* Add support for hardware-enforced cache coherency on AMD which

obviates the need to flush cachelines before changing the PTE encryption
 bit, by Krish Sadhukhan.
 
 * Add Centaur initialization support for families >= 7, by Tony W
 Wang-oc.
 
 * Add a feature flag for, and expose TSX suspend load tracking feature
 to KVM, by Cathy Zhang.
 
 * Emulate SLDT and STR so that windows programs don't crash on UMIP
 machines, by Brendan Shanks and Ricardo Neri.
 
 * Use the new SERIALIZE insn on Intel hardware which supports it, by
 Ricardo Neri.
 
 * Misc cleanups and fixes.
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Merge tag 'x86_cpu_for_v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 cpu updates from Borislav Petkov:

 - Add support for hardware-enforced cache coherency on AMD which
   obviates the need to flush cachelines before changing the PTE
   encryption bit (Krish Sadhukhan)

 - Add Centaur initialization support for families >= 7 (Tony W Wang-oc)

 - Add a feature flag for, and expose TSX suspend load tracking feature
   to KVM (Cathy Zhang)

 - Emulate SLDT and STR so that windows programs don't crash on UMIP
   machines (Brendan Shanks and Ricardo Neri)

 - Use the new SERIALIZE insn on Intel hardware which supports it
   (Ricardo Neri)

 - Misc cleanups and fixes

* tag 'x86_cpu_for_v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  KVM: SVM: Don't flush cache if hardware enforces cache coherency across encryption domains
  x86/mm/pat: Don't flush cache if hardware enforces cache coherency across encryption domnains
  x86/cpu: Add hardware-enforced cache coherency as a CPUID feature
  x86/cpu/centaur: Add Centaur family >=7 CPUs initialization support
  x86/cpu/centaur: Replace two-condition switch-case with an if statement
  x86/kvm: Expose TSX Suspend Load Tracking feature
  x86/cpufeatures: Enumerate TSX suspend load address tracking instructions
  x86/umip: Add emulation/spoofing for SLDT and STR instructions
  x86/cpu: Fix typos and improve the comments in sync_core()
  x86/cpu: Use XGETBV and XSETBV mnemonics in fpu/internal.h
  x86/cpu: Use SERIALIZE in sync_core() when available

arch/x86/include/asm/cpufeatures.h

@@ -96,7 +96,7 @@
 #define X86_FEATURE_SYSCALL32		( 3*32+14) /* "" syscall in IA32 userspace */
 #define X86_FEATURE_SYSENTER32		( 3*32+15) /* "" sysenter in IA32 userspace */
 #define X86_FEATURE_REP_GOOD		( 3*32+16) /* REP microcode works well */
-/* free					( 3*32+17) */
+#define X86_FEATURE_SME_COHERENT	( 3*32+17) /* "" AMD hardware-enforced cache coherency */
 #define X86_FEATURE_LFENCE_RDTSC	( 3*32+18) /* "" LFENCE synchronizes RDTSC */
 #define X86_FEATURE_ACC_POWER		( 3*32+19) /* AMD Accumulated Power Mechanism */
 #define X86_FEATURE_NOPL		( 3*32+20) /* The NOPL (0F 1F) instructions */
@@ -368,6 +368,7 @@
 #define X86_FEATURE_MD_CLEAR		(18*32+10) /* VERW clears CPU buffers */
 #define X86_FEATURE_TSX_FORCE_ABORT	(18*32+13) /* "" TSX_FORCE_ABORT */
 #define X86_FEATURE_SERIALIZE		(18*32+14) /* SERIALIZE instruction */
+#define X86_FEATURE_TSXLDTRK		(18*32+16) /* TSX Suspend Load Address Tracking */
 #define X86_FEATURE_PCONFIG		(18*32+18) /* Intel PCONFIG */
 #define X86_FEATURE_ARCH_LBR		(18*32+19) /* Intel ARCH LBR */
 #define X86_FEATURE_SPEC_CTRL		(18*32+26) /* "" Speculation Control (IBRS + IBPB) */

arch/x86/include/asm/fpu/internal.h

@@ -602,9 +602,7 @@ static inline u64 xgetbv(u32 index)
 {
 	u32 eax, edx;
 
