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From: Jarkko Sakkinen <jarkko@kernel.org>
To: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Shuah Khan <shuah@kernel.org>,
	haitao.huang@intel.com, Kai Huang <kai.huang@intel.com>,
	x86@kernel.org, linux-sgx@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linux-kselftest@vger.kernel.org,
	Jia Zhang <zhang.jia@linux.alibaba.com>
Subject: Re: [PATCH] x86/sgx: Fix free_cnt counting logic in epc section
Date: Wed, 20 Jan 2021 16:36:31 +0200	[thread overview]
Message-ID: <YAg/705sWZFriAdK@kernel.org> (raw)
In-Reply-To: <20210118133347.99158-1-tianjia.zhang@linux.alibaba.com>

On Mon, Jan 18, 2021 at 09:33:47PM +0800, Tianjia Zhang wrote:
> Increase `section->free_cnt` in sgx_sanitize_section() is
> more reasonable, which is called in ksgxd kernel thread,
> instead of assigning it to epc section pages number at
> initialization. Although this is unlikely to fail, these
> pages cannot be allocated after initialization, and which
> need to be reset by ksgxd.
> 
> Reported-by: Jia Zhang <zhang.jia@linux.alibaba.com>
> Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>

There is nothing broken in the logic. Convince me otherwise.

I.e. what is exactly broken, and how?

/Jarkko

> ---
>  arch/x86/kernel/cpu/sgx/main.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
> index c519fc5f6948..9e9a3cf7c00b 100644
> --- a/arch/x86/kernel/cpu/sgx/main.c
> +++ b/arch/x86/kernel/cpu/sgx/main.c
> @@ -48,9 +48,10 @@ static void sgx_sanitize_section(struct sgx_epc_section *section)
>  					struct sgx_epc_page, list);
>  
>  		ret = __eremove(sgx_get_epc_virt_addr(page));
> -		if (!ret)
> +		if (!ret) {
>  			list_move(&page->list, &section->page_list);
> -		else
> +			section->free_cnt += 1;
> +		} else
>  			list_move_tail(&page->list, &dirty);
>  
>  		spin_unlock(&section->lock);
> @@ -646,7 +647,6 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size,
>  		list_add_tail(&section->pages[i].list, &section->init_laundry_list);
>  	}
>  
> -	section->free_cnt = nr_pages;
>  	return true;
>  }
>  
> -- 
> 2.19.1.3.ge56e4f7
> 
> 

      parent reply	other threads:[~2021-01-20 14:38 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-18 13:33 [PATCH] x86/sgx: Fix free_cnt counting logic in epc section Tianjia Zhang
2021-01-19 20:24 ` Sean Christopherson
2021-01-20 14:36 ` Jarkko Sakkinen [this message]

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