1 files changed, 712 insertions, 186 deletions

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index c8def1b7f8fb..d28829403ed0 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -4,21 +4,33 @@
  *
  * Author: Suresh Siddha <suresh.b.siddha@intel.com>
  */
+#include <linux/bitops.h>
 #include <linux/compat.h>
 #include <linux/cpu.h>
 #include <linux/mman.h>
+#include <linux/nospec.h>
 #include <linux/pkeys.h>
 #include <linux/seq_file.h>
 #include <linux/proc_fs.h>
+#include <linux/vmalloc.h>
 
 #include <asm/fpu/api.h>
-#include <asm/fpu/internal.h>
-#include <asm/fpu/signal.h>
 #include <asm/fpu/regset.h>
-#include <asm/fpu/xstate.h>
+#include <asm/fpu/signal.h>
+#include <asm/fpu/xcr.h>
 
 #include <asm/tlbflush.h>
-#include <asm/cpufeature.h>
+#include <asm/prctl.h>
+#include <asm/elf.h>
+
+#include "context.h"
+#include "internal.h"
+#include "legacy.h"
+#include "xstate.h"
+
+#define for_each_extended_xfeature(bit, mask)				\
+	(bit) = FIRST_EXTENDED_XFEATURE;				\
+	for_each_set_bit_from(bit, (unsigned long *)&(mask), 8 * sizeof(mask))
 
 /*
  * Although we spell it out in here, the Processor Trace
@@ -39,29 +51,32 @@ static const char *xfeature_names[] =
 	"Protection Keys User registers",
 	"PASID state",
 	"unknown xstate feature"	,
+	"unknown xstate feature"	,
+	"unknown xstate feature"	,
+	"unknown xstate feature"	,
+	"unknown xstate feature"	,
+	"unknown xstate feature"	,
+	"AMX Tile config"		,
+	"AMX Tile data"			,
+	"unknown xstate feature"	,
 };
 
-static short xsave_cpuid_features[] __initdata = {
-	X86_FEATURE_FPU,
-	X86_FEATURE_XMM,
-	X86_FEATURE_AVX,
-	X86_FEATURE_MPX,
-	X86_FEATURE_MPX,
-	X86_FEATURE_AVX512F,
-	X86_FEATURE_AVX512F,
-	X86_FEATURE_AVX512F,
-	X86_FEATURE_INTEL_PT,
-	X86_FEATURE_PKU,
-	X86_FEATURE_ENQCMD,
+static unsigned short xsave_cpuid_features[] __initdata = {
+	[XFEATURE_FP]				= X86_FEATURE_FPU,
+	[XFEATURE_SSE]				= X86_FEATURE_XMM,
+	[XFEATURE_YMM]				= X86_FEATURE_AVX,
+	[XFEATURE_BNDREGS]			= X86_FEATURE_MPX,
+	[XFEATURE_BNDCSR]			= X86_FEATURE_MPX,
+	[XFEATURE_OPMASK]			= X86_FEATURE_AVX512F,
+	[XFEATURE_ZMM_Hi256]			= X86_FEATURE_AVX512F,
+	[XFEATURE_Hi16_ZMM]			= X86_FEATURE_AVX512F,
+	[XFEATURE_PT_UNIMPLEMENTED_SO_FAR]	= X86_FEATURE_INTEL_PT,
+	[XFEATURE_PKRU]				= X86_FEATURE_PKU,
+	[XFEATURE_PASID]			= X86_FEATURE_ENQCMD,
+	[XFEATURE_XTILE_CFG]			= X86_FEATURE_AMX_TILE,
+	[XFEATURE_XTILE_DATA]			= X86_FEATURE_AMX_TILE,
 };
 
-/*
- * This represents the full set of bits that should ever be set in a kernel
- * XSAVE buffer, both supervisor and user xstates.
- */
-u64 xfeatures_mask_all __ro_after_init;
-EXPORT_SYMBOL_GPL(xfeatures_mask_all);
-
 static unsigned int xstate_offsets[XFEATURE_MAX] __ro_after_init =
 	{ [ 0 ... XFEATURE_MAX - 1] = -1};
 static unsigned int xstate_sizes[XFEATURE_MAX] __ro_after_init =
@@ -72,20 +87,13 @@ static unsigned int xstate_supervisor_only_offsets[XFEATURE_MAX] __ro_after_init
 	{ [ 0 ... XFEATURE_MAX - 1] = -1};
 
 /*
- * The XSAVE area of kernel can be in standard or compacted format;
- * it is always in standard format for user mode. This is the user
- * mode standard format size used for signal and ptrace frames.
- */
-unsigned int fpu_user_xstate_size __ro_after_init;
-
-/*
  * Return whether the system supports a given xfeature.
  *
  * Also return the name of the (most advanced) feature that the caller requested:
  */
 int cpu_has_xfeatures(u64 xfeatures_needed, const char **feature_name)
 {
-	u64 xfeatures_missing = xfeatures_needed & ~xfeatures_mask_all;
+	u64 xfeatures_missing = xfeatures_needed & ~fpu_kernel_cfg.max_features;
 
 	if (unlikely(feature_name)) {
 		long xfeature_idx, max_idx;
@@ -135,17 +143,26 @@ static bool xfeature_is_supervisor(int xfeature_nr)
  */
 void fpu__init_cpu_xstate(void)
 {
-	if (!boot_cpu_has(X86_FEATURE_XSAVE) || !xfeatures_mask_all)
+	if (!boot_cpu_has(X86_FEATURE_XSAVE) || !fpu_kernel_cfg.max_features)
 		return;
 
 	cr4_set_bits(X86_CR4_OSXSAVE);
 
 	/*
+	 * Must happen after CR4 setup and before xsetbv() to allow KVM
+	 * lazy passthrough.  Write independent of the dynamic state static
+	 * key as that does not work on the boot CPU. This also ensures
+	 * that any stale state is wiped out from XFD.
+	 */
+	if (cpu_feature_enabled(X86_FEATURE_XFD))
+		wrmsrl(MSR_IA32_XFD, init_fpstate.xfd);
+
+	/*
 	 * XCR_XFEATURE_ENABLED_MASK (aka. XCR0) sets user features
 	 * managed by XSAVE{C, OPT, S} and XRSTOR{S}.  Only XSAVE user
 	 * states can be set here.
 	 */
-	xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask_uabi());
+	xsetbv(XCR_XFEATURE_ENABLED_MASK, fpu_user_cfg.max_features);
 
 	/*
 	 * MSR_IA32_XSS sets supervisor states managed by XSAVES.
@@ -158,7 +175,7 @@ void fpu__init_cpu_xstate(void)
 
 static bool xfeature_enabled(enum xfeature xfeature)
 {
-	return xfeatures_mask_all & BIT_ULL(xfeature);
+	return fpu_kernel_cfg.max_features & BIT_ULL(xfeature);
 }
 
