Re: FAILED: patch "[PATCH] KVM: Play nice with read-only memslots when querying host" failed to apply to 5.5-stable tree

[Sasha Levin <sashal@kernel.org>]

On Sun, Feb 09, 2020 at 01:36:52PM +0100, gregkh@linuxfoundation.org wrote:
>
>The patch below does not apply to the 5.5-stable tree.
>If someone wants it applied there, or to any other stable or longterm
>tree, then please email the backport, including the original git commit
>id to <stable@vger.kernel.org>.
>
>thanks,
>
>greg k-h
>
>------------------ original commit in Linus's tree ------------------
>
>From 42cde48b2d39772dba47e680781a32a6c4b7dc33 Mon Sep 17 00:00:00 2001
>From: Sean Christopherson <sean.j.christopherson@intel.com>
>Date: Wed, 8 Jan 2020 12:24:38 -0800
>Subject: [PATCH] KVM: Play nice with read-only memslots when querying host
> page size
>
>Avoid the "writable" check in __gfn_to_hva_many(), which will always fail
>on read-only memslots due to gfn_to_hva() assuming writes.  Functionally,
>this allows x86 to create large mappings for read-only memslots that
>are backed by HugeTLB mappings.
>
>Note, the changelog for commit 05da45583de9 ("KVM: MMU: large page
>support") states "If the largepage contains write-protected pages, a
>large pte is not used.", but "write-protected" refers to pages that are
>temporarily read-only, e.g. read-only memslots didn't even exist at the
>time.
>
>Fixes: 4d8b81abc47b ("KVM: introduce readonly memslot")
>Cc: stable@vger.kernel.org
>Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
>[Redone using kvm_vcpu_gfn_to_memslot_prot. - Paolo]
>Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

I'm not sure what was wrong with 5.5-4.14, it applied/built fine for me.

For 4.9 and 4.4, it depends on f9b84e19221e ("KVM: Use vcpu-specific
gva->hva translation when querying host page size") which wasn't
backported that far, so this one should also be backported to 4.9 and
4.4.

-- 
Thanks,
Sasha