Merge tag 'x86_microcode_for_v6.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 microcode loading updates from Borislav Petkov:

 - Add infrastructure to be able to debug the microcode loader in a guest

 - Refresh Intel old microcode revisions

* tag 'x86_microcode_for_v6.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/microcode: Add microcode loader debugging functionality
  x86/microcode: Add microcode= cmdline parsing
  x86/microcode/intel: Refresh the revisions that determine old_microcode

Author: torvalds

Documentation/admin-guide/kernel-parameters.txt

@@ -3767,8 +3767,16 @@
 
 	mga=		[HW,DRM]
 
-	microcode.force_minrev=	[X86]
-			Format: <bool>
+	microcode=      [X86] Control the behavior of the microcode loader.
+	                Available options, comma separated:
+
+			base_rev=X - with <X> with format: <u32>
+			Set the base microcode revision of each thread when in
+			debug mode.
+
+			dis_ucode_ldr: disable the microcode loader
+
+			force_minrev:
 			Enable or disable the microcode minimal revision
 			enforcement for the runtime microcode loader.
 

arch/x86/Kconfig

@@ -1321,7 +1321,7 @@ config MICROCODE_LATE_LOADING
 	  use this at your own risk. Late loading taints the kernel unless the
 	  microcode header indicates that it is safe for late loading via the
 	  minimal revision check. This minimal revision check can be enforced on
-	  the kernel command line with "microcode.minrev=Y".
+	  the kernel command line with "microcode=force_minrev".
 
 config MICROCODE_LATE_FORCE_MINREV
 	bool "Enforce late microcode loading minimal revision check"
@@ -1337,10 +1337,22 @@ config MICROCODE_LATE_FORCE_MINREV
 	  revision check fails.
 
 	  This minimal revision check can also be controlled via the
-	  "microcode.minrev" parameter on the kernel command line.
+	  "microcode=force_minrev" parameter on the kernel command line.
 
 	  If unsure say Y.
 
+config MICROCODE_DBG
+	bool "Enable microcode loader debugging"
+	default n
+	depends on MICROCODE
+	help
+	  Enable code which allows for debugging the microcode loader in
+	  a guest. Meaning the patch loading is simulated but everything else
+	  related to patch parsing and handling is done as on baremetal with
+	  the purpose of debugging solely the software side of things.
+
+	  You almost certainly want to say n here.
+
 config X86_MSR
 	tristate "/dev/cpu/*/msr - Model-specific register support"
 	help

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

@@ -269,15 +269,6 @@ static bool verify_sha256_digest(u32 patch_id, u32 cur_rev, const u8 *data, unsi
 	return true;
 }
 
-static u32 get_patch_level(void)
-{
-	u32 rev, dummy __always_unused;
-
-	native_rdmsr(MSR_AMD64_PATCH_LEVEL, rev, dummy);
-
-	return rev;
-}
-
 static union cpuid_1_eax ucode_rev_to_cpuid(unsigned int val)
 {
 	union zen_patch_rev p;
@@ -295,6 +286,30 @@ static union cpuid_1_eax ucode_rev_to_cpuid(unsigned int val)
 	return c;
 }
 
+static u32 get_patch_level(void)
+{
+	u32 rev, dummy __always_unused;
+
+	if (IS_ENABLED(CONFIG_MICROCODE_DBG)) {
+		int cpu = smp_processor_id();
+
+		if (!microcode_rev[cpu]) {
+			if (!base_rev)
+				base_rev = cpuid_to_ucode_rev(bsp_cpuid_1_eax);
+
+			microcode_rev[cpu] = base_rev;
+
+			ucode_dbg("CPU%d, base_rev: 0x%x\n", cpu, base_rev);
+		}
+
+		return microcode_rev[cpu];
+	}
+
+	native_rdmsr(MSR_AMD64_PATCH_LEVEL, rev, dummy);
+
+	return rev;
+}
+
 static u16 find_equiv_id(struct equiv_cpu_table *et, u32 sig)
 {
 	unsigned int i;
@@ -324,13 +339,13 @@ static bool verify_container(const u8 *buf, size_t buf_size)
 	u32 cont_magic;
 
 	if (buf_size <= CONTAINER_HDR_SZ) {
-		pr_debug("Truncated microcode container header.\n");
+		ucode_dbg("Truncated microcode container header.\n");
 		return false;
 	}
 
 	cont_magic = *(const u32 *)buf;
 	if (cont_magic != UCODE_MAGIC) {
-		pr_debug("Invalid magic value (0x%08x).\n", cont_magic);
+		ucode_dbg("Invalid magic value (0x%08x).\n", cont_magic);
 		return false;
 	}
 