 /*
@@ -184,10 +201,7 @@ static void __init setup_xstate_features(void)
 	xstate_sizes[XFEATURE_SSE]	= sizeof_field(struct fxregs_state,
 						       xmm_space);
 
-	for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
-		if (!xfeature_enabled(i))
-			continue;
-
+	for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) {
 		cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
 
 		xstate_sizes[i] = eax;
@@ -236,6 +250,8 @@ static void __init print_xstate_features(void)
 	print_xstate_feature(XFEATURE_MASK_Hi16_ZMM);
 	print_xstate_feature(XFEATURE_MASK_PKRU);
 	print_xstate_feature(XFEATURE_MASK_PASID);
+	print_xstate_feature(XFEATURE_MASK_XTILE_CFG);
+	print_xstate_feature(XFEATURE_MASK_XTILE_DATA);
 }
 
 /*
@@ -291,20 +307,15 @@ static void __init setup_xstate_comp_offsets(void)
 	xstate_comp_offsets[XFEATURE_SSE] = offsetof(struct fxregs_state,
 						     xmm_space);
 
-	if (!boot_cpu_has(X86_FEATURE_XSAVES)) {
-		for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
-			if (xfeature_enabled(i))
-				xstate_comp_offsets[i] = xstate_offsets[i];
-		}
+	if (!cpu_feature_enabled(X86_FEATURE_XSAVES)) {
+		for_each_extended_xfeature(i, fpu_kernel_cfg.max_features)
+			xstate_comp_offsets[i] = xstate_offsets[i];
 		return;
 	}
 
 	next_offset = FXSAVE_SIZE + XSAVE_HDR_SIZE;
 
-	for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
-		if (!xfeature_enabled(i))
-			continue;
-
+	for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) {
 		if (xfeature_is_aligned(i))
 			next_offset = ALIGN(next_offset, 64);
 
@@ -328,8 +339,8 @@ static void __init setup_supervisor_only_offsets(void)
 
 	next_offset = FXSAVE_SIZE + XSAVE_HDR_SIZE;
 
-	for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
-		if (!xfeature_enabled(i) || !xfeature_is_supervisor(i))
+	for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) {
+		if (!xfeature_is_supervisor(i))
 			continue;
 
 		if (xfeature_is_aligned(i))
@@ -347,15 +358,36 @@ static void __init print_xstate_offset_size(void)
 {
 	int i;
 
-	for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
-		if (!xfeature_enabled(i))
-			continue;
+	for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) {
 		pr_info("x86/fpu: xstate_offset[%d]: %4d, xstate_sizes[%d]: %4d\n",
 			 i, xstate_comp_offsets[i], i, xstate_sizes[i]);
 	}
 }
 
 /*
+ * This function is called only during boot time when x86 caps are not set
+ * up and alternative can not be used yet.
+ */
+static __init void os_xrstor_booting(struct xregs_state *xstate)
+{
+	u64 mask = fpu_kernel_cfg.max_features & XFEATURE_MASK_FPSTATE;
+	u32 lmask = mask;
+	u32 hmask = mask >> 32;
+	int err;
+
+	if (cpu_feature_enabled(X86_FEATURE_XSAVES))
+		XSTATE_OP(XRSTORS, xstate, lmask, hmask, err);
+	else
+		XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);
+
+	/*
+	 * We should never fault when copying from a kernel buffer, and the FPU
+	 * state we set at boot time should be valid.
+	 */
+	WARN_ON_FPU(err);
+}
+
+/*
  * All supported features have either init state all zeros or are
  * handled in setup_init_fpu() individually. This is an explicit
  * feature list and does not use XFEATURE_MASK*SUPPORTED to catch
@@ -372,36 +404,30 @@ static void __init print_xstate_offset_size(void)
 	 XFEATURE_MASK_PKRU |			\
 	 XFEATURE_MASK_BNDREGS |		\
 	 XFEATURE_MASK_BNDCSR |			\
-	 XFEATURE_MASK_PASID)
+	 XFEATURE_MASK_PASID |			\
+	 XFEATURE_MASK_XTILE)
 
 /*
  * setup the xstate image representing the init state
  */
 static void __init setup_init_fpu_buf(void)
 {
-	static int on_boot_cpu __initdata = 1;
-
 	BUILD_BUG_ON((XFEATURE_MASK_USER_SUPPORTED |
 		      XFEATURE_MASK_SUPERVISOR_SUPPORTED) !=
 		     XFEATURES_INIT_FPSTATE_HANDLED);
 
-	WARN_ON_FPU(!on_boot_cpu);
-	on_boot_cpu = 0;
-
 	if (!boot_cpu_has(X86_FEATURE_XSAVE))
 		return;
 
 	setup_xstate_features();
 	print_xstate_features();
 
-	if (boot_cpu_has(X86_FEATURE_XSAVES))
-		init_fpstate.xsave.header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT |
-						     xfeatures_mask_all;
+	xstate_init_xcomp_bv(&init_fpstate.regs.xsave, fpu_kernel_cfg.max_features);
 
 	/*
 	 * Init all the features state with header.xfeatures being 0x0
 	 */
-	os_xrstor_booting(&init_fpstate.xsave);
+	os_xrstor_booting(&init_fpstate.regs.xsave);
 
 	/*
 	 * All components are now in init state. Read the state back so
@@ -419,7 +445,7 @@ static void __init setup_init_fpu_buf(void)
 	 * state is all zeroes or if not to add the necessary handling
 	 * here.
 	 */
-	fxsave(&init_fpstate.fxsave);
+	fxsave(&init_fpstate.regs.fxsave);
 }
 
 static int xfeature_uncompacted_offset(int xfeature_nr)
@@ -451,10 +477,11 @@ int xfeature_size(int xfeature_nr)
 }
 
 /* Validate an xstate header supplied by userspace (ptrace or sigreturn) */
-static int validate_user_xstate_header(const struct xstate_header *hdr)
+static int validate_user_xstate_header(const struct xstate_header *hdr,
+				       struct fpstate *fpstate)
 {
 	/* No unknown or supervisor features may be set */
-	if (hdr->xfeatures & ~xfeatures_mask_uabi())
+	if (hdr->xfeatures & ~fpstate->user_xfeatures)
 		return -EINVAL;
 
 	/* Userspace must use the uncompacted format */
@@ -474,7 +501,7 @@ static int validate_user_xstate_header(const struct xstate_header *hdr)
 	return 0;
 }
 
-static void __xstate_dump_leaves(void)
+static void __init __xstate_dump_leaves(void)
 {
 	int i;
 	u32 eax, ebx, ecx, edx;
@@ -509,12 +536,73 @@ static void __xstate_dump_leaves(void)
 	}								\
 } while (0)
 
