linux-kernel - Re: [PATCH v17 04/10] x86: kdump: move xen_pv_domain() check and insert_resource() to setup

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Message-ID: <d328aede-1282-b4d5-f17a-aa9c3e9f6563@huawei.com>
Date:   Tue, 14 Dec 2021 19:40:50 +0800
From:   "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        <x86@...nel.org>, "H . Peter Anvin" <hpa@...or.com>,
        <linux-kernel@...r.kernel.org>, Dave Young <dyoung@...hat.com>,
        Baoquan He <bhe@...hat.com>, Vivek Goyal <vgoyal@...hat.com>,
        Eric Biederman <ebiederm@...ssion.com>,
        <kexec@...ts.infradead.org>,
        Catalin Marinas <catalin.marinas@....com>,
        "Will Deacon" <will@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        <devicetree@...r.kernel.org>, Jonathan Corbet <corbet@....net>,
        <linux-doc@...r.kernel.org>
CC:     Randy Dunlap <rdunlap@...radead.org>,
        Feng Zhou <zhoufeng.zf@...edance.com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        "Chen Zhou" <dingguo.cz@...group.com>
Subject: Re: [PATCH v17 04/10] x86: kdump: move xen_pv_domain() check and
 insert_resource() to setup_arch()



On 2021/12/10 14:55, Zhen Lei wrote:
> From: Chen Zhou <chenzhou10@...wei.com>
> 
> We will make the functions reserve_crashkernel() as generic, the
> xen_pv_domain() check in reserve_crashkernel() is relevant only to
> x86, the same as insert_resource() in reserve_crashkernel[_low]().
> So move xen_pv_domain() check and insert_resource() to setup_arch()
> to keep them in x86.
> 
> Suggested-by: Mike Rapoport <rppt@...nel.org>
> Signed-off-by: Chen Zhou <chenzhou10@...wei.com>
> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
> Tested-by: John Donnelly <John.p.donnelly@...cle.com>
> Tested-by: Dave Kleikamp <dave.kleikamp@...cle.com>
> Acked-by: Baoquan He <bhe@...hat.com>
> ---
>  arch/x86/kernel/setup.c | 19 +++++++++++--------
>  1 file changed, 11 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index bb2a0973b98059e..7ae00716a208f82 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -456,7 +456,6 @@ static int __init reserve_crashkernel_low(void)
>  
>  	crashk_low_res.start = low_base;
>  	crashk_low_res.end   = low_base + low_size - 1;
> -	insert_resource(&iomem_resource, &crashk_low_res);
>  #endif
>  	return 0;
>  }
> @@ -480,11 +479,6 @@ static void __init reserve_crashkernel(void)
>  		high = true;
>  	}
>  
> -	if (xen_pv_domain()) {
> -		pr_info("Ignoring crashkernel for a Xen PV domain\n");
> -		return;
> -	}
> -
>  	/* 0 means: find the address automatically */
>  	if (!crash_base) {
>  		/*
> @@ -531,7 +525,6 @@ static void __init reserve_crashkernel(void)
>  
>  	crashk_res.start = crash_base;
>  	crashk_res.end   = crash_base + crash_size - 1;
> -	insert_resource(&iomem_resource, &crashk_res);
>  }
>  #else
>  static void __init reserve_crashkernel(void)
> @@ -1143,7 +1136,17 @@ void __init setup_arch(char **cmdline_p)
>  	 * Reserve memory for crash kernel after SRAT is parsed so that it
>  	 * won't consume hotpluggable memory.
>  	 */
> -	reserve_crashkernel();

Hi Baoquan:
  How about move "#ifdef CONFIG_KEXEC_CORE" here, so that we can remove the
empty reserve_crashkernel(). In fact, xen_pv_domain() is invoked only
when CONFIG_KEXEC_CORE is enabled before.

> +	if (xen_pv_domain())
> +		pr_info("Ignoring crashkernel for a Xen PV domain\n");
> +	else {
> +		reserve_crashkernel();
> +#ifdef CONFIG_KEXEC_CORE
> +		if (crashk_res.end > crashk_res.start)
> +			insert_resource(&iomem_resource, &crashk_res);
> +		if (crashk_low_res.end > crashk_low_res.start)
> +			insert_resource(&iomem_resource, &crashk_low_res);
> +#endif
> +	}
>  
>  	memblock_find_dma_reserve();
>  
>