linux-kernel - Re: [PATCH] x86/boot: Use efi_setup_data for searching RSDP on kexec-ed kernel

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Message-ID: <20190329082929.GH4234@localhost.localdomain>
Date:   Fri, 29 Mar 2019 16:29:29 +0800
From:   Chao Fan <fanc.fnst@...fujitsu.com>
To:     Junichi Nomura <j-nomura@...jp.nec.com>
CC:     Borislav Petkov <bp@...en8.de>, "bhe@...hat.com" <bhe@...hat.com>,
        Dave Young <dyoung@...hat.com>,
        "kasong@...hat.com" <kasong@...hat.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86/boot: Use efi_setup_data for searching RSDP on
 kexec-ed kernel

On Fri, Mar 29, 2019 at 07:20:38AM +0000, Junichi Nomura wrote:
>Commit 3a63f70bf4c3a ("x86/boot: Early parse RSDP and save it in
>boot_params") broke kexec boot on EFI systems.  efi_get_rsdp_addr()
>in the early parsing code tries to search RSDP from EFI table but
>that will crash because the table address is virtual when the kernel
>was booted by kexec.
[...]
>-			guid  = tbl->guid;
>-			table = tbl->table;
>-		}
>-
>-		if (!(efi_guidcmp(guid, ACPI_TABLE_GUID)))
>-			rsdp_addr = table;
>-		else if (!(efi_guidcmp(guid, ACPI_20_TABLE_GUID)))
>-			return table;
>-	}
>+	return __efi_get_rsdp_addr(config_tables, nr_tables, efi_64);
>+#else
>+	return 0;
> #endif
>-	return rsdp_addr;

I remeber the rsdp_addr is defined before #ifdef CONFIG_EFI
If so, you don't need
#else
	return 0;

BY the way, what's your patch based on? I like add patch on my local
branch and then review code, but failed.
I try to use 'patch -p1 <' your patch to the latest tip master branch,
but failed.

Thanks,
Chao Fan

> }
> 
> static u8 compute_checksum(u8 *buffer, u32 length)
>@@ -221,6 +284,9 @@ acpi_physical_address get_rsdp_addr(void)
> 		pa = boot_params->acpi_rsdp_addr;
> 
> 	if (!pa)
>+		pa = kexec_get_rsdp_addr();
>+
>+	if (!pa)
> 		pa = efi_get_rsdp_addr();
> 
> 	if (!pa)
>
>