linux-kernel - Re: [PATCH] KVM: x86: Skip pae_root shadow allocation if tdp enabled

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Message-ID: <2027f8c1-15c6-1c2a-65b0-cc7f095af28d@redhat.com>
Date:   Thu, 2 Aug 2018 14:57:57 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Liang Chen <liangchen.linux@...il.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: x86: Skip pae_root shadow allocation if tdp enabled

On 25/07/2018 10:32, Liang Chen wrote:
> Considering the fact that the pae_root shadow is not needed when
> tdp is in use, skip the pae_root shadow page allocation to allow
> mmu creation even not being able to obtain memory from DMA32
> zone when particular cgroup cpuset.mems or mempolicy control is
> applied.
> 
> Signed-off-by: Liang Chen <liangchen.linux@...il.com>
> ---
>  arch/x86/kvm/mmu.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index d594690..af8cc1e 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -5029,6 +5029,9 @@ static int alloc_mmu_pages(struct kvm_vcpu *vcpu)
>  	struct page *page;
>  	int i;
>  
> +	if (tdp_enabled)
> +		return 0;
> +
>  	/*
>  	 * When emulating 32-bit mode, cr3 is only 32 bits even on x86_64.
>  	 * Therefore we need to allocate shadow page tables in the first
> 

Queued, thanks.

Paolo