Commit message: x86, cpu, amd: Add workaround for family 16h, erratum 793

This adds the workaround for erratum 793 as a precaution in case not
every BIOS implements it.  This addresses CVE-2013-6885.

Erratum text:

[Revision Guide for AMD Family 16h Models 00h-0Fh Processors,
document 51810 Rev. 3.04 November 2013]

793 Specific Combination of Writes to Write Combined Memory Types and
Locked Instructions May Cause Core Hang

Description

Under a highly specific and detailed set of internal timing
conditions, a locked instruction may trigger a timing sequence whereby
the write to a write combined memory type is not flushed, causing the
locked instruction to stall indefinitely.

Potential Effect on System

Processor core hang.

Suggested Workaround

BIOS should set MSR
C001_1020[15] = 1b.

Fix Planned

No fix planned

[ hpa: updated description, fixed typo in MSR name ]

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/20140114230711.GS29865@pd.tnic
Tested-by: Aravind Gopalakrishnan <aravind.gopalakrishnan@amd.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
CVE: CVE-2013-6885
CWE: CWE-399
Vulnerability description: The microcode on AMD 16h 00h through 0Fh processors does not properly handle the interaction between locked instructions and write-combined memory types, which allows local users to cause a denial of service (system hang) via a crafted application, aka the errata 793 issue.

Project: tip
File: amd.c

static void init_amd_k7(struct cpuinfo_x86 *c)
{
	u32 l, h;

	/*
	 * Bit 15 of Athlon specific MSR 15, needs to be 0
	 * to enable SSE on Palomino/Morgan/Barton CPU's.
	 * If the BIOS didn't enable it already, enable it here.
	 */
	if (c->x86_model >= 6 && c->x86_model <= 10) {
		if (!cpu_has(c, X86_FEATURE_XMM)) {
			printk(KERN_INFO "Enabling disabled K7/SSE Support.\n");
			rdmsr(MSR_K7_HWCR, l, h);
			l &= ~0x00008000;
			wrmsr(MSR_K7_HWCR, l, h);
			set_cpu_cap(c, X86_FEATURE_XMM);
		}
	}

	/*
	 * It's been determined by AMD that Athlons since model 8 stepping 1
	 * are more robust with CLK_CTL set to 200xxxxx instead of 600xxxxx
	 * As per AMD technical note 27212 0.2
	 */
	if ((c->x86_model == 8 && c->x86_mask >= 1) || (c->x86_model > 8)) {
		rdmsr(MSR_K7_CLK_CTL, l, h);
		if ((l & 0xfff00000) != 0x20000000) {
			printk(KERN_INFO
			    "CPU: CLK_CTL MSR was %x. Reprogramming to %x\n",
					l, ((l & 0x000fffff)|0x20000000));
			wrmsr(MSR_K7_CLK_CTL, (l & 0x000fffff)|0x20000000, h);
		}
	}

	set_cpu_cap(c, X86_FEATURE_K7);

	amd_k7_smp_check(c);
}

Project: tip
File: amd.c

static void early_init_amd(struct cpuinfo_x86 *c)
{
	early_init_amd_mc(c);

	/*
	 * c->x86_power is 8000_0007 edx. Bit 8 is TSC runs at constant rate
	 * with P/T states and does not stop in deep C-states
	 */
	if (c->x86_power & (1 << 8)) {
		set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
		set_cpu_cap(c, X86_FEATURE_NONSTOP_TSC);
		if (!check_tsc_unstable())
			sched_clock_stable = 1;
	}

#ifdef CONFIG_X86_64
	set_cpu_cap(c, X86_FEATURE_SYSCALL32);
#else
	/*  Set MTRR capability flag if appropriate */
	if (c->x86 == 5)
		if (c->x86_model == 13 || c->x86_model == 9 ||
		    (c->x86_model == 8 && c->x86_mask >= 8))
			set_cpu_cap(c, X86_FEATURE_K6_MTRR);
#endif
#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_PCI)
	/* check CPU config space for extended APIC ID */
	if (cpu_has_apic && c->x86 >= 0xf) {
		unsigned int val;
		val = read_pci_config(0, 24, 0, 0x68);
		if ((val & ((1 << 17) | (1 << 18))) == ((1 << 17) | (1 << 18)))
			set_cpu_cap(c, X86_FEATURE_EXTD_APICID);
	}
#endif

