diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h
index d22e973845c6..1bb2d16f485b 100644
--- a/arch/x86/include/asm/fpu/xstate.h
+++ b/arch/x86/include/asm/fpu/xstate.h
@@ -111,8 +111,4 @@ void copy_supervisor_to_kernel(struct xregs_state *xsave);
 void copy_dynamic_supervisor_to_kernel(struct xregs_state *xstate, u64 mask);
 void copy_kernel_to_dynamic_supervisor(struct xregs_state *xstate, u64 mask);
 
-
-/* Validate an xstate header supplied by userspace (ptrace or sigreturn) */
-int validate_user_xstate_header(const struct xstate_header *hdr);
-
 #endif
diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
index 6bb874441de8..a50c0a935499 100644
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -2,11 +2,13 @@
 /*
  * FPU register's regset abstraction, for ptrace, core dumps, etc.
  */
+#include <linux/sched/task_stack.h>
+#include <linux/vmalloc.h>
+
 #include <asm/fpu/internal.h>
 #include <asm/fpu/signal.h>
 #include <asm/fpu/regset.h>
 #include <asm/fpu/xstate.h>
-#include <linux/sched/task_stack.h>
 
 /*
  * The xstateregs_active() routine is the same as the regset_fpregs_active() routine,
@@ -108,10 +110,10 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
 		  const void *kbuf, const void __user *ubuf)
 {
 	struct fpu *fpu = &target->thread.fpu;
-	struct xregs_state *xsave;
+	struct xregs_state *tmpbuf = NULL;
 	int ret;
 
-	if (!boot_cpu_has(X86_FEATURE_XSAVE))
+	if (!cpu_feature_enabled(X86_FEATURE_XSAVE))
 		return -ENODEV;
 
 	/*
@@ -120,32 +122,22 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
 	if (pos != 0 || count != fpu_user_xstate_size)
 		return -EFAULT;
 
-	xsave = &fpu->state.xsave;
+	if (!kbuf) {
+		tmpbuf = vmalloc(count);
+		if (!tmpbuf)
+			return -ENOMEM;
 
-	fpu__prepare_write(fpu);
-
-	if (using_compacted_format()) {
-		if (kbuf)
-			ret = copy_kernel_to_xstate(xsave, kbuf);
-		else
-			ret = copy_user_to_xstate(xsave, ubuf);
-	} else {
-		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
-		if (!ret)
-			ret = validate_user_xstate_header(&xsave->header);
+		if (copy_from_user(tmpbuf, ubuf, count)) {
+			ret = -EFAULT;
+			goto out;
+		}
 	}
 
-	/*
-	 * mxcsr reserved bits must be masked to zero for security reasons.
-	 */
-	xsave->i387.mxcsr &= mxcsr_feature_mask;
-
-	/*
-	 * In case of failure, mark all states as init:
-	 */
-	if (ret)
-		fpstate_init(&fpu->state);
+	fpu__prepare_write(fpu);
+	ret = copy_kernel_to_xstate(&fpu->state.xsave, kbuf ?: tmpbuf);
 
+out:
+	vfree(tmpbuf);
 	return ret;
 }
 
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index b82879cd9151..2b7b579f06b6 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -543,7 +543,7 @@ int using_compacted_format(void)
 }
 
 /* Validate an xstate header supplied by userspace (ptrace or sigreturn) */
-int validate_user_xstate_header(const struct xstate_header *hdr)
+static int validate_user_xstate_header(const struct xstate_header *hdr)
 {
 	/* No unknown or supervisor features may be set */
 	if (hdr->xfeatures & ~xfeatures_mask_user())
@@ -1155,7 +1155,7 @@ void copy_xstate_to_kernel(struct membuf to, struct xregs_state *xsave)
 }
 
 /*
- * Convert from a ptrace standard-format kernel buffer to kernel XSAVES format
+ * 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().
  */
 int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
@@ -1202,14 +1202,16 @@ int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
 	 */
 	xsave->header.xfeatures |= hdr.xfeatures;
 
+	/* mxcsr reserved bits must be masked to zero for historical reasons. */
+	xsave->i387.mxcsr &= mxcsr_feature_mask;
+
 	return 0;
 }
 
 /*
- * Convert from a ptrace or sigreturn standard-format user-space buffer to
- * kernel XSAVES format and copy to the target thread. This is called from
- * xstateregs_set(), as well as potentially from the sigreturn() and
- * rt_sigreturn() system calls.
+ * 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_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf)
 {