linux-kernel - Re: [PATCH 1/3] x86/ioremap: introduce helper to check if physical address is in setup

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Message-ID: <d6c946f5-8e7c-ca06-ed0a-4d4e8a82d679@amd.com>
Date: Fri, 15 Nov 2024 08:22:24 -0600
From: Tom Lendacky <thomas.lendacky@....com>
To: Baoquan He <bhe@...hat.com>, linux-kernel@...r.kernel.org, bp@...en8.de
Cc: x86@...nel.org
Subject: Re: [PATCH 1/3] x86/ioremap: introduce helper to check if physical
 address is in setup_data

On 11/14/24 19:21, Baoquan He wrote:
> Functions memremap_is_setup_data() and early_memremap_is_setup_data()
> share completely the same process and handling, except of the
> different memremap/unmap invocations.
> 
> Add helper __memremap_is_setup_data() to extract the common part,
> parameter 'early' is used to decide what kind of memremap/unmap
> APIs are called.
> 
> Signed-off-by: Baoquan He <bhe@...hat.com>
> ---
>  arch/x86/mm/ioremap.c | 81 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 81 insertions(+)
> 
> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
> index 8d29163568a7..5ef6182db630 100644
> --- a/arch/x86/mm/ioremap.c
> +++ b/arch/x86/mm/ioremap.c
> @@ -628,6 +628,87 @@ static bool memremap_is_efi_data(resource_size_t phys_addr,
>  	return false;
>  }
>  
> +#define SD_SIZE sizeof(struct setup_data)
> +/*
> + * Examine the physical address to determine if it is boot data by checking
> + * it against the boot params setup_data chain.
> + */
> +static bool __init __memremap_is_setup_data(resource_size_t phys_addr,

You should remove the __init for this helper since it is called by a
function that is outside of __init.

> +						bool early)
> +{
> +	struct setup_indirect *indirect;
> +	struct setup_data *data;
> +	u64 paddr, paddr_next;
> +
> +	paddr = boot_params.hdr.setup_data;
> +	while (paddr) {
> +		unsigned int len, size;
> +
> +		if (phys_addr == paddr)
> +			return true;
> +
> +		if (early)
> +			data = early_memremap_decrypted(paddr, SD_SIZE);
> +		else
> +			data = memremap(paddr, SD_SIZE,
> +					MEMREMAP_WB | MEMREMAP_DEC);
> +		if (!data) {
> +			pr_warn("failed to memremap setup_data entry\n");
> +			return false;
> +		}
> +
> +		size = SD_SIZE;

Just me, but I would use sizeof(*data) here instead of using a #define
that is later undefined below.

Thanks,
Tom

> +
> +		paddr_next = data->next;
> +		len = data->len;
> +
> +		if ((phys_addr > paddr) &&
> +		    (phys_addr < (paddr + SD_SIZE + len))) {
> +			if (early)
> +				early_memunmap(data, SD_SIZE);
> +			else
> +				memunmap(data);
> +			return true;
> +		}
> +
> +		if (data->type == SETUP_INDIRECT) {
> +			size += len;
> +			if (early) {
> +				early_memunmap(data, SD_SIZE);
> +				data = early_memremap_decrypted(paddr, size);
> +			} else {
> +				memunmap(data);
> +				data = memremap(paddr, size,
> +						MEMREMAP_WB | MEMREMAP_DEC);
> +			}
> +			if (!data) {
> +				pr_warn("failed to memremap indirect setup_data\n");
> +				return false;
> +			}
> +
> +			indirect = (struct setup_indirect *)data->data;
> +
> +			if (indirect->type != SETUP_INDIRECT) {
> +				paddr = indirect->addr;
> +				len = indirect->len;
> +			}
> +		}
> +
> +		if (early)
> +			early_memunmap(data, size);
> +		else
> +			memunmap(data);
> +
> +		if ((phys_addr > paddr) && (phys_addr < (paddr + len)))
> +			return true;
> +
> +		paddr = paddr_next;
> +	}
> +
> +	return false;
> +}
> +#undef SD_SIZE
> +
>  /*
>   * Examine the physical address to determine if it is boot data by checking
>   * it against the boot params setup_data chain.