@@ -355,8 +370,8 @@ static bool verify_equivalence_table(const u8 *buf, size_t buf_size)
 
 	cont_type = hdr[1];
 	if (cont_type != UCODE_EQUIV_CPU_TABLE_TYPE) {
-		pr_debug("Wrong microcode container equivalence table type: %u.\n",
-			 cont_type);
+		ucode_dbg("Wrong microcode container equivalence table type: %u.\n",
+			  cont_type);
 		return false;
 	}
 
@@ -365,7 +380,7 @@ static bool verify_equivalence_table(const u8 *buf, size_t buf_size)
 	equiv_tbl_len = hdr[2];
 	if (equiv_tbl_len < sizeof(struct equiv_cpu_entry) ||
 	    buf_size < equiv_tbl_len) {
-		pr_debug("Truncated equivalence table.\n");
+		ucode_dbg("Truncated equivalence table.\n");
 		return false;
 	}
 
@@ -385,7 +400,7 @@ static bool __verify_patch_section(const u8 *buf, size_t buf_size, u32 *sh_psize
 	const u32 *hdr;
 
 	if (buf_size < SECTION_HDR_SIZE) {
-		pr_debug("Truncated patch section.\n");
+		ucode_dbg("Truncated patch section.\n");
 		return false;
 	}
 
@@ -394,13 +409,13 @@ static bool __verify_patch_section(const u8 *buf, size_t buf_size, u32 *sh_psize
 	p_size = hdr[1];
 
 	if (p_type != UCODE_UCODE_TYPE) {
-		pr_debug("Invalid type field (0x%x) in container file section header.\n",
-			 p_type);
+		ucode_dbg("Invalid type field (0x%x) in container file section header.\n",
+			  p_type);
 		return false;
 	}
 
 	if (p_size < sizeof(struct microcode_header_amd)) {
-		pr_debug("Patch of size %u too short.\n", p_size);
+		ucode_dbg("Patch of size %u too short.\n", p_size);
 		return false;
 	}
 
@@ -477,12 +492,12 @@ static int verify_patch(const u8 *buf, size_t buf_size, u32 *patch_size)
 	 * size sh_psize, as the section claims.
 	 */
 	if (buf_size < sh_psize) {
-		pr_debug("Patch of size %u truncated.\n", sh_psize);
+		ucode_dbg("Patch of size %u truncated.\n", sh_psize);
 		return -1;
 	}
 
 	if (!__verify_patch_size(sh_psize, buf_size)) {
-		pr_debug("Per-family patch size mismatch.\n");
+		ucode_dbg("Per-family patch size mismatch.\n");
 		return -1;
 	}
 
@@ -496,6 +511,9 @@ static int verify_patch(const u8 *buf, size_t buf_size, u32 *patch_size)
 
 	proc_id	= mc_hdr->processor_rev_id;
 	patch_fam = 0xf + (proc_id >> 12);
+
+	ucode_dbg("Patch-ID 0x%08x: family: 0x%x\n", mc_hdr->patch_id, patch_fam);
+
 	if (patch_fam != family)
 		return 1;
 
@@ -566,9 +584,14 @@ static size_t parse_container(u8 *ucode, size_t size, struct cont_desc *desc)
 		}
 
 		mc = (struct microcode_amd *)(buf + SECTION_HDR_SIZE);
+
+		ucode_dbg("patch_id: 0x%x\n", mc->hdr.patch_id);
+
 		if (mc_patch_matches(mc, eq_id)) {
 			desc->psize = patch_size;
 			desc->mc = mc;
+
+			ucode_dbg(" match: size: %d\n", patch_size);
 		}
 
 skip:
@@ -639,8 +662,14 @@ static bool __apply_microcode_amd(struct microcode_amd *mc, u32 *cur_rev,
 			invlpg(p_addr_end);
 	}
 