	/* F16h erratum 793, CVE-2013-6885 */
	if (c->x86 == 0x16 && c->x86_model <= 0xf) {
		u64 val;

		rdmsrl(MSR_AMD64_LS_CFG, val);
		if (!(val & BIT(15)))
			wrmsrl(MSR_AMD64_LS_CFG, val | BIT(15));
	}

}

Project: tip
File: amd.c

static bool cpu_has_amd_erratum(struct cpuinfo_x86 *cpu, const int *erratum)
{
	int osvw_id = *erratum++;
	u32 range;
	u32 ms;

	if (osvw_id >= 0 && osvw_id < 65536 &&
	    cpu_has(cpu, X86_FEATURE_OSVW)) {
		u64 osvw_len;

		rdmsrl(MSR_AMD64_OSVW_ID_LENGTH, osvw_len);
		if (osvw_id < osvw_len) {
			u64 osvw_bits;

			rdmsrl(MSR_AMD64_OSVW_STATUS + (osvw_id >> 6),
			    osvw_bits);
			return osvw_bits & (1ULL << (osvw_id & 0x3f));
		}
	}

	/* OSVW unavailable or ID unknown, match family-model-stepping range */
	ms = (cpu->x86_model << 4) | cpu->x86_mask;
	while ((range = *erratum++))
		if ((cpu->x86 == AMD_MODEL_RANGE_FAMILY(range)) &&
		    (ms >= AMD_MODEL_RANGE_START(range)) &&
		    (ms <= AMD_MODEL_RANGE_END(range)))
			return true;

	return false;
}

Project: tip
File: amd.c

static void bsp_init_amd(struct cpuinfo_x86 *c)
{
	if (cpu_has(c, X86_FEATURE_CONSTANT_TSC)) {

		if (c->x86 > 0x10 ||
		    (c->x86 == 0x10 && c->x86_model >= 0x2)) {
			u64 val;

			rdmsrl(MSR_K7_HWCR, val);
			if (!(val & BIT(24)))
				printk(KERN_WARNING FW_BUG "TSC doesn't count "
					"with P0 frequency!\n");
		}
	}

	if (c->x86 == 0x15) {
		unsigned long upperbit;
		u32 cpuid, assoc;

		cpuid	 = cpuid_edx(0x80000005);
		assoc	 = cpuid >> 16 & 0xff;
		upperbit = ((cpuid >> 24) << 10) / assoc;

		va_align.mask	  = (upperbit - 1) & PAGE_MASK;
		va_align.flags    = ALIGN_VA_32 | ALIGN_VA_64;
	}
}

Project: tip
File: amd.c

static inline int rdmsrl_amd_safe(unsigned msr, unsigned long long *p)
{
	u32 gprs[8] = { 0 };
	int err;

	WARN_ONCE((boot_cpu_data.x86 != 0xf),
		  "%s should only be used on K8!\n", __func__);

	gprs[1] = msr;
	gprs[7] = 0x9c5a203a;

	err = rdmsr_safe_regs(gprs);

	*p = gprs[0] | ((u64)gprs[2] << 32);

	return err;
}

Project: tip
File: amd.c

static void init_amd_k6(struct cpuinfo_x86 *c)
{
	u32 l, h;
	int mbytes = get_num_physpages() >> (20-PAGE_SHIFT);

	if (c->x86_model < 6) {
		/* Based on AMD doc 20734R - June 2000 */
		if (c->x86_model == 0) {
			clear_cpu_cap(c, X86_FEATURE_APIC);
			set_cpu_cap(c, X86_FEATURE_PGE);
		}
		return;
	}

	if (c->x86_model == 6 && c->x86_mask == 1) {
		const int K6_BUG_LOOP = 1000000;
		int n;
		void (*f_vide)(void);
		unsigned long d, d2;

		printk(KERN_INFO "AMD K6 stepping B detected - ");

