From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Subject: Re: [RFC][PATCH v2 11/21] kvm: allocate page table pages from DRAM
Date: Tue, 01 Jan 2019 14:53:07 +0530
Message-ID: <87pntg7mv8.fsf@linux.ibm.com>
References: <20181226131446.330864849@intel.com> <20181226133351.703380444@intel.com>
Mime-Version: 1.0
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Cc: Linux Memory Management List <linux-mm@kvack.org>,
        Yao Yuan <yuan.yao@intel.com>,
        Fengguang Wu <fengguang.wu@intel.com>, kvm@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>, Fan Du <fan.du@intel.com>,
        Peng Dong <dongx.peng@intel.com>,
        Huang Ying <ying.huang@intel.com>,
        Liu Jingqi <jingqi.liu@intel.com>,
        Dong Eddie <eddie.dong@intel.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Zhang Yi <yi.z.zhang@linux.intel.com>,
        Dan Williams <dan.j.williams@intel.com>
To: Fengguang Wu <fengguang.wu@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <20181226133351.703380444@intel.com>
Sender: linux-kernel-owner@vger.kernel.org
List-Id: kvm.vger.kernel.org

Fengguang Wu <fengguang.wu@intel.com> writes:

> From: Yao Yuan <yuan.yao@intel.com>
>
> Signed-off-by: Yao Yuan <yuan.yao@intel.com>
> Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
> ---
> arch/x86/kvm/mmu.c |   12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
>
> --- linux.orig/arch/x86/kvm/mmu.c	2018-12-26 20:54:48.846720344 +0800
> +++ linux/arch/x86/kvm/mmu.c	2018-12-26 20:54:48.842719614 +0800
> @@ -950,6 +950,16 @@ static void mmu_free_memory_cache(struct
>  		kmem_cache_free(cache, mc->objects[--mc->nobjs]);
>  }
>  
> +static unsigned long __get_dram_free_pages(gfp_t gfp_mask)
> +{
> +       struct page *page;
> +
> +       page = __alloc_pages(GFP_KERNEL_ACCOUNT, 0, numa_node_id());
> +       if (!page)
> +	       return 0;
> +       return (unsigned long) page_address(page);
> +}
> +

May be it is explained in other patches. What is preventing the
allocation from pmem here? Is it that we are not using the memory
policy prefered node id and hence the zone list we built won't have the
PMEM node?


>  static int mmu_topup_memory_cache_page(struct kvm_mmu_memory_cache *cache,
>  				       int min)
>  {
> @@ -958,7 +968,7 @@ static int mmu_topup_memory_cache_page(s
>  	if (cache->nobjs >= min)
>  		return 0;
>  	while (cache->nobjs < ARRAY_SIZE(cache->objects)) {
> -		page = (void *)__get_free_page(GFP_KERNEL_ACCOUNT);
> +		page = (void *)__get_dram_free_pages(GFP_KERNEL_ACCOUNT);
>  		if (!page)
>  			return cache->nobjs >= min ? 0 : -ENOMEM;
>  		cache->objects[cache->nobjs++] = page;

-aneesh