Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/l…

…inux/kernel/git/tip/tip

Pull x86 fixes from Thomas Gleixner:
 "A few fixes for x86:

   - Fix a boot regression caused by the recent bootparam sanitizing
     change, which escaped the attention of all people who reviewed that
     code.

   - Address a boot problem on machines with broken E820 tables caused
     by an underflow which ended up placing the trampoline start at
     physical address 0.

   - Handle machines which do not advertise a legacy timer of any form,
     but need calibration of the local APIC timer gracefully by making
     the calibration routine independent from the tick interrupt. Marked
     for stable as well as there seems to be quite some new laptops
     rolled out which expose this.

   - Clear the RDRAND CPUID bit on AMD family 15h and 16h CPUs which are
     affected by broken firmware which does not initialize RDRAND
     correctly after resume. Add a command line parameter to override
     this for machine which either do not use suspend/resume or have a
     fixed BIOS. Unfortunately there is no way to detect this on boot,
     so the only safe decision is to turn it off by default.

   - Prevent RFLAGS from being clobbers in CALL_NOSPEC on 32bit which
     caused fast KVM instruction emulation to break.

   - Explain the Intel CPU model naming convention so that the repeating
     discussions come to an end"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/retpoline: Don't clobber RFLAGS during CALL_NOSPEC on i386
  x86/boot: Fix boot regression caused by bootparam sanitizing
  x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h
  x86/boot/compressed/64: Fix boot on machines with broken E820 table
  x86/apic: Handle missing global clockevent gracefully
  x86/cpu: Explain Intel model naming convention

Documentation/admin-guide/kernel-parameters.txt

@@ -4090,6 +4090,13 @@
 			Run specified binary instead of /init from the ramdisk,
 			used for early userspace startup. See initrd.
 
+	rdrand=		[X86]
+			force - Override the decision by the kernel to hide the
+				advertisement of RDRAND support (this affects
+				certain AMD processors because of buggy BIOS
+				support, specifically around the suspend/resume
+				path).
+
 	rdt=		[HW,X86,RDT]
 			Turn on/off individual RDT features. List is:
 			cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp,

arch/x86/boot/compressed/pgtable_64.c

@@ -72,6 +72,8 @@ static unsigned long find_trampoline_placement(void)
 
 	/* Find the first usable memory region under bios_start. */
 	for (i = boot_params->e820_entries - 1; i >= 0; i--) {
+		unsigned long new;
+
 		entry = &boot_params->e820_table[i];
 
 		/* Skip all entries above bios_start. */
@@ -84,15 +86,20 @@ static unsigned long find_trampoline_placement(void)
 
 		/* Adjust bios_start to the end of the entry if needed. */
 		if (bios_start > entry->addr + entry->size)
-			bios_start = entry->addr + entry->size;
+			new = entry->addr + entry->size;
 
 		/* Keep bios_start page-aligned. */
-		bios_start = round_down(bios_start, PAGE_SIZE);
+		new = round_down(new, PAGE_SIZE);
 
 		/* Skip the entry if it's too small. */
-		if (bios_start - TRAMPOLINE_32BIT_SIZE < entry->addr)
+		if (new - TRAMPOLINE_32BIT_SIZE < entry->addr)
 			continue;
 
+		/* Protect against underflow. */
+		if (new - TRAMPOLINE_32BIT_SIZE > bios_start)
+			break;
+
+		bios_start = new;
 		break;
 	}
 

arch/x86/include/asm/bootparam_utils.h

@@ -59,7 +59,6 @@ static void sanitize_boot_params(struct boot_params *boot_params)
 			BOOT_PARAM_PRESERVE(apm_bios_info),
 			BOOT_PARAM_PRESERVE(tboot_addr),
 			BOOT_PARAM_PRESERVE(ist_info),
-			BOOT_PARAM_PRESERVE(acpi_rsdp_addr),
 			BOOT_PARAM_PRESERVE(hd0_info),
 			BOOT_PARAM_PRESERVE(hd1_info),
 			BOOT_PARAM_PRESERVE(sys_desc_table),
@@ -71,6 +70,7 @@ static void sanitize_boot_params(struct boot_params *boot_params)
 			BOOT_PARAM_PRESERVE(eddbuf_entries),
 			BOOT_PARAM_PRESERVE(edd_mbr_sig_buf_entries),
 			BOOT_PARAM_PRESERVE(edd_mbr_sig_buffer),
+			BOOT_PARAM_PRESERVE(hdr),
 			BOOT_PARAM_PRESERVE(e820_table),
 			BOOT_PARAM_PRESERVE(eddbuf),
 		};

