linux-kernel - [PATCH] x86/microcode: Adjust ramdisk address when accessing by virtual address

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Date:   Mon, 19 Dec 2016 10:32:13 -0500
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     bp@...en8.de
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>
Subject: [PATCH] x86/microcode: Adjust ramdisk address when accessing by virtual address

When searching for microcode in the ramdisk image we need to adjust the
start address after paging has been turned on (in 32-bit mode).

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
---
 arch/x86/kernel/cpu/microcode/core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index c4bb2f7..bc8c3345 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -227,8 +227,11 @@ struct cpio_data find_microcode_in_initrd(const char *path, bool use_pa)
 	 * Set start only if we have an initrd image. We cannot use initrd_start
 	 * because it is not set that early yet.
 	 */
-	if (size)
+	if (size) {
 		start = params->hdr.ramdisk_image;
+		if (!use_pa)
+			start += PAGE_OFFSET;
+	}
 
 # else /* CONFIG_X86_64 */
 	size  = (unsigned long)boot_params.ext_ramdisk_size << 32;
-- 
2.5.5