linux-kernel - [tip: x86/microcode] platform/x86/intel/ifs: Add metadata support

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Date:   Sat, 19 Nov 2022 16:24:04 -0000
From:   "tip-bot2 for Ashok Raj" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Ashok Raj <ashok.raj@...el.com>,
        Jithu Joseph <jithu.joseph@...el.com>,
        Borislav Petkov <bp@...e.de>, Tony Luck <tony.luck@...el.com>,
        Sohil Mehta <sohil.mehta@...el.com>,
        Hans de Goede <hdegoede@...hat.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/microcode] platform/x86/intel/ifs: Add metadata support

The following commit has been merged into the x86/microcode branch of tip:

Commit-ID:     8382fee3bb86526bde1bfb1a06834f056140e0dd
Gitweb:        https://git.kernel.org/tip/8382fee3bb86526bde1bfb1a06834f056140e0dd
Author:        Ashok Raj <ashok.raj@...el.com>
AuthorDate:    Wed, 16 Nov 2022 19:59:29 -08:00
Committer:     Borislav Petkov <bp@...e.de>
CommitterDate: Sat, 19 Nov 2022 10:39:08 +01:00

platform/x86/intel/ifs: Add metadata support

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

The location of metadata section within microcode header is as shown
below:

    Microcode Blob 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.

  [ bp: Massage commit message. ]

Signed-off-by: Ashok Raj <ashok.raj@...el.com>
Signed-off-by: Jithu Joseph <jithu.joseph@...el.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Tony Luck <tony.luck@...el.com>
Reviewed-by: Sohil Mehta <sohil.mehta@...el.com>
Reviewed-by: Hans de Goede <hdegoede@...hat.com>
Link: https://lore.kernel.org/r/20221117035935.4136738-11-jithu.joseph@intel.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 8423c48..9228da5 100644
--- a/drivers/platform/x86/intel/ifs/load.c
+++ b/drivers/platform/x86/intel/ifs/load.c
@@ -43,6 +43,38 @@ static const char * const scan_authentication_status[] = {
 	[2] = "Chunk authentication error. The hash of chunk did not match expected value"
 };
 
+#define MC_HEADER_META_TYPE_END		(0)
+
+struct metadata_header {
+	unsigned int		type;
+	unsigned int		blk_size;
+};
+
+static struct metadata_header *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 != MC_HEADER_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.