Patch "MIPS: KVM: Check for pfn noslot case" has been added to the 4.7-stable tree

This is a note to let you know that I've just added the patch titled

MIPS: KVM: Check for pfn noslot case

to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
mips-kvm-check-for-pfn-noslot-case.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: James Hogan <[email protected]>
Date: Fri, 19 Aug 2016 14:30:29 +0100
Subject: MIPS: KVM: Check for pfn noslot case
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From: James Hogan <[email protected]>

commit ba913e4f72fc9cfd03dad968dfb110eb49211d80 upstream.

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.

---
 arch/mips/kvm/tlb.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -159,7 +159,7 @@ static int kvm_mips_map_page(struct kvm
 	srcu_idx = srcu_read_lock(&kvm->srcu);
 	pfn = kvm_mips_gfn_to_pfn(kvm, gfn);
 
-	if (kvm_mips_is_error_pfn(pfn)) {
+	if (is_error_noslot_pfn(pfn)) {
 		kvm_err("Couldn't get pfn for gfn %#" PRIx64 "!\n", gfn);
 		err = -EFAULT;
 		goto out;

Patches currently in stable-queue which might be from [email protected] are

queue-4.7/mips-kvm-check-for-pfn-noslot-case.patch