+/**
+ * check_xtile_data_against_struct - Check tile data state size.
+ *
+ * Calculate the state size by multiplying the single tile size which is
+ * recorded in a C struct, and the number of tiles that the CPU informs.
+ * Compare the provided size with the calculation.
+ *
+ * @size:	The tile data state size
+ *
+ * Returns:	0 on success, -EINVAL on mismatch.
+ */
+static int __init check_xtile_data_against_struct(int size)
+{
+	u32 max_palid, palid, state_size;
+	u32 eax, ebx, ecx, edx;
+	u16 max_tile;
+
+	/*
+	 * Check the maximum palette id:
+	 *   eax: the highest numbered palette subleaf.
+	 */
+	cpuid_count(TILE_CPUID, 0, &max_palid, &ebx, &ecx, &edx);
+
+	/*
+	 * Cross-check each tile size and find the maximum number of
+	 * supported tiles.
+	 */
+	for (palid = 1, max_tile = 0; palid <= max_palid; palid++) {
+		u16 tile_size, max;
+
+		/*
+		 * Check the tile size info:
+		 *   eax[31:16]:  bytes per title
+		 *   ebx[31:16]:  the max names (or max number of tiles)
+		 */
+		cpuid_count(TILE_CPUID, palid, &eax, &ebx, &edx, &edx);
+		tile_size = eax >> 16;
+		max = ebx >> 16;
+
+		if (tile_size != sizeof(struct xtile_data)) {
+			pr_err("%s: struct is %zu bytes, cpu xtile %d bytes\n",
+			       __stringify(XFEATURE_XTILE_DATA),
+			       sizeof(struct xtile_data), tile_size);
+			__xstate_dump_leaves();
+			return -EINVAL;
+		}
+
+		if (max > max_tile)
+			max_tile = max;
+	}
+
+	state_size = sizeof(struct xtile_data) * max_tile;
+	if (size != state_size) {
+		pr_err("%s: calculated size is %u bytes, cpu state %d bytes\n",
+		       __stringify(XFEATURE_XTILE_DATA), state_size, size);
+		__xstate_dump_leaves();
+		return -EINVAL;
+	}
+	return 0;
+}
+
 /*
  * We have a C struct for each 'xstate'.  We need to ensure
  * that our software representation matches what the CPU
  * tells us about the state's size.
  */
-static void check_xstate_against_struct(int nr)
+static bool __init check_xstate_against_struct(int nr)
 {
 	/*
 	 * Ask the CPU for the size of the state.
@@ -532,6 +620,11 @@ static void check_xstate_against_struct(int nr)
 	XCHECK_SZ(sz, nr, XFEATURE_Hi16_ZMM,  struct avx_512_hi16_state);
 	XCHECK_SZ(sz, nr, XFEATURE_PKRU,      struct pkru_state);
 	XCHECK_SZ(sz, nr, XFEATURE_PASID,     struct ia32_pasid_state);
+	XCHECK_SZ(sz, nr, XFEATURE_XTILE_CFG, struct xtile_cfg);
+
+	/* The tile data size varies between implementations. */
+	if (nr == XFEATURE_XTILE_DATA)
+		check_xtile_data_against_struct(sz);
 
 	/*
 	 * Make *SURE* to add any feature numbers in below if
@@ -541,10 +634,39 @@ static void check_xstate_against_struct(int nr)
 	if ((nr < XFEATURE_YMM) ||
 	    (nr >= XFEATURE_MAX) ||
 	    (nr == XFEATURE_PT_UNIMPLEMENTED_SO_FAR) ||
-	    ((nr >= XFEATURE_RSRVD_COMP_11) && (nr <= XFEATURE_LBR))) {
+	    ((nr >= XFEATURE_RSRVD_COMP_11) && (nr <= XFEATURE_RSRVD_COMP_16))) {
 		WARN_ONCE(1, "no structure for xstate: %d\n", nr);
 		XSTATE_WARN_ON(1);
+		return false;
+	}
+	return true;
+}
+
+static unsigned int xstate_calculate_size(u64 xfeatures, bool compacted)
+{
+	unsigned int size = FXSAVE_SIZE + XSAVE_HDR_SIZE;
+	int i;
+
+	for_each_extended_xfeature(i, xfeatures) {
+		/* Align from the end of the previous feature */
+		if (xfeature_is_aligned(i))
+			size = ALIGN(size, 64);
+		/*
+		 * In compacted format the enabled features are packed,
+		 * i.e. disabled features do not occupy space.
+		 *
+		 * In non-compacted format the offsets are fixed and
+		 * disabled states still occupy space in the memory buffer.
+		 */
+		if (!compacted)
+			size = xfeature_uncompacted_offset(i);
+		/*
+		 * Add the feature size even for non-compacted format
+		 * to make the end result correct
+		 */
+		size += xfeature_size(i);
 	}
+	return size;
 }
 
 /*
@@ -556,44 +678,29 @@ static void check_xstate_against_struct(int nr)
  * covered by these checks. Only the size of the buffer for task->fpu
  * is checked here.
  */
-static void do_extra_xstate_size_checks(void)
+static bool __init paranoid_xstate_size_valid(unsigned int kernel_size)
 {
-	int paranoid_xstate_size = FXSAVE_SIZE + XSAVE_HDR_SIZE;
+	bool compacted = cpu_feature_enabled(X86_FEATURE_XSAVES);
+	unsigned int size = FXSAVE_SIZE + XSAVE_HDR_SIZE;
 	int i;
 
-	for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
-		if (!xfeature_enabled(i))
-			continue;
-
-		check_xstate_against_struct(i);
+	for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) {
+		if (!check_xstate_against_struct(i))
+			return false;
 		/*
 		 * Supervisor state components can be managed only by
 		 * XSAVES.
 		 */
-		if (!cpu_feature_enabled(X86_FEATURE_XSAVES))
-			XSTATE_WARN_ON(xfeature_is_supervisor(i));
-
-		/* Align from the end of the previous feature */
-		if (xfeature_is_aligned(i))
-			paranoid_xstate_size = ALIGN(paranoid_xstate_size, 64);
-		/*
-		 * The offset of a given state in the non-compacted
-		 * format is given to us in a CPUID leaf.  We check
-		 * them for being ordered (increasing offsets) in
-		 * setup_xstate_features(). XSAVES uses compacted format.
-		 */
-		if (!cpu_feature_enabled(X86_FEATURE_XSAVES))
-			paranoid_xstate_size = xfeature_uncompacted_offset(i);
-		/*
-		 * The compacted-format offset always depends on where
-		 * the previous state ended.
-		 */
-		paranoid_xstate_size += xfeature_size(i);
+		if (!compacted && xfeature_is_supervisor(i)) {
+			XSTATE_WARN_ON(1);
+			return false;
+		}
 	}
-	XSTATE_WARN_ON(paranoid_xstate_size != fpu_kernel_xstate_size);
+	size = xstate_calculate_size(fpu_kernel_cfg.max_features, compacted);
+	XSTATE_WARN_ON(size != kernel_size);
+	return size == kernel_size;
 }
 
