linux-kernel - Re: [PATCH v9 6/6] KVM: x86/mmu: Handle non-refcounted pages

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Message-ID: <14db8c0b-77de-34ec-c847-d7360025a571@collabora.com>
Date:   Mon, 18 Sep 2023 12:58:32 +0300
From:   Dmitry Osipenko <dmitry.osipenko@...labora.com>
To:     David Stevens <stevensd@...omium.org>,
        Sean Christopherson <seanjc@...gle.com>
Cc:     Yu Zhang <yu.c.zhang@...ux.intel.com>,
        Isaku Yamahata <isaku.yamahata@...il.com>,
        Zhi Wang <zhi.wang.linux@...il.com>, kvmarm@...ts.linux.dev,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH v9 6/6] KVM: x86/mmu: Handle non-refcounted pages

On 9/11/23 05:16, David Stevens wrote:
> From: David Stevens <stevensd@...omium.org>
> 
> Handle non-refcounted pages in __kvm_faultin_pfn. This allows the host
> to map memory into the guest that is backed by non-refcounted struct
> pages - for example, the tail pages of higher order non-compound pages
> allocated by the amdgpu driver via ttm_pool_alloc_page.
> 
> The bulk of this change is tracking the is_refcounted_page flag so that
> non-refcounted pages don't trigger page_count() == 0 warnings. This is
> done by storing the flag in an unused bit in the sptes. There are no
> bits available in PAE SPTEs, so non-refcounted pages can only be handled
> on TDP and x86-64.
> 
> Signed-off-by: David Stevens <stevensd@...omium.org>
> ---
>  arch/x86/kvm/mmu/mmu.c          | 52 +++++++++++++++++++++++----------
>  arch/x86/kvm/mmu/mmu_internal.h |  1 +
>  arch/x86/kvm/mmu/paging_tmpl.h  |  8 +++--
>  arch/x86/kvm/mmu/spte.c         |  4 ++-
>  arch/x86/kvm/mmu/spte.h         | 12 +++++++-
>  arch/x86/kvm/mmu/tdp_mmu.c      | 22 ++++++++------
>  include/linux/kvm_host.h        |  3 ++
>  virt/kvm/kvm_main.c             |  6 ++--
>  8 files changed, 76 insertions(+), 32 deletions(-)

Could you please tell which kernel tree you used for the base of this
series? This patch #6 doesn't apply cleanly to stable/mainline/next/kvm

error: sha1 information is lacking or useless (arch/x86/kvm/mmu/mmu.c).
error: could not build fake ancestor

-- 
Best regards,
Dmitry