		/*
		 * It looks like AMD fixed the 2.6.2 bug and improved indirect
		 * calls at the same time.
		 */

		n = K6_BUG_LOOP;
		f_vide = vide;
		rdtscl(d);
		while (n--)
			f_vide();
		rdtscl(d2);
		d = d2-d;

		if (d > 20*K6_BUG_LOOP)
			printk(KERN_CONT
				"system stability may be impaired when more than 32 MB are used.\n");
		else
			printk(KERN_CONT "probably OK (after B9730xxxx).\n");
	}

	/* K6 with old style WHCR */
	if (c->x86_model < 8 ||
	   (c->x86_model == 8 && c->x86_mask < 8)) {
		/* We can only write allocate on the low 508Mb */
		if (mbytes > 508)
			mbytes = 508;

		rdmsr(MSR_K6_WHCR, l, h);
		if ((l&0x0000FFFF) == 0) {
			unsigned long flags;
			l = (1<<0)|((mbytes/4)<<1);
			local_irq_save(flags);
			wbinvd();
			wrmsr(MSR_K6_WHCR, l, h);
			local_irq_restore(flags);
			printk(KERN_INFO "Enabling old style K6 write allocation for %d Mb\n",
				mbytes);
		}
		return;
	}

	if ((c->x86_model == 8 && c->x86_mask > 7) ||
	     c->x86_model == 9 || c->x86_model == 13) {
		/* The more serious chips .. */

		if (mbytes > 4092)
			mbytes = 4092;

		rdmsr(MSR_K6_WHCR, l, h);
		if ((l&0xFFFF0000) == 0) {
			unsigned long flags;
			l = ((mbytes>>2)<<22)|(1<<16);
			local_irq_save(flags);
			wbinvd();
			wrmsr(MSR_K6_WHCR, l, h);
			local_irq_restore(flags);
			printk(KERN_INFO "Enabling new style K6 write allocation for %d Mb\n",
				mbytes);
		}

		return;
	}

	if (c->x86_model == 10) {
		/* AMD Geode LX is model 10 */
		/* placeholder for any needed mods */
		return;
	}
}

Project: tip
File: amd.c

u16 amd_get_nb_id(int cpu)
{
	u16 id = 0;
#ifdef CONFIG_SMP
	id = per_cpu(cpu_llc_id, cpu);
#endif
	return id;
}

Project: tip
File: amd.c

static void init_amd_k5(struct cpuinfo_x86 *c)
{
/*
 * General Systems BIOSen alias the cpu frequency registers
 * of the Elan at 0x000df000. Unfortuantly, one of the Linux
 * drivers subsequently pokes it, and changes the CPU speed.
 * Workaround : Remove the unneeded alias.
 */
#define CBAR		(0xfffc) /* Configuration Base Address  (32-bit) */
#define CBAR_ENB	(0x80000000)
#define CBAR_KEY	(0X000000CB)
	if (c->x86_model == 9 || c->x86_model == 10) {
		if (inl(CBAR) & CBAR_ENB)
			outl(0 | CBAR_KEY, CBAR);
	}
}

Project: tip
File: amd.c

static void cpu_set_tlb_flushall_shift(struct cpuinfo_x86 *c)
{
	tlb_flushall_shift = 5;

	if (c->x86 <= 0x11)
		tlb_flushall_shift = 4;
}

Project: tip
File: amd.c

static void early_init_amd_mc(struct cpuinfo_x86 *c)
{
#ifdef CONFIG_X86_HT
	unsigned bits, ecx;

	/* Multi core CPU? */
	if (c->extended_cpuid_level < 0x80000008)
		return;

	ecx = cpuid_ecx(0x80000008);

	c->x86_max_cores = (ecx & 0xff) + 1;

	/* CPU telling us the core id bits shift? */
	bits = (ecx >> 12) & 0xF;

	/* Otherwise recompute */
	if (bits == 0) {
		while ((1 << bits) < c->x86_max_cores)
			bits++;
	}

	c->x86_coreid_bits = bits;
#endif
}

Project: tip
File: amd.c

static unsigned int amd_size_cache(struct cpuinfo_x86 *c, unsigned int size)
{
	/* AMD errata T13 (order #21922) */
	if ((c->x86 == 6)) {
		/* Duron Rev A0 */
		if (c->x86_model == 3 && c->x86_mask == 0)
			size = 64;
		/* Tbird rev A1/A2 */
		if (c->x86_model == 4 &&
			(c->x86_mask == 0 || c->x86_mask == 1))
			size = 256;
	}
	return size;
}

