On 19/08/2016 15:30, James Hogan wrote:
> When mapping a page into the guest we error check using is_error_pfn(),
> however this doesn't detect a value of KVM_PFN_NOSLOT, indicating an
> error HVA for the page. This can only happen on MIPS right now due to
> unusual memslot management (e.g. being moved / removed / resized), or
> with an Enhanced Virtual Memory (EVA) configuration where the default
> KVM_HVA_ERR_* and kvm_is_error_hva() definitions are unsuitable (fixed
> in a later patch). This case will be treated as a pfn of zero, mapping
> the first page of physical memory into the guest.
>
> It would appear the MIPS KVM port wasn't updated prior to being merged
> (in v3.10) to take commit 81c52c56e2b4 ("KVM: do not treat noslot pfn as
> a error pfn") into account (merged v3.8), which converted a bunch of
> is_error_pfn() calls to is_error_noslot_pfn(). Switch to using
> is_error_noslot_pfn() instead to catch this case properly.
>
> Fixes: 858dd5d45733 ("KVM/MIPS32: MMU/TLB operations for the Guest.")
> Signed-off-by: James Hogan <james.hogan@xxxxxxxxxx>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: "Radim Krčmář" <rkrcmar@xxxxxxxxxx>
> Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
> Cc: linux-mips@xxxxxxxxxxxxxx
> Cc: kvm@xxxxxxxxxxxxxxx
> Cc: <stable@xxxxxxxxxxxxxxx> # 3.10.y-
> ---
> arch/mips/kvm/mmu.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/mips/kvm/mmu.c b/arch/mips/kvm/mmu.c
> index 6cfdcf55572d..121008c0fcc9 100644
> --- a/arch/mips/kvm/mmu.c
> +++ b/arch/mips/kvm/mmu.c
> @@ -40,7 +40,7 @@ static int kvm_mips_map_page(struct kvm *kvm, gfn_t gfn)
> srcu_idx = srcu_read_lock(&kvm->srcu);
> pfn = gfn_to_pfn(kvm, gfn);
>
> - if (is_error_pfn(pfn)) {
> + if (is_error_noslot_pfn(pfn)) {
> kvm_err("Couldn't get pfn for gfn %#llx!\n", gfn);
> err = -EFAULT;
> goto out;
>
Queued for 4.8-rc3, thanks.
