Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1843 insertions, 0 deletions

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
new file mode 100644
index 000000000..ebe698f8a
--- /dev/null
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -0,0 +1,1843 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * xsave/xrstor support.
+ *
+ * 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/regset.h>
+#include <asm/fpu/signal.h>
+#include <asm/fpu/xcr.h>
+
+#include <asm/tlbflush.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
+ * xfeature is completely unused.  We use other mechanisms
+ * to save/restore PT state in Linux.
+ */
+static const char *xfeature_names[] =
+{
+	"x87 floating point registers"	,
+	"SSE registers"			,
+	"AVX registers"			,
+	"MPX bounds registers"		,
+	"MPX CSR"			,
+	"AVX-512 opmask"		,
+	"AVX-512 Hi256"			,
+	"AVX-512 ZMM_Hi256"		,
+	"Processor Trace (unused)"	,
+	"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 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,
+};
+
+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 =
+	{ [ 0 ... XFEATURE_MAX - 1] = -1};
+static unsigned int xstate_flags[XFEATURE_MAX] __ro_after_init;
+
+#define XSTATE_FLAG_SUPERVISOR	BIT(0)
+#define XSTATE_FLAG_ALIGNED64	BIT(1)
+
+/*
+ * 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 & ~fpu_kernel_cfg.max_features;
+
+	if (unlikely(feature_name)) {
+		long xfeature_idx, max_idx;
+		u64 xfeatures_print;
+		/*
+		 * So we use FLS here to be able to print the most advanced
+		 * feature that was requested but is missing. So if a driver
+		 * asks about "XFEATURE_MASK_SSE | XFEATURE_MASK_YMM" we'll print the
+		 * missing AVX feature - this is the most informative message
+		 * to users:
+		 */
+		if (xfeatures_missing)
+			xfeatures_print = xfeatures_missing;
+		else
+			xfeatures_print = xfeatures_needed;
+
+		xfeature_idx = fls64(xfeatures_print)-1;
+		max_idx = ARRAY_SIZE(xfeature_names)-1;
+		xfeature_idx = min(xfeature_idx, max_idx);
+
+		*feature_name = xfeature_names[xfeature_idx];
+	}
+
+	if (xfeatures_missing)
+		return 0;
+
+	return 1;
+}
+EXPORT_SYMBOL_GPL(cpu_has_xfeatures);
+
+static bool xfeature_is_aligned64(int xfeature_nr)
+{
+	return xstate_flags[xfeature_nr] & XSTATE_FLAG_ALIGNED64;
+}
+
+static bool xfeature_is_supervisor(int xfeature_nr)
+{
+	return xstate_flags[xfeature_nr] & XSTATE_FLAG_SUPERVISOR;
+}
+
+static unsigned int xfeature_get_offset(u64 xcomp_bv, int xfeature)
+{
+	unsigned int offs, i;
+
+	/*
+	 * Non-compacted format and legacy features use the cached fixed
+	 * offsets.
+	 */
+	if (!cpu_feature_enabled(X86_FEATURE_XCOMPACTED) ||
+	    xfeature <= XFEATURE_SSE)
+		return xstate_offsets[xfeature];
+
+	/*
+	 * Compacted format offsets depend on the actual content of the
+	 * compacted xsave area which is determined by the xcomp_bv header
+	 * field.
+	 */
+	offs = FXSAVE_SIZE + XSAVE_HDR_SIZE;
+	for_each_extended_xfeature(i, xcomp_bv) {
+		if (xfeature_is_aligned64(i))
+			offs = ALIGN(offs, 64);
+		if (i == xfeature)
+			break;
+		offs += xstate_sizes[i];
+	}
+	return offs;
+}
+
+/*
+ * Enable the extended processor state save/restore feature.
+ * Called once per CPU onlining.
+ */
+void fpu__init_cpu_xstate(void)
+{
+	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, fpu_user_cfg.max_features);
+
+	/*
+	 * MSR_IA32_XSS sets supervisor states managed by XSAVES.
+	 */
+	if (boot_cpu_has(X86_FEATURE_XSAVES)) {
+		wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor() |
+				     xfeatures_mask_independent());
+	}
+}
+
+static bool xfeature_enabled(enum xfeature xfeature)
+{
+	return fpu_kernel_cfg.max_features & BIT_ULL(xfeature);
+}
+
+/*
+ * Record the offsets and sizes of various xstates contained
+ * in the XSAVE state memory layout.
+ */
+static void __init setup_xstate_cache(void)
+{
+	u32 eax, ebx, ecx, edx, i;
+	/* start at the beginning of the "extended state" */
+	unsigned int last_good_offset = offsetof(struct xregs_state,
+						 extended_state_area);
+	/*
+	 * The FP xstates and SSE xstates are legacy states. They are always
+	 * in the fixed offsets in the xsave area in either compacted form
+	 * or standard form.
+	 */
+	xstate_offsets[XFEATURE_FP]	= 0;
+	xstate_sizes[XFEATURE_FP]	= offsetof(struct fxregs_state,
+						   xmm_space);
+
+	xstate_offsets[XFEATURE_SSE]	= xstate_sizes[XFEATURE_FP];
+	xstate_sizes[XFEATURE_SSE]	= sizeof_field(struct fxregs_state,
+						       xmm_space);
+
+	for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) {
+		cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
+
+		xstate_sizes[i] = eax;
+		xstate_flags[i] = ecx;
+
+		/*
+		 * If an xfeature is supervisor state, the offset in EBX is
+		 * invalid, leave it to -1.
+		 */
+		if (xfeature_is_supervisor(i))
+			continue;
+
+		xstate_offsets[i] = ebx;
+
+		/*
+		 * In our xstate size checks, we assume that the highest-numbered
+		 * xstate feature has the highest offset in the buffer.  Ensure
+		 * it does.
