Patch "KVM: PPC: Book3S HV: Always flush TLB in kvmppc_alloc_reset_hpt()" has been added to the 4.14-stable tree

[<gregkh@linuxfoundation.org>]

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

    KVM: PPC: Book3S HV: Always flush TLB in kvmppc_alloc_reset_hpt()

to the 4.14-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:
     kvm-ppc-book3s-hv-always-flush-tlb-in-kvmppc_alloc_reset_hpt.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From ecba8297aafd50db6ae867e90844eead1611ef1c Mon Sep 17 00:00:00 2001
From: David Gibson <david@gibson.dropbear.id.au>
Date: Wed, 10 Jan 2018 17:04:39 +1100
Subject: KVM: PPC: Book3S HV: Always flush TLB in kvmppc_alloc_reset_hpt()

From: David Gibson <david@gibson.dropbear.id.au>

commit ecba8297aafd50db6ae867e90844eead1611ef1c upstream.

The KVM_PPC_ALLOCATE_HTAB ioctl(), implemented by kvmppc_alloc_reset_hpt()
is supposed to completely clear and reset a guest's Hashed Page Table (HPT)
allocating or re-allocating it if necessary.

In the case where an HPT of the right size already exists and it just
zeroes it, it forces a TLB flush on all guest CPUs, to remove any stale TLB
entries loaded from the old HPT.

However, that situation can arise when the HPT is resizing as well - or
even when switching from an RPT to HPT - so those cases need a TLB flush as
well.

So, move the TLB flush to trigger in all cases except for errors.

Fixes: f98a8bf9ee20 ("KVM: PPC: Book3S HV: Allow KVM_PPC_ALLOCATE_HTAB ioctl() to change HPT size")
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/powerpc/kvm/book3s_64_mmu_hv.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -165,8 +165,6 @@ long kvmppc_alloc_reset_hpt(struct kvm *
 		 * Reset all the reverse-mapping chains for all memslots
 		 */
 		kvmppc_rmap_reset(kvm);
-		/* Ensure that each vcpu will flush its TLB on next entry. */
-		cpumask_setall(&kvm->arch.need_tlb_flush);
 		err = 0;
 		goto out;
 	}
@@ -182,6 +180,10 @@ long kvmppc_alloc_reset_hpt(struct kvm *
 	kvmppc_set_hpt(kvm, &info);
 
 out:
+	if (err == 0)
+		/* Ensure that each vcpu will flush its TLB on next entry. */
+		cpumask_setall(&kvm->arch.need_tlb_flush);
+
 	mutex_unlock(&kvm->lock);
 	return err;
 }


Patches currently in stable-queue which might be from david@gibson.dropbear.id.au are

queue-4.14/kvm-ppc-book3s-hv-always-flush-tlb-in-kvmppc_alloc_reset_hpt.patch
queue-4.14/kvm-ppc-book3s-hv-drop-prepare_done-from-struct-kvm_resize_hpt.patch
queue-4.14/kvm-ppc-book3s-hv-fix-use-after-free-in-case-of-multiple-resize-requests.patch