linux-kernel - [PATCH v2 08/14] platform/x86/intel/ifs: Add metadata support

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Date:   Mon,  7 Nov 2022 14:53:17 -0800
From:   Jithu Joseph <jithu.joseph@...el.com>
To:     hdegoede@...hat.com, markgross@...nel.org
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
        gregkh@...uxfoundation.org, jithu.joseph@...el.com,
        ashok.raj@...el.com, tony.luck@...el.com,
        linux-kernel@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        patches@...ts.linux.dev, ravi.v.shankar@...el.com,
        thiago.macieira@...el.com, athenas.jimenez.gonzalez@...el.com,
        sohil.mehta@...el.com
Subject: [PATCH v2 08/14] platform/x86/intel/ifs: Add metadata support

From: Ashok Raj <ashok.raj@...el.com>

One of the existing reserved fields in microcode header has been
allocated to indicate the size for metadata structures.

The metadata section within microcode header is as shown below:

    Microcode Format
   +----------------------+  Base
   |Header Version        |
   +----------------------+
   |Update revision       |
   +----------------------+
   |Date DDMMYYYY         |
   +----------------------+
   |Sig                   |
   +----------------------+
   |Checksum              |
   +----------------------+
   |Loader Version        |
   +----------------------+
   |Processor Flags       |
   +----------------------+
   |Data Size             |
   +----------------------+
   |Total Size            |
   +----------------------+
   |Meta Size             |
   +----------------------+
   |Reserved              |
   +----------------------+
   |Reserved              |
   +----------------------+  Base+48
   |                      |
   |                      |
   |                      |
   |                      |
   |    Microcode         |
   |                      |
   |     Data             |
   |                      |
   |                      |
   +----------------------+  Base+48+data_size-
   |                      |     meta_size
   |   Meta Data          |
   |   structure(s)       |
   |                      |
   +----------------------+  Base+48+data_size
   |   Extended Signature |
   |        Table         |
   |                      |
   |                      |
   |                      |
   |                      |
   |                      |
   +----------------------+  Base+total_size

Add an accessor function which will return a pointer to the
start of a specific meta_type being queried.

In subsequent patches, IFS test image file (which reuse microcode header
format) will make use of metadata section.

Reviewed-by: Tony Luck <tony.luck@...el.com>
Signed-off-by: Ashok Raj <ashok.raj@...el.com>
Signed-off-by: Jithu Joseph <jithu.joseph@...el.com>
---
 drivers/platform/x86/intel/ifs/load.c | 32 +++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/platform/x86/intel/ifs/load.c b/drivers/platform/x86/intel/ifs/load.c
index 89ce265887ea..60ba5a057f91 100644
--- a/drivers/platform/x86/intel/ifs/load.c
+++ b/drivers/platform/x86/intel/ifs/load.c
@@ -44,6 +44,38 @@ static const char * const scan_authentication_status[] = {
 	[2] = "Chunk authentication error. The hash of chunk did not match expected value"
 };
 
+#define META_TYPE_END		(0)
+
+struct metadata_header {
+	unsigned int		type;
+	unsigned int		blk_size;
+};
+
+static struct metadata_header *ifs_find_meta_data(void *ucode, unsigned int meta_type)
+{
+	struct metadata_header *meta_header;
+	unsigned long data_size, total_meta;
+	unsigned long meta_size = 0;
+
+	data_size = get_datasize(ucode);
+	total_meta = ((struct microcode_intel *)ucode)->hdr.metasize;
+
+	if (!total_meta)
+		return NULL;
+
+	meta_header = (ucode + MC_HEADER_SIZE + data_size) - total_meta;
+
+	while ((meta_header->type != META_TYPE_END) && meta_header->blk_size &&
+	       meta_size < total_meta) {
+		meta_size += meta_header->blk_size;
+		if (meta_header->type == meta_type)
+			return meta_header;
+
+		meta_header = (void *)meta_header + meta_header->blk_size;
+	}
+	return NULL;
+}
+
 /*
  * To copy scan hashes and authenticate test chunks, the initiating cpu must point
  * to the EDX:EAX to the test image in linear address.
-- 
2.25.1