linux-kernel - [PATCH 05/14] x86/microcode/intel: Expose find_matching

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Date:   Fri, 21 Oct 2022 13:34:04 -0700
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
Subject: [PATCH 05/14] x86/microcode/intel: Expose find_matching_signature() for IFS

IFS uses 'scan test images' provided by Intel that can be regarded as
firmware. IFS test image carries microcode header with extended signature
table.

Expose find_matching_signature() for verifying if the test image
header or the extended signature table indicate whether an IFS test image
is fit to run on a system. Add microcode_intel_ prefix to the
function name.

No functional change

Reviewed-by: Tony Luck <tony.luck@...el.com>
Reviewed-by: Ashok Raj <ashok.raj@...el.com>
Signed-off-by: Jithu Joseph <jithu.joseph@...el.com>
---
 arch/x86/include/asm/microcode_intel.h |  3 +++
 arch/x86/kernel/cpu/microcode/intel.c  | 19 ++++++++++---------
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/microcode_intel.h b/arch/x86/include/asm/microcode_intel.h
index 4c92cea7e4b5..33db2a62ed34 100644
--- a/arch/x86/include/asm/microcode_intel.h
+++ b/arch/x86/include/asm/microcode_intel.h
@@ -74,12 +74,15 @@ extern void load_ucode_intel_ap(void);
 extern void show_ucode_info_early(void);
 extern int __init save_microcode_in_initrd_intel(void);
 void reload_ucode_intel(void);
+int microcode_intel_find_matching_signature(void *mc, unsigned int csig, int cpf);
 #else
 static inline __init void load_ucode_intel_bsp(void) {}
 static inline void load_ucode_intel_ap(void) {}
 static inline void show_ucode_info_early(void) {}
 static inline int __init save_microcode_in_initrd_intel(void) { return -EINVAL; }
 static inline void reload_ucode_intel(void) {}
+static inline int microcode_intel_find_matching_signature(void *mc, unsigned int csig, int cpf)
+	{ return 0; }
 #endif
 
 #endif /* _ASM_X86_MICROCODE_INTEL_H */
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index 025c8f0cd948..f0cc60d92dfc 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -48,7 +48,7 @@ static int llc_size_per_core;
 /*
  * Returns 1 if update has been found, 0 otherwise.
  */
-static int find_matching_signature(void *mc, unsigned int csig, int cpf)
+int microcode_intel_find_matching_signature(void *mc, unsigned int csig, int cpf)
 {
 	struct microcode_header_intel *mc_hdr = mc;
 	struct extended_sigtable *ext_hdr;
@@ -72,6 +72,7 @@ static int find_matching_signature(void *mc, unsigned int csig, int cpf)
 	}
 	return 0;
 }
+EXPORT_SYMBOL_GPL(microcode_intel_find_matching_signature);
 
 /*
  * Returns 1 if update has been found, 0 otherwise.
@@ -83,7 +84,7 @@ static int has_newer_microcode(void *mc, unsigned int csig, int cpf, int new_rev
 	if (mc_hdr->rev <= new_rev)
 		return 0;
 
-	return find_matching_signature(mc, csig, cpf);
+	return microcode_intel_find_matching_signature(mc, csig, cpf);
 }
 
 static struct ucode_patch *memdup_patch(void *data, unsigned int size)
@@ -117,7 +118,7 @@ static void save_microcode_patch(struct ucode_cpu_info *uci, void *data, unsigne
 		sig	     = mc_saved_hdr->sig;
 		pf	     = mc_saved_hdr->pf;
 
-		if (find_matching_signature(data, sig, pf)) {
+		if (microcode_intel_find_matching_signature(data, sig, pf)) {
 			prev_found = true;
 
 			if (mc_hdr->rev <= mc_saved_hdr->rev)
@@ -149,7 +150,7 @@ static void save_microcode_patch(struct ucode_cpu_info *uci, void *data, unsigne
 	if (!p)
 		return;
 
-	if (!find_matching_signature(p->data, uci->cpu_sig.sig, uci->cpu_sig.pf))
+	if (!microcode_intel_find_matching_signature(p->data, uci->cpu_sig.sig, uci->cpu_sig.pf))
 		return;
 
 	/*
@@ -286,8 +287,8 @@ scan_microcode(void *data, size_t size, struct ucode_cpu_info *uci, bool save)
 
 		size -= mc_size;
 
-		if (!find_matching_signature(data, uci->cpu_sig.sig,
-					     uci->cpu_sig.pf)) {
+		if (!microcode_intel_find_matching_signature(data, uci->cpu_sig.sig,
+							     uci->cpu_sig.pf)) {
 			data += mc_size;
 			continue;
 		}
@@ -652,9 +653,9 @@ static struct microcode_intel *find_patch(struct ucode_cpu_info *uci)
 		if (phdr->rev <= uci->cpu_sig.rev)
 			continue;
 
-		if (!find_matching_signature(phdr,
-					     uci->cpu_sig.sig,
-					     uci->cpu_sig.pf))
+		if (!microcode_intel_find_matching_signature(phdr,
+							     uci->cpu_sig.sig,
+							     uci->cpu_sig.pf))
 			continue;
 
 		return iter->data;
-- 
2.25.1