Patch "x86/microcode: Attempt late loading only when new microcode is present" has been added to the 4.15-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    x86/microcode: Attempt late loading only when new microcode is present

to the 4.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     x86-microcode-attempt-late-loading-only-when-new-microcode-is-present.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 2613f36ed965d0e5a595a1d931fd3b480e82d6fd Mon Sep 17 00:00:00 2001
From: Borislav Petkov <bp@suse.de>
Date: Wed, 14 Mar 2018 19:36:14 +0100
Subject: x86/microcode: Attempt late loading only when new microcode is present

From: Borislav Petkov <bp@suse.de>

commit 2613f36ed965d0e5a595a1d931fd3b480e82d6fd upstream.

Return UCODE_NEW from the scanning functions to denote that new microcode
was found and only then attempt the expensive synchronization dance.

Reported-by: Emanuel Czirai <xftroxgpx@protonmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Emanuel Czirai <xftroxgpx@protonmail.com>
Tested-by: Ashok Raj <ashok.raj@intel.com>
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lkml.kernel.org/r/20180314183615.17629-1-bp@alien8.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/include/asm/microcode.h      |    1 +
 arch/x86/kernel/cpu/microcode/amd.c   |   34 +++++++++++++++++++++-------------
 arch/x86/kernel/cpu/microcode/core.c  |    8 +++-----
 arch/x86/kernel/cpu/microcode/intel.c |    4 +++-
 4 files changed, 28 insertions(+), 19 deletions(-)

--- a/arch/x86/include/asm/microcode.h
+++ b/arch/x86/include/asm/microcode.h
@@ -39,6 +39,7 @@ struct device;
 
 enum ucode_state {
 	UCODE_OK	= 0,
+	UCODE_NEW,
 	UCODE_UPDATED,
 	UCODE_NFOUND,
 	UCODE_ERROR,
--- a/arch/x86/kernel/cpu/microcode/amd.c
+++ b/arch/x86/kernel/cpu/microcode/amd.c
@@ -339,7 +339,7 @@ int __init save_microcode_in_initrd_amd(
 		return -EINVAL;
 
 	ret = load_microcode_amd(true, x86_family(cpuid_1_eax), desc.data, desc.size);
-	if (ret != UCODE_OK)
+	if (ret > UCODE_UPDATED)
 		return -EINVAL;
 
 	return 0;
@@ -683,27 +683,35 @@ static enum ucode_state __load_microcode
 static enum ucode_state
 load_microcode_amd(bool save, u8 family, const u8 *data, size_t size)
 {
+	struct ucode_patch *p;
 	enum ucode_state ret;
 
 	/* free old equiv table */
 	free_equiv_cpu_table();
 
 	ret = __load_microcode_amd(family, data, size);
-
-	if (ret != UCODE_OK)
+	if (ret != UCODE_OK) {
 		cleanup();
+		return ret;
+	}
 
-#ifdef CONFIG_X86_32
-	/* save BSP's matching patch for early load */
-	if (save) {
-		struct ucode_patch *p = find_patch(0);
-		if (p) {
-			memset(amd_ucode_patch, 0, PATCH_MAX_SIZE);
-			memcpy(amd_ucode_patch, p->data, min_t(u32, ksize(p->data),
-							       PATCH_MAX_SIZE));
-		}
+	p = find_patch(0);
+	if (!p) {
+		return ret;
+	} else {
+		if (boot_cpu_data.microcode == p->patch_id)
+			return ret;
+
+		ret = UCODE_NEW;
 	}
-#endif
+
+	/* save BSP's matching patch for early load */
+	if (!save)
+		return ret;
+
+	memset(amd_ucode_patch, 0, PATCH_MAX_SIZE);
+	memcpy(amd_ucode_patch, p->data, min_t(u32, ksize(p->data), PATCH_MAX_SIZE));
+
 	return ret;
 }
 
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -607,7 +607,7 @@ static ssize_t reload_store(struct devic
 		return size;
 
 	tmp_ret = microcode_ops->request_microcode_fw(bsp, &microcode_pdev->dev, true);
-	if (tmp_ret != UCODE_OK)
+	if (tmp_ret != UCODE_NEW)
 		return size;
 
 	get_online_cpus();
@@ -691,10 +691,8 @@ static enum ucode_state microcode_init_c
 	if (system_state != SYSTEM_RUNNING)
 		return UCODE_NFOUND;
 
-	ustate = microcode_ops->request_microcode_fw(cpu, &microcode_pdev->dev,
-						     refresh_fw);
-
-	if (ustate == UCODE_OK) {
+	ustate = microcode_ops->request_microcode_fw(cpu, &microcode_pdev->dev, refresh_fw);
+	if (ustate == UCODE_NEW) {
 		pr_debug("CPU%d updated upon init\n", cpu);
 		apply_microcode_on_target(cpu);
 	}
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -862,6 +862,7 @@ static enum ucode_state generic_load_mic
 	unsigned int leftover = size;
 	unsigned int curr_mc_size = 0, new_mc_size = 0;
 	unsigned int csig, cpf;
+	enum ucode_state ret = UCODE_OK;
 
 	while (leftover) {
 		struct microcode_header_intel mc_header;
@@ -903,6 +904,7 @@ static enum ucode_state generic_load_mic
 			new_mc  = mc;
 			new_mc_size = mc_size;
 			mc = NULL;	/* trigger new vmalloc */
+			ret = UCODE_NEW;
 		}
 
 		ucode_ptr += mc_size;
@@ -932,7 +934,7 @@ static enum ucode_state generic_load_mic
 	pr_debug("CPU%d found a matching microcode update with version 0x%x (current=0x%x)\n",
 		 cpu, new_rev, uci->cpu_sig.rev);
 
-	return UCODE_OK;
+	return ret;
 }
 
 static int get_ucode_fw(void *to, const void *from, size_t n)


Patches currently in stable-queue which might be from bp@suse.de are

queue-4.15/x86-microcode-intel-check-microcode-revision-before-updating-sibling-threads.patch
queue-4.15/x86-microcode-attempt-late-loading-only-when-new-microcode-is-present.patch
queue-4.15/x86-microcode-propagate-return-value-from-updating-functions.patch
queue-4.15/x86-cpu-check-cpu-feature-bits-after-microcode-upgrade.patch
queue-4.15/x86-microcode-intel-writeback-and-invalidate-caches-before-updating-microcode.patch
queue-4.15/x86-microcode-intel-look-into-the-patch-cache-first.patch
queue-4.15/edac-mv64x60-fix-an-error-handling-path.patch
queue-4.15/x86-microcode-request-microcode-on-the-bsp.patch
queue-4.15/x86-microcode-get-rid-of-struct-apply_microcode_ctx.patch
queue-4.15/x86-microcode-fix-cpu-synchronization-routine.patch
queue-4.15/x86-microcode-synchronize-late-microcode-loading.patch
queue-4.15/x86-microcode-do-not-upload-microcode-if-cpus-are-offline.patch
queue-4.15/x86-cpu-add-a-microcode-loader-callback.patch