-
 /*
  * Get total size of enabled xstates in XCR0 | IA32_XSS.
  *
@@ -644,7 +751,7 @@ static unsigned int __init get_xsaves_size_no_independent(void)
 	return size;
 }
 
-static unsigned int __init get_xsave_size(void)
+static unsigned int __init get_xsave_size_user(void)
 {
 	unsigned int eax, ebx, ecx, edx;
 	/*
@@ -662,44 +769,54 @@ static unsigned int __init get_xsave_size(void)
  * Will the runtime-enumerated 'xstate_size' fit in the init
  * task's statically-allocated buffer?
  */
-static bool is_supported_xstate_size(unsigned int test_xstate_size)
+static bool __init is_supported_xstate_size(unsigned int test_xstate_size)
 {
-	if (test_xstate_size <= sizeof(union fpregs_state))
+	if (test_xstate_size <= sizeof(init_fpstate.regs))
 		return true;
 
 	pr_warn("x86/fpu: xstate buffer too small (%zu < %d), disabling xsave\n",
-			sizeof(union fpregs_state), test_xstate_size);
+			sizeof(init_fpstate.regs), test_xstate_size);
 	return false;
 }
 
 static int __init init_xstate_size(void)
 {
 	/* Recompute the context size for enabled features: */
-	unsigned int possible_xstate_size;
-	unsigned int xsave_size;
+	unsigned int user_size, kernel_size, kernel_default_size;
+	bool compacted = cpu_feature_enabled(X86_FEATURE_XSAVES);
 
-	xsave_size = get_xsave_size();
+	/* Uncompacted user space size */
+	user_size = get_xsave_size_user();
 
-	if (boot_cpu_has(X86_FEATURE_XSAVES))
-		possible_xstate_size = get_xsaves_size_no_independent();
+	/*
+	 * XSAVES kernel size includes supervisor states and
+	 * uses compacted format when available.
+	 *
+	 * XSAVE does not support supervisor states so
+	 * kernel and user size is identical.
+	 */
+	if (compacted)
+		kernel_size = get_xsaves_size_no_independent();
 	else
-		possible_xstate_size = xsave_size;
+		kernel_size = user_size;
+
+	kernel_default_size =
+		xstate_calculate_size(fpu_kernel_cfg.default_features, compacted);
 
-	/* Ensure we have the space to store all enabled: */
-	if (!is_supported_xstate_size(possible_xstate_size))
+	/* Ensure we have the space to store all default enabled features. */
+	if (!is_supported_xstate_size(kernel_default_size))
 		return -EINVAL;
 
-	/*
-	 * The size is OK, we are definitely going to use xsave,
-	 * make it known to the world that we need more space.
-	 */
-	fpu_kernel_xstate_size = possible_xstate_size;
-	do_extra_xstate_size_checks();
+	if (!paranoid_xstate_size_valid(kernel_size))
+		return -EINVAL;
+
+	fpu_kernel_cfg.max_size = kernel_size;
+	fpu_user_cfg.max_size = user_size;
+
+	fpu_kernel_cfg.default_size = kernel_default_size;
+	fpu_user_cfg.default_size =
+		xstate_calculate_size(fpu_user_cfg.default_features, false);
 
-	/*
-	 * User space is always in standard format.
-	 */
-	fpu_user_xstate_size = xsave_size;
 	return 0;
 }
 
@@ -707,28 +824,38 @@ static int __init init_xstate_size(void)
  * We enabled the XSAVE hardware, but something went wrong and
  * we can not use it.  Disable it.
  */
-static void fpu__init_disable_system_xstate(void)
+static void __init fpu__init_disable_system_xstate(unsigned int legacy_size)
 {
-	xfeatures_mask_all = 0;
+	fpu_kernel_cfg.max_features = 0;
 	cr4_clear_bits(X86_CR4_OSXSAVE);
 	setup_clear_cpu_cap(X86_FEATURE_XSAVE);
+
+	/* Restore the legacy size.*/
+	fpu_kernel_cfg.max_size = legacy_size;
+	fpu_kernel_cfg.default_size = legacy_size;
+	fpu_user_cfg.max_size = legacy_size;
+	fpu_user_cfg.default_size = legacy_size;
+
+	/*
+	 * Prevent enabling the static branch which enables writes to the
+	 * XFD MSR.
+	 */
+	init_fpstate.xfd = 0;
+
+	fpstate_reset(&current->thread.fpu);
 }
 
 /*
  * Enable and initialize the xsave feature.
  * Called once per system bootup.
  */
-void __init fpu__init_system_xstate(void)
+void __init fpu__init_system_xstate(unsigned int legacy_size)
 {
 	unsigned int eax, ebx, ecx, edx;
-	static int on_boot_cpu __initdata = 1;
 	u64 xfeatures;
 	int err;
 	int i;
 
-	WARN_ON_FPU(!on_boot_cpu);
-	on_boot_cpu = 0;
-
 	if (!boot_cpu_has(X86_FEATURE_FPU)) {
 		pr_info("x86/fpu: No FPU detected\n");
 		return;
@@ -749,22 +876,22 @@ void __init fpu__init_system_xstate(void)
 	 * Find user xstates supported by the processor.
 	 */
 	cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
-	xfeatures_mask_all = eax + ((u64)edx << 32);
+	fpu_kernel_cfg.max_features = eax + ((u64)edx << 32);
 
 	/*
 	 * Find supervisor xstates supported by the processor.
 	 */
 	cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx);
-	xfeatures_mask_all |= ecx + ((u64)edx << 32);
+	fpu_kernel_cfg.max_features |= ecx + ((u64)edx << 32);
 
-	if ((xfeatures_mask_uabi() & XFEATURE_MASK_FPSSE) != XFEATURE_MASK_FPSSE) {
+	if ((fpu_kernel_cfg.max_features & XFEATURE_MASK_FPSSE) != XFEATURE_MASK_FPSSE) {
 		/*
 		 * This indicates that something really unexpected happened
 		 * with the enumeration.  Disable XSAVE and try to continue
 		 * booting without it.  This is too early to BUG().
 		 */
 		pr_err("x86/fpu: FP/SSE not present amongst the CPU's xstate features: 0x%llx.\n",
-		       xfeatures_mask_all);
+		       fpu_kernel_cfg.max_features);
 		goto out_disable;
 	}
 
