using large (host) pages with qemu,
    because qemu currently has a hardcoded 4096-byte alignment for guest memory
    allocations.
    
    Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
    Signed-off-by: Avi Kivity <avi@redhat.com>
---
 virt/kvm/kvm_main.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index a65baa9..0a0a959 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -715,6 +715,8 @@ int __kvm_set_memory_region(struct kvm *kvm,
 		goto out;
 	if (mem->guest_phys_addr & (PAGE_SIZE - 1))
 		goto out;
+	if (mem->userspace_addr & (PAGE_SIZE - 1))
+		goto out;
 	if (mem->slot >= KVM_MEMORY_SLOTS + KVM_PRIVATE_MEM_SLOTS)
 		goto out;
 	if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr)
--
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KVM: ensure that memslot userspace addresses are page-aligned, Linux Kernel Mailing ..., (Fri Jan 2, 2:00 pm)