-	asm volatile(".byte 0x0f,0x01,0xd0" /* xgetbv */
+	asm volatile("xgetbv" : "=a" (eax), "=d" (edx) : "c" (index));
-		     : "=a" (eax), "=d" (edx)
-		     : "c" (index));
 	return eax + ((u64)edx << 32);
 }
 
@@ -613,8 +611,7 @@ static inline void xsetbv(u32 index, u64 value)
 	u32 eax = value;
 	u32 edx = value >> 32;
 
-	asm volatile(".byte 0x0f,0x01,0xd1" /* xsetbv */
+	asm volatile("xsetbv" :: "a" (eax), "d" (edx), "c" (index));
-		     : : "a" (eax), "d" (edx), "c" (index));
 }
 
 #endif /* _ASM_X86_FPU_INTERNAL_H */

arch/x86/include/asm/special_insns.h

@@ -234,6 +234,12 @@ static inline void clwb(volatile void *__p)
 
 #define nop() asm volatile ("nop")
 
+static inline void serialize(void)
+{
+	/* Instruction opcode for SERIALIZE; supported in binutils >= 2.35. */
+	asm volatile(".byte 0xf, 0x1, 0xe8" ::: "memory");
+}
+
 #endif /* __KERNEL__ */
 
 #endif /* _ASM_X86_SPECIAL_INSNS_H */

arch/x86/include/asm/sync_core.h

@@ -5,6 +5,7 @@
 #include <linux/preempt.h>
 #include <asm/processor.h>
 #include <asm/cpufeature.h>
+#include <asm/special_insns.h>
 
 #ifdef CONFIG_X86_32
 static inline void iret_to_self(void)
@@ -46,22 +47,34 @@ static inline void iret_to_self(void)
  *
  *  b) Text was modified on a different CPU, may subsequently be
  *     executed on this CPU, and you want to make sure the new version
- *     gets executed.  This generally means you're calling this in a IPI.
+ *     gets executed.  This generally means you're calling this in an IPI.
  *
  * If you're calling this for a different reason, you're probably doing
  * it wrong.
+ *
+ * Like all of Linux's memory ordering operations, this is a
+ * compiler barrier as well.
  */
 static inline void sync_core(void)
 {
 	/*
-	 * There are quite a few ways to do this.  IRET-to-self is nice
+	 * The SERIALIZE instruction is the most straightforward way to
-	 * because it works on every CPU, at any CPL (so it's compatible
+	 * do this, but it is not universally available.
-	 * with paravirtualization), and it never exits to a hypervisor.
+	 */
-	 * The only down sides are that it's a bit slow (it seems to be
+	if (static_cpu_has(X86_FEATURE_SERIALIZE)) {
-	 * a bit more than 2x slower than the fastest options) and that
+		serialize();
-	 * it unmasks NMIs.  The "push %cs" is needed because, in
+		return;
-	 * paravirtual environments, __KERNEL_CS may not be a valid CS
+	}
-	 * value when we do IRET directly.
+
+	/*
+	 * For all other processors, there are quite a few ways to do this.
+	 * IRET-to-self is nice because it works on every CPU, at any CPL
+	 * (so it's compatible with paravirtualization), and it never exits
+	 * to a hypervisor.  The only downsides are that it's a bit slow
+	 * (it seems to be a bit more than 2x slower than the fastest
+	 * options) and that it unmasks NMIs.  The "push %cs" is needed,
+	 * because in paravirtual environments __KERNEL_CS may not be a
+	 * valid CS value when we do IRET directly.
 	 *
 	 * In case NMI unmasking or performance ever becomes a problem,
 	 * the next best option appears to be MOV-to-CR2 and an
@@ -71,9 +84,6 @@ static inline void sync_core(void)
 	 * CPUID is the conventional way, but it's nasty: it doesn't
 	 * exist on some 486-like CPUs, and it usually exits to a
 	 * hypervisor.
-	 *
-	 * Like all of Linux's memory ordering operations, this is a
-	 * compiler barrier as well.
 	 */
 	iret_to_self();
 }