@@ -772,15 +899,39 @@ void __init fpu__init_system_xstate(void)
 	 * Clear XSAVE features that are disabled in the normal CPUID.
 	 */
 	for (i = 0; i < ARRAY_SIZE(xsave_cpuid_features); i++) {
-		if (!boot_cpu_has(xsave_cpuid_features[i]))
-			xfeatures_mask_all &= ~BIT_ULL(i);
+		unsigned short cid = xsave_cpuid_features[i];
+
+		/* Careful: X86_FEATURE_FPU is 0! */
+		if ((i != XFEATURE_FP && !cid) || !boot_cpu_has(cid))
+			fpu_kernel_cfg.max_features &= ~BIT_ULL(i);
 	}
 
-	xfeatures_mask_all &= XFEATURE_MASK_USER_SUPPORTED |
+	if (!cpu_feature_enabled(X86_FEATURE_XFD))
+		fpu_kernel_cfg.max_features &= ~XFEATURE_MASK_USER_DYNAMIC;
+
+	fpu_kernel_cfg.max_features &= XFEATURE_MASK_USER_SUPPORTED |
 			      XFEATURE_MASK_SUPERVISOR_SUPPORTED;
 
+	fpu_user_cfg.max_features = fpu_kernel_cfg.max_features;
+	fpu_user_cfg.max_features &= XFEATURE_MASK_USER_SUPPORTED;
+
+	/* Clean out dynamic features from default */
+	fpu_kernel_cfg.default_features = fpu_kernel_cfg.max_features;
+	fpu_kernel_cfg.default_features &= ~XFEATURE_MASK_USER_DYNAMIC;
+
+	fpu_user_cfg.default_features = fpu_user_cfg.max_features;
+	fpu_user_cfg.default_features &= ~XFEATURE_MASK_USER_DYNAMIC;
+
 	/* Store it for paranoia check at the end */
-	xfeatures = xfeatures_mask_all;
+	xfeatures = fpu_kernel_cfg.max_features;
+
+	/*
+	 * Initialize the default XFD state in initfp_state and enable the
+	 * dynamic sizing mechanism if dynamic states are available.  The
+	 * static key cannot be enabled here because this runs before
+	 * jump_label_init(). This is delayed to an initcall.
+	 */
+	init_fpstate.xfd = fpu_user_cfg.max_features & XFEATURE_MASK_USER_DYNAMIC;
 
 	/* Enable xstate instructions to be able to continue with initialization: */
 	fpu__init_cpu_xstate();
@@ -788,13 +939,16 @@ void __init fpu__init_system_xstate(void)
 	if (err)
 		goto out_disable;
 
+	/* Reset the state for the current task */
+	fpstate_reset(&current->thread.fpu);
+
 	/*
 	 * Update info used for ptrace frames; use standard-format size and no
 	 * supervisor xstates:
 	 */
-	update_regset_xstate_info(fpu_user_xstate_size, xfeatures_mask_uabi());
+	update_regset_xstate_info(fpu_user_cfg.max_size,
+				  fpu_user_cfg.max_features);
 
-	fpu__init_prepare_fx_sw_frame();
 	setup_init_fpu_buf();
 	setup_xstate_comp_offsets();
 	setup_supervisor_only_offsets();
@@ -803,22 +957,22 @@ void __init fpu__init_system_xstate(void)
 	 * Paranoia check whether something in the setup modified the
 	 * xfeatures mask.
 	 */
-	if (xfeatures != xfeatures_mask_all) {
+	if (xfeatures != fpu_kernel_cfg.max_features) {
 		pr_err("x86/fpu: xfeatures modified from 0x%016llx to 0x%016llx during init, disabling XSAVE\n",
-		       xfeatures, xfeatures_mask_all);
+		       xfeatures, fpu_kernel_cfg.max_features);
 		goto out_disable;
 	}
 
 	print_xstate_offset_size();
 	pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is %d bytes, using '%s' format.\n",
-		xfeatures_mask_all,
-		fpu_kernel_xstate_size,
+		fpu_kernel_cfg.max_features,
+		fpu_kernel_cfg.max_size,
 		boot_cpu_has(X86_FEATURE_XSAVES) ? "compacted" : "standard");
 	return;
 
 out_disable:
 	/* something went wrong, try to boot without any XSAVE support */
-	fpu__init_disable_system_xstate();
+	fpu__init_disable_system_xstate(legacy_size);
 }
 
 /*
@@ -830,7 +984,7 @@ void fpu__resume_cpu(void)
 	 * Restore XCR0 on xsave capable CPUs:
 	 */
 	if (cpu_feature_enabled(X86_FEATURE_XSAVE))
-		xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask_uabi());
+		xsetbv(XCR_XFEATURE_ENABLED_MASK, fpu_user_cfg.max_features);
 
 	/*
 	 * Restore IA32_XSS. The same CPUID bit enumerates support
@@ -840,6 +994,9 @@ void fpu__resume_cpu(void)
 		wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor()  |
 				     xfeatures_mask_independent());
 	}
+
+	if (fpu_state_size_dynamic())
+		wrmsrl(MSR_IA32_XFD, current->thread.fpu.fpstate->xfd);
 }
 
 /*
@@ -886,7 +1043,7 @@ void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
 	 * We should not ever be requesting features that we
 	 * have not enabled.
 	 */
-	WARN_ONCE(!(xfeatures_mask_all & BIT_ULL(xfeature_nr)),
+	WARN_ONCE(!(fpu_kernel_cfg.max_features & BIT_ULL(xfeature_nr)),
 		  "get of unsupported state");
 	/*
 	 * This assumes the last 'xsave*' instruction to
@@ -904,7 +1061,6 @@ void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
 
 	return __raw_xsave_addr(xsave, xfeature_nr);
 }
-EXPORT_SYMBOL_GPL(get_xsave_addr);
 
 #ifdef CONFIG_ARCH_HAS_PKEYS
 
@@ -961,9 +1117,10 @@ static void copy_feature(bool from_xstate, struct membuf *to, void *xstate,
 }
 
 /**
- * copy_xstate_to_uabi_buf - Copy kernel saved xstate to a UABI buffer
+ * __copy_xstate_to_uabi_buf - Copy kernel saved xstate to a UABI buffer
  * @to:		membuf descriptor
- * @tsk:	The task from which to copy the saved xstate
+ * @fpstate:	The fpstate buffer from which to copy
+ * @pkru_val:	The PKRU value to store in the PKRU component
  * @copy_mode:	The requested copy mode
  *
  * Converts from kernel XSAVE or XSAVES compacted format to UABI conforming
@@ -972,14 +1129,15 @@ static void copy_feature(bool from_xstate, struct membuf *to, void *xstate,
  *
  * It supports partial copy but @to.pos always starts from zero.
  */
-void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk,
-			     enum xstate_copy_mode copy_mode)
+void __copy_xstate_to_uabi_buf(struct membuf to, struct fpstate *fpstate,
+			       u32 pkru_val, enum xstate_copy_mode copy_mode)
 {
 	const unsigned int off_mxcsr = offsetof(struct fxregs_state, mxcsr);
-	struct xregs_state *xsave = &tsk->thread.fpu.state.xsave;
-	struct xregs_state *xinit = &init_fpstate.xsave;
+	struct xregs_state *xinit = &init_fpstate.regs.xsave;
+	struct xregs_state *xsave = &fpstate->regs.xsave;
 	struct xstate_header header;
 	unsigned int zerofrom;
+	u64 mask;
 	int i;
 
 	memset(&header, 0, sizeof(header));
@@ -996,7 +1154,7 @@ void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk,
 		break;
 
 	case XSTATE_COPY_XSAVE:
-		header.xfeatures &= xfeatures_mask_uabi();
+		header.xfeatures &= fpstate->user_xfeatures;
 		break;
 	}
 