Project: tip
File: amd.c

static void cpu_detect_tlb_amd(struct cpuinfo_x86 *c)
{
	u32 ebx, eax, ecx, edx;
	u16 mask = 0xfff;

	if (c->x86 < 0xf)
		return;

	if (c->extended_cpuid_level < 0x80000006)
		return;

	cpuid(0x80000006, &eax, &ebx, &ecx, &edx);

	tlb_lld_4k[ENTRIES] = (ebx >> 16) & mask;
	tlb_lli_4k[ENTRIES] = ebx & mask;

	/*
	 * K8 doesn't have 2M/4M entries in the L2 TLB so read out the L1 TLB
	 * characteristics from the CPUID function 0x80000005 instead.
	 */
	if (c->x86 == 0xf) {
		cpuid(0x80000005, &eax, &ebx, &ecx, &edx);
		mask = 0xff;
	}

	/* Handle DTLB 2M and 4M sizes, fall back to L1 if L2 is disabled */
	if (!((eax >> 16) & mask)) {
		u32 a, b, c, d;

		cpuid(0x80000005, &a, &b, &c, &d);
		tlb_lld_2m[ENTRIES] = (a >> 16) & 0xff;
	} else {
		tlb_lld_2m[ENTRIES] = (eax >> 16) & mask;
	}

	/* a 4M entry uses two 2M entries */
	tlb_lld_4m[ENTRIES] = tlb_lld_2m[ENTRIES] >> 1;

	/* Handle ITLB 2M and 4M sizes, fall back to L1 if L2 is disabled */
	if (!(eax & mask)) {
		/* Erratum 658 */
		if (c->x86 == 0x15 && c->x86_model <= 0x1f) {
			tlb_lli_2m[ENTRIES] = 1024;
		} else {
			cpuid(0x80000005, &eax, &ebx, &ecx, &edx);
			tlb_lli_2m[ENTRIES] = eax & 0xff;
		}
	} else
		tlb_lli_2m[ENTRIES] = eax & mask;

	tlb_lli_4m[ENTRIES] = tlb_lli_2m[ENTRIES] >> 1;

	cpu_set_tlb_flushall_shift(c);
}

Project: tip
File: amd.c

static void srat_detect_node(struct cpuinfo_x86 *c)
{
#ifdef CONFIG_NUMA
	int cpu = smp_processor_id();
	int node;
	unsigned apicid = c->apicid;

	node = numa_cpu_node(cpu);
	if (node == NUMA_NO_NODE)
		node = per_cpu(cpu_llc_id, cpu);

	/*
	 * On multi-fabric platform (e.g. Numascale NumaChip) a
	 * platform-specific handler needs to be called to fixup some
	 * IDs of the CPU.
	 */
	if (x86_cpuinit.fixup_cpu_id)
		x86_cpuinit.fixup_cpu_id(c, node);

	if (!node_online(node)) {
		/*
		 * Two possibilities here:
		 *
		 * - The CPU is missing memory and no node was created.  In
		 *   that case try picking one from a nearby CPU.
		 *
		 * - The APIC IDs differ from the HyperTransport node IDs
		 *   which the K8 northbridge parsing fills in.  Assume
		 *   they are all increased by a constant offset, but in
		 *   the same order as the HT nodeids.  If that doesn't
		 *   result in a usable node fall back to the path for the
		 *   previous case.
		 *
		 * This workaround operates directly on the mapping between
		 * APIC ID and NUMA node, assuming certain relationship
		 * between APIC ID, HT node ID and NUMA topology.  As going
		 * through CPU mapping may alter the outcome, directly
		 * access __apicid_to_node[].
		 */
		int ht_nodeid = c->initial_apicid;

		if (ht_nodeid >= 0 &&
		    __apicid_to_node[ht_nodeid] != NUMA_NO_NODE)
			node = __apicid_to_node[ht_nodeid];
		/* Pick a nearby node */
		if (!node_online(node))
			node = nearby_node(apicid);
	}
	numa_set_node(cpu, node);
#endif
}

