Hi Keqian,

On 3/15/21 6:33 PM, Keqian Zhu wrote:
FYI, this has been fixed by Marc in commit 262b003d059c.


Yeah, I didn't check 5.12.rc3 code where the issue has been
fixed. So please ignore this one and sorry for the noise.

Thanks,
Gavin
On 2021/3/15 12:18, Gavin Shan wrote:
The last (IPA) page can't be specified when a new memory slot is
added. The error -EFAULT is returned when the memory slot is added
with the following parameters for the VM, which has 40-bits IPA
limit. The host has 4KB base page size. It's not correct because
the last (IPA) page is still usable.

    struct kvm_userspace_memory_region {
       __u32 slot;               /* 1            */
       __u32 flags;              /* 0            */
       __u64 guest_phys_addr;    /* 0xfffffff000 */
       __u64 memory_size;        /* 0x1000       */
       __u64 userspace_addr;
    };

Signed-off-by: Gavin Shan <[email protected]>
---
  arch/arm64/kvm/mmu.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 286b603ed0d3..a5a8ade9fde4 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1313,7 +1313,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
         * Prevent userspace from creating a memory region outside of the IPA
         * space addressable by the KVM guest IPA space.
         */
-       if (memslot->base_gfn + memslot->npages >=
+       if (memslot->base_gfn + memslot->npages >
            (kvm_phys_size(kvm) >> PAGE_SHIFT))
                return -EFAULT;


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