Merge branch 'x86/microcode' into x86/core, to merge dependent commits

Prepare to resolve conflicts with an upstream series of fixes that conflict
with pending x86 changes:

  6f5bf94 Merge tag 'its-for-linus-20250509' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Signed-off-by: Ingo Molnar <[email protected]>

Author: Ingo Molnar

Documentation/ABI/testing/sysfs-devices-system-cpu

@@ -516,6 +516,7 @@ What:		/sys/devices/system/cpu/vulnerabilities
 		/sys/devices/system/cpu/vulnerabilities/mds
 		/sys/devices/system/cpu/vulnerabilities/meltdown
 		/sys/devices/system/cpu/vulnerabilities/mmio_stale_data
+		/sys/devices/system/cpu/vulnerabilities/old_microcode
 		/sys/devices/system/cpu/vulnerabilities/reg_file_data_sampling
 		/sys/devices/system/cpu/vulnerabilities/retbleed
 		/sys/devices/system/cpu/vulnerabilities/spec_store_bypass

Documentation/admin-guide/hw-vuln/index.rst

@@ -23,3 +23,4 @@ are configurable at compile, boot or run time.
    gather_data_sampling
    reg-file-data-sampling
    rsb
+   old_microcode

Documentation/admin-guide/hw-vuln/old_microcode.rst

@@ -0,0 +1,21 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============
+Old Microcode
+=============
+
+The kernel keeps a table of released microcode. Systems that had
+microcode older than this at boot will say "Vulnerable".  This means
+that the system was vulnerable to some known CPU issue. It could be
+security or functional, the kernel does not know or care.
+
+You should update the CPU microcode to mitigate any exposure. This is
+usually accomplished by updating the files in
+/lib/firmware/intel-ucode/ via normal distribution updates. Intel also
+distributes these files in a github repo:
+
+	https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files.git
+
+Just like all the other hardware vulnerabilities, exposure is
+determined at boot. Runtime microcode updates do not change the status
+of this vulnerability.

arch/x86/include/asm/cpufeatures.h

@@ -534,4 +534,6 @@
 #define X86_BUG_BHI			X86_BUG( 1*32+ 3) /* "bhi" CPU is affected by Branch History Injection */
 #define X86_BUG_IBPB_NO_RET		X86_BUG( 1*32+ 4) /* "ibpb_no_ret" IBPB omits return target predictions */
 #define X86_BUG_SPECTRE_V2_USER		X86_BUG( 1*32+ 5) /* "spectre_v2_user" CPU is affected by Spectre variant 2 attack between user processes */
+#define X86_BUG_OLD_MICROCODE		X86_BUG( 1*32+ 6) /* "old_microcode" CPU has old microcode, it is surely vulnerable to something */
+
 #endif /* _ASM_X86_CPUFEATURES_H */

arch/x86/kernel/cpu/bugs.c

@@ -2963,6 +2963,14 @@ static ssize_t rfds_show_state(char *buf)
 	return sysfs_emit(buf, "%s\n", rfds_strings[rfds_mitigation]);
 }
 
+static ssize_t old_microcode_show_state(char *buf)
+{
+	if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
+		return sysfs_emit(buf, "Unknown: running under hypervisor");
+
+	return sysfs_emit(buf, "Vulnerable\n");
+}
+
 static char *stibp_state(void)
 {
 	if (spectre_v2_in_eibrs_mode(spectre_v2_enabled) &&
@@ -3144,6 +3152,9 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr
 	case X86_BUG_RFDS:
 		return rfds_show_state(buf);
 
+	case X86_BUG_OLD_MICROCODE:
+		return old_microcode_show_state(buf);
+
 	default:
 		break;
 	}
@@ -3220,6 +3231,11 @@ ssize_t cpu_show_reg_file_data_sampling(struct device *dev, struct device_attrib
 {
 	return cpu_show_common(dev, attr, buf, X86_BUG_RFDS);
 }
+
+ssize_t cpu_show_old_microcode(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	return cpu_show_common(dev, attr, buf, X86_BUG_OLD_MICROCODE);
+}
 #endif
 
 void __warn_thunk(void)

arch/x86/kernel/cpu/common.c

@@ -1320,10 +1320,52 @@ static bool __init vulnerable_to_rfds(u64 x86_arch_cap_msr)
 	return cpu_matches(cpu_vuln_blacklist, RFDS);
 }
 