@@ -1033,17 +1191,15 @@ void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk,
 
 	zerofrom = offsetof(struct xregs_state, extended_state_area);
 
-	for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
-		/*
-		 * The ptrace buffer is in non-compacted XSAVE format.
-		 * In non-compacted format disabled features still occupy
-		 * state space, but there is no state to copy from in the
-		 * compacted init_fpstate. The gap tracking will zero this
-		 * later.
-		 */
-		if (!(xfeatures_mask_uabi() & BIT_ULL(i)))
-			continue;
+	/*
+	 * The ptrace buffer is in non-compacted XSAVE format.  In
+	 * non-compacted format disabled features still occupy state space,
+	 * but there is no state to copy from in the compacted
+	 * init_fpstate. The gap tracking will zero these states.
+	 */
+	mask = fpstate->user_xfeatures;
 
+	for_each_extended_xfeature(i, mask) {
 		/*
 		 * If there was a feature or alignment gap, zero the space
 		 * in the destination buffer.
@@ -1055,10 +1211,9 @@ void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk,
 			struct pkru_state pkru = {0};
 			/*
 			 * PKRU is not necessarily up to date in the
-			 * thread's XSAVE buffer.  Fill this part from the
-			 * per-thread storage.
+			 * XSAVE buffer. Use the provided value.
 			 */
-			pkru.pkru = tsk->thread.pkru;
+			pkru.pkru = pkru_val;
 			membuf_write(&to, &pkru, sizeof(pkru));
 		} else {
 			copy_feature(header.xfeatures & BIT_ULL(i), &to,
@@ -1078,6 +1233,25 @@ out:
 		membuf_zero(&to, to.left);
 }
 
+/**
+ * copy_xstate_to_uabi_buf - Copy kernel saved xstate to a UABI buffer
+ * @to:		membuf descriptor
+ * @tsk:	The task from which to copy the saved xstate
+ * @copy_mode:	The requested copy mode
+ *
+ * Converts from kernel XSAVE or XSAVES compacted format to UABI conforming
+ * format, i.e. from the kernel internal hardware dependent storage format
+ * to the requested @mode. UABI XSTATE is always uncompacted!
+ *
+ * It supports partial copy but @to.pos always starts from zero.
+ */
+void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk,
+			     enum xstate_copy_mode copy_mode)
+{
+	__copy_xstate_to_uabi_buf(to, tsk->thread.fpu.fpstate,
+				  tsk->thread.pkru, copy_mode);
+}
+
 static int copy_from_buffer(void *dst, unsigned int offset, unsigned int size,
 			    const void *kbuf, const void __user *ubuf)
 {
@@ -1091,9 +1265,10 @@ static int copy_from_buffer(void *dst, unsigned int offset, unsigned int size,
 }
 
 
-static int copy_uabi_to_xstate(struct xregs_state *xsave, const void *kbuf,
+static int copy_uabi_to_xstate(struct fpstate *fpstate, const void *kbuf,
 			       const void __user *ubuf)
 {
+	struct xregs_state *xsave = &fpstate->regs.xsave;
 	unsigned int offset, size;
 	struct xstate_header hdr;
 	u64 mask;
@@ -1103,7 +1278,7 @@ static int copy_uabi_to_xstate(struct xregs_state *xsave, const void *kbuf,
 	if (copy_from_buffer(&hdr, offset, sizeof(hdr), kbuf, ubuf))
 		return -EFAULT;
 
-	if (validate_user_xstate_header(&hdr))
+	if (validate_user_xstate_header(&hdr, fpstate))
 		return -EINVAL;
 
 	/* Validate MXCSR when any of the related features is in use */
@@ -1156,12 +1331,11 @@ static int copy_uabi_to_xstate(struct xregs_state *xsave, const void *kbuf,
 
 /*
  * Convert from a ptrace standard-format kernel buffer to kernel XSAVE[S]
- * format and copy to the target thread. This is called from
- * xstateregs_set().
+ * format and copy to the target thread. Used by ptrace and KVM.
  */
-int copy_uabi_from_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
+int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf)
 {
-	return copy_uabi_to_xstate(xsave, kbuf, NULL);
+	return copy_uabi_to_xstate(fpstate, kbuf, NULL);
 }
 
 /*
@@ -1169,26 +1343,20 @@ int copy_uabi_from_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
  * XSAVE[S] format and copy to the target thread. This is called from the
  * sigreturn() and rt_sigreturn() system calls.
  */
-int copy_sigframe_from_user_to_xstate(struct xregs_state *xsave,
+int copy_sigframe_from_user_to_xstate(struct fpstate *fpstate,
 				      const void __user *ubuf)
 {
-	return copy_uabi_to_xstate(xsave, NULL, ubuf);
+	return copy_uabi_to_xstate(fpstate, NULL, ubuf);
 }
 
-static bool validate_xsaves_xrstors(u64 mask)
+static bool validate_independent_components(u64 mask)
 {
 	u64 xchk;
 
 	if (WARN_ON_FPU(!cpu_feature_enabled(X86_FEATURE_XSAVES)))
 		return false;
-	/*
-	 * Validate that this is either a task->fpstate related component
-	 * subset or an independent one.
-	 */
-	if (mask & xfeatures_mask_independent())
-		xchk = ~xfeatures_mask_independent();
-	else
-		xchk = ~xfeatures_mask_all;
+
+	xchk = ~xfeatures_mask_independent();
 
 	if (WARN_ON_ONCE(!mask || mask & xchk))
 		return false;
@@ -1206,14 +1374,13 @@ static bool validate_xsaves_xrstors(u64 mask)
  * buffer should be zeroed otherwise a consecutive XRSTORS from that buffer
  * can #GP.
  *
- * The feature mask must either be a subset of the independent features or
- * a subset of the task->fpstate related features.
+ * The feature mask must be a subset of the independent features.
  */
 void xsaves(struct xregs_state *xstate, u64 mask)
 {
 	int err;
 
-	if (!validate_xsaves_xrstors(mask))
+	if (!validate_independent_components(mask))
 		return;
 