arch/x86/include/asm/intel-family.h

@@ -11,6 +11,21 @@
  * While adding a new CPUID for a new microarchitecture, add a new
  * group to keep logically sorted out in chronological order. Within
  * that group keep the CPUID for the variants sorted by model number.
+ *
+ * The defined symbol names have the following form:
+ *	INTEL_FAM6{OPTFAMILY}_{MICROARCH}{OPTDIFF}
+ * where:
+ * OPTFAMILY	Describes the family of CPUs that this belongs to. Default
+ *		is assumed to be "_CORE" (and should be omitted). Other values
+ *		currently in use are _ATOM and _XEON_PHI
+ * MICROARCH	Is the code name for the micro-architecture for this core.
+ *		N.B. Not the platform name.
+ * OPTDIFF	If needed, a short string to differentiate by market segment.
+ *		Exact strings here will vary over time. _DESKTOP, _MOBILE, and
+ *		_X (short for Xeon server) should be used when they are
+ *		appropriate.
+ *
+ * The #define line may optionally include a comment including platform names.
  */
 
 #define INTEL_FAM6_CORE_YONAH		0x0E

arch/x86/include/asm/msr-index.h

@@ -381,6 +381,7 @@
 #define MSR_AMD64_PATCH_LEVEL		0x0000008b
 #define MSR_AMD64_TSC_RATIO		0xc0000104
 #define MSR_AMD64_NB_CFG		0xc001001f
+#define MSR_AMD64_CPUID_FN_1		0xc0011004
 #define MSR_AMD64_PATCH_LOADER		0xc0010020
 #define MSR_AMD64_OSVW_ID_LENGTH	0xc0010140
 #define MSR_AMD64_OSVW_STATUS		0xc0010141

arch/x86/include/asm/nospec-branch.h

@@ -192,7 +192,7 @@
 	"    	lfence;\n"					\
 	"       jmp    902b;\n"					\
 	"       .align 16\n"					\
-	"903:	addl   $4, %%esp;\n"				\
+	"903:	lea    4(%%esp), %%esp;\n"			\
 	"       pushl  %[thunk_target];\n"			\
 	"       ret;\n"						\
 	"       .align 16\n"					\

arch/x86/kernel/apic/apic.c

@@ -722,7 +722,7 @@ static __initdata unsigned long lapic_cal_pm1, lapic_cal_pm2;
 static __initdata unsigned long lapic_cal_j1, lapic_cal_j2;
 
 /*
- * Temporary interrupt handler.
+ * Temporary interrupt handler and polled calibration function.
  */
 static void __init lapic_cal_handler(struct clock_event_device *dev)
 {
@@ -851,7 +851,8 @@ bool __init apic_needs_pit(void)
 static int __init calibrate_APIC_clock(void)
 {
 	struct clock_event_device *levt = this_cpu_ptr(&lapic_events);
-	void (*real_handler)(struct clock_event_device *dev);
+	u64 tsc_perj = 0, tsc_start = 0;
+	unsigned long jif_start;
 	unsigned long deltaj;
 	long delta, deltatsc;
 	int pm_referenced = 0;
@@ -878,28 +879,64 @@ static int __init calibrate_APIC_clock(void)
 	apic_printk(APIC_VERBOSE, "Using local APIC timer interrupts.\n"
 		    "calibrating APIC timer ...\n");
 
+	/*
+	 * There are platforms w/o global clockevent devices. Instead of
+	 * making the calibration conditional on that, use a polling based
+	 * approach everywhere.
+	 */
 	local_irq_disable();
 
-	/* Replace the global interrupt handler */
-	real_handler = global_clock_event->event_handler;
-	global_clock_event->event_handler = lapic_cal_handler;
-
 	/*
 	 * Setup the APIC counter to maximum. There is no way the lapic
 	 * can underflow in the 100ms detection time frame
 	 */
 	__setup_APIC_LVTT(0xffffffff, 0, 0);
 
-	/* Let the interrupts run */
+	/*
+	 * Methods to terminate the calibration loop:
+	 *  1) Global clockevent if available (jiffies)
+	 *  2) TSC if available and frequency is known
+	 */
+	jif_start = READ_ONCE(jiffies);
+
+	if (tsc_khz) {
+		tsc_start = rdtsc();
+		tsc_perj = div_u64((u64)tsc_khz * 1000, HZ);
+	}
+
+	/*
+	 * Enable interrupts so the tick can fire, if a global
+	 * clockevent device is available
+	 */
 	local_irq_enable();
 
-	while (lapic_cal_loops <= LAPIC_CAL_LOOPS)
-		cpu_relax();
+	while (lapic_cal_loops <= LAPIC_CAL_LOOPS) {
+		/* Wait for a tick to elapse */
+		while (1) {
+			if (tsc_khz) {
+				u64 tsc_now = rdtsc();
+				if ((tsc_now - tsc_start) >= tsc_perj) {
+					tsc_start += tsc_perj;
+					break;
+				}
+			} else {
+				unsigned long jif_now = READ_ONCE(jiffies);
 