Project: tip
File: amd.c

static inline int wrmsrl_amd_safe(unsigned msr, unsigned long long val)
{
	u32 gprs[8] = { 0 };

	WARN_ONCE((boot_cpu_data.x86 != 0xf),
		  "%s should only be used on K8!\n", __func__);

	gprs[0] = (u32)val;
	gprs[1] = msr;
	gprs[2] = val >> 32;
	gprs[7] = 0x9c5a203a;

	return wrmsr_safe_regs(gprs);
}

Project: tip
File: amd.c

static void amd_k7_smp_check(struct cpuinfo_x86 *c)
{
	/* calling is from identify_secondary_cpu() ? */
	if (!c->cpu_index)
		return;

	/*
	 * Certain Athlons might work (for various values of 'work') in SMP
	 * but they are not certified as MP capable.
	 */
	/* Athlon 660/661 is valid. */
	if ((c->x86_model == 6) && ((c->x86_mask == 0) ||
	    (c->x86_mask == 1)))
		return;

	/* Duron 670 is valid */
	if ((c->x86_model == 7) && (c->x86_mask == 0))
		return;

	/*
	 * Athlon 662, Duron 671, and Athlon >model 7 have capability
	 * bit. It's worth noting that the A5 stepping (662) of some
	 * Athlon XP's have the MP bit set.
	 * See http://www.heise.de/newsticker/data/jow-18.10.01-000 for
	 * more.
	 */
	if (((c->x86_model == 6) && (c->x86_mask >= 2)) ||
	    ((c->x86_model == 7) && (c->x86_mask >= 1)) ||
	     (c->x86_model > 7))
		if (cpu_has_mp)
			return;

	/* If we get here, not a certified SMP capable AMD system. */

	/*
	 * Don't taint if we are running SMP kernel on a single non-MP
	 * approved Athlon
	 */
	WARN_ONCE(1, "WARNING: This combination of AMD"
		" processors is not suitable for SMP.\n");
	add_taint(TAINT_UNSAFE_SMP, LOCKDEP_NOW_UNRELIABLE);
}

Project: tip
File: amd.c

static int nearby_node(int apicid)
{
	int i, node;

	for (i = apicid - 1; i >= 0; i--) {
		node = __apicid_to_node[i];
		if (node != NUMA_NO_NODE && node_online(node))
			return node;
	}
	for (i = apicid + 1; i < MAX_LOCAL_APIC; i++) {
		node = __apicid_to_node[i];
		if (node != NUMA_NO_NODE && node_online(node))
			return node;
	}
	return first_node(node_online_map); /* Shouldn't happen */
}

Project: tip
File: amd.c

static void amd_get_topology(struct cpuinfo_x86 *c)
{
	u32 nodes, cores_per_cu = 1;
	u8 node_id;
	int cpu = smp_processor_id();

	/* get information required for multi-node processors */
	if (cpu_has_topoext) {
		u32 eax, ebx, ecx, edx;

		cpuid(0x8000001e, &eax, &ebx, &ecx, &edx);
		nodes = ((ecx >> 8) & 7) + 1;
		node_id = ecx & 7;

		/* get compute unit information */
		smp_num_siblings = ((ebx >> 8) & 3) + 1;
		c->compute_unit_id = ebx & 0xff;
		cores_per_cu += ((ebx >> 8) & 3);
	} else if (cpu_has(c, X86_FEATURE_NODEID_MSR)) {
		u64 value;

		rdmsrl(MSR_FAM10H_NODE_ID, value);
		nodes = ((value >> 3) & 7) + 1;
		node_id = value & 7;
	} else
		return;

	/* fixup multi-node processor information */
	if (nodes > 1) {
		u32 cores_per_node;
		u32 cus_per_node;

		set_cpu_cap(c, X86_FEATURE_AMD_DCM);
		cores_per_node = c->x86_max_cores / nodes;
		cus_per_node = cores_per_node / cores_per_cu;

		/* store NodeID, use llc_shared_map to store sibling info */
		per_cpu(cpu_llc_id, cpu) = node_id;

		/* core id has to be in the [0 .. cores_per_node - 1] range */
		c->cpu_core_id %= cores_per_node;
		c->compute_unit_id %= cus_per_node;
	}
}