+		 */
+		WARN_ONCE(last_good_offset > xstate_offsets[i],
+			  "x86/fpu: misordered xstate at %d\n", last_good_offset);
+
+		last_good_offset = xstate_offsets[i];
+	}
+}
+
+static void __init print_xstate_feature(u64 xstate_mask)
+{
+	const char *feature_name;
+
+	if (cpu_has_xfeatures(xstate_mask, &feature_name))
+		pr_info("x86/fpu: Supporting XSAVE feature 0x%03Lx: '%s'\n", xstate_mask, feature_name);
+}
+
+/*
+ * Print out all the supported xstate features:
+ */
+static void __init print_xstate_features(void)
+{
+	print_xstate_feature(XFEATURE_MASK_FP);
+	print_xstate_feature(XFEATURE_MASK_SSE);
+	print_xstate_feature(XFEATURE_MASK_YMM);
+	print_xstate_feature(XFEATURE_MASK_BNDREGS);
+	print_xstate_feature(XFEATURE_MASK_BNDCSR);
+	print_xstate_feature(XFEATURE_MASK_OPMASK);
+	print_xstate_feature(XFEATURE_MASK_ZMM_Hi256);
+	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);
+}
+
+/*
+ * This check is important because it is easy to get XSTATE_*
+ * confused with XSTATE_BIT_*.
+ */
+#define CHECK_XFEATURE(nr) do {		\
+	WARN_ON(nr < FIRST_EXTENDED_XFEATURE);	\
+	WARN_ON(nr >= XFEATURE_MAX);	\
+} while (0)
+
+/*
+ * Print out xstate component offsets and sizes
+ */
+static void __init print_xstate_offset_size(void)
+{
+	int i;
+
+	for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) {
+		pr_info("x86/fpu: xstate_offset[%d]: %4d, xstate_sizes[%d]: %4d\n",
+			i, xfeature_get_offset(fpu_kernel_cfg.max_features, 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
+ * newly added supported features at build time and make people
+ * actually look at the init state for the new feature.
+ */
+#define XFEATURES_INIT_FPSTATE_HANDLED		\
+	(XFEATURE_MASK_FP |			\
+	 XFEATURE_MASK_SSE |			\
+	 XFEATURE_MASK_YMM |			\
+	 XFEATURE_MASK_OPMASK |			\
+	 XFEATURE_MASK_ZMM_Hi256 |		\
+	 XFEATURE_MASK_Hi16_ZMM	 |		\
+	 XFEATURE_MASK_PKRU |			\
+	 XFEATURE_MASK_BNDREGS |		\
+	 XFEATURE_MASK_BNDCSR |			\
+	 XFEATURE_MASK_PASID |			\
+	 XFEATURE_MASK_XTILE)
+
+/*
+ * setup the xstate image representing the init state
+ */
+static void __init setup_init_fpu_buf(void)
+{
+	BUILD_BUG_ON((XFEATURE_MASK_USER_SUPPORTED |
+		      XFEATURE_MASK_SUPERVISOR_SUPPORTED) !=
+		     XFEATURES_INIT_FPSTATE_HANDLED);
+
+	if (!boot_cpu_has(X86_FEATURE_XSAVE))
+		return;
+
+	print_xstate_features();
+
+	xstate_init_xcomp_bv(&init_fpstate.regs.xsave, init_fpstate.xfeatures);
+
+	/*
+	 * Init all the features state with header.xfeatures being 0x0
+	 */
+	os_xrstor_booting(&init_fpstate.regs.xsave);
+
+	/*
+	 * All components are now in init state. Read the state back so
+	 * that init_fpstate contains all non-zero init state. This only
+	 * works with XSAVE, but not with XSAVEOPT and XSAVEC/S because
+	 * those use the init optimization which skips writing data for
+	 * components in init state.
+	 *
+	 * XSAVE could be used, but that would require to reshuffle the
+	 * data when XSAVEC/S is available because XSAVEC/S uses xstate
+	 * compaction. But doing so is a pointless exercise because most
+	 * components have an all zeros init state except for the legacy
+	 * ones (FP and SSE). Those can be saved with FXSAVE into the
+	 * legacy area. Adding new features requires to ensure that init
+	 * state is all zeroes or if not to add the necessary handling
+	 * here.
+	 */
+	fxsave(&init_fpstate.regs.fxsave);
+}
+
+int xfeature_size(int xfeature_nr)
+{
+	u32 eax, ebx, ecx, edx;
+
+	CHECK_XFEATURE(xfeature_nr);
+	cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
+	return eax;
+}
+
+/* Validate an xstate header supplied by userspace (ptrace or sigreturn) */
+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 & ~fpstate->user_xfeatures)
+		return -EINVAL;
+
+	/* Userspace must use the uncompacted format */
+	if (hdr->xcomp_bv)
+		return -EINVAL;
+
+	/*
+	 * If 'reserved' is shrunken to add a new field, make sure to validate
+	 * that new field here!
+	 */
+	BUILD_BUG_ON(sizeof(hdr->reserved) != 48);
+
+	/* No reserved bits may be set */
+	if (memchr_inv(hdr->reserved, 0, sizeof(hdr->reserved)))
+		return -EINVAL;
+
+	return 0;
+}
+
+static void __init __xstate_dump_leaves(void)
+{
+	int i;
+	u32 eax, ebx, ecx, edx;
+	static int should_dump = 1;
+
+	if (!should_dump)
+		return;
+	should_dump = 0;
+	/*
+	 * Dump out a few leaves past the ones that we support
+	 * just in case there are some goodies up there
+	 */
+	for (i = 0; i < XFEATURE_MAX + 10; i++) {
+		cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
+		pr_warn("CPUID[%02x, %02x]: eax=%08x ebx=%08x ecx=%08x edx=%08x\n",
+			XSTATE_CPUID, i, eax, ebx, ecx, edx);
+	}
+}
+
+#define XSTATE_WARN_ON(x, fmt, ...) do {					\
+	if (WARN_ONCE(x, "XSAVE consistency problem: " fmt, ##__VA_ARGS__)) {	\
+		__xstate_dump_leaves();						\
+	}									\
+} while (0)
+
+#define XCHECK_SZ(sz, nr, nr_macro, __struct) do {			\
+	if ((nr == nr_macro) &&						\
+	    WARN_ONCE(sz != sizeof(__struct),				\
+		"%s: struct is %zu bytes, cpu state %d bytes\n",	\
+		__stringify(nr_macro), sizeof(__struct), sz)) {		\
+		__xstate_dump_leaves();					\
+	}								\
+} 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 bool __init check_xstate_against_struct(int nr)
+{
+	/*
+	 * Ask the CPU for the size of the state.