+static struct x86_cpu_id cpu_latest_microcode[] = {
+#include "microcode/intel-ucode-defs.h"
+	{}
+};
+
+static bool __init cpu_has_old_microcode(void)
+{
+	const struct x86_cpu_id *m = x86_match_cpu(cpu_latest_microcode);
+
+	/* Give unknown CPUs a pass: */
+	if (!m) {
+		/* Intel CPUs should be in the list. Warn if not: */
+		if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
+			pr_info("x86/CPU: Model not found in latest microcode list\n");
+		return false;
+	}
+
+	/*
+	 * Hosts usually lie to guests with a super high microcode
+	 * version. Just ignore what hosts tell guests:
+	 */
+	if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
+		return false;
+
+	/* Consider all debug microcode to be old: */
+	if (boot_cpu_data.microcode & BIT(31))
+		return true;
+
+	/* Give new microcode a pass: */
+	if (boot_cpu_data.microcode >= m->driver_data)
+		return false;
+
+	/* Uh oh, too old: */
+	return true;
+}
+
 static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
 {
 	u64 x86_arch_cap_msr = x86_read_arch_cap_msr();
 
+	if (cpu_has_old_microcode()) {
+		pr_warn("x86/CPU: Running old microcode\n");
+		setup_force_cpu_bug(X86_BUG_OLD_MICROCODE);
+		add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
+	}
+
 	/* Set ITLB_MULTIHIT bug if cpu is not in the whitelist and not mitigated */
 	if (!cpu_matches(cpu_vuln_whitelist, NO_ITLB_MULTIHIT) &&
 	    !(x86_arch_cap_msr & ARCH_CAP_PSCHANGE_MC_NO))

arch/x86/kernel/cpu/microcode/amd.c

@@ -217,7 +217,6 @@ static bool verify_sha256_digest(u32 patch_id, u32 cur_rev, const u8 *data, unsi
 {
 	struct patch_digest *pd = NULL;
 	u8 digest[SHA256_DIGEST_SIZE];
-	struct sha256_state s;
 	int i;
 
 	if (x86_family(bsp_cpuid_1_eax) < 0x17)
@@ -235,9 +234,7 @@ static bool verify_sha256_digest(u32 patch_id, u32 cur_rev, const u8 *data, unsi
 		return false;
 	}
 
-	sha256_init(&s);
-	sha256_update(&s, data, len);
-	sha256_final(&s, digest);
+	sha256(data, len, digest);
 
 	if (memcmp(digest, pd->sha256, sizeof(digest))) {
 		pr_err("Patch 0x%x SHA256 digest mismatch!\n", patch_id);
@@ -1178,11 +1175,18 @@ static void microcode_fini_cpu_amd(int cpu)
 	uci->mc = NULL;
 }
 
+static void finalize_late_load_amd(int result)
+{
+	if (result)
+		cleanup();
+}
+
 static struct microcode_ops microcode_amd_ops = {
 	.request_microcode_fw	= request_microcode_amd,
 	.collect_cpu_info	= collect_cpu_info_amd,
 	.apply_microcode	= apply_microcode_amd,
 	.microcode_fini_cpu	= microcode_fini_cpu_amd,
+	.finalize_late_load	= finalize_late_load_amd,
 	.nmi_safe		= true,
 };
 

arch/x86/kernel/cpu/microcode/core.c

@@ -696,6 +696,8 @@ static int load_late_locked(void)
 		return load_late_stop_cpus(true);
 	case UCODE_NFOUND:
 		return -ENOENT;
+	case UCODE_OK:
+		return 0;
 	default:
 		return -EBADFD;
 	}