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

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Message-ID: <20190329092001.GK4234@localhost.localdomain>
Date:   Fri, 29 Mar 2019 17:20:01 +0800
From:   Chao Fan <fanc.fnst@...fujitsu.com>
To:     "bhe@...hat.com" <bhe@...hat.com>
CC:     Junichi Nomura <j-nomura@...jp.nec.com>,
        Borislav Petkov <bp@...en8.de>, 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 05:16:55PM +0800, bhe@...hat.com wrote:
>On 03/29/19 at 04:29pm, Chao Fan wrote:
>> 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;
>
>it doesn't change the old logic. Junichi moved rsdp_addr definition inside
>the CONFIG_EFI iedeffery block.

Yes, got it. Thanks for your explain.

Thanks,
Chao Fan
>> 
>> 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)
>> >
>> >
>> 
>> 
>
>