+	 */
+	int sz = xfeature_size(nr);
+	/*
+	 * Match each CPU state with the corresponding software
+	 * structure.
+	 */
+	XCHECK_SZ(sz, nr, XFEATURE_YMM,       struct ymmh_struct);
+	XCHECK_SZ(sz, nr, XFEATURE_BNDREGS,   struct mpx_bndreg_state);
+	XCHECK_SZ(sz, nr, XFEATURE_BNDCSR,    struct mpx_bndcsr_state);
+	XCHECK_SZ(sz, nr, XFEATURE_OPMASK,    struct avx_512_opmask_state);
+	XCHECK_SZ(sz, nr, XFEATURE_ZMM_Hi256, struct avx_512_zmm_uppers_state);
+	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
+	 * there are "holes" in the xsave state component
+	 * numbers.
+	 */
+	if ((nr < XFEATURE_YMM) ||
+	    (nr >= XFEATURE_MAX) ||
+	    (nr == XFEATURE_PT_UNIMPLEMENTED_SO_FAR) ||
+	    ((nr >= XFEATURE_RSRVD_COMP_11) && (nr <= XFEATURE_RSRVD_COMP_16))) {
+		XSTATE_WARN_ON(1, "No structure for xstate: %d\n", nr);
+		return false;
+	}
+	return true;
+}
+
+static unsigned int xstate_calculate_size(u64 xfeatures, bool compacted)
+{
+	unsigned int topmost = fls64(xfeatures) -  1;
+	unsigned int offset = xstate_offsets[topmost];
+
+	if (topmost <= XFEATURE_SSE)
+		return sizeof(struct xregs_state);
+
+	if (compacted)
+		offset = xfeature_get_offset(xfeatures, topmost);
+	return offset + xstate_sizes[topmost];
+}
+
+/*
+ * This essentially double-checks what the cpu told us about
+ * how large the XSAVE buffer needs to be.  We are recalculating
+ * it to be safe.
+ *
+ * Independent XSAVE features allocate their own buffers and are not
+ * covered by these checks. Only the size of the buffer for task->fpu
+ * is checked here.
+ */
+static bool __init paranoid_xstate_size_valid(unsigned int kernel_size)
+{
+	bool compacted = cpu_feature_enabled(X86_FEATURE_XCOMPACTED);
+	bool xsaves = cpu_feature_enabled(X86_FEATURE_XSAVES);
+	unsigned int size = FXSAVE_SIZE + XSAVE_HDR_SIZE;
+	int 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 (!xsaves && xfeature_is_supervisor(i)) {
+			XSTATE_WARN_ON(1, "Got supervisor feature %d, but XSAVES not advertised\n", i);
+			return false;
+		}
+	}
+	size = xstate_calculate_size(fpu_kernel_cfg.max_features, compacted);
+	XSTATE_WARN_ON(size != kernel_size,
+		       "size %u != kernel_size %u\n", size, kernel_size);
+	return size == kernel_size;
+}
+
+/*
+ * Get total size of enabled xstates in XCR0 | IA32_XSS.
+ *
+ * Note the SDM's wording here.  "sub-function 0" only enumerates
+ * the size of the *user* states.  If we use it to size a buffer
+ * that we use 'XSAVES' on, we could potentially overflow the
+ * buffer because 'XSAVES' saves system states too.
+ *
+ * This also takes compaction into account. So this works for
+ * XSAVEC as well.
+ */
+static unsigned int __init get_compacted_size(void)
+{
+	unsigned int eax, ebx, ecx, edx;
+	/*
+	 * - CPUID function 0DH, sub-function 1:
+	 *    EBX enumerates the size (in bytes) required by
+	 *    the XSAVES instruction for an XSAVE area
+	 *    containing all the state components
+	 *    corresponding to bits currently set in
+	 *    XCR0 | IA32_XSS.
+	 *
+	 * When XSAVES is not available but XSAVEC is (virt), then there
+	 * are no supervisor states, but XSAVEC still uses compacted
+	 * format.
+	 */
+	cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx);
+	return ebx;
+}
+
+/*
+ * Get the total size of the enabled xstates without the independent supervisor
+ * features.
+ */
+static unsigned int __init get_xsave_compacted_size(void)
+{
+	u64 mask = xfeatures_mask_independent();
+	unsigned int size;
+
+	if (!mask)
+		return get_compacted_size();
+
+	/* Disable independent features. */
+	wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor());
+
+	/*
+	 * Ask the hardware what size is required of the buffer.
+	 * This is the size required for the task->fpu buffer.
+	 */
+	size = get_compacted_size();
+
+	/* Re-enable independent features so XSAVES will work on them again. */
+	wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor() | mask);
+
+	return size;
+}
+
+static unsigned int __init get_xsave_size_user(void)
+{
+	unsigned int eax, ebx, ecx, edx;
+	/*
+	 * - CPUID function 0DH, sub-function 0:
+	 *    EBX enumerates the size (in bytes) required by
+	 *    the XSAVE instruction for an XSAVE area
+	 *    containing all the *user* state components
+	 *    corresponding to bits currently set in XCR0.