 	XSTATE_OP(XSAVES, xstate, (u32)mask, (u32)(mask >> 32), err);
@@ -1231,20 +1398,379 @@ void xsaves(struct xregs_state *xstate, u64 mask)
  * Proper usage is to restore the state which was saved with
  * xsaves() into @xstate.
  *
- * The feature mask must either be a subset of the independent features or
- * a subset of the task->fpstate related features.
+ * The feature mask must be a subset of the independent features.
  */
 void xrstors(struct xregs_state *xstate, u64 mask)
 {
 	int err;
 
-	if (!validate_xsaves_xrstors(mask))
+	if (!validate_independent_components(mask))
 		return;
 
 	XSTATE_OP(XRSTORS, xstate, (u32)mask, (u32)(mask >> 32), err);
 	WARN_ON_ONCE(err);
 }
 
+#if IS_ENABLED(CONFIG_KVM)
+void fpstate_clear_xstate_component(struct fpstate *fps, unsigned int xfeature)
+{
+	void *addr = get_xsave_addr(&fps->regs.xsave, xfeature);
+
+	if (addr)
+		memset(addr, 0, xstate_sizes[xfeature]);
+}
+EXPORT_SYMBOL_GPL(fpstate_clear_xstate_component);
+#endif
+
+#ifdef CONFIG_X86_64
+
+#ifdef CONFIG_X86_DEBUG_FPU
+/*
+ * Ensure that a subsequent XSAVE* or XRSTOR* instruction with RFBM=@mask
+ * can safely operate on the @fpstate buffer.
+ */
+static bool xstate_op_valid(struct fpstate *fpstate, u64 mask, bool rstor)
+{
+	u64 xfd = __this_cpu_read(xfd_state);
+
+	if (fpstate->xfd == xfd)
+		return true;
+
+	 /*
+	  * The XFD MSR does not match fpstate->xfd. That's invalid when
+	  * the passed in fpstate is current's fpstate.
+	  */
+	if (fpstate->xfd == current->thread.fpu.fpstate->xfd)
+		return false;
+
+	/*
+	 * XRSTOR(S) from init_fpstate are always correct as it will just
+	 * bring all components into init state and not read from the
+	 * buffer. XSAVE(S) raises #PF after init.
+	 */
+	if (fpstate == &init_fpstate)
+		return rstor;
+
+	/*
+	 * XSAVE(S): clone(), fpu_swap_kvm_fpu()
+	 * XRSTORS(S): fpu_swap_kvm_fpu()
+	 */
+
+	/*
+	 * No XSAVE/XRSTOR instructions (except XSAVE itself) touch
+	 * the buffer area for XFD-disabled state components.
+	 */
+	mask &= ~xfd;
+
+	/*
+	 * Remove features which are valid in fpstate. They
+	 * have space allocated in fpstate.
+	 */
+	mask &= ~fpstate->xfeatures;
+
+	/*
+	 * Any remaining state components in 'mask' might be written
+	 * by XSAVE/XRSTOR. Fail validation it found.
+	 */
+	return !mask;
+}
+
+void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor)
+{
+	WARN_ON_ONCE(!xstate_op_valid(fpstate, mask, rstor));
+}
+#endif /* CONFIG_X86_DEBUG_FPU */
+
+static int __init xfd_update_static_branch(void)
+{
+	/*
+	 * If init_fpstate.xfd has bits set then dynamic features are
+	 * available and the dynamic sizing must be enabled.
+	 */
+	if (init_fpstate.xfd)
+		static_branch_enable(&__fpu_state_size_dynamic);
+	return 0;
+}
+arch_initcall(xfd_update_static_branch)
+
+void fpstate_free(struct fpu *fpu)
+{
+	if (fpu->fpstate && fpu->fpstate != &fpu->__fpstate)
+		vfree(fpu->fpstate);
+}
+
+/**
+ * fpu_install_fpstate - Update the active fpstate in the FPU
+ *
+ * @fpu:	A struct fpu * pointer
+ * @newfps:	A struct fpstate * pointer
+ *
+ * Returns:	A null pointer if the last active fpstate is the embedded
+ *		one or the new fpstate is already installed;
+ *		otherwise, a pointer to the old fpstate which has to
+ *		be freed by the caller.
+ */
+static struct fpstate *fpu_install_fpstate(struct fpu *fpu,
+					   struct fpstate *newfps)
+{
+	struct fpstate *oldfps = fpu->fpstate;
+
+	if (fpu->fpstate == newfps)
+		return NULL;
+
+	fpu->fpstate = newfps;
+	return oldfps != &fpu->__fpstate ? oldfps : NULL;
+}
+
+/**
+ * fpstate_realloc - Reallocate struct fpstate for the requested new features
+ *
+ * @xfeatures:	A bitmap of xstate features which extend the enabled features
+ *		of that task
+ * @ksize:	The required size for the kernel buffer
+ * @usize:	The required size for user space buffers
+ *
+ * Note vs. vmalloc(): If the task with a vzalloc()-allocated buffer
+ * terminates quickly, vfree()-induced IPIs may be a concern, but tasks
+ * with large states are likely to live longer.
+ *
+ * Returns: 0 on success, -ENOMEM on allocation error.
+ */
+static int fpstate_realloc(u64 xfeatures, unsigned int ksize,
+			   unsigned int usize)
+{
+	struct fpu *fpu = &current->thread.fpu;
+	struct fpstate *curfps, *newfps = NULL;
+	unsigned int fpsize;
+
+	curfps = fpu->fpstate;
+	fpsize = ksize + ALIGN(offsetof(struct fpstate, regs), 64);
+
+	newfps = vzalloc(fpsize);
+	if (!newfps)
+		return -ENOMEM;
+	newfps->size = ksize;
+	newfps->user_size = usize;
+	newfps->is_valloc = true;
+
+	fpregs_lock();
+	/*
+	 * Ensure that the current state is in the registers before
+	 * swapping fpstate as that might invalidate it due to layout
+	 * changes.
+	 */
+	if (test_thread_flag(TIF_NEED_FPU_LOAD))
+		fpregs_restore_userregs();
+
+	newfps->xfeatures = curfps->xfeatures | xfeatures;
+	newfps->user_xfeatures = curfps->user_xfeatures | xfeatures;
+	newfps->xfd = curfps->xfd & ~xfeatures;
+
+	curfps = fpu_install_fpstate(fpu, newfps);
+
+	/* Do the final updates within the locked region */
+	xstate_init_xcomp_bv(&newfps->regs.xsave, newfps->xfeatures);
+	xfd_update_state(newfps);
+
+	fpregs_unlock();
+
+	vfree(curfps);
+	return 0;
+}
+
+static int validate_sigaltstack(unsigned int usize)
+{
+	struct task_struct *thread, *leader = current->group_leader;
+	unsigned long framesize = get_sigframe_size();
+
