On Wed, Nov 10, 2021 at 05:37:32PM +0100, Borislav Petkov wrote:

On Mon, Sep 13, 2021 at 05:55:58PM +0200, Joerg Roedel wrote:

quoted

 extern unsigned char real_mode_blob[];

diff --git a/arch/x86/include/asm/sev-ap-jumptable.h b/arch/x86/include/asm/sev-ap-jumptable.h
new file mode 100644
index 000000000000..1c8b2ce779e2
--- /dev/null
+++ b/arch/x86/include/asm/sev-ap-jumptable.h

Why a separate header? arch/x86/include/asm/sev.h looks small enough.

The header is included in assembly, so I made a separate one.

quoted

+void __init sev_es_setup_ap_jump_table_data(void *base, u32 pa)

Why is this a separate function?

It is all part of the jump table setup.

Right, but the sev_es_setup_ap_jump_table_blob() function is already
pretty big and I wanted to keep things readable.

quoted

+		return 0;

Why are you returning 0 here and below?

This is in an initcall and it returns just 0 when the environment is not
ready to setup the ap jump table. Returning non-zero would create a
warning message in the caller for something that is not a bug in the
kernel.

quoted

+ * This file contains the source code for the binary blob which gets copied to
+ * the SEV-ES AP Jumptable to park APs while offlining CPUs or booting a new

I've seen "Jumptable", "Jump Table" and "jump table" at least. I'd say, do
the last one everywhere pls.

Fair, sorry for my english being too german :) I changed everything to
'jump table'.

quoted

+	/* Reset remaining registers */
+	movl	$0, %esp
+	movl	$0, %eax
+	movl	$0, %ebx
+	movl	$0, %edx

All 4: use xor

XOR changes EFLAGS, can not use them here.

quoted

+
+	/* Reset CR0 to get out of protected mode */
+	movl	$0x60000010, %ecx

Another magic naked number.

This is the CR0 reset value. I have updated the comment to make this
more clear.

Thanks,

-- 
Jörg Rödel
jroedel@suse.de

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