+	if (IS_ENABLED(CONFIG_MICROCODE_DBG))
+		microcode_rev[smp_processor_id()] = mc->hdr.patch_id;
+
 	/* verify patch application was successful */
 	*cur_rev = get_patch_level();
+
+	ucode_dbg("updated rev: 0x%x\n", *cur_rev);
+
 	if (*cur_rev != mc->hdr.patch_id)
 		return false;
 
@@ -1026,7 +1055,7 @@ static int verify_and_add_patch(u8 family, u8 *fw, unsigned int leftover,
 	patch->patch_id  = mc_hdr->patch_id;
 	patch->equiv_cpu = proc_id;
 
-	pr_debug("%s: Adding patch_id: 0x%08x, proc_id: 0x%04x\n",
+	ucode_dbg("%s: Adding patch_id: 0x%08x, proc_id: 0x%04x\n",
 		 __func__, patch->patch_id, proc_id);
 
 	/* ... and add to cache. */
@@ -1169,7 +1198,7 @@ static enum ucode_state request_microcode_amd(int cpu, struct device *device)
 		snprintf(fw_name, sizeof(fw_name), "amd-ucode/microcode_amd_fam%.2xh.bin", c->x86);
 
 	if (request_firmware_direct(&fw, (const char *)fw_name, device)) {
-		pr_debug("failed to load file %s\n", fw_name);
+		ucode_dbg("failed to load file %s\n", fw_name);
 		goto out;
 	}
 

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

@@ -43,10 +43,19 @@
 #include "internal.h"
 
 static struct microcode_ops *microcode_ops;
-static bool dis_ucode_ldr = false;
+static bool dis_ucode_ldr;
 
 bool force_minrev = IS_ENABLED(CONFIG_MICROCODE_LATE_FORCE_MINREV);
-module_param(force_minrev, bool, S_IRUSR | S_IWUSR);
+
+/*
+ * Those below should be behind CONFIG_MICROCODE_DBG ifdeffery but in
+ * order to not uglify the code with ifdeffery and use IS_ENABLED()
+ * instead, leave them in. When microcode debugging is not enabled,
+ * those are meaningless anyway.
+ */
+/* base microcode revision for debugging */
+u32 base_rev;
+u32 microcode_rev[NR_CPUS] = {};
 
 /*
  * Synchronization.
@@ -119,20 +128,48 @@ bool __init microcode_loader_disabled(void)
 	 *    overwritten.
 	 */
 	if (!cpuid_feature() ||
-	    native_cpuid_ecx(1) & BIT(31) ||
+	    ((native_cpuid_ecx(1) & BIT(31)) &&
+	      !IS_ENABLED(CONFIG_MICROCODE_DBG)) ||
 	    amd_check_current_patch_level())
 		dis_ucode_ldr = true;
 
 	return dis_ucode_ldr;
 }
 
+static void early_parse_cmdline(void)
+{
+	char cmd_buf[64] = {};
+	char *s, *p = cmd_buf;
+
+	if (cmdline_find_option(boot_command_line, "microcode", cmd_buf, sizeof(cmd_buf)) > 0) {
+		while ((s = strsep(&p, ","))) {
+			if (IS_ENABLED(CONFIG_MICROCODE_DBG)) {
+				if (strstr(s, "base_rev=")) {
+					/* advance to the option arg */
+					strsep(&s, "=");
+					if (kstrtouint(s, 16, &base_rev)) { ; }
+				}
+			}
+
+			if (!strcmp("force_minrev", s))
+				force_minrev = true;
+
+			if (!strcmp(s, "dis_ucode_ldr"))
+				dis_ucode_ldr = true;
+		}
+	}
+
+	/* old, compat option */
+	if (cmdline_find_option_bool(boot_command_line, "dis_ucode_ldr") > 0)
+		dis_ucode_ldr = true;
+}
+
 void __init load_ucode_bsp(void)
 {
 	unsigned int cpuid_1_eax;
 	bool intel = true;
 
-	if (cmdline_find_option_bool(boot_command_line, "dis_ucode_ldr") > 0)
-		dis_ucode_ldr = true;
+	early_parse_cmdline();
 
 	if (microcode_loader_disabled())
 		return;