Project: tip
File: amd.c

static void init_amd(struct cpuinfo_x86 *c)
{
	u32 dummy;
	unsigned long long value;

#ifdef CONFIG_SMP
	/*
	 * Disable TLB flush filter by setting HWCR.FFDIS on K8
	 * bit 6 of msr C001_0015
	 *
	 * Errata 63 for SH-B3 steppings
	 * Errata 122 for all steppings (F+ have it disabled by default)
	 */
	if (c->x86 == 0xf) {
		rdmsrl(MSR_K7_HWCR, value);
		value |= 1 << 6;
		wrmsrl(MSR_K7_HWCR, value);
	}
#endif

	early_init_amd(c);

	/*
	 * Bit 31 in normal CPUID used for nonstandard 3DNow ID;
	 * 3DNow is IDd by bit 31 in extended CPUID (1*32+31) anyway
	 */
	clear_cpu_cap(c, 0*32+31);

#ifdef CONFIG_X86_64
	/* On C+ stepping K8 rep microcode works well for copy/memset */
	if (c->x86 == 0xf) {
		u32 level;

		level = cpuid_eax(1);
		if ((level >= 0x0f48 && level < 0x0f50) || level >= 0x0f58)
			set_cpu_cap(c, X86_FEATURE_REP_GOOD);

		/*
		 * Some BIOSes incorrectly force this feature, but only K8
		 * revision D (model = 0x14) and later actually support it.
		 * (AMD Erratum #110, docId: 25759).
		 */
		if (c->x86_model < 0x14 && cpu_has(c, X86_FEATURE_LAHF_LM)) {
			clear_cpu_cap(c, X86_FEATURE_LAHF_LM);
			if (!rdmsrl_amd_safe(0xc001100d, &value)) {
				value &= ~(1ULL << 32);
				wrmsrl_amd_safe(0xc001100d, value);
			}
		}

	}
	if (c->x86 >= 0x10)
		set_cpu_cap(c, X86_FEATURE_REP_GOOD);

	/* get apicid instead of initial apic id from cpuid */
	c->apicid = hard_smp_processor_id();
#else

	/*
	 *	FIXME: We should handle the K5 here. Set up the write
	 *	range and also turn on MSR 83 bits 4 and 31 (write alloc,
	 *	no bus pipeline)
	 */

	switch (c->x86) {
	case 4:
		init_amd_k5(c);
		break;
	case 5:
		init_amd_k6(c);
		break;
	case 6: /* An Athlon/Duron */
		init_amd_k7(c);
		break;
	}

	/* K6s reports MCEs but don't actually have all the MSRs */
	if (c->x86 < 6)
		clear_cpu_cap(c, X86_FEATURE_MCE);
#endif

	/* Enable workaround for FXSAVE leak */
	if (c->x86 >= 6)
		set_cpu_cap(c, X86_FEATURE_FXSAVE_LEAK);

	if (!c->x86_model_id[0]) {
		switch (c->x86) {
		case 0xf:
			/* Should distinguish Models here, but this is only
			   a fallback anyways. */
			strcpy(c->x86_model_id, "Hammer");
			break;
		}
	}

	/* re-enable TopologyExtensions if switched off by BIOS */
	if ((c->x86 == 0x15) &&
	    (c->x86_model >= 0x10) && (c->x86_model <= 0x1f) &&
	    !cpu_has(c, X86_FEATURE_TOPOEXT)) {

		if (!rdmsrl_safe(0xc0011005, &value)) {
			value |= 1ULL << 54;
			wrmsrl_safe(0xc0011005, value);
			rdmsrl(0xc0011005, value);
			if (value & (1ULL << 54)) {
				set_cpu_cap(c, X86_FEATURE_TOPOEXT);
				printk(KERN_INFO FW_INFO "CPU: Re-enabling "
				  "disabled Topology Extensions Support\n");
			}
		}
	}

	/*
	 * The way access filter has a performance penalty on some workloads.
	 * Disable it on the affected CPUs.
	 */
	if ((c->x86 == 0x15) &&
	    (c->x86_model >= 0x02) && (c->x86_model < 0x20)) {

		if (!rdmsrl_safe(0xc0011021, &value) && !(value & 0x1E)) {
			value |= 0x1E;
			wrmsrl_safe(0xc0011021, value);
		}
	}

	cpu_detect_cache_sizes(c);

