[SIMD]: FPU register save/restore is also required on 5.0 kernels~

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
Acked-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>

debian/patches/0010-SIMD-FPU-register-save-restore-is-also-required-on-5.patch

@@ -0,0 +1,57 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Thomas Lamprecht <t.lamprecht@proxmox.com>
+Date: Wed, 25 Sep 2019 10:48:48 +0200
+Subject: [PATCH] [SIMD]: FPU register save/restore is also required on 5.0
+ kernels
+
+NOTE: the kernel needs to have the copy_kernel_to_xregs_err,
+copy_kernel_to_fxregs_err and copy_kernel_to_fregs_err funcitons
+backported for this to work.
+
+Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
+---
+ include/linux/simd_x86.h | 11 +----------
+ 1 file changed, 1 insertion(+), 10 deletions(-)
+
+diff --git a/include/linux/simd_x86.h b/include/linux/simd_x86.h
+index 5f243e0cc..aac63d964 100644
+--- a/include/linux/simd_x86.h
++++ b/include/linux/simd_x86.h
+@@ -179,7 +179,6 @@ kfpu_begin(void)
+ 	preempt_disable();
+ 	local_irq_disable();
+ 
+-#if defined(HAVE_KERNEL_TIF_NEED_FPU_LOAD)
+ 	/*
+ 	 * The current FPU registers need to be preserved by kfpu_begin()
+ 	 * and restored by kfpu_end().  This is required because we can
+@@ -188,20 +187,13 @@ kfpu_begin(void)
+ 	 * context switch.
+ 	 */
+ 	copy_fpregs_to_fpstate(&current->thread.fpu);
+-#elif defined(HAVE_KERNEL_FPU_INITIALIZED)
+-	/*
+-	 * There is no need to preserve and restore the FPU registers.
+-	 * They will always be restored from the task's stored FPU state
+-	 * when switching contexts.
+-	 */
++
+ 	WARN_ON_ONCE(current->thread.fpu.initialized == 0);
+-#endif
+ }
+ 
+ static inline void
+ kfpu_end(void)
+ {
+-#if defined(HAVE_KERNEL_TIF_NEED_FPU_LOAD)
+ 	union fpregs_state *state = &current->thread.fpu.state;
+ 	int error;
+ 
+@@ -213,7 +205,6 @@ kfpu_end(void)
+ 		error = copy_kernel_to_fregs_err(&state->fsave);
+ 	}
+ 	WARN_ON_ONCE(error);
+-#endif
+ 
+ 	local_irq_enable();
+ 	preempt_enable();

debian/patches/series

@@ -7,3 +7,4 @@
 0007-Fix-race-in-parallel-mount-s-thread-dispatching-algo.patch
 0008-Linux-5.0-compat-SIMD-compatibility.patch
 0009-Fix-CONFIG_X86_DEBUG_FPU-build-failure.patch
+0010-SIMD-FPU-register-save-restore-is-also-required-on-5.patch