x86/fpu: Convert restore_fpregs_from_fpstate() to struct fpstate

Convert restore_fpregs_from_fpstate() and related code to the new
register storage mechanism in preparation for dynamically sized buffers.

No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211013145322.347395546@linutronix.de

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

@@ -40,7 +40,7 @@ extern bool copy_fpstate_to_sigframe(void __user *buf, void __user *fp, int size
 extern void fpu__clear_user_states(struct fpu *fpu);
 extern bool fpu__restore_sig(void __user *buf, int ia32_frame);
 
-extern void restore_fpregs_from_fpstate(union fpregs_state *fpstate, u64 mask);
+extern void restore_fpregs_from_fpstate(struct fpstate *fpstate, u64 mask);
 
 extern bool copy_fpstate_to_sigframe(void __user *buf, void __user *fp, int size);
 

arch/x86/kernel/fpu/context.h

@@ -74,7 +74,7 @@ static inline void fpregs_restore_userregs(void)
 		 */
 		mask = xfeatures_mask_restore_user() |
 			xfeatures_mask_supervisor();
-		restore_fpregs_from_fpstate(&fpu->state, mask);
+		restore_fpregs_from_fpstate(fpu->fpstate, mask);
 
 		fpregs_activate(fpu);
 		fpu->last_cpu = cpu;

arch/x86/kernel/fpu/core.c

@@ -129,7 +129,7 @@ void save_fpregs_to_fpstate(struct fpu *fpu)
 	frstor(&fpu->state.fsave);
 }
 
-void restore_fpregs_from_fpstate(union fpregs_state *fpstate, u64 mask)
+void restore_fpregs_from_fpstate(struct fpstate *fpstate, u64 mask)
 {
 	/*
 	 * AMD K7/K8 and later CPUs up to Zen don't save/restore
@@ -146,18 +146,18 @@ void restore_fpregs_from_fpstate(union fpregs_state *fpstate, u64 mask)
 	}
 
 	if (use_xsave()) {
-		os_xrstor(&fpstate->xsave, mask);
+		os_xrstor(&fpstate->regs.xsave, mask);
 	} else {
 		if (use_fxsr())
-			fxrstor(&fpstate->fxsave);
+			fxrstor(&fpstate->regs.fxsave);
 		else
-			frstor(&fpstate->fsave);
+			frstor(&fpstate->regs.fsave);
 	}
 }
 
 void fpu_reset_from_exception_fixup(void)
 {
-	restore_fpregs_from_fpstate(&init_fpstate.regs, xfeatures_mask_fpstate());
+	restore_fpregs_from_fpstate(&init_fpstate, xfeatures_mask_fpstate());
 }
 
 #if IS_ENABLED(CONFIG_KVM)
@@ -176,7 +176,7 @@ void fpu_swap_kvm_fpu(struct fpu *save, struct fpu *rstor, u64 restore_mask)
 
 	if (rstor) {
 		restore_mask &= xfeatures_mask_fpstate();
-		restore_fpregs_from_fpstate(&rstor->state, restore_mask);
+		restore_fpregs_from_fpstate(rstor->fpstate, restore_mask);
 	}
 
 	fpregs_mark_activate();