-	local_irq_disable();
+				if (time_after(jif_now, jif_start)) {
+					jif_start = jif_now;
+					break;
+				}
+			}
+			cpu_relax();
+		}
 
-	/* Restore the real event handler */
-	global_clock_event->event_handler = real_handler;
+		/* Invoke the calibration routine */
+		local_irq_disable();
+		lapic_cal_handler(NULL);
+		local_irq_enable();
+	}
+
+	local_irq_disable();
 
 	/* Build delta t1-t2 as apic timer counts down */
 	delta = lapic_cal_t1 - lapic_cal_t2;
@@ -943,10 +980,11 @@ static int __init calibrate_APIC_clock(void)
 	levt->features &= ~CLOCK_EVT_FEAT_DUMMY;
 
 	/*
-	 * PM timer calibration failed or not turned on
-	 * so lets try APIC timer based calibration
+	 * PM timer calibration failed or not turned on so lets try APIC
+	 * timer based calibration, if a global clockevent device is
+	 * available.
 	 */
-	if (!pm_referenced) {
+	if (!pm_referenced && global_clock_event) {
 		apic_printk(APIC_VERBOSE, "... verify APIC timer\n");
 
 		/*

arch/x86/kernel/cpu/amd.c

@@ -804,6 +804,64 @@ static void init_amd_ln(struct cpuinfo_x86 *c)
 	msr_set_bit(MSR_AMD64_DE_CFG, 31);
 }
 
+static bool rdrand_force;
+
+static int __init rdrand_cmdline(char *str)
+{
+	if (!str)
+		return -EINVAL;
+
+	if (!strcmp(str, "force"))
+		rdrand_force = true;
+	else
+		return -EINVAL;
+
+	return 0;
+}
+early_param("rdrand", rdrand_cmdline);
+
+static void clear_rdrand_cpuid_bit(struct cpuinfo_x86 *c)
+{
+	/*
+	 * Saving of the MSR used to hide the RDRAND support during
+	 * suspend/resume is done by arch/x86/power/cpu.c, which is
+	 * dependent on CONFIG_PM_SLEEP.
+	 */
+	if (!IS_ENABLED(CONFIG_PM_SLEEP))
+		return;
+
+	/*
+	 * The nordrand option can clear X86_FEATURE_RDRAND, so check for
+	 * RDRAND support using the CPUID function directly.
+	 */
+	if (!(cpuid_ecx(1) & BIT(30)) || rdrand_force)
+		return;
+
+	msr_clear_bit(MSR_AMD64_CPUID_FN_1, 62);
+
+	/*
+	 * Verify that the CPUID change has occurred in case the kernel is
+	 * running virtualized and the hypervisor doesn't support the MSR.
+	 */
+	if (cpuid_ecx(1) & BIT(30)) {
+		pr_info_once("BIOS may not properly restore RDRAND after suspend, but hypervisor does not support hiding RDRAND via CPUID.\n");
+		return;
+	}
+
+	clear_cpu_cap(c, X86_FEATURE_RDRAND);
+	pr_info_once("BIOS may not properly restore RDRAND after suspend, hiding RDRAND via CPUID. Use rdrand=force to reenable.\n");
+}
+
+static void init_amd_jg(struct cpuinfo_x86 *c)
+{
+	/*
+	 * Some BIOS implementations do not restore proper RDRAND support
+	 * across suspend and resume. Check on whether to hide the RDRAND
+	 * instruction support via CPUID.
+	 */
+	clear_rdrand_cpuid_bit(c);
+}
+
 static void init_amd_bd(struct cpuinfo_x86 *c)
 {
 	u64 value;
@@ -818,6 +876,13 @@ static void init_amd_bd(struct cpuinfo_x86 *c)
 			wrmsrl_safe(MSR_F15H_IC_CFG, value);
 		}
 	}
+
+	/*
+	 * Some BIOS implementations do not restore proper RDRAND support
+	 * across suspend and resume. Check on whether to hide the RDRAND
+	 * instruction support via CPUID.
+	 */
+	clear_rdrand_cpuid_bit(c);
 }
 
 static void init_amd_zn(struct cpuinfo_x86 *c)
@@ -860,6 +925,7 @@ static void init_amd(struct cpuinfo_x86 *c)
 	case 0x10: init_amd_gh(c); break;
 	case 0x12: init_amd_ln(c); break;
 	case 0x15: init_amd_bd(c); break;
+	case 0x16: init_amd_jg(c); break;
 	case 0x17: init_amd_zn(c); break;
 	}