+	lockdep_assert_held(&current->sighand->siglock);
+
+	/* get_sigframe_size() is based on fpu_user_cfg.max_size */
+	framesize -= fpu_user_cfg.max_size;
+	framesize += usize;
+	for_each_thread(leader, thread) {
+		if (thread->sas_ss_size && thread->sas_ss_size < framesize)
+			return -ENOSPC;
+	}
+	return 0;
+}
+
+static int __xstate_request_perm(u64 permitted, u64 requested)
+{
+	/*
+	 * This deliberately does not exclude !XSAVES as we still might
+	 * decide to optionally context switch XCR0 or talk the silicon
+	 * vendors into extending XFD for the pre AMX states, especially
+	 * AVX512.
+	 */
+	bool compacted = cpu_feature_enabled(X86_FEATURE_XSAVES);
+	struct fpu *fpu = &current->group_leader->thread.fpu;
+	unsigned int ksize, usize;
+	u64 mask;
+	int ret;
+
+	/* Check whether fully enabled */
+	if ((permitted & requested) == requested)
+		return 0;
+
+	/* Calculate the resulting kernel state size */
+	mask = permitted | requested;
+	ksize = xstate_calculate_size(mask, compacted);
+
+	/* Calculate the resulting user state size */
+	mask &= XFEATURE_MASK_USER_SUPPORTED;
+	usize = xstate_calculate_size(mask, false);
+
+	ret = validate_sigaltstack(usize);
+	if (ret)
+		return ret;
+
+	/* Pairs with the READ_ONCE() in xstate_get_group_perm() */
+	WRITE_ONCE(fpu->perm.__state_perm, requested);
+	/* Protected by sighand lock */
+	fpu->perm.__state_size = ksize;
+	fpu->perm.__user_state_size = usize;
+	return ret;
+}
+
+/*
+ * Permissions array to map facilities with more than one component
+ */
+static const u64 xstate_prctl_req[XFEATURE_MAX] = {
+	[XFEATURE_XTILE_DATA] = XFEATURE_MASK_XTILE_DATA,
+};
+
+static int xstate_request_perm(unsigned long idx)
+{
+	u64 permitted, requested;
+	int ret;
+
+	if (idx >= XFEATURE_MAX)
+		return -EINVAL;
+
+	/*
+	 * Look up the facility mask which can require more than
+	 * one xstate component.
+	 */
+	idx = array_index_nospec(idx, ARRAY_SIZE(xstate_prctl_req));
+	requested = xstate_prctl_req[idx];
+	if (!requested)
+		return -EOPNOTSUPP;
+
+	if ((fpu_user_cfg.max_features & requested) != requested)
+		return -EOPNOTSUPP;
+
+	/* Lockless quick check */
+	permitted = xstate_get_host_group_perm();
+	if ((permitted & requested) == requested)
+		return 0;
+
+	/* Protect against concurrent modifications */
+	spin_lock_irq(&current->sighand->siglock);
+	permitted = xstate_get_host_group_perm();
+	ret = __xstate_request_perm(permitted, requested);
+	spin_unlock_irq(&current->sighand->siglock);
+	return ret;
+}
+
+int xfd_enable_feature(u64 xfd_err)
+{
+	u64 xfd_event = xfd_err & XFEATURE_MASK_USER_DYNAMIC;
+	unsigned int ksize, usize;
+	struct fpu *fpu;
+
+	if (!xfd_event) {
+		pr_err_once("XFD: Invalid xfd error: %016llx\n", xfd_err);
+		return 0;
+	}
+
+	/* Protect against concurrent modifications */
+	spin_lock_irq(&current->sighand->siglock);
+
+	/* If not permitted let it die */
+	if ((xstate_get_host_group_perm() & xfd_event) != xfd_event) {
+		spin_unlock_irq(&current->sighand->siglock);
+		return -EPERM;
+	}
+
+	fpu = &current->group_leader->thread.fpu;
+	ksize = fpu->perm.__state_size;
+	usize = fpu->perm.__user_state_size;
+	/*
+	 * The feature is permitted. State size is sufficient.  Dropping
+	 * the lock is safe here even if more features are added from
+	 * another task, the retrieved buffer sizes are valid for the
+	 * currently requested feature(s).
+	 */
+	spin_unlock_irq(&current->sighand->siglock);
+
+	/*
+	 * Try to allocate a new fpstate. If that fails there is no way
+	 * out.
+	 */
+	if (fpstate_realloc(xfd_event, ksize, usize))
+		return -EFAULT;
+	return 0;
+}
+#else /* CONFIG_X86_64 */
+static inline int xstate_request_perm(unsigned long idx)
+{
+	return -EPERM;
+}
+#endif  /* !CONFIG_X86_64 */
+
+/**
+ * fpu_xstate_prctl - xstate permission operations
+ * @tsk:	Redundant pointer to current
+ * @option:	A subfunction of arch_prctl()
+ * @arg2:	option argument
+ * Return:	0 if successful; otherwise, an error code
+ *
+ * Option arguments:
+ *
+ * ARCH_GET_XCOMP_SUPP: Pointer to user space u64 to store the info
+ * ARCH_GET_XCOMP_PERM: Pointer to user space u64 to store the info
+ * ARCH_REQ_XCOMP_PERM: Facility number requested
+ *
+ * For facilities which require more than one XSTATE component, the request
+ * must be the highest state component number related to that facility,
+ * e.g. for AMX which requires XFEATURE_XTILE_CFG(17) and
+ * XFEATURE_XTILE_DATA(18) this would be XFEATURE_XTILE_DATA(18).
+ */
+long fpu_xstate_prctl(struct task_struct *tsk, int option, unsigned long arg2)
+{
+	u64 __user *uptr = (u64 __user *)arg2;
+	u64 permitted, supported;
+	unsigned long idx = arg2;
+
+	if (tsk != current)
+		return -EPERM;
+
+	switch (option) {
+	case ARCH_GET_XCOMP_SUPP:
+		supported = fpu_user_cfg.max_features |	fpu_user_cfg.legacy_features;
+		return put_user(supported, uptr);
+
+	case ARCH_GET_XCOMP_PERM:
+		/*
+		 * Lockless snapshot as it can also change right after the
+		 * dropping the lock.
+		 */
+		permitted = xstate_get_host_group_perm();
+		permitted &= XFEATURE_MASK_USER_SUPPORTED;
+		return put_user(permitted, uptr);
+
+	case ARCH_REQ_XCOMP_PERM:
+		if (!IS_ENABLED(CONFIG_X86_64))
+			return -EOPNOTSUPP;
+
+		return xstate_request_perm(idx);
+
+	default:
+		return -EINVAL;
+	}
+}
+
 #ifdef CONFIG_PROC_PID_ARCH_STATUS
 /*
  * Report the amount of time elapsed in millisecond since last AVX512