arch/x86/kernel/cpu/centaur.c

@@ -65,6 +65,9 @@ static void init_c3(struct cpuinfo_x86 *c)
 		c->x86_cache_alignment = c->x86_clflush_size * 2;
 		set_cpu_cap(c, X86_FEATURE_REP_GOOD);
 	}
+
+	if (c->x86 >= 7)
+		set_cpu_cap(c, X86_FEATURE_REP_GOOD);
 }
 
 enum {
@@ -90,18 +93,15 @@ enum {
 
 static void early_init_centaur(struct cpuinfo_x86 *c)
 {
-	switch (c->x86) {
 #ifdef CONFIG_X86_32
-	case 5:
+	/* Emulate MTRRs using Centaur's MCR. */
-		/* Emulate MTRRs using Centaur's MCR. */
+	if (c->x86 == 5)
 		set_cpu_cap(c, X86_FEATURE_CENTAUR_MCR);
-		break;
 #endif
-	case 6:
+	if ((c->x86 == 6 && c->x86_model >= 0xf) ||
-		if (c->x86_model >= 0xf)
+	    (c->x86 >= 7))
-			set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
+		set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
-		break;
+
-	}
 #ifdef CONFIG_X86_64
 	set_cpu_cap(c, X86_FEATURE_SYSENTER32);
 #endif
@@ -145,9 +145,8 @@ static void init_centaur(struct cpuinfo_x86 *c)
 			set_cpu_cap(c, X86_FEATURE_ARCH_PERFMON);
 	}
 
-	switch (c->x86) {
 #ifdef CONFIG_X86_32
-	case 5:
+	if (c->x86 == 5) {
 		switch (c->x86_model) {
 		case 4:
 			name = "C6";
@@ -207,12 +206,10 @@ static void init_centaur(struct cpuinfo_x86 *c)
 			c->x86_cache_size = (cc>>24)+(dd>>24);
 		}
 		sprintf(c->x86_model_id, "WinChip %s", name);
-		break;
-#endif
-	case 6:
-		init_c3(c);
-		break;
 	}
+#endif
+	if (c->x86 == 6 || c->x86 >= 7)
+		init_c3(c);
 #ifdef CONFIG_X86_64
 	set_cpu_cap(c, X86_FEATURE_LFENCE_RDTSC);
 #endif

arch/x86/kernel/cpu/scattered.c

@@ -41,6 +41,7 @@ static const struct cpuid_bit cpuid_bits[] = {
 	{ X86_FEATURE_MBA,		CPUID_EBX,  6, 0x80000008, 0 },
 	{ X86_FEATURE_SME,		CPUID_EAX,  0, 0x8000001f, 0 },
 	{ X86_FEATURE_SEV,		CPUID_EAX,  1, 0x8000001f, 0 },
+	{ X86_FEATURE_SME_COHERENT,	CPUID_EAX, 10, 0x8000001f, 0 },
 	{ 0, 0, 0, 0, 0 }
 };
 

arch/x86/kernel/umip.c

@@ -45,11 +45,12 @@
  * value that, lies close to the top of the kernel memory. The limit for the GDT
  * and the IDT are set to zero.
  *
- * Given that SLDT and STR are not commonly used in programs that run on WineHQ
+ * The instruction SMSW is emulated to return the value that the register CR0
- * or DOSEMU2, they are not emulated.
- *
- * The instruction smsw is emulated to return the value that the register CR0
  * has at boot time as set in the head_32.
+ * SLDT and STR are emulated to return the values that the kernel programmatically
+ * assigns:
+ * - SLDT returns (GDT_ENTRY_LDT * 8) if an LDT has been set, 0 if not.
+ * - STR returns (GDT_ENTRY_TSS * 8).
  *
  * Emulation is provided for both 32-bit and 64-bit processes.
  *
@@ -244,16 +245,34 @@ static int emulate_umip_insn(struct insn *insn, int umip_inst,
 		*data_size += UMIP_GDT_IDT_LIMIT_SIZE;
 		memcpy(data, &dummy_limit, UMIP_GDT_IDT_LIMIT_SIZE);
 