+	 */
+	cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
+	return ebx;
+}
+
+static int __init init_xstate_size(void)
+{
+	/* Recompute the context size for enabled features: */
+	unsigned int user_size, kernel_size, kernel_default_size;
+	bool compacted = cpu_feature_enabled(X86_FEATURE_XCOMPACTED);
+
+	/* Uncompacted user space size */
+	user_size = get_xsave_size_user();
+
+	/*
+	 * XSAVES kernel size includes supervisor states and uses compacted
+	 * format. XSAVEC uses compacted format, but does not save
+	 * supervisor states.
+	 *
+	 * XSAVE[OPT] do not support supervisor states so kernel and user
+	 * size is identical.
+	 */
+	if (compacted)
+		kernel_size = get_xsave_compacted_size();
+	else
+		kernel_size = user_size;
+
+	kernel_default_size =
+		xstate_calculate_size(fpu_kernel_cfg.default_features, compacted);
+
+	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);
+
+	return 0;
+}
+
+/*
+ * We enabled the XSAVE hardware, but something went wrong and
+ * we can not use it.  Disable it.
+ */
+static void __init fpu__init_disable_system_xstate(unsigned int legacy_size)
+{
+	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(unsigned int legacy_size)
+{
+	unsigned int eax, ebx, ecx, edx;
+	u64 xfeatures;
+	int err;
+	int i;
+
+	if (!boot_cpu_has(X86_FEATURE_FPU)) {
+		pr_info("x86/fpu: No FPU detected\n");
+		return;
+	}
+
+	if (!boot_cpu_has(X86_FEATURE_XSAVE)) {
+		pr_info("x86/fpu: x87 FPU will use %s\n",
+			boot_cpu_has(X86_FEATURE_FXSR) ? "FXSAVE" : "FSAVE");
+		return;
+	}
+
+	if (boot_cpu_data.cpuid_level < XSTATE_CPUID) {
+		WARN_ON_FPU(1);
+		return;
+	}
+
+	/*
+	 * Find user xstates supported by the processor.
+	 */
+	cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
+	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);
+	fpu_kernel_cfg.max_features |= ecx + ((u64)edx << 32);
+
+	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",
+		       fpu_kernel_cfg.max_features);
+		goto out_disable;
+	}
+
+	/*
+	 * Clear XSAVE features that are disabled in the normal CPUID.
+	 */
+	for (i = 0; i < ARRAY_SIZE(xsave_cpuid_features); 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);
+	}
+
+	if (!cpu_feature_enabled(X86_FEATURE_XFD))
+		fpu_kernel_cfg.max_features &= ~XFEATURE_MASK_USER_DYNAMIC;
+
+	if (!cpu_feature_enabled(X86_FEATURE_XSAVES))
+		fpu_kernel_cfg.max_features &= XFEATURE_MASK_USER_SUPPORTED;
+	else
+		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 = 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;
+
+	/* Set up compaction feature bit */
+	if (cpu_feature_enabled(X86_FEATURE_XSAVEC) ||
+	    cpu_feature_enabled(X86_FEATURE_XSAVES))
+		setup_force_cpu_cap(X86_FEATURE_XCOMPACTED);
+
+	/* Enable xstate instructions to be able to continue with initialization: */
+	fpu__init_cpu_xstate();
+
+	/* Cache size, offset and flags for initialization */
+	setup_xstate_cache();
+
+	err = init_xstate_size();
+	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_cfg.max_size,
+				  fpu_user_cfg.max_features);
+
+	/*
+	 * init_fpstate excludes dynamic states as they are large but init
+	 * state is zero.
+	 */
+	init_fpstate.size		= fpu_kernel_cfg.default_size;
+	init_fpstate.xfeatures		= fpu_kernel_cfg.default_features;
+
+	if (init_fpstate.size > sizeof(init_fpstate.regs)) {
+		pr_warn("x86/fpu: init_fpstate buffer too small (%zu < %d), disabling XSAVE\n",
+			sizeof(init_fpstate.regs), init_fpstate.size);
+		goto out_disable;
+	}
+
+	setup_init_fpu_buf();
+
+	/*
+	 * Paranoia check whether something in the setup modified the
+	 * xfeatures mask.
+	 */
+	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, fpu_kernel_cfg.max_features);
+		goto out_disable;
+	}
+
+	/*
+	 * CPU capabilities initialization runs before FPU init. So
+	 * X86_FEATURE_OSXSAVE is not set. Now that XSAVE is completely
+	 * functional, set the feature bit so depending code works.
+	 */
+	setup_force_cpu_cap(X86_FEATURE_OSXSAVE);
+
+	print_xstate_offset_size();
+	pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is %d bytes, using '%s' format.\n",
+		fpu_kernel_cfg.max_features,
+		fpu_kernel_cfg.max_size,
+		boot_cpu_has(X86_FEATURE_XCOMPACTED) ? "compacted" : "standard");
+	return;
+
+out_disable:
+	/* something went wrong, try to boot without any XSAVE support */
+	fpu__init_disable_system_xstate(legacy_size);
+}
+
+/*
+ * Restore minimal FPU state after suspend:
+ */
+void fpu__resume_cpu(void)
+{
+	/*
+	 * Restore XCR0 on xsave capable CPUs:
+	 */
+	if (cpu_feature_enabled(X86_FEATURE_XSAVE))
+		xsetbv(XCR_XFEATURE_ENABLED_MASK, fpu_user_cfg.max_features);
+
+	/*
+	 * Restore IA32_XSS. The same CPUID bit enumerates support
+	 * of XSAVES and MSR_IA32_XSS.
