linux-kernel - RE: [PATCH] virt: acrn: obtain pa from VMA with PFNMAP flag

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Date:   Fri, 11 Mar 2022 06:14:26 +0000
From:   "Huang, Yonghua" <yonghua.huang@...el.com>
To:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "Chatre, Reinette" <reinette.chatre@...el.com>,
        "Wang, Zhi A" <zhi.a.wang@...el.com>,
        "Wang, Yu1" <yu1.wang@...el.com>, "Li, Fei1" <fei1.li@...el.com>,
        "Huang, Yonghua" <yonghua.huang@...el.com>
Subject: RE: [PATCH] virt: acrn: obtain pa from VMA with PFNMAP flag

Hello Greg,

   Can you kindly help review this patch? Thank you😊


-Yonghua

> -----Original Message-----
> From: Huang, Yonghua <yonghua.huang@...el.com>
> Sent: Monday, February 28, 2022 10:22
> To: gregkh@...uxfoundation.org
> Cc: linux-kernel@...r.kernel.org; stable@...r.kernel.org; Chatre, Reinette
> <reinette.chatre@...el.com>; Wang, Zhi A <zhi.a.wang@...el.com>; Wang,
> Yu1 <yu1.wang@...el.com>; Li, Fei1 <fei1.li@...el.com>; Huang, Yonghua
> <yonghua.huang@...el.com>; Li, Fei1 <fei1.li@...el.com>
> Subject: [PATCH] virt: acrn: obtain pa from VMA with PFNMAP flag
> 
>  acrn_vm_ram_map can't pin the user pages with VM_PFNMAP flag  by
> calling get_user_pages_fast(), the PA(physical pages)  may be mapped by
> kernel driver and set PFNMAP flag.
> 
>  This patch fixes logic to setup EPT mapping for PFN mapped RAM region  by
> checking the memory attribute before adding EPT mapping for them.
> 
> Fixes: 88f537d5e8dd ("virt: acrn: Introduce EPT mapping management")
> Signed-off-by: Yonghua Huang <yonghua.huang@...el.com>
> Signed-off-by: Fei Li <fei1.li@...el.com>
> ---
>  drivers/virt/acrn/mm.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/drivers/virt/acrn/mm.c b/drivers/virt/acrn/mm.c index
> c4f2e15c8a2b..3b1b1e7a844b 100644
> --- a/drivers/virt/acrn/mm.c
> +++ b/drivers/virt/acrn/mm.c
> @@ -162,10 +162,34 @@ int acrn_vm_ram_map(struct acrn_vm *vm, struct
> acrn_vm_memmap *memmap)
>  	void *remap_vaddr;
>  	int ret, pinned;
>  	u64 user_vm_pa;
> +	unsigned long pfn;
> +	struct vm_area_struct *vma;
> 
>  	if (!vm || !memmap)
>  		return -EINVAL;
> 
> +	mmap_read_lock(current->mm);
> +	vma = vma_lookup(current->mm, memmap->vma_base);
> +	if (vma && ((vma->vm_flags & VM_PFNMAP) != 0)) {
> +		if ((memmap->vma_base + memmap->len) > vma->vm_end)
> {
> +			mmap_read_unlock(current->mm);
> +			return -EINVAL;
> +		}
> +
> +		ret = follow_pfn(vma, memmap->vma_base, &pfn);
> +		mmap_read_unlock(current->mm);
> +		if (ret < 0) {
> +			dev_dbg(acrn_dev.this_device,
> +				"Failed to lookup PFN at VMA:%pK.\n", (void
> *)memmap->vma_base);
> +			return ret;
> +		}
> +
> +		return acrn_mm_region_add(vm, memmap->user_vm_pa,
> +			 PFN_PHYS(pfn), memmap->len,
> +			 ACRN_MEM_TYPE_WB, memmap->attr);
> +	}
> +	mmap_read_unlock(current->mm);
> +
>  	/* Get the page number of the map region */
>  	nr_pages = memmap->len >> PAGE_SHIFT;
>  	pages = vzalloc(nr_pages * sizeof(struct page *));
> 
> base-commit: 73878e5eb1bd3c9656685ca60bc3a49d17311e0c
> --
> 2.25.1