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

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Date:   Fri, 29 Mar 2019 17:16:55 +0800
From:   "bhe@...hat.com" <bhe@...hat.com>
To:     Chao Fan <fanc.fnst@...fujitsu.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 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.
> 
> 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)
> >
> >
> 
>