+	 */
+	if (cpu_feature_enabled(X86_FEATURE_XSAVES)) {
+		wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor()  |
+				     xfeatures_mask_independent());
+	}
+
+	if (fpu_state_size_dynamic())
+		wrmsrl(MSR_IA32_XFD, current->thread.fpu.fpstate->xfd);
+}
+
+/*
+ * Given an xstate feature nr, calculate where in the xsave
+ * buffer the state is.  Callers should ensure that the buffer
+ * is valid.
+ */
+static void *__raw_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
+{
+	u64 xcomp_bv = xsave->header.xcomp_bv;
+
+	if (WARN_ON_ONCE(!xfeature_enabled(xfeature_nr)))
+		return NULL;
+
+	if (cpu_feature_enabled(X86_FEATURE_XCOMPACTED)) {
+		if (WARN_ON_ONCE(!(xcomp_bv & BIT_ULL(xfeature_nr))))
+			return NULL;
+	}
+
+	return (void *)xsave + xfeature_get_offset(xcomp_bv, xfeature_nr);
+}
+
+/*
+ * Given the xsave area and a state inside, this function returns the
+ * address of the state.
+ *
+ * This is the API that is called to get xstate address in either
+ * standard format or compacted format of xsave area.
+ *
+ * Note that if there is no data for the field in the xsave buffer
+ * this will return NULL.
+ *
+ * Inputs:
+ *	xstate: the thread's storage area for all FPU data
+ *	xfeature_nr: state which is defined in xsave.h (e.g. XFEATURE_FP,
+ *	XFEATURE_SSE, etc...)
+ * Output:
+ *	address of the state in the xsave area, or NULL if the
+ *	field is not present in the xsave buffer.
+ */
+void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
+{
+	/*
+	 * Do we even *have* xsave state?
+	 */
+	if (!boot_cpu_has(X86_FEATURE_XSAVE))
+		return NULL;
+
+	/*
+	 * We should not ever be requesting features that we
+	 * have not enabled.
+	 */
+	if (WARN_ON_ONCE(!xfeature_enabled(xfeature_nr)))
+		return NULL;
+
+	/*
+	 * This assumes the last 'xsave*' instruction to
+	 * have requested that 'xfeature_nr' be saved.
+	 * If it did not, we might be seeing and old value
+	 * of the field in the buffer.
+	 *
+	 * This can happen because the last 'xsave' did not
+	 * request that this feature be saved (unlikely)
+	 * or because the "init optimization" caused it
+	 * to not be saved.
+	 */
+	if (!(xsave->header.xfeatures & BIT_ULL(xfeature_nr)))
+		return NULL;
+
+	return __raw_xsave_addr(xsave, xfeature_nr);
+}
+
+#ifdef CONFIG_ARCH_HAS_PKEYS
+
+/*
+ * This will go out and modify PKRU register to set the access
+ * rights for @pkey to @init_val.
+ */
+int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
+			      unsigned long init_val)
+{
+	u32 old_pkru, new_pkru_bits = 0;
+	int pkey_shift;
+
+	/*
+	 * This check implies XSAVE support.  OSPKE only gets
+	 * set if we enable XSAVE and we enable PKU in XCR0.
+	 */
+	if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
+		return -EINVAL;
+
+	/*
+	 * This code should only be called with valid 'pkey'
+	 * values originating from in-kernel users.  Complain
+	 * if a bad value is observed.
+	 */
+	if (WARN_ON_ONCE(pkey >= arch_max_pkey()))
+		return -EINVAL;
+
+	/* Set the bits we need in PKRU:  */
+	if (init_val & PKEY_DISABLE_ACCESS)
+		new_pkru_bits |= PKRU_AD_BIT;
+	if (init_val & PKEY_DISABLE_WRITE)
+		new_pkru_bits |= PKRU_WD_BIT;
+
+	/* Shift the bits in to the correct place in PKRU for pkey: */
+	pkey_shift = pkey * PKRU_BITS_PER_PKEY;
+	new_pkru_bits <<= pkey_shift;
+
+	/* Get old PKRU and mask off any old bits in place: */
+	old_pkru = read_pkru();
+	old_pkru &= ~((PKRU_AD_BIT|PKRU_WD_BIT) << pkey_shift);
+
+	/* Write old part along with new part: */
+	write_pkru(old_pkru | new_pkru_bits);
+
+	return 0;
+}
+#endif /* ! CONFIG_ARCH_HAS_PKEYS */
+
+static void copy_feature(bool from_xstate, struct membuf *to, void *xstate,
+			 void *init_xstate, unsigned int size)
+{
+	membuf_write(to, from_xstate ? xstate : init_xstate, size);
+}
+
+/**
+ * __copy_xstate_to_uabi_buf - Copy kernel saved xstate to a UABI buffer
+ * @to:		membuf descriptor
+ * @fpstate:	The fpstate buffer from which to copy
+ * @xfeatures:	The mask of xfeatures to save (XSAVE mode only)
+ * @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
+ * 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 fpstate *fpstate,
+			       u64 xfeatures, u32 pkru_val,
+			       enum xstate_copy_mode copy_mode)
+{
+	const unsigned int off_mxcsr = offsetof(struct fxregs_state, mxcsr);
+	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));
+	header.xfeatures = xsave->header.xfeatures;
+
+	/* Mask out the feature bits depending on copy mode */
+	switch (copy_mode) {
+	case XSTATE_COPY_FP:
+		header.xfeatures &= XFEATURE_MASK_FP;
+		break;
+
+	case XSTATE_COPY_FX:
+		header.xfeatures &= XFEATURE_MASK_FP | XFEATURE_MASK_SSE;
+		break;
+
+	case XSTATE_COPY_XSAVE:
+		header.xfeatures &= fpstate->user_xfeatures & xfeatures;
+		break;
+	}
+
+	/* Copy FP state up to MXCSR */
+	copy_feature(header.xfeatures & XFEATURE_MASK_FP, &to, &xsave->i387,
+		     &xinit->i387, off_mxcsr);
+
+	/* Copy MXCSR when SSE or YMM are set in the feature mask */
+	copy_feature(header.xfeatures & (XFEATURE_MASK_SSE | XFEATURE_MASK_YMM),
+		     &to, &xsave->i387.mxcsr, &xinit->i387.mxcsr,
+		     MXCSR_AND_FLAGS_SIZE);
+
+	/* Copy the remaining FP state */
+	copy_feature(header.xfeatures & XFEATURE_MASK_FP,
+		     &to, &xsave->i387.st_space, &xinit->i387.st_space,
+		     sizeof(xsave->i387.st_space));
+
+	/* Copy the SSE state - shared with YMM, but independently managed */
+	copy_feature(header.xfeatures & XFEATURE_MASK_SSE,
+		     &to, &xsave->i387.xmm_space, &xinit->i387.xmm_space,
+		     sizeof(xsave->i387.xmm_space));
+
+	if (copy_mode != XSTATE_COPY_XSAVE)
+		goto out;
+
+	/* Zero the padding area */
+	membuf_zero(&to, sizeof(xsave->i387.padding));
+
+	/* Copy xsave->i387.sw_reserved */
+	membuf_write(&to, xstate_fx_sw_bytes, sizeof(xsave->i387.sw_reserved));
+
+	/* Copy the user space relevant state of @xsave->header */
+	membuf_write(&to, &header, sizeof(header));
+
+	zerofrom = offsetof(struct xregs_state, extended_state_area);
+
+	/*
+	 * This 'mask' indicates which states to copy from fpstate.