-	} else if (umip_inst == UMIP_INST_SMSW) {
+	} else if (umip_inst == UMIP_INST_SMSW || umip_inst == UMIP_INST_SLDT ||
-		unsigned long dummy_value = CR0_STATE;
+		   umip_inst == UMIP_INST_STR) {
+		unsigned long dummy_value;
+
+		if (umip_inst == UMIP_INST_SMSW) {
+			dummy_value = CR0_STATE;
+		} else if (umip_inst == UMIP_INST_STR) {
+			dummy_value = GDT_ENTRY_TSS * 8;
+		} else if (umip_inst == UMIP_INST_SLDT) {
+#ifdef CONFIG_MODIFY_LDT_SYSCALL
+			down_read(&current->mm->context.ldt_usr_sem);
+			if (current->mm->context.ldt)
+				dummy_value = GDT_ENTRY_LDT * 8;
+			else
+				dummy_value = 0;
+			up_read(&current->mm->context.ldt_usr_sem);
+#else
+			dummy_value = 0;
+#endif
+		}
 
 		/*
-		 * Even though the CR0 register has 4 bytes, the number
+		 * For these 3 instructions, the number
 		 * of bytes to be copied in the result buffer is determined
 		 * by whether the operand is a register or a memory location.
 		 * If operand is a register, return as many bytes as the operand
 		 * size. If operand is memory, return only the two least
-		 * siginificant bytes of CR0.
+		 * siginificant bytes.
 		 */
 		if (X86_MODRM_MOD(insn->modrm.value) == 3)
 			*data_size = insn->opnd_bytes;
@@ -261,7 +280,6 @@ static int emulate_umip_insn(struct insn *insn, int umip_inst,
 			*data_size = 2;
 
 		memcpy(data, &dummy_value, *data_size);
-	/* STR and SLDT  are not emulated */
 	} else {
 		return -EINVAL;
 	}
@@ -383,10 +401,6 @@ bool fixup_umip_exception(struct pt_regs *regs)
 	umip_pr_warn(regs, "%s instruction cannot be used by applications.\n",
 			umip_insns[umip_inst]);
 
-	/* Do not emulate (spoof) SLDT or STR. */
-	if (umip_inst == UMIP_INST_STR || umip_inst == UMIP_INST_SLDT)
-		return false;
-
 	umip_pr_warn(regs, "For now, expensive software emulation returns the result.\n");
 
 	if (emulate_umip_insn(&insn, umip_inst, dummy_data, &dummy_data_size,

arch/x86/kvm/cpuid.c

@@ -371,7 +371,7 @@ void kvm_set_cpu_caps(void)
 		F(AVX512_4VNNIW) | F(AVX512_4FMAPS) | F(SPEC_CTRL) |
 		F(SPEC_CTRL_SSBD) | F(ARCH_CAPABILITIES) | F(INTEL_STIBP) |
 		F(MD_CLEAR) | F(AVX512_VP2INTERSECT) | F(FSRM) |
-		F(SERIALIZE)
+		F(SERIALIZE) | F(TSXLDTRK)
 	);
 
 	/* TSC_ADJUST and ARCH_CAPABILITIES are emulated in software. */

arch/x86/kvm/svm/sev.c

@@ -384,7 +384,8 @@ static void sev_clflush_pages(struct page *pages[], unsigned long npages)
 	uint8_t *page_virtual;
 	unsigned long i;
 
-	if (npages == 0 || pages == NULL)
+	if (this_cpu_has(X86_FEATURE_SME_COHERENT) || npages == 0 ||
+	    pages == NULL)
 		return;
 
 	for (i = 0; i < npages; i++) {

arch/x86/mm/pat/set_memory.c

@@ -1999,7 +1999,7 @@ static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
 	/*
 	 * Before changing the encryption attribute, we need to flush caches.
 	 */
-	cpa_flush(&cpa, 1);
+	cpa_flush(&cpa, !this_cpu_has(X86_FEATURE_SME_COHERENT));
 
 	ret = __change_page_attr_set_clr(&cpa, 1);