	/* Multi core CPU? */
	if (c->extended_cpuid_level >= 0x80000008) {
		amd_detect_cmp(c);
		srat_detect_node(c);
	}

#ifdef CONFIG_X86_32
	detect_ht(c);
#endif

	init_amd_cacheinfo(c);

	if (c->x86 >= 0xf)
		set_cpu_cap(c, X86_FEATURE_K8);

	if (cpu_has_xmm2) {
		/* MFENCE stops RDTSC speculation */
		set_cpu_cap(c, X86_FEATURE_MFENCE_RDTSC);
	}

#ifdef CONFIG_X86_64
	if (c->x86 == 0x10) {
		/* do this for boot cpu */
		if (c == &boot_cpu_data)
			check_enable_amd_mmconf_dmi();

		fam10h_check_enable_mmcfg();
	}

	if (c == &boot_cpu_data && c->x86 >= 0xf) {
		unsigned long long tseg;

		/*
		 * Split up direct mapping around the TSEG SMM area.
		 * Don't do it for gbpages because there seems very little
		 * benefit in doing so.
		 */
		if (!rdmsrl_safe(MSR_K8_TSEG_ADDR, &tseg)) {
			unsigned long pfn = tseg >> PAGE_SHIFT;

			printk(KERN_DEBUG "tseg: %010llx\n", tseg);
			if (pfn_range_is_mapped(pfn, pfn + 1))
				set_memory_4k((unsigned long)__va(tseg), 1);
		}
	}
#endif

	/*
	 * Family 0x12 and above processors have APIC timer
	 * running in deep C states.
	 */
	if (c->x86 > 0x11)
		set_cpu_cap(c, X86_FEATURE_ARAT);

	if (c->x86 == 0x10) {
		/*
		 * Disable GART TLB Walk Errors on Fam10h. We do this here
		 * because this is always needed when GART is enabled, even in a
		 * kernel which has no MCE support built in.
		 * BIOS should disable GartTlbWlk Errors themself. If
		 * it doesn't do it here as suggested by the BKDG.
		 *
		 * Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=33012
		 */
		u64 mask;
		int err;

		err = rdmsrl_safe(MSR_AMD64_MCx_MASK(4), &mask);
		if (err == 0) {
			mask |= (1 << 10);
			wrmsrl_safe(MSR_AMD64_MCx_MASK(4), mask);
		}

		/*
		 * On family 10h BIOS may not have properly enabled WC+ support,
		 * causing it to be converted to CD memtype. This may result in
		 * performance degradation for certain nested-paging guests.
		 * Prevent this conversion by clearing bit 24 in
		 * MSR_AMD64_BU_CFG2.
		 *
		 * NOTE: we want to use the _safe accessors so as not to #GP kvm
		 * guests on older kvm hosts.
		 */

		rdmsrl_safe(MSR_AMD64_BU_CFG2, &value);
		value &= ~(1ULL << 24);
		wrmsrl_safe(MSR_AMD64_BU_CFG2, value);

		if (cpu_has_amd_erratum(c, amd_erratum_383))
			set_cpu_bug(c, X86_BUG_AMD_TLB_MMATCH);
	}

	if (cpu_has_amd_erratum(c, amd_erratum_400))
		set_cpu_bug(c, X86_BUG_AMD_APIC_C1E);

	rdmsr_safe(MSR_AMD64_PATCH_LEVEL, &c->microcode, &dummy);
}

Project: tip
File: amd.c

static void amd_detect_cmp(struct cpuinfo_x86 *c)
{
#ifdef CONFIG_X86_HT
	unsigned bits;
	int cpu = smp_processor_id();

	bits = c->x86_coreid_bits;
	/* Low order bits define the core id (index of core in socket) */
	c->cpu_core_id = c->initial_apicid & ((1 << bits)-1);
	/* Convert the initial APIC ID into the socket ID */
	c->phys_proc_id = c->initial_apicid >> bits;
	/* use socket ID also for last level cache */
	per_cpu(cpu_llc_id, cpu) = c->phys_proc_id;
	amd_get_topology(c);
#endif
}