+	 * Those extended states that are not present in fpstate are
+	 * either disabled or initialized:
+	 *
+	 * 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.
+	 *
+	 * The extended features have an all zeroes init state. Thus,
+	 * remove them from 'mask' to zero those features in the user
+	 * buffer instead of retrieving them from init_fpstate.
+	 */
+	mask = header.xfeatures;
+
+	for_each_extended_xfeature(i, mask) {
+		/*
+		 * If there was a feature or alignment gap, zero the space
+		 * in the destination buffer.
+		 */
+		if (zerofrom < xstate_offsets[i])
+			membuf_zero(&to, xstate_offsets[i] - zerofrom);
+
+		if (i == XFEATURE_PKRU) {
+			struct pkru_state pkru = {0};
+			/*
+			 * PKRU is not necessarily up to date in the
+			 * XSAVE buffer. Use the provided value.
+			 */
+			pkru.pkru = pkru_val;
+			membuf_write(&to, &pkru, sizeof(pkru));
+		} else {
+			membuf_write(&to,
+				     __raw_xsave_addr(xsave, i),
+				     xstate_sizes[i]);
+		}
+		/*
+		 * Keep track of the last copied state in the non-compacted
+		 * target buffer for gap zeroing.
+		 */
+		zerofrom = xstate_offsets[i] + xstate_sizes[i];
+	}
+
+out:
+	if (to.left)
+		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.fpu.fpstate->user_xfeatures,
+				  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)
+{
+	if (kbuf) {
+		memcpy(dst, kbuf + offset, size);
+	} else {
+		if (copy_from_user(dst, ubuf + offset, size))
+			return -EFAULT;
+	}
+	return 0;
+}
+
+
+/**
+ * copy_uabi_to_xstate - Copy a UABI format buffer to the kernel xstate
+ * @fpstate:	The fpstate buffer to copy to
+ * @kbuf:	The UABI format buffer, if it comes from the kernel
+ * @ubuf:	The UABI format buffer, if it comes from userspace
+ * @pkru:	The location to write the PKRU value to
+ *
+ * Converts from the UABI format into the kernel internal hardware
+ * dependent format.
+ *
+ * This function ultimately has three different callers with distinct PKRU
+ * behavior.
+ * 1.	When called from sigreturn the PKRU register will be restored from
+ *	@fpstate via an XRSTOR. Correctly copying the UABI format buffer to
+ *	@fpstate is sufficient to cover this case, but the caller will also
+ *	pass a pointer to the thread_struct's pkru field in @pkru and updating
+ *	it is harmless.
+ * 2.	When called from ptrace the PKRU register will be restored from the
+ *	thread_struct's pkru field. A pointer to that is passed in @pkru.
+ *	The kernel will restore it manually, so the XRSTOR behavior that resets
+ *	the PKRU register to the hardware init value (0) if the corresponding
+ *	xfeatures bit is not set is emulated here.
+ * 3.	When called from KVM the PKRU register will be restored from the vcpu's
+ *	pkru field. A pointer to that is passed in @pkru. KVM hasn't used
+ *	XRSTOR and hasn't had the PKRU resetting behavior described above. To
+ *	preserve that KVM behavior, it passes NULL for @pkru if the xfeatures
+ *	bit is not set.
+ */
+static int copy_uabi_to_xstate(struct fpstate *fpstate, const void *kbuf,
+			       const void __user *ubuf, u32 *pkru)
+{
+	struct xregs_state *xsave = &fpstate->regs.xsave;
+	unsigned int offset, size;
+	struct xstate_header hdr;
+	u64 mask;
+	int i;
+
+	offset = offsetof(struct xregs_state, header);
+	if (copy_from_buffer(&hdr, offset, sizeof(hdr), kbuf, ubuf))
+		return -EFAULT;
+
+	if (validate_user_xstate_header(&hdr, fpstate))
+		return -EINVAL;
+
+	/* Validate MXCSR when any of the related features is in use */
+	mask = XFEATURE_MASK_FP | XFEATURE_MASK_SSE | XFEATURE_MASK_YMM;
+	if (hdr.xfeatures & mask) {
+		u32 mxcsr[2];
+
+		offset = offsetof(struct fxregs_state, mxcsr);
+		if (copy_from_buffer(mxcsr, offset, sizeof(mxcsr), kbuf, ubuf))
+			return -EFAULT;
+
+		/* Reserved bits in MXCSR must be zero. */
+		if (mxcsr[0] & ~mxcsr_feature_mask)
+			return -EINVAL;
+
+		/* SSE and YMM require MXCSR even when FP is not in use. */
+		if (!(hdr.xfeatures & XFEATURE_MASK_FP)) {
+			xsave->i387.mxcsr = mxcsr[0];
+			xsave->i387.mxcsr_mask = mxcsr[1];
+		}
+	}
+
+	for (i = 0; i < XFEATURE_MAX; i++) {
+		mask = BIT_ULL(i);
+
+		if (hdr.xfeatures & mask) {
+			void *dst = __raw_xsave_addr(xsave, i);
+
+			offset = xstate_offsets[i];
+			size = xstate_sizes[i];
+
+			if (copy_from_buffer(dst, offset, size, kbuf, ubuf))
+				return -EFAULT;
+		}
+	}
+
+	if (hdr.xfeatures & XFEATURE_MASK_PKRU) {
+		struct pkru_state *xpkru;
+
+		xpkru = __raw_xsave_addr(xsave, XFEATURE_PKRU);
+		*pkru = xpkru->pkru;
+	} else {
+		/*
+		 * KVM may pass NULL here to indicate that it does not need
+		 * PKRU updated.
+		 */
+		if (pkru)
+			*pkru = 0;
+	}
+
+	/*
+	 * The state that came in from userspace was user-state only.
+	 * Mask all the user states out of 'xfeatures':
+	 */
+	xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR_ALL;
+
+	/*
+	 * Add back in the features that came in from userspace:
+	 */
+	xsave->header.xfeatures |= hdr.xfeatures;
+
+	return 0;
+}
+
+/*
+ * Convert from a ptrace standard-format kernel buffer to kernel XSAVE[S]
+ * format and copy to the target thread. Used by ptrace and KVM.
+ */
+int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf, u32 *pkru)
+{
+	return copy_uabi_to_xstate(fpstate, kbuf, NULL, pkru);
+}
+
+/*
+ * Convert from a sigreturn standard-format user-space buffer to kernel
+ * 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 task_struct *tsk,
+				      const void __user *ubuf)
+{
+	return copy_uabi_to_xstate(tsk->thread.fpu.fpstate, NULL, ubuf, &tsk->thread.pkru);
+}
+
+static bool validate_independent_components(u64 mask)
+{
+	u64 xchk;
+
+	if (WARN_ON_FPU(!cpu_feature_enabled(X86_FEATURE_XSAVES)))
+		return false;
+
+	xchk = ~xfeatures_mask_independent();
+
+	if (WARN_ON_ONCE(!mask || mask & xchk))
+		return false;
+
+	return true;
+}
+
+/**
+ * xsaves - Save selected components to a kernel xstate buffer
+ * @xstate:	Pointer to the buffer
+ * @mask:	Feature mask to select the components to save
+ *
+ * The @xstate buffer must be 64 byte aligned and correctly initialized as
+ * XSAVES does not write the full xstate header. Before first use the
+ * buffer should be zeroed otherwise a consecutive XRSTORS from that buffer
+ * can #GP.
+ *
+ * The feature mask must be a subset of the independent features.
+ */
+void xsaves(struct xregs_state *xstate, u64 mask)
+{
+	int err;
+
+	if (!validate_independent_components(mask))
+		return;
+
+	XSTATE_OP(XSAVES, xstate, (u32)mask, (u32)(mask >> 32), err);
+	WARN_ON_ONCE(err);
+}
+
+/**
+ * xrstors - Restore selected components from a kernel xstate buffer
+ * @xstate:	Pointer to the buffer
+ * @mask:	Feature mask to select the components to restore
+ *
+ * The @xstate buffer must be 64 byte aligned and correctly initialized
+ * otherwise XRSTORS from that buffer can #GP.
+ *
+ * Proper usage is to restore the state which was saved with
+ * xsaves() into @xstate.
+ *
+ * The feature mask must be a subset of the independent features.
+ */
+void xrstors(struct xregs_state *xstate, u64 mask)
+{
+	int err;
+
+	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);
+}
+
+/**
+ * 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
+ * @guest_fpu:	Pointer to a guest FPU container. NULL for host allocations
+ *
+ * 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_guest *guest_fpu)
+{
+	struct fpu *fpu = &current->thread.fpu;
+	struct fpstate *curfps, *newfps = NULL;
+	unsigned int fpsize;
+	bool in_use;
+
+	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;
+
+	/*
+	 * When a guest FPU is supplied, use @guest_fpu->fpstate
+	 * as reference independent whether it is in use or not.
+	 */
+	curfps = guest_fpu ? guest_fpu->fpstate : fpu->fpstate;
+
+	/* Determine whether @curfps is the active fpstate */
+	in_use = fpu->fpstate == curfps;
+
+	if (guest_fpu) {
+		newfps->is_guest = true;
+		newfps->is_confidential = curfps->is_confidential;
+		newfps->in_use = curfps->in_use;
+		guest_fpu->xfeatures |= xfeatures;
+		guest_fpu->uabi_size = usize;
+	}
+
+	fpregs_lock();
+	/*
+	 * If @curfps is in use, ensure that the current state is in the
+	 * registers before swapping fpstate as that might invalidate it
+	 * due to layout changes.
+	 */
+	if (in_use && 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;
+
+	/* Do the final updates within the locked region */
+	xstate_init_xcomp_bv(&newfps->regs.xsave, newfps->xfeatures);
+
+	if (guest_fpu) {
+		guest_fpu->fpstate = newfps;
+		/* If curfps is active, update the FPU fpstate pointer */
+		if (in_use)
+			fpu->fpstate = newfps;
+	} else {
+		fpu->fpstate = newfps;
+	}
+
+	if (in_use)
+		xfd_update_state(fpu->fpstate);
+	fpregs_unlock();
+
+	/* Only free valloc'ed state */
+	if (curfps && curfps->is_valloc)
+		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, bool guest)
+{
+	/*
+	 * 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_XCOMPACTED);
+	struct fpu *fpu = &current->group_leader->thread.fpu;
+	struct fpu_state_perm *perm;
+	unsigned int ksize, usize;
+	u64 mask;
+	int ret = 0;
+
+	/* Check whether fully enabled */
+	if ((permitted & requested) == requested)
+		return 0;
+
+	/* Calculate the resulting kernel state size */
+	mask = permitted | requested;
+	/* Take supervisor states into account on the host */
+	if (!guest)
+		mask |= xfeatures_mask_supervisor();
+	ksize = xstate_calculate_size(mask, compacted);
+
+	/* Calculate the resulting user state size */
+	mask &= XFEATURE_MASK_USER_SUPPORTED;
+	usize = xstate_calculate_size(mask, false);
+
+	if (!guest) {
+		ret = validate_sigaltstack(usize);
+		if (ret)
+			return ret;
+	}
+
+	perm = guest ? &fpu->guest_perm : &fpu->perm;
+	/* Pairs with the READ_ONCE() in xstate_get_group_perm() */
+	WRITE_ONCE(perm->__state_perm, mask);
+	/* Protected by sighand lock */
+	perm->__state_size = ksize;
+	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, bool guest)
+{
+	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_group_perm(guest);
+	if ((permitted & requested) == requested)
+		return 0;
+
+	/* Protect against concurrent modifications */
+	spin_lock_irq(&current->sighand->siglock);
+	permitted = xstate_get_group_perm(guest);
+
+	/* First vCPU allocation locks the permissions. */
+	if (guest && (permitted & FPU_GUEST_PERM_LOCKED))
+		ret = -EBUSY;
+	else
+		ret = __xstate_request_perm(permitted, requested, guest);
+	spin_unlock_irq(&current->sighand->siglock);
+	return ret;
+}
+
+int __xfd_enable_feature(u64 xfd_err, struct fpu_guest *guest_fpu)
+{
+	u64 xfd_event = xfd_err & XFEATURE_MASK_USER_DYNAMIC;
+	struct fpu_state_perm *perm;
+	unsigned int ksize, usize;
+	struct fpu *fpu;
+
+	if (!xfd_event) {
+		if (!guest_fpu)
+			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_group_perm(!!guest_fpu) & xfd_event) != xfd_event) {
+		spin_unlock_irq(&current->sighand->siglock);
+		return -EPERM;
+	}
+
+	fpu = &current->group_leader->thread.fpu;
+	perm = guest_fpu ? &fpu->guest_perm : &fpu->perm;
+	ksize = perm->__state_size;
+	usize = 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, guest_fpu))
+		return -EFAULT;
+	return 0;
+}
+
+int xfd_enable_feature(u64 xfd_err)
+{
+	return __xfd_enable_feature(xfd_err, NULL);
+}
+
+#else /* CONFIG_X86_64 */
+static inline int xstate_request_perm(unsigned long idx, bool guest)
+{
+	return -EPERM;
+}
+#endif  /* !CONFIG_X86_64 */
+
+u64 xstate_get_guest_group_perm(void)
+{
+	return xstate_get_group_perm(true);
+}
+EXPORT_SYMBOL_GPL(xstate_get_guest_group_perm);
+
+/**
+ * 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(int option, unsigned long arg2)
+{
+	u64 __user *uptr = (u64 __user *)arg2;
+	u64 permitted, supported;
+	unsigned long idx = arg2;
+	bool guest = false;
+
+	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_GET_XCOMP_GUEST_PERM:
+		permitted = xstate_get_guest_group_perm();
+		permitted &= XFEATURE_MASK_USER_SUPPORTED;
+		return put_user(permitted, uptr);
+
+	case ARCH_REQ_XCOMP_GUEST_PERM:
+		guest = true;
+		fallthrough;
+
+	case ARCH_REQ_XCOMP_PERM:
+		if (!IS_ENABLED(CONFIG_X86_64))
+			return -EOPNOTSUPP;
+
+		return xstate_request_perm(idx, guest);
+
+	default:
+		return -EINVAL;
+	}
+}
+
+#ifdef CONFIG_PROC_PID_ARCH_STATUS
+/*
+ * Report the amount of time elapsed in millisecond since last AVX512
+ * use in the task.
+ */
+static void avx512_status(struct seq_file *m, struct task_struct *task)
+{
+	unsigned long timestamp = READ_ONCE(task->thread.fpu.avx512_timestamp);
+	long delta;
+
+	if (!timestamp) {
+		/*
+		 * Report -1 if no AVX512 usage
+		 */
+		delta = -1;
+	} else {
+		delta = (long)(jiffies - timestamp);
+		/*
+		 * Cap to LONG_MAX if time difference > LONG_MAX
+		 */
+		if (delta < 0)
+			delta = LONG_MAX;
+		delta = jiffies_to_msecs(delta);
+	}
+
+	seq_put_decimal_ll(m, "AVX512_elapsed_ms:\t", delta);
+	seq_putc(m, '\n');
+}
+
+/*
+ * Report architecture specific information
+ */
+int proc_pid_arch_status(struct seq_file *m, struct pid_namespace *ns,
+			struct pid *pid, struct task_struct *task)
+{
+	/*
+	 * Report AVX512 state if the processor and build option supported.
+	 */
+	if (cpu_feature_enabled(X86_FEATURE_AVX512F))
+		avx512_status(m, task);
+
+	return 0;
+}
+#endif /* CONFIG_PROC